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Slam Life Assessment Method for Closures Durability | The Slam Life Assessment Method (SLAM) is a CAE solution that predicts the durability of automotive closures subject to a repetitive slamming load. Moreover, SLAM is a fully automated program that integrates several software and CAE analyses into a single turnkey solution. SLAM employs the physics of the slam event to succeed where prior analysis methods fail. Standard CAE analyses such as inertia relief, normal modes, and forced loading response cannot capture the physics of the dynamic stress states that occur during a durability slam event. Furthermore, SLAM produces insight into the behavior of the door system that cannot be gained through testing. We have shown that it is possible to predict the performance of a door subject to a slam-closed event with 80-90% reliability. This method has been realized via motivation to solve numerous door panel cracking issues associated with preliminary door designs. Correlation of SLAM methods with physical tests led to the ability to ?쐖irtually??slam and redesign doors before prototypes were made. To date, SLAM is used mainly on door systems, however, it is easily extended to hood, decklid, and liftgate systems. SLAM simulations have proven their usefulness on aluminum hood ?쐔ea cup??designs. SLAM saves product development time and money by reducing the number of prototypes needed to evaluate a design proposal. It allows evaluation of more design alternatives, reduces weight, and results in fewer production level failures. As the automotive industry moves towards a 10-year durability life, the testing times and number of samples continues to increase in order to meet these tougher requirements. Door slam testing can take several months to schedule and complete, whereas, SLAM can reduce this process to a few hours. The net result is a benefit to the customer in the form of a structurally optimized closure assembly that has no durability problems. |
Ultralight Intercostal Automatic Fastening System | A high level directive is in place at the St. Louis facility to increase the use of automation in our assembly processes. Likewise, the C-17 program has implemented a series of cost reduction initiatives. In line with these initiatives we have been implementing automatic fastening equipment into a variety of non-traditional applications. The C-17 Cargo Door Intercostals can easily be described as ?쐍on-traditional??and represent unique challenges for automatic fastening. The concept for The Intercostal Riveter uses proven drill and riveting techniques. However, it has miniaturized components and will be utilized like a portable power tool. Manipulated by a single operator, it will be maneuvered around and throughout the C-17 Cargo Door Assembly Jig. It is ultra-lightweight and will have a C-Frame constructed from carbon-epoxy composite material. |
A New Component Test Methodology Concept for Side Impact Simulation | This paper describes the development of a new component test methodology concept for simulating NHTSA side impact, to evaluate the performance of door subsystems, trim panels and possible safety countermeasures (foam padding, side airbags, etc.). The concept was developed using MADYMO software and the model was validated with a DOT-SID dummy. Moreover, this method is not restricted to NHTSA side impact, but can be also be used for simulating the European procedure, with some modifications. This method uses a combination of HYGE and VIA decelerator to achieve the desired door velocity profile from onset of crash event until door-dummy separation, and also takes into account the various other factors such as the door/B pillar-dummy contact velocity, door compliance, shape of intruding side structure, seat-to-door interaction and initial door-dummy distance. This method is capable of reproducing the characteristic ?쐂ouble-peak??of the door velocity profile and, can be used for side airbag evaluation, by simulating the close-in velocity and distance between the side structure and dummy. In this approach, the door velocity profile is simulated in four phases: In the first phase, a pre-crushed door mounted on a ?쁃oor sled??(at approximately the same distance from the dummy as in a car), is accelerated by the HYGE until it impacts the stationary dummy, to generate the first peak. In the second phase, from the onset of dummy contact, the door sled is decelerated by a honeycomb block (mounted on another ?쁁ase sled??, simulating the first ride-down of the velocity profile. During this phase, the HYGE is dormant. In the third phase, the HYGE accelerates both the Door and Base sleds together to simulate the second peak. In the fourth phase, the Door and Base sleds are decelerated until door-dummy separation by means of a VIA decelerator system, thus simulating the entire door velocity profile from start of crash event until the door and dummy separate. In conclusion, the MADYMO model demonstrates the feasibility of the concept, pending experimental prove-out on the sled. |
Thermal Qualification of the Sciamachy Passive Cryogenic Cooler | This paper describes the design and qualification of this SCIAMACHY Radiant Cooler and focuses on the methods and results of the thermal balance and thermal verification test of the Radiator Reflector Unit flight model, performed late summer 1998. A new type of temperature control has been used that proved to increase speed, simplicity and accuracy of the test itself as well as the evaluation afterwards. The RRU TB/TV test was successful in gathering all significant thermal parameters. After refurbishment of the cooler door and a requalification test of its transient performance all cooler parameters are acceptable and its thermal performance is within specification. |
Accuracy Determination of Sheet Metal Forming Simulation Using One-Step Code | The use of numerical simulation in the design of stamped components has become common industrial practice. Inverse one-step codes are among the fastest to provide answers but, unlike incremental codes, they need an additional verification phase. Given this context, IVECO has conducted experimental testing work on the plastic deformations measured on two industrial components obtained by means of sheet steel stamping. The two components, one with structural functions (sliding door upper reinforcement) and the other one with esthetic functions (rear left door skin), have been selected as representative of the various feasibility and process issues connected with sheet metal drawing. |
Experimental and Computational Study of Vehicle Surface Contamination on a Generic Bluff Body | This paper focuses on methods used to model vehicle surface contamination arising as a result of rear wake aerodynamics. Besides being unsightly, contamination, such as self-soiling from rear tyre spray, can degrade the performance of lighting, rear view cameras and obstruct visibility through windows. In order to accurately predict likely contamination patterns, it is necessary to consider the aerodynamics and multiphase spray processes together. This paper presents an experimental and numerical (CFD) investigation of the phenomenon. The experimental study investigates contamination with controlled conditions in a wind tunnel using a generic bluff body (the Windsor model.) Contamination is represented by a water spray located beneath the rear of the vehicle. The aim is to investigate the fundamentals of contamination in a case where both flow field and contamination patterns can be measured, and also to provide validation of modelling techniques in a case where flow and spray conditions are known. CFD results were obtained using both steady RANS and unsteady URANS solvers, combined with particle tracking methods. Steady RANS does not capture the wake structures accurately and this affects the contamination prediction. URANS is able to recover the large-scale wake unsteadiness seen in the experimental data, but the difference between the experimental and computational contamination distributions is still notable. The CFD is also able to provide further insight by showing the behaviour of particles of different sizes. Large particles are found to take on a ballistic trajectory and penetrate the wake. In contrast, small particles are shown to be less likely to become entrained into the wake. |
PSV Emergency Exits: Passenger Behaviour and Exit Design | This study tested the speed and ease with which individual passengers could open and use the emergency exits currently provided on buses and coaches. The survey found that passengers believed that certain emergency exits, such as doors and hinged windows, would be easy to use in an emergency, that they knew how to use them and that instructions would help if they were uncertain. Twenty exit types were then tested with passengers, including emergency doors, ?쁟ontinental??doors, roof hatches, hinged windows, breakglass windows and the emergency operation of service doors. It was found that passengers' expectations were generally not being met. Inappropriate handle design, location, feedback, anti-tamper cover guards and unclear instructions were found to result in significant delays in evacuation. The study recommends design improvements in these areas together with a consistent approach to the design and provision of emergency exit signage, conspicuity and instructions. It also recommends that high level doors are equipped with steps and that if window exits are to be retained these should be hinged rather than break-glass as the latter have severe disadvantages. |
Safety and Security Considerations of New Closure Systems | A closure system for automotive security and driver comfort has been developed. The system combines a passive entry system and an electronic door latch system. The passive entry system utilises a single chip transponder for vehicle immobilisation, passive entry and remote control functionality. The form factor free transponder enables the integration into a key fob or a smart card. The system can be activated by either pulling the door handle or by using a push button transponder. Due to the inductive coupling between the transponder and the vehicle mounted antennas, the vehicle door or trunk opens on successful verification as if there were no locks. Additionally, inside the vehicle, the transponder can be used as a far range immobiliser. The electronic door latch system utilises electronically controlled latches. Symmetrical housing of the electronic latch (E-latch) and the absence of a mechanical connection to the actuators enable the latch to be used not only for the left and right side doors but also for trunk applications. The locking pawl of the E-latch is controlled by an electric motor and the functionality is entirely software dependent. |
Design and Development of a Generic Door Hardware Module Concept | This paper documents the design methodology, part performance, and economic considerations for a generic hardware module applied to a front passenger-car door. Engineering thermoplastics (ETPs), widely used in automotive applications for their excellent mechanical performance, design flexibility, and parts integration, can also help advance the development of modular door-hardware systems. Implementation of these hardware carriers is being driven by pressures to increase manufacturing efficiencies, reduce mass, lower part-count numbers, decrease warranty issues, and cut overall systems costs. In this case, a joint team from GE Plastics, Magna-Atoma International/Dortec, and Excel Automotive Systems assessed the opportunity for using a thermoplastic door hardware module in a current mid-size production vehicle. Finite-element analysis showed that the thermoplastic module under study withstood the inertial load of the door being slammed shut at low, room, and elevated temperatures. |
Sound Quality of Impulsive Noises: An Applied Study of Automotive Door Closing Sounds | This paper discusses four general attributes which quantify the character of an impulsive sound event. These attributes include the time duration, amplitude and frequency content of the impulsive noise. A three dimensional plot relating time, frequency and amplitude have been developed for the presentation of the measured data. This format allows graphic illustration of the noise event, providing fast interpretation and communication of the measured sound. Application of this methodology to the sound of an automotive door closing event is presented here. Representative door closing sound events are analyzed, with correlation presented between the attributes above to dynamic events of the physical hardware within the door and vehicle systems. Modifications of the door-in-white, internal door hardware, seal systems and additional content are investigated for their effect on the sound quality of the door closing event. Finally, recommended values for these attributes are presented. In general, a pleasing door closing sound event will be developed if the stated values are obtained. Furthermore, general insight is also provided that would indicate how directional changes to these attributes may allow customization of the door closing sound event to achieve a desired sound quality. |
Sound Transmission Analysis of Vehicle Door Sealing System | A finite element-based acoustic-structure interaction analysis tool has been developed to determine the noise transmission loss characteristics of door seal systems. This tool has been applied to determine the effects of the individual parameters, such as seal material density, seal constitutive model, separation distance between seal layers, external cavity shape, and seal prestress field, on noise transmission characteristics. Our findings indicate that the external and internal cavity shapes, seal material density, and deformed seal geometry are the key factors affecting the noise transmission through seal system. Increasing seal material density decreases the resonance frequencies and increases the overall sound transmission loss. Changing the separation distance between seal layers changes the sound transmission characteristics without changing the compression load deflection behavior of the seal system. Moving the resonant frequencies to desired frequency regions, we can reduce seal system contribution to the vehicle interior noise level. The nature of the resonance frequencies of this coupled system have also been determined. This analysis tool was applied to determine the noise transmission characteristics of a vehicle door seal system, and the seal system contribution to the vehicle interior noise level. |
A Field Evaluation of the S-1 Pedestrian Guard: Transit and Shuttle Bus Applications | The need to reduce the injury to pedestrians that are run over or pinned beneath a bus is an ongoing concern for transit authorities and other operators. Occasionally, a pedestrian will be run over by the right rear wheel while exiting the rear door. This accident occurs in various scenarios such as when people exit the bus and become entangled in the door grab bars, or when they fall between the curb and the bus while it approaches or departs. With all scenarios, the S-1 Gard acts similar to a cow catcher, pushing the fallen pedestrian out and away from the rear tire. This paper will: outline various incident scenarios, evaluate the S-1 Gard's performance in a city environment, review installation of the guard as well as its maintenance requirements. The purpose of this paper is to bring to the attention of transit authorities and shuttle operators the overall value of this device. |
Performance Improvement in Leak Noise Reduction | One of the most important quality required for luxury vehicle is quieter cabin. Up to the present, for its improvement, various countermeasures have been carried out. For example, additional weather-strips were added around door for noise reduction and quieter engines were developed. But, with all these performance improvements, local leak noise becomes major remaining. In order to achieve quieter vehicles, the noise has to be stopped by every possible means. In this report, performance improvement in noise reduction is studied by connecting both ends of inner belt weather-strip and glass run. And the influence of connecting portion for glass sliding durability is evaluated. |
Development and Application of Laser Scanning Method to Automotive Component Manufacturing | The majority of current measurement methods in the manufacturing arena use coordinate measurement machines (CMM) and special gages with fixtures. The use of CMM's for offline metrology is prevalent throughout the manufacturing community, however the time required to inspect a part is sometimes prohibitive. The special low cost gages open the door to operator error and in most cases it cannot capture more than few measurements at once. Automated laser scanning equipment was selected to evaluate the possibility of reduced inspection as well as for global quality feedback. Although many laser scanning methods and applications are available in the market today, very little is understood with regards to its capabilities and its use in the automotive manufacturing arena particularly for the inspection of large parts. This paper explores the methodology one can use to apply such devices to improve upon current quality methods for both large and small automotive parts. |
Surface Finishing Compression Molding (SFC): A Comparative Cost Study for Paint vs. Paint Film Finishing | New technologies are required to sustain an industrial society. Their fragile early life must be nurtured by the risk takers in the beginning stages of development for new technologies to survive. In the automotive industry, new technologies that focus on reduced cost, reduced pollution and/or reduced energy consumption are being carefully evaluated. The Valyi Surface Finishing Compression Molding (SFC Molding짰) process addresses all three issues1,2. This process is in the early stage of development. Large, thermoplastic, exterior panels (door/hood size) have been made on commercial equipment to demonstrate general feasibility but there are no ?쐓how me??production parts for the risk averse. In the absence of production case studies, an investor (licensee candidate) must examine the potential benefits of the process relative to the state-of-the-art technology. This paper examines an approximation of the cost to produce a major exterior panel (roof) by SFC molding versus conventional steel and paint. |
A Study of Occupant Ejection Mitigation During Rollovers for Front Row Occupants | As a part of its ejection mitigation research, the National Highway Traffic Safety Administration (NHTSA) has proposed a linear impact test that uses a featureless head-form to impact a vehicle's side windows' daylight opening at various positions. The test measures the excursion of the head-form beyond the plane of the window glazing. The intention is to evaluate the ability of a vehicle's ejection mitigation countermeasures, such as the curtain airbag or other vehicle features, to manage the impactor energy and limit excursion. However, at this time NHTSA has not yet established the performance criteria for the excursion. Additionally, there is no clear agreement on the energy level to be used for ejection mitigation testing. The agency has considered three energy levels for the head-form impact: 178, 280, and 400 Joules [ 9 ]. This paper discusses the results from computer modeling used to study an ejection representative energy level that can be employed for evaluating ejection mitigation systems. Additionally, the authors will present a parameter study in which the stiffness of a curtain airbag has been optimized considering both the NHTSA's ejection mitigation research test method as well as side impact performance. |
A FE Based Procedure for Optimal Design of Damping Package, with Presence of the Insulation Trim | Typically, in the automotive industry, the design of the body damping treatment package with respect to NVH targets is carried out in such a way to achieve panel mobility targets, within given weight and cost constraints. Vibration mobility reduction can be efficiently achieved thanks to dedicated CAE FE tools, which can take into account the properties of damping composites, and also, which can provide their optimal location on the body structure, for a minimal added mass and a maximized efficiency. This need has led to the development of different numerical design and optimization strategies, all based on the modeling of the damping composites by mean of equivalent shell representations, which is a versatile solution for the full vehicle simulation with various damping layouts. However, these approaches, which can estimate correctly the beneficial vibration effect of damping pads application on the vehicle body, address the body NVH target with no consideration of the impact that the presence of the insulation on body panels can have on the final vibration result. On the other hand, the efforts carried out in the last years for FE implementations of Biot's system of equations have led to simulation methods at vehicle level, which can take into consideration the dynamical behaviour of porous materials and which allow including in an efficient and flexible way sound package parts into vehicle FE models used for NVH analyses. This paper presents a FE-based procedure, thanks to which it is possible to design the optimal damping lay-out with respect of panel mobility targets, while taking into account the presence of the insulation part on body panels. In a first section a design methodology for damping layout is presented. This method, that is completely integrated in Nastran, is able to provides the ranking and vibration pattern of the vehicle panels with highest mobility for a given frequency range and set of loads in order to maximize the effect of the damping treatment. Then the problem of the influence of the acoustic treatment on the panel vibrations has been addressed. The proposed solution is represented by an implementation in MSC/Nastran of the Biot-Allard theory for porous media. This procedure allows a smart coupling of structural FE model with a FE boundary representation of the acoustic part. In the last section, the benefits of the joined use of the two techniques are highlighted by mean of their application on a simple test case as well as on a full-vehicle. |
Electromagnetic Compatibility of Conductive Heat Reflecting Automotive Windows | One of the challenges of automotive designs which utilize heat reflecting glazing is the conductivity of the reflective coating. Significant attenuation of electromagnetic energy occurs when devices which send or receive signal through the glazing are mounted on or very near heat reflecting windows. A number of methods are available to maintain electromagnetic compatibility and the function of these and other devices in the passenger compartment which communicate with devices outside of the vehicle. |
Helmholtz Resonators Acting as Sound Source in Automotive Aeroacoustics | Helmholtz-resonators are discussed in technical acoustics normally in conjunction with attenuation of sound, not with amplification or even production of sound. On the other hand everybody knows the sound produced by a bottle, when someone blows over the orifice. During the investigation of the sound produced in body gaps it was found that the underlying flow physics are closely related to the Helmholtz-resonator. But different from the typical Helmholtz-resonator generated noise ??as for example the blown bottle or, from the automotive world, the sun roof buffeting ??there is no fluid resonance involved in the process. For body gaps the random pressure fluctuation of the turbulent boundary layer is sufficient to excite the acoustic resonance in the cavity. The sound generation is characterized by a continuous rise in sound pressure level with increasing velocity, the rise is proportional to U with varying exponents. It will be shown that the fluid resonance is shifted to much higher velocities than one would expect from Rossiters feedback model. This is the reason that it can not be found in body gaps. Nevertheless even without fluid resonance the body gaps represent the most important noise source for modern automobiles. A vehicle is much more silent in the interior if all gaps are closed as if, for example, the wing mirrors are removed and the A-Pillar-radius is doubled. The shift of the fluid resonance to higher velocities mentioned above is associated with a reduced transport velocity for vortices over small orifices. Experimental evidence will be shown that this transport velocity is dramatically reduced for orifices buried under a thick turbulent boundary layer. |
Scaling Laws in Automotive Aeroacoustics | Scaling laws - for example the variation of sound pressure with wind speed - are a key to the physical understanding of aeroacoustic phenomena. Aeroacoustics in Automotive applications differs from other fields of aeroacoustics: It is limited to low Mach numbers, the flow field is dominated by separated flows and the radiation into the far field is typically not of primary interest. On the other hand there are of course many common problems and findings shared with other fields in aeroacoustics. Therefore it is important to identify common areas with other, probably more advanced directions in aeroacoustics. But this has to be done without forgetting the practical demands of automotive application. Main sources for interior wind noise in vehicles are leakage noise, cavity noise and the noise generated by separated flows at the outer surface. All three of these noise sources will be investigated in this paper. Of special interest will be the dependence on the wind velocity. It will be shown that three different exponents (U4, U6 and U8), corresponding in aeroacoustics to monopole, dipole and quadrupole noise, can be present in a single source. |
Time - Frequency Analysis Techniques Applied to Automotive Noise and Vibration Signals | Automotive stationary noise and vibration signals are normally analyzed using Fourier methods. However, many noise and vibration signals are non-stationary (transient or time-varying). In those situations, the time characteristics of the signals can be lost using standard Fourier methods. Lately, time-frequency (TF) analysis methods have become more popular and are applied in many different areas of NVH (Noise, Vibration, and Harshness) in order to preserve the time-frequency information. The objective of this paper is to present some of the different time-frequency analysis tools, such as the Short Time Fourier transform (spectrogram), the Gabor Transform, the Wavelet transforms (scalograms), and the Wigner-Ville Distribution. Examples of application of these techniques to automotive non-stationary noise and vibration signals are presented. |
Noise Source Localization on Washing Machines by Conformal Array Technique and Near Field Acoustic Holography | The acoustic emission of a washing machine has been deeply studied by comparing three different techniques, which are: - conventional acoustic intensity, - planar near-field acoustic holography and - conformal array technique based on the Helmotz Equations Least Squares method. These techniques have been used to measure the front of a washing machine, i.e. the more critical side from the acoustic comfort point of view in the working environment. The acoustic intensity measurement has been taken as reference for the comparison of the two other techniques. The sound intensity probe has been scanned over a grid of several discrete positions and the acoustic intensity and pressure on the measurement plane have been determined. For both the conformal and planar near-field acoustic holography techniques an antenna of 30 microphones has been employed scanning over several positions in order to cover the entire washing machine front with a spatial resolution of 2.5 cm (maximum frequency 13720 Hz). Advantages and limitations of the noise source location techniques have been examined thoroughly. |
Experimental Investigation into Friction Induced Noise of Automotive Wiper System | The test is carried out to examine the vehicle interior noise, windscreen vibration and wiper blade vibration induced by wiper friction, under the combination conditions with various wiping speed and windscreen wetness. The noise's time-frequency characteristics, influence factors and noise source were approached by means of time domain, frequency domain and time-frequency domain analysis. The results indicated that wiper noise can be classified into reversal noise and wiping noise. The reversal noise is characterized by impulsive noise, and wiping noise is featured by wide-band noise with harmonic components. The nature of both types of noises is strongly affected by the windshield wetness; however, it is far less affected by the wiping speed. The wiping noise is mainly resulted from lateral and vertical vibration of wiper blades. Nevertheless, the wiping noises under wet and half-dry conditions are respectively caused by the wiper blade vibration of driver side and that of co-driver side. |
Aeroacoustics Predictions of Automotive HVAC Systems | Acoustics comfort is a key point for the ground transportation market and in particular in the automotive area. A significant contributor to the noise levels in the cabin in the range 200Hz to 3000Hz is the HVAC (Heating, Ventilating, and Air Conditioning) system, consisting of sub-systems such as the air intake duct, thermal mixing unit, blower, ducts, and outlet vents. The noise produced by an HVAC system is mainly due to aeroacoustics mechanisms related to the flow fluctuations induced by the blower rotation. The structure borne noise related to the surface induced vibrations and to the noise transmission through the dash or plastic panels may also contribute but is not considered in this study. This study presents a digital approach for HVAC aeroacoustics noise predictions related to the ducts and outlet vents. In order to validate the numerical method flow and acoustics measurements are performed on production HVAC systems placed in an anechoic room. The flow is generated using a fan located outside the room and a muffler is used to create a silent incoming flow. The dependency between the volume flow rate and the noise levels is investigated together with the effect of the outlet vents on the aeroacoustics mechanisms. The aeroacoustics simulations are performed using a time explicit, unsteady and compressible method in which flow and acoustics are calculated at the same time. The numerical results are compared to the experimental ones and certain analyses, not easily accessible through measurements, are provided. In particular, duct mode behavior and the influence of the outlet vents on the acoustic radiation are highlighted. The numerical predictions are shown to correlate reasonably well to the test measurements, and the developed method can be used during the vehicle development process to evaluate and optimize the aeroacoustics performance of the HVAC system. |
Attenuation of Vehicle Noise using Different Trunk Insulation Systems | Attenuation of noise from the rear of a vehicle was evaluated for different trunk insulation systems using a combination of poro-elastic material modeling and a full vehicle SEA model. The model considered the interaction between the trunk and the passenger cabin. The sound absorption coefficients and acoustic impedance for each of the material systems used in the trunk were measured and the poro-elastic Biot properties were calculated to define the acoustic treatments in the SEA model. Several levels of acoustical treatment for the trunk were studied ranging from a trunk with no decorative liner to a trunk with a liner and maximum acoustical treatment. The results show the contribution of the trunk material in reducing cabin noise for different levels of noise originating at the rear of the vehicle. These results demonstrate the value of combining poro-elastic material modeling and SEA models for selecting efficient material systems early in a vehicle design. They also highlight vehicle designs that require acoustically tuned trunk material to prevent compromises in the overall NVH performance. |
Vehicle Noise, Vibration, and Sound Quality | This book gives readers a working knowledge of vehicle vibration, noise, and sound quality. The knowledge it imparts can be applied to analyze real-world problems and devise solutions that reduce vibration, control noise, and improve sound quality in all vehicles?봥round, aerospace, rail, and marine. Also described and illustrated are fundamental principles, analytical formulations, design approaches, and testing techniques. Whole vehicle systems are discussed, as are individual components. The latest measurement and computation tools are presented to help readers with vehicle noise, vibration, and sound quality issues. The book opens with a presentation of the fundamentals of vibrations and basic acoustic concepts, as well as how to analyze, test, and control noise and vibrations. The next 2 chapters delve into noise and vibrations that emanate from powertrains, bodies, and chassis. The book finishes with an in-depth discussion on evaluating noise, vibration, and sound quality, giving readers a solid grounding in the fundamentals of the subject, as well as information they can apply to situations in their day-to-day work. This book is intended for: ?줦pper-level undergraduate and graduate students of vehicle engineering ?줡racticing engineers ?줔esigners ?줣esearchers ?줕ducators |
International Space Station United States Operational Segment Crew Quarters On-orbit vs. Design Performance Comparison | The International Space Station (ISS) United States Operational Segment (USOS) received the first two permanent ISS Crew Quarters (CQ) on Utility Logistics Flight Two (ULF2) in November 2008. As many as four CQs can be installed in the Node 2 element to increase the ISS crew member size to six. The CQs provide crew members with private space that has enhanced acoustic noise mitigation, integrated radiation-reduction material, communication equipment, redundant electrical systems, and redundant caution and warning systems. The rack-sized CQ system has multiple crew member restraints, adjustable lighting, controllable ventilation, and interfaces that allow each crew member to personalize his or her CQ workspace. The deployment and initial operational checkout during integration of the ISS CQ to Node 2 is described in this paper. On-orbit to original design performance is also compared for the following key operational parameters: interior acoustic performance, airflow rate, temperature rise, and crew member feedback on provisioning and re-straint layout. |
International Space Station USOS Crew Quarters Development | The International Space Station (ISS) United States Operational Segment (USOS) currently provides a Temporary Sleep Station (TeSS) as crew quarters for one crewmember in the Laboratory Module. The Russian Segment provides permanent crew quarters (Kayutas) for two crewmembers in the Service Module. The TeSS provides limited electrical, communication, and ventilation functionality. A new permanent rack sized USOS ISS Crew Quarters (CQ) is being developed. Up to four CQs can be installed into the Node 2 element to increase the ISS crewmember size to six. The new CQs will provide private crewmember space with enhanced acoustic noise mitigation, integrated radiation reduction material, controllable airflow, communication equipment, redundant electrical systems, and redundant caution and warning systems. The rack sized CQ is a system with multiple crewmember restraints, adjustable lighting, controllable ventilation, and interfaces that allow each crewmember to personalize their CQ workspace. Providing an acoustically quiet and visually isolated environment, while ensuring crewmember safety, is critical for crewmember rest and comfort to enable long term crewmember performance. The numerous human factor, engineering, and program considerations during the concept, design, and prototyping are outlined in the paper. |
Development of an Automatic Windshield Defogging System | The development of an automatic defogging system using an accurate windshield humidity sensor and the existing HVAC hardware is described herein. Improved cabin temperature control and forward visibility for the driver was achieved using a sophisticated automatic defogging strategy integrated into the Automatic Temperature Control microprocessor. Laboratory tests were conducted under various weather conditions and test modes using a climate wind tunnel and field tests were conducted in North America The automatic defogging system worked well in all cases |
Modelling of the Combustion Influence on Diesel Engines Noise Level for MAR-I Applications | Since January 2015, Brazil put into effect the PROCONVE/MAR-I (Programa de Controle da Polui챌찾o do Ar por Ve챠culos Automotores para M찼quinas Agr챠colas e Rodovi찼rias), which drives the country to the same stringent emissions standards used by the American (EPA Tier III) and European (Euro Stage IIIA) markets. As a result, new pollutants and noise emissions levels were established and although very important for the society health, this issue (noise) has been left behind in this kind of vehicle. Therefore, an extremely challenging target has to be pursued, regarding the current political and economical situation and also the resources availability to achieve those targets. The present work investigates the influence of the noise generated during the combustion process in MAR-I engines by modeling the calibration parameters, which allows to identify the contribution of the combustion in the global engine noise and possibly reducing it and hence the product reckoned costs. |
Vibroacoustic Transfer Function Study in the Design of Vehicle Suspensions | Noise, vibration and Harshness in the automotive industry became important mainly because the development of modern automobiles and the increased of customer demands for quieter vehicles and with comfortable vibration levels. The sources of vibration and noise inside the vehicle are caused by the engine, tires, transmission systems, suspension, air conditioning, among others. In this work, vibroacoustic transfer function is obtained to analyze the internal noise in two sport utility vehicle with distinctive silhouette. Furthermore, it was analyzed the influence of elastomeric bushings rigidity of the damper in reducing internal noise and vibration and the effect of adding mass in some framework positions for attenuation of vibration peaks due to structural resonance. In the physical tests, it was used accelerometers installed on top of the fixing bracket of the damper and in specific positions in the vehicle body, a microphone installed on the right ear position of the passenger of the right rear seat and an impact hammer used to excite the system to obtain the vibroacoustic transfer function. Temporal measurements are carried out with vehicles on irregular track to a constant speed. The data are processed and analyzed in the frequency domain. The results show that the use of vibroacoustic transfer function is important for understanding and analysis of the noise within the vehicle cabin and that changes in the stiffness of the dampers bushings can reduce noise within the vehicle. Furthermore, the adding of mass to the structure was efficient to attenuate the vibration due to structural resonance. |
Practical Approaches for Detecting DoS Attacks on CAN Network | Some of the recent studies reveal that it is possible to access the in-vehicle networks and inject malicious messages to alter the behavior of the vehicle. Researchers have shown that, it is possible to hack a car?셲 communication network and remotely take control of brake, steering, power window systems, etc. Hence, it becomes inevitable to implement schemes that detect anomalies and prevent attacks on Controller Area Network (CAN). Our work explores the complete anomaly detection process for CAN. We cover the techniques followed, available tools and challenges at every stage. Beginning with what makes CAN protocol vulnerable, we discuss case studies about attacks on CAN with major focus on Denial of Service (DoS) attack. We analyze the pattern of normal CAN messages obtained from real vehicle, along with patterns of simulated attack data using different methods/tools. The work in this paper presents a statistical data analysis based machine learning algorithm with two approaches ?쐔ime-based??and ?쐌essage-based??to detect DoS attack on CAN bus. Comparative analysis of observations and accuracy results are highlighted. The average accuracy obtained for ?쐔ime-based??approach is 81% while that for ?쐌essage-based??is 80%. |
CFD/CAE Combinations in Open Cavity Noise Predictions for Real Vehicle Sunroof Buffeting | Though some practitioners consider the simulation process for sunroof and side window buffeting to be mature, there remain considerable uncertainties and inefficiencies as how in predictive methodologies to account for interior panel flexibility, vehicle structural stiffness, seals leakages and interior materials surface finish. Automotive OEMs and component suppliers rightly target flow simulation of open sunroofs and passenger windows with a view to reducing the severely uncomfortable low-frequency booming disturbance. The phenomenon is closely related to open cavity noise experienced also in other transportation sectors; for example in Aerospace, landing gear and store release cavities, and in Rail Transportation, cavities for HVAC intakes and the bogie environment. Recent studies published by the author demonstrate that the uncertainties can be correctly quantified by modeling. This publication defines a hierarchy of CFD/CAE based methods which overcome many of the a-posteriori tuning of simulations based on experiment, and considerably improve the predictive nature and efficiency of the simulation process. The methods range from fully deterministic simulations to phenomenological models requiring standard experimental pre-qualifications of the acoustical response of the system. The former involves CAE-coupling of CFD (Computational Fluid Dynamics) to CAA (Computational Aeroacoustics) and to CSM (Computational Structural Mechanics). The latter incorporates new correlation models published here for the first time. |
Dynamic Alert Generation Technology for Health & Usage Monitoring Systems | Current alert setting methodologies based on setting defect detection alert thresholds for vibration and other Health & Usage Monitoring Systems (HUMS) indicators have many limitations, principally there is necessarily a compromise to be achieved between the true negative and false positive diagnostic metrics. This is true for all alert detection techniques from fixed thresholds through to Support Vector Machines. In this paper we describe techniques, validated using helicopter HUMS data, which do not invoke this compromise and independently minimise both the true negative and false positive rates. This paper will also demonstrate how the alert processing can be made more robust and overcome the problems introduced by HUMS data being both non-stationary, non-ergodic i.e. characteristics that change both with time and from platform to platform. Two techniques utilised in the CFAR-Autotrend proprietary alert detection technology are described; a) The Constant False Alarm Rate technique for setting thresholds based on signal amplitude and detecting level changes b) The Box- Car technique for the automatic detection of local trends. These techniques produce alerts that are based on a significant change in local, not global, conditions in the data stream and are not based on an a priori model of the statistics of the signal. The performance of these techniques on real world HUMS generated vibration data and the engineering of the processes to automatically produce reliable and robust alerts are reviewed. False positives have been verified to be reduced to be less than 10% of true positives; a level where the diagnostics process becomes robust. The sensitivity to defects is improved to a level where the true negative rate has been reduced to a level where the diagnostic processes can be relied on and the prognostic interval becomes reliable. The consequential impact of this level of performance on HUMS dynamic alert processing is assessed. The automation of alert processing breaks the link between the number of aircraft fitted with HUMS and the manpower required to process the data. More importantly it will permit the scarce resource of HUMS specialists trained to diagnose defects to be concentrated on that task, not dissipated processing false alerts. For the future the Remaining Useful Life (RUL) realised from the increased sensitivity of the technique is at a magnitude where the benefits promised by Condition Based Maintenance can become a reality. |
Direct Aeroacoustics Predictions of Automotive HVAC Systems based on Lattice Boltzmann Method | The demand for low noise level in vehicle cabin continues to rise lately. In particular, noise generated by eco-friendly cars such as hybrid and electric ones tends to become lower and lower. In this market environment, the noise contributions caused by HVAC systems are also increasing. Therefore, it becomes increasingly important to accurately predict noise generated by HVAC systems and analyze the noise sources and resolve the noise issue. In this study, direct acoustics prediction approach based on Lattice Boltzmann Method is applied to predict the flow-induced noise from HVAC systems including blower and ducts and find noise sources. In order to validate the simulation result, acoustics measurements are performed on HVAC systems in an anechoic room and the results are compared to each other. A new technique is applied to finding a noise source for a specific frequency and shows improved noise level through modifying the geometry related to noise sources detected by the simulation. |
Comprehensive Hybrid Stiff Insulators Family: The Chips Urethane Contribution | The lightweighting research on noise treatments since years tends to prove the efficiency of the combination of good insulation with steep insulation slopes with broadband absorption, even in the context of bad passthroughs management implying strong leakages. The real issue lies more in the industrial capacity to adapt the barrier mass per unit area to the acoustic target from low to high segment or from low petrol to high diesel sources, while remaining easy to manipulate. The hybrid stiff insulator family can realize this easily with hard felts barriers backfoamed weighting from 800 g/m2 to 2000 g/m2 typically with compressions below 10 mm. Above these equivalent barrier weights and traditional compressions of 7 mm for example, the high density of the felts begins to destroy the open porosity and thus the absorption properties (insulation works anyway here, whenever vibration modes do not appear due to too high stiffness??. The felt costs begin to be critical for these intermediate weights above 2000 g/m2 as well. From 2000 g/m2 up to 3000 g/m2 or 3500 g/m2 equivalent barriers, the use of a traditional intermediate heavy layer is still not relevant from a process and cost point of view (ABA - Absorber/Barrier/Absorber systems). An original way to circumvent the issue consists in using a double porosity material like compressed chips urethane bound with bicomponent thin fibers. Airflow resistivities and porosities remain high while reasonable even at high compressions and thus deliver very good absorption, while being stiff enough to allow mass-spring like insulation slopes, as well as not too stiff in order to avoid bad modal resonances. The acoustic performance of this unconventional hybrid stiff insulator solution will be discussed with poro-elastic finite element modeling compared to measurements and to other hybrid stiff or ABA existing solutions of the same mass per unit area. |
A Subjective Evaluation Method for Sound Insulation of Vehicle Body in Reverberation Room and an Objective Prediction Model | A subjective evaluation method for the air-borne sound insulation of vehicle body in reverberation room is developed and the correlation between the subjective preference and objective noise reduction level (NRL) is investigated in this paper. The stationary vehicle's interior noise is recorded by using a digital artificial head under a given white noise excitation in the reverberation room, which demonstrates more credible than those in traditional road test methods. The recorded noises of six different vehicles are replayed and evaluated subjectively by 22 appraisers in a sound quality room. The paired comparison scoring method is employed and the check and statistic methods for the subjective scores are introduced. The subjective preference is introduced and calculated by the statistics and normalization of the effective scores, which can indicate an overall preference ranking of all the six vehicles numerically. Furthermore, an objective prediction model is established based on the correlation analyses and linear regressions. The subjective preference is proved to be attributed to the average NRL in 2k-5kHz frequency range only. The subjective evaluation method and the prediction model provide the guidance for the evaluation, prediction, target setting and optimization of the vehicle sound insulation. |
Improved Full Vehicle Finite Element Tire Road Noise Prediction | This paper presents the application to full vehicle finite element simulation of a steady state rolling tire/wheel/cavity finite element model developed in previous work and validated at the subsystem level. Its originality consists in presenting validation results not only for a wheel on a test bench, but for a full vehicle on the road. The excitation is based on measured road data. Two methods are considered: enforced displacement on the patch centerline and enforced displacement on a 2D patch mesh. Finally the importance of taking the rotation of the tire into account is highlighted. Numerical results and test track measurements are compared in the 20-300 Hz frequency range showing good agreement for wheel hub vibration as well as for acoustic pressure at the occupant?셲 ears. |
An Optimal Camera Monitor System (OCMS) to Improve the Visibility Performance and Safety of Commercial Vehicles and Trucks | Similar to Passenger Vehicles (PV), Commercial Vehicles and Trucks (ComVecT) use standard rearview mirrors to improve the visibility of the surrounding environment and facilitate a safer maneuvering of large vehicles. Standard rearview mirrors used in ComVecT are large and flat to cover outside areas as specified in theFMVSS 111 standard, or other requirements like ECE-R46. In addition, ComVecT are also equipped with optional mirrors with different Field of View (FoV), such as wide angle, look-down cross proximity, and front mirrors. These optional mirrors cover wider or specific areas around the vehicle which might not be possible otherwise with standard mirrors only. While these mirrors tend to enhance the visibility around the truck, they create undesirable blind zones to the driver. These blind zones can be gaps between the direct vision through the windows and indirect vision provided by the mirror. These can also be invisible areas occluded by the vehicle structure and hidden to the driver. Or, these can be obstructed areas concealed behind the mirror. In this paper, we demonstrate the feasibility and design of an Optimal Camera Monitor System (OCMS) to ideally eliminate the blind zones around the ComVecT with the goal of enhancing the driver visibility. We show that blind zones occur naturally due to the vehicle structure and large dimensions; number of mirrors used and mirror sizes. The optimal design takes into consideration not only the position, FoV, and resolution of the camera, but also the position, size, and resolution of the display inside the vehicle. The optimal design takes also into consideration human constraints like driver position and visual acuity of the human eye. |
Interior Noise Design of a Light Rail Vehicle Using Statistical Energy Analysis | This paper addresses the NVH design of a light rail vehicle whose maximum allowable interior SPL levels at certain speeds are regulated and may vary between countries, states, and cities. The objective of this study was to predict sound pressure levels (SPL) at several interior locations across a wide range of frequencies and estimate if the current design configuration will meet the noise level limits. Statistical Energy Analysis (SEA) was used to predict interior SPL and to understand and rank the various noise contribution paths and give a better understanding of the physics of transmission and what types of design changes are most effective to reduce the overall interior SPL to meet targets. A typical light rail vehicle is composed of a frame-like structure covered by lightweight panels and with interior panels that are increasingly made from composites, sandwich, laminated, or honeycomb materials or extruded panels. These lightweight structures made from materials that have previously been used primarily in aerospace applications have modal characteristics and transmission properties that require more advanced modeling than for simpler monolithic panels. Evaluation of the dominant noise transmission paths from the dominant sources allows sensitivity studies to evaluate which noise paths are the best candidates for improvement to overall vehicle NVH and which parts may be candidates for cost and weight reduction without significant degradation of the acoustic performance. This paper describes the motivation for this study and the details of the light rail vehicle construction. The SEA modeling approach is discussed, including the modeling of the structures and the main contributing sources. The contribution path ranking and the interior SPL predicted by the SEA model at several target locations are presented and compared to measured interior SPL data. Conclusions about the results and recommendations for future work are given. |
Application of Near-field Acoustic Holography to Low Temperature Engine Start-up Noise Issue Resolution | An issue of engine squealing in low temperature range (around ??5째C) right after start-up emerged for a significant number of vehicles in a vehicle program. The earlier effort had focused on typical common culprits such as the pulley-belt systems etc. However, much effort, by subjective listening and guestimating hardware replacement, yielded no fruitful results for more than a year. The application of near-field acoustic holography on top of the engine in a climate chamber quickly identified several noise source locations. Further noise source identification effort on top, front and left side of the engine pinpointed the top three noise source locations: the idler pulley and water pump on front, the air compressor on right side, and the air intake throttle on top. Then a series of experiments were subsequently conducted, leading to a conclusion that the idler pulley was the source of the issue. Finally, investigation of the pulley system confirmed that the insufficient lubricating capacity at low temperature was the root cause. By switching to a type of lower base oil viscosity lubricating grease characterized by lower rotation torque in cold temperature conditions, the issue was successfully resolved. |
MMLV: NVH Sound Package Development and Full Vehicle Testing | The Multi Material Lightweight Vehicle (MMLV) developed by Magna International and Ford Motor Company is a result of a US Department of Energy project DE-EE0005574. The project demonstrates the lightweighting potential of a five passenger sedan, while maintaining vehicle performance and occupant safety. Prototype vehicles were manufactured and limited full vehicle testing was conducted. The Mach-1 vehicle design, comprised of commercially available materials and production processes, achieved a 364 kg (23.5%) full vehicle mass reduction, enabling the application of a 1-liter 3-cylinder engine resulting in a significant environmental benefit and fuel reduction. This paper includes details associated with the noise, vibration and harshness (NVH) sound package design and testing. Lightweight design actions on radiating panels enclosing the vehicle cabin typically cause vehicle interior acoustic degradation due to the reduction of panel surface mass. To reduce this deficiency, an MMLV vehicle sound package development was conducted to improve NVH performance of MMLV with ultra-light weight sound package technologies. The project goal was to improve acoustical performance of MMLV by 2 dB without increasing the total sound package weight of ?쏺ehicle A??which is the baseline vehicle for MMLV. This paper presents the lightweight sound package development process for MMLV as well as the full vehicle NVH test results in the high frequency range of 200-10000 Hz. Floor damping treatment strategy and body NVH test results in the low frequency range are also discussed. Full vehicle SEA (Statistical Energy Analysis) simulations are used to evaluate and guide the design and development of MMLV sound package. The final MMLV vehicle sound package design improves the vehicle's engine noise reduction (ENR) by 3.3 dB and improves the front tire patch noise reduction (TPNR) by 1.2 dB without increasing the baseline sound package weight. |
A Virtual ECU and Its Application to Control System Analysis - Power Window System Demonstration | A virtual power window control system was built in order to look into and demonstrate applications of microcontroller models. A virtual ECU simulated microcontroller hardware operations. The microcontroller program, which was written in binary digital codes, was executed step-by-step as the virtual ECU simulation went on. Thus, production-ready codes of ECUs are of primary interest in this research. The mechanical system of the power window, the DC motor to lift the window glass, the H-bridge MOSFET drivers, and the current sensing circuit to detect window locking are also modeled. This means that the hardware system of the control system was precisely modeled in terms of mechanical and circuit components. By integrating these models into continuous and discrete co-simulation, the power window control system was analyzed in detail from the microscopic command execution of the microcontroller to the macroscopic motion of the window mechanism altogether. The minute microcontroller operation in a few nanosecond time span and slower window lifting were observed in the same time traces. Obviously, the accuracy and the simulation time of the co-simulation were a trade-off. In this paper the techniques to deal with the causes of the timing errors in co-simulation were discussed. Possible use of this technology includes detailed analysis of control operation and verification of the fail-safe response to component failures. As the co-simulation includes both the control system hardware in component level and the control software in execution format, components failures are easily injected in any level. This work was one of the outcomes of the vECU-MBD WG (Virtual ECU Model-Based Development Working Group) in Japan. |
Anti-Pinch Mechanism for Power Window | New generation automobiles are equipped with power windows which eases the passenger?셲 effort in moving the vehicle windows up and down. Many of them are stuffed with advanced features like automatic up/down option for ensuring functionality with a single press of the switch. Even though it adds comfort to driver & passenger, inadvertent use of power window can be fatal if a person?셲 body part gets trapped inside. An effective solution for this problem is anti-pinch mechanism, which releases the object safely just when it gets trapped. It detects the object trapped and immediately moves the window down so that trapped object will get released easily. The anti-pinch algorithm used in this project is based on the ?쏮ethod of Monitoring Movable Element?? method monitor traveling distance of a power window pane. In order to achieve this different from conventional techniques we are using Ultrasonic sensor. The anti-pinch technology of power window has to meet standards issued by EU and United States. The maximum force a power window is allowed to exert on any object is 100N. Compliance with this limit must be monitored and enforced in a range of 4mm to 100mm from the top window frame, which is successfully meet by prototype designed. The goal of this project is to provide ultimate protection from power window injuries by implementing this simple & effective safety system to vehicles which are already running on road. Compactness & independent functionality ensures great compliance of this accessory with existing power windows. |
Windows Opening Influence on the Drag Coefficient of a Hatchback Vehicle | Aerodynamics plays a key role in nowadays vehicle development, aiming efficiency on fuel consumption, which leads to a green technology. Several initiatives around the world are regulating emissions and efficiency of vehicles such as EURO for European Marketing and the INOVAR Auto Project to be implemented in Brazil on 2017. In order to meet requirements in terms of performance, especially on aerodynamics, automakers are focusing on aero-efficient exterior designs and also adding deflectors, covers, active spoilers and several other features to meet the drag coefficient. Usually, the aerodynamics properties of a vehicle are measured in both CFD simulations and wind tunnels, which provide controlled conditions for the test that could be easily reproduced. During the real operations conditions, external factors can affect the flow over the vehicle such as cross wind in open highways. The aerodynamic behavior of the vehicle can also be affected by the influence of the user such as by opening the windows in order to cool down the cabin, which is the main topic of this paper. In this work, 12 different window-opening combinations are presented and the drag values compared with a baseline model, considering fully closed windows. The study was conducted using CFD simulations of a current production hatchback vehicle, with two passenger inside and full interior cabin representation. Results show drag increment for all presented cases, compared with baseline configuration, which also implies in fuel consumption increase. Further studies on cabin cooling effects and passenger?셲 thermal comfort are conducted in order to complement this paper. |
Design Optimization of Vehicle Body NVH Performance Based on Dynamic Response Analysis | Noise-vibration-harshness (NVH) design optimization problems have become major concerns in the vehicle product development process. The Body-in-White (BIW) plays an important role in determining the dynamic characteristics of vehicle system during the concept design phase. Finite Element (FE) models are commonly used for vehicle design. However, even though the speed of computers has been increased a lot, the simulation of FE models is still too time-consuming due to the increase in model complexity. For complex systems, like vehicle body structures, the numerous design variables and constraints make the FE simulations based optimization design inefficient. This calls for the development of a systematic and efficient approach that can effectively perform optimization to further improve the NVH performance, while satisfying the stringent design constraints. In the present work, an efficient method to optimize the structural dynamic response is proposed considering the low-frequency NVH performances. As a first step, to reduce computational burden, a response sensitivity analysis is performed to detect the most important variables prior to the design optimization. Then an analytical approximation model of vibration resonance peak is constructed and coupled with the adaptive simulated annealing (ASA) algorithm to replace the time-consuming finite element analysis. Subsequently, an optimization of NVH performance considering dynamic response is formulated and carried out. The methodology aims at improving the NVH behavior of body structure by simultaneously suppressing several resonance peaks. Finally, the proposed method and its process are successfully illustrated through a vehicle body example. The results demonstrate that the proposed method of incorporating response surface model with ASA algorithm is feasible and cost-efficient in solving the vibration optimization problem. |
Modelling Techniques for Noise and Vibration Control of the Body and Chassis | The basic function of a motorcycle frame is somewhat similar to that of the skeleton in the human body, i.e. to hold together the different parts in one rigid structure. One of the major benefits (for a motorcycle enthusiast) of using an advanced frame design lies in the sporty handling characteristics of the bike. A well designed frame can add to the joy of riding a motorcycle as the bike would feel more stable, effortless, and confident around corners, in straight lines and while braking. A well approved modeling [2] techniques or adequate guide line principles have to be followed while designing the body and chassis in order to achieve the vibration within control. This paper depicts a methodological right approach (guide lines) while designing the body and chassis of a two wheeler in order to control noise and vibration of the body and chassis. |
Optimization of Bushing Stiffness Using Numerical Approximation Model to Improve Automotive NVH Performance | An efficient method to determine optimal bushing stiffness for improving noise and vibration of passenger cars is developed. In general, a passenger vehicle includes various bushings to connect body and chassis systems. These bushings control forces transferred between the systems. Noise and vibration of a vehicle are mainly caused by the forces from powertrain (engine and transmission) and road excitation. If bushings transfer less force to the body, levels of noise and vibration will be decreased. In order to manage the forces, bushing stiffness plays an important role. Therefore, it is required to properly design bushing stiffness when developing passenger vehicles. In the development process of a vehicle, bushing stiffness is decided in the early stage (before the test of an actual vehicle) and it is not validated until the test is performed. If it turns out that vehicle performances are not satisfied in the test, another test with bushing changed needs to be conducted, which requires additional costs. Several tests are usually performed to identify bushings which achieve target performances. In addition, the decision of bushing stiffness is complicated since there is typically a conflict between requirements for bushing stiffness from various vehicle performances, such as ride, handling, noise, and vibration. Therefore, in the design stage, the validation of bushing stiffness is desirable to save costs of the vehicle development and ensure the performances of the vehicle. In this paper, a novel optimization methodology based on a numerical approximation model is presented. This method is used to determine optimal stiffness values of bushings in a vehicle for improving the vehicle noise. By using the method, it is found that bushing stiffness is well optimized while reducing the noise. |
Characteristics of Non-Stationary Sources of Wind Noise Measured with a Surface Pressure Array | Measurements of interior wind noise sound pressure level have shown that dBA and Loudness are not adequate metrics of wind noise sound quality due to non-stationary characteristics such as temporal modulation and impulse. A surface microphone array with high spatio-temporal resolution has been used to measure and analyze the corresponding non-stationary characteristics of the exterior aero-acoustic loading. Wavenumber filtering is used to observe the unsteady character of the low wavenumber aero-acoustic loading components most likely to be exciting glass vibration and transmitting sound. |
A Research on the Sound Quality Contribution of Vehicle Body Panel | Sound quality of vehicle interior noise affects passenger comfort. In order to improve the sound quality of a micro commercial vehicle, the vehicle interior noise under different conditions such as idle, constant speeds and accelerating is recorded by using artificial head with dual microphones. The sound quality of recorded noise is evaluated in both objective and subjective ways. Physical parameters of interior noise are calculated objectively, and annoyance score is analyzed subjectively using paired-comparison method. According to the regression analyzing of the annoyance score and the physical parameters, an objective evaluation parameter of the sound quality is employed. To analyze the vehicle body panel contribution to interior noise sound quality, the location and spectrum characteristics of major panel emission noise sources are identified based on partial singular valued decomposition (PSVD) method. By investigating the contribution of each noise sources to the sound quality evaluation formula, the dominant interior noise source is determined. That provides technical support for subsequent research on improving the sound quality of vehicles. |
Evaluation on the Solar Reduction Glass in an Electric Vehicle by Experimental Measurements in a Climate Chamber | Solar energy through glass windows has an influence on the thermal environment in the cabin and thermal comfort of occupants. A medium-size electric vehicle (EV) is conducted for evaluating the performance of solar reduction glass under summer conditions in the climate chamber by experimental measurements. For this purpose, two kinds of glass are attached to the medium-size EV with different performance of solar reduction rate (IR-cut type and normal type). In this paper, two types of experimental measurements, steady state and unsteady state conditions, are conducted. Surface temperature, air temperature and electric consumption of air conditioner are measured under some conditions of air-conditioner. EHT (Equivalent Homogeneous Temperature) by thermal manikin, thermal sensation and thermal comfort by male and female subjects are also measured. Significant difference in the measured surface temperature of the instrument panel where solar radiation reaches through the glass window is found between IR-Cut glass and normal glass. In addition, one or two rank difference in the thermal comfort at the part where solar radiation reaches is found, and ?쐆ot??thermal sensation and discomfort in the female subject is much improved. Heat load of the air conditioner can be decreased by 20% from the view point of controlling the air conditioner by thermal comfort of the occupants. The solar reduction glass such as IR-cut glass has a significant influence on the thermal sensation, thermal comfort of car occupants and electric consumption of EV. |
Identification of Vibro-Acoustic Coupled Modes for Vehicle | In performing noise control design for vehicles, there is a benefit to identifying important vibro-acoustic coupled mode. The purpose of this study is ?쐇dentifying the coupled mode of a vehicle through FRF (frequency response function) measurement?? A speaker which measure the internal acoustic pressure was used as a new experimental method. An acoustic input is estimated by the fluctuation of the acoustic pressure inside the speaker box. Acoustic pressures are measured by using some microphones, the vibrations of the structure are measured by using some accelerometers. Main experiment was carried out for measure the vibro-acoustic mode. First acoustic mode was identified in about 66 Hz. And structure associated mode with this mode was identified. Hence, the vibro-acoustic mode identification was carried out. |
Experimental Determination of Acoustic Cavity Resonances of Vehicle Sub-Systems | The present quiet and comfortable automobiles are the result of years of research carried out by NVH engineers across the world. Extensive studies helped engineers to attenuate the noise generated by major sources such as engine, transmission, driveline and road excitations to a considerable extent, which made other noise sources such as intake, exhaust and tire perceivable inside. Many active and passive methods are available to reduce the effect of said noise sources, but enough care needs to be taken at the design level itself to eliminate the effect of cavity resonances. Experimental investigation of cavity resonances of real systems is necessary besides the FEA model based calculations. Acoustic cavity resonance of vehicle sub systems show their presence in the interior noise through structure borne and air borne excitations. Cavity resonances for some systems e.g. intake can only be suppressed through resonators. The exact location and nature of acoustic cavity resonance needs to be found as accurately as possible to bring out the best from a resonator. Different approaches are used to excite and identify the cavity resonances depending on the operational differences of various systems. Cabin cavity modes are analyzed by arranging an array of microphones inside the cabin and exciting the cavity with help of a low frequency volume acceleration source. The cavity modes of inflated tire are analyzed by placing accelerometers circumferentially and exciting the cavity by intermittent deflation. The cavity resonances of intake system are investigated using microphones by providing excitation through a low frequency volume acceleration source. Acoustic modal analysis is carried out to identify and understand the mode shapes. |
Method for Measuring and Analyzing Transient Powertrain Vibrations of Hybrid Electric Vehicles on an Acoustic Roller Test Bench | In terms of customer requirements, driving comfort is an important evaluation criterion. Regarding hybrid electric vehicles (HEVs), maneuver-based measurements are necessary to analyze this comfort characteristic [1]. Such measurements can be performed on acoustic roller test benches, yielding time efficient and reproducible results. Due to full hybrid vehicles??various operation modes, new noise and vibration phenomena can occur. The Noise Vibration Harshness (NVH) performance of such vehicles can be influenced by transient powertrain vibrations e.g. by the starting and stopping of the internal combustion engine in different driving conditions. The paper at hand shows a methodical procedure to measure and analyze the NVH of HEVs in different driving conditions. In order to investigate the influence of noise and vibrations by restarting and stopping the internal combustion engine (ICE) (like switching between electric and hybrid driving or the start-stop function) on the driver, acoustic and vibration measurements are performed inside the vehicle. A binaural artificial head is used to examine the acoustic effects on the vehicle interior noise. The vibration behavior is analyzed using acceleration sensors at defined measurement positions. Regarding the human perception of the NVH performance, characteristic values, related to the vibrational response of the vehicle, are needed for a vehicle evaluation. By combining the measurement data of the transient powertrain vibrations with evaluation approaches (ISO 2631-1, DIN EN 61672-1, spectrograms using Fourier transform (FFT) and subsequent psychoacoustic criteria) a frequency-dependent vibration analysis is performed. The analysis, depending on measurements on an acoustic roller test bench, supports the development of HEVs??NVH performance, regarding the perceived driving comfort by the customer. |
Analysis of Gear Rattle Noise and Vibration Characteristics Using Relative Approaches | Noise signals of the driver?셲 right ear include those of engine, environment, chassis dynamometer, loaded gears and unloaded gears when they are recorded in full vehicle on chassis dynamometer in semi-anechoic room. Gear rattle noise signals of the driver?셲 right ear caused by unloaded gear pairs can?셳 be identified or quantified directly. To solve the problems, relative approaches are used to identify and quantify the gear rattle noise signals. Firstly, the rattle noise signals of the driver?셲 right ear are filtered by human ear characteristic functions and steady noise signals are extracted by regression and smoothing processes. The noise signals are regressed at 200ms interval in the hearing critical frequency bands and smoothed in the flanking frequencies. Then, the noise relative approaches are obtained by subtracting the steady noise signals from the filtered noise signals, which are the transient noise signals of the unloaded gear pairs inducing the rattle noise. Finally, the occurrence time, frequency and level of the rattle noise are obtained from the noise relative approaches. Through this method, ten rattle noise signals of the highest relative approaches are identified within 3.5 s in the full vehicle test. The results show that the occurrence time obtained by the rattle noise relative approaches is entirely coincided with that of the ten rattle noise signals which is recorded in the raw noise signals playback. The results of the rattle noise identification are consistent with that of the subjective perception. Thus the gear rattle noise is identified accurately. The interference of the noise signals of the engine, the chassis dynamometer, the environment and the loaded gears is effectively removed by the noise relative approaches to avoid false diagnosis. Gear rattle vibration signals on transmission housing obtained in the full vehicle test are similar to those of the rattle noise. Therefore, the occurrence time, frequency and level of the rattle vibration also can be obtained by the relative approaches. Results show that bigger relative approach represents higher gear rattle noise and vibration level. The gear rattle vibration signals of the transmission housing always coincide with all the rattle noise signals of the driver?셲 right ear which delay the rattle vibration signals for 0.01??.04 s. Thus the transmission housing is the major transfer pathway of the gear rattle noise. The frequency range of the gear rattle noise is within that of the rattle vibration because of the noise transfer function from the transmission housing to the driver?셲 right ear. The gear rattle vibration characteristics of each surface and direction are different. Therefore, the rattle anisotropy can be considered when rattle mechanism is investigated. The rattle vibration of the upper, front and left surfaces on the transmission housing is higher than other surfaces. Those three surfaces are the major improvement targets for optimization of the rattle performance. |
A Multiproduct Multimaterial Solution for Lightweight Vehicle Doors | Light weighting of vehicle doors is a challenge faced by all vehicle manufacturers - whether passenger cars and vans or large commercial vehicles like trucks and buses. This need is driven not only by the desire to improve the vehicle's fuel economy, but also by the implication of the doors on the buyer's perception of the vehicle's quality. The best solutions to these needs emerge from an unbiased consideration of different materials and product forms in the design and development of lightweight doors. To demonstrate this notion, a truck door was designed that has the potential of providing both improved fit as well as enhanced structural performance. The concept also simplifies the manufacturing process thereby minimizing system cost while offering approximately 7% additional weight saving compared the door already made from light weight materials (aluminum). This paper describes the design concept for lightweight vehicle doors using aluminum in its various product forms as well as other materials. |
Development of Power Sliding Door (PSD) System with Push-Pull Cable Driving Method | We have developed a power sliding door (PSD) system driven by a push-pull cable. The door closure and slide are operated by different actuators to limit the force required for a compact, light-weight drive unit. This paper introduces the concept of the PSD system using a push-pull cable drive. Two new technologies to achieve the PSD system are also described. One is the door position control for increasing the push-pull cable reliability. The other is a compact position sensor to accurately detect the sliding door's position. |
Door Open Overload: Margin and Flushness Approach | Since doors are repeatedly used by vehicle owner, they have a great influence on his or her perception of vehicle quality. The door open overload is an abusive load requirement for customer usage. The doors must withstand loads which force the door open against its stop, leading to concern over the effects of permanent set to the functioning of the door system and the margins/ flushness. Traditionally, the CAE is utilized to objectively evaluate the deflections and permanent set at the door latch to evaluate door open overload requirement. In this study, the FEA methodology has been applied to expand the scope beyond traditional method to simulate door open overload condition. The change in the margin and flushness due to the permanent set are evaluated using nonlinear analysis (ABAQUS). The results show that the method helps designers to ensure the door meets the margin/flushness criteria for door open overload condition during early stage of the door design process. |
Experimental Assessment Of Door Window Glass Smooth Operation And Tracking | Since the door glass windows are used regularly, they have a great influence on the vehicle owner's perception of vehicle quality. Today's customers demand that moveable door window glass operates smoothly. Experimental methods have been developed to evaluate window glass smoothness and positional stability. This paper presents experimental results that quantify the chattering and positional stability of the window glass. For window glass smooth operation and tracking, the measurements were taken on glass chatter, glass velocity, motor current, motor voltage, and glass stall force. The change in glass position was measured on the vehicle during several stages of four poster durability testing to evaluate window glass positional stability during road induced vibrations. Using these experimental methods, the designers should be able to evaluate several window glass functional requirements and achieve cost/time savings. |
Sled System Requirements for the Analysis of Side Impact Thoracic Injury Criteria and Occupant Protection | This paper discusses struck-side occupant thoracic response to side-impact loading and the requirements of a sled system capable of reproducing the relevant motions of a laterally impacted vehicle. A simplified viscoelastic representation of a thorax is used to evaluate the effect of the door velocity-time profile on injury criteria and on the internal stress state of the thorax. Simulations using a prescribed door velocity-time profile (punch impact) are contrasted against simulations using a constant-velocity impact (Heidelberg-type impact). It is found that the stress distribution and magnitude within the thorax, in addition to the maximum thorax compression and viscous response, depend not only on the door-occupant closing velocity, but also on the shape of the door velocity-time profile throughout the time of contact with the occupant. A sled system capable of properly reproducing side-impact door and seat motion is described. |
Analysis and Design of Slow Build Studies During Sheet Metal Assembly Validations | Several manufacturers are adopting six sigma programs in efforts to reduce stamping variation. This requires the crucial step of establishing dimensional relationships for the stamping dimensional outputs that become key process inputs to the assembly process. This paper describes a methodology used to determine the root cause of dimensional changes in a front door assembly. Among the key findings in this study are the importance of understanding the effects of the datum-locating scheme and the significant influence of assembly processing variables, rather than stamping variability, on the final door assembly dimensional quality. |
Parametric study of side impact thoracic injury criteria using the MADYMO human body model | This paper presents a computational study of the effects of three parameters on the resulting thoracic injury criteria in side impacts. The parameters evaluated are a) door velocity-time (V-t) profile, b) door interior padding modulus, and c) initial door-to-occupant offset. Regardless of pad modulus, initial offset, or the criterion used to assess injury, higher peak door velocity is shown to correspond with more severe injury. Injury outcome is not, however, found to be sensitive to the door velocity at the time of first occupant contact. A larger initial offset generally is found to result in lower injury, even when the larger offset results in a higher door velocity at occupant contact, because the increased offset results in contact later in the door V-t profile - closer to the point at which the door velocity begins to decrease. Cases of contradictory injury criteria trends are identified, particularly in response to changes in the pad modulus. Maximum chest deflection and maximum viscous criterion gradually decrease as the padding modulus increases. TTI, however, increases with some increases in pad modulus. Complex interactions among the three parameters are observed, and their interpretation is shown to depend on the specific injury criterion analyzed. |
Evaluation of Variation in the Excursion Measured in the FMVSS 226 Ejection Mitigation Test Resulting from Test Vehicle Setup | Federal Motor Vehicle Safety Standard 226 outlines a component test methodology that consists of a linear impact test that uses a featureless head-form with a mass of 18 kg to impact a vehicle's side windows' daylight openings at various positions. The test measures the excursion of the head-form beyond the plane of the window glazing. The intention is to evaluate the ability of a vehicle's ejection mitigation system, such as the curtain airbag or other vehicle features, to manage the impactor energy and limit excursion. However, there are several factors which may cause variation in the amount of excursion measured in the test. These factors include how the vehicle is restrained for the test, the friction of the linear impactor shaft and the lateral deflection of the impactor shaft among others. This paper will present background information from a previous study on variability involving the impactor shaft as well as a study which identifies the effects of vehicle restraint on the excursion measured in the Federal Motor Vehicle Safety Standard (FMVSS) 226 test. |
Structural-Acoustic Analysis of Vehicle Body Panel Participation to Interior Acoustic Boom Noise | A structural-acoustic finite element model of an automotive vehicle is developed and applied to evaluate the effect of structural and acoustic modifications to reduce low-frequency ?쁞oom??noise in the passenger compartment. The structural-acoustic model is developed from a trimmed body structural model that is coupled with an acoustic model of the passenger compartment and trunk cavities. The interior noise response is computed for shaker excitation loads at the powertrain mount attachment locations on the body. The body panel and modal participation diagrams at the peak response frequencies are evaluated. A polar diagram identifies the dominant body panel contributions to the ?쁞oom??noise. A modal participation diagram determines the body modes that contribute to the ?쁞oom??noise. Finally, structural and acoustic modifications are evaluated to determine their effect on reducing the ?쁞oom??noise and on the overall lower-frequency sound pressure level response. |
NVH Improvement for Three Wheeler | In India, demand for three wheelers with low noise is increasing among the customers thereby the noise reduction of three wheelers is necessary. In order to overcome the demand in the market, manufactures are giving more importance to noise levels at passenger ear level and driver ear level. In test vehicle it was found that engine is the main noise source, biggest challenge was to reduce noise transfer from engine compartment to passenger and driver ear. In three wheelers it is more difficult as there is no close cabin. This paper main objective is to reduce noise levels at driver and passenger ear level. The objective and subjective evaluations of both vehicles were carried out to identify the levels at driver ear level and passenger ear level. First task was to find out noise sources in engine. Most dominating noise source was tappet and flywheel area. Modifications were done on tappet cover and flywheel cover to reduce noise levels. Different techniques were used in this project like partial enclosure of engine, modifications in vehicle engine compartment. The result shows reduction in sound levels at passenger and driver ear level in modified vehicle comparing with old vehicle. |
Use of Statistical Energy Analysis in Vehicle NVH Design Cycle | Statistical Energy Analysis (SEA) is used to predict high-frequency acoustic and vibration response in vehicle NVH design. Early in the design cycle prototype hardware is not yet available for testing and the geometry is still too poorly defined and changing too quickly for Finite Element Analysis or Boundary Element Analysis to be an effective NVH analysis tool. For most of the concept phase and early design phase, SEA uniquely offers the ability to virtually predict the main noise transfer paths and to support target setting for component and full vehicle NVH design. At later stages of the design process, SEA combines with NVH testing to provide more accurate predictions and to provide guidance for more efficient testing. This paper describes the established uses of SEA in the vehicle industry and presents an overview of the NVH design cycle and how SEA is used to support NVH development at different stages. The synergy between SEA analysis and full-vehicle and component-level NVH testing is discussed. The types of testing that most effectively validate the SEA models and the methodology for validating the models are presented. Case studies for several vehicle NVH applications are presented with examples of the use of SEA prediction and validation measurements. Overall advantages, limitations, and use of SEA to increase the efficiency of the NVH development test effort are summarized. |
Acoustical Performance of Baffle Design Options for Water Management | Expandable cavity sealers have become a critical component of the overall acoustic package that contributes to the documented noise reduction in passenger car applications over the course of the last twenty years. They encompass a variety of technologies, some of which are delivered into the supply chain as bulk materials and others which are highly engineered parts and assemblies. As the market for smaller and more fuel efficient vehicles continues to expand, design architectures of the base vehicle platforms are evolving to include body designs with smaller spaces between adjacent layers of sheet metal. As this space, or cavity, between the adjacent layers of sheet metal is shrinking, the complexity of components that must be integrated into the space between these layers of steel is increasing. Complex arrays of airbags, corresponding wire harnesses, and water management tools are now standard requirements in the design process. To manage the complexity of these lightweight and fuel efficient vehicle architectures, new engineering design solutions are required to meet stringent acoustic requirements. The supply base of acoustic products to the automotive OEMs has also matured over this time period, creating a very competitive environment, both regionally and globally. Design solutions that go beyond the basic functionality of a cavity filler are becoming more common. This paper will evaluate a recent design challenge presented by an OEM to improve visibility for the driver. Here, the hardware to direct water drainage is moved from outside the windshield pillar cavity body metal to inside the cavity metal. A new cavity filler solution is conceptualized to manage this unique packaging and acoustic performance need. Although it's in its infancy, the solution, along with other means of water management, are measured for Insertion Loss and compared. This initial study supports the promise for acoustic performance of a solution that does not exist in the market today. |
ULSAC - Lightweight Steel Automotive Closures | Following the success of the UltraLight Steel Auto Body (ULSAB) in 1997, the UltraLight Steel Auto Closure (ULSAC) Consortium representing steel producers from all over the world was founded. Porsche Engineering Services, Inc. (PES) was commissioned to conduct a concept study for the development of UltraLight Steel Auto Closure concept designs for all types of automotive closures that were structurally sound at affordable cost. The Validation Phase began in November 1998. In spring 2000, the ULSAC DH Door Structures featuring stamped Door Outer Panels were built and tested for structural performance, dent resistance and oil canning. The tested doors show state-of-the-art structural performance compared to today's frameless door structures, and the mass reduction ranges from 22 to 42% compared to the normalized mass of benchmarked doors. In the Validation Phase, a cost model was developed and the cost to produce the ULSAC frameless door structure was calculated. The results of this cost estimation show that the ULSAC door can be manufactured in high-volume production with no cost penalty. |
Dimensional Management - Setting Static and Dynamic Dimensional Goals Concurrently | The main element of dimensional management is specification cascading where customer requirements are translated into dimensional targets. It also includes GD&T, datum strategy, and tolerance optimization. These elements can only be effective if all of the work is done concurrently among various disciplines of an organization that have a stake in the fit, finish, and performance of the final product. When setting static dimensional goals during product development, vehicle performance targets and dynamic goals have to be defined simultaneously. One example is of the final door appearance for gaps and flushness on an automotive body from static standpoint. The wind-noise and door flutter are examples of dynamic performance goals. It becomes very costly to fix static fit and finish issues caused by the dynamic state of the vehicle late into the product development cycle or at the customer locations. |
Developing a Sonar-Assisted Device for the Blind | At Wake Forest University, Winston-Salem, NC, a biology professor researching echolocation in bats teamed up with an associate professor of computer science and an interdisciplinary team of students to develop a device that can help the visually impaired navigate better. Their research focused on developing a device that could be worn like a watch by a visually-impaired person as a supplement to other aids like a cane or guide dog. |
Automotive Engineering: May 2018 | Testing for cold-climate comfort AE goes way north to the Arctic Circle for an inside look at Hyundai's winter testing of the new Nexo FCV and Kona EV and their unique and critical HVAC systems. Innovation more than skin deep A new wave of engineered plastics are delivering structural, mass-reducing, and aesthetic benefits for new vehicle applications. A secret weapon for roof-crush testing Before you crush that bus or racecar chassis, find out how engineers at CAPE are optimizing test-rig performance. Editorial: Tesla's Model 3 is two very different cars SAE Standards News A hive of activity Supplier Eye Why aren't there more unibody pickups? The Navigator We can't trust humans to supervise machines Acura and ArcelorMittal debut world-first hot-stamped door ring system on 2019 RDX Powertrain analyst: Light-vehicle fleet needs big gains to meet tightening emissions regs Toyota unveils more gasoline ICEs with 40% efficiency IAV using 3D-printed pistons for engine testing 2018 Kona debuts Hyundai's new B-SUV platform Nissan variable-compression engine gets first shot at volume with new 2019 Altima Q&A Honeywell's Geoff Duff talks turbos |
Windshield Defrosting Systems Test Procedure and Performance Requirements?봗rucks, Buses, and Multipurpose Vehicles | This SAE Recommended Practice establishes uniform test procedures and performance requirements for the defrosting system of enclosed cab trucks, buses, and multipurpose vehicles. It is limited to a test that can be conducted on uniform test equipment in commercially available laboratory facilities. Current engineering practice prescribes that for laboratory evaluation of defroster systems, an ice coating of known thickness be applied to the windshield and left- and right-hand side windows to provide more uniform and repeatable test results, even though under actual conditions such a coating would necessarily be scraped off before driving. The test condition, therefore, represents a more severe condition than the actual condition, where the defroster system must merely be capable of maintaining a cleared viewing area. Because of the special nature of the operation of most of these vehicles (where vehicles are generally kept in a garage or warmed up before driving) and since defrosting under steady-state over-the-road operations is the main concern, test conditions have been adopted which assume that the engine is warm before the vehicle is driven. There are two options for producing hot coolant in this recommended practice. Testing using these two approaches on the same vehicle will not necessarily provide identical results. Many vehicle models are offered with optional engines, and each engine has varying coolant temperatures and flow rates. If the test is being conducted to compare the performance of one defroster design to another defroster design, then the external coolant source approach (Test A) will yield the most comparable results. If the test is being conducted to validate the defroster installation on a specific vehicle model with a specific engine, then using the engine to heat the coolant (Test B) will be more appropriate. This document will be reviewed and revised as technological progress in vehicle defroster test procedure requires. |
Road Noise Identification and Reduction Measures | In a scenario where cost and weight targets are becoming critical, we tend to produce lighter and more powerful vehicles. In this context, NVH becomes one of crucial parameters in overall performance delivery. Other than power train, road induced noise also becomes an important parameter within vehicle development. Predecessor vehicle is body over frame structure and here a monocoque vehicle is considered for study. Different techniques like transfer path analysis, vibro-acoustic modal analysis, operational deflection shapes are used to identify the major force paths, radiating panels and their sensitivity to noise at operator ear location. Simulation model of body is built with good correlation and input forces are given at different attachment points to predict the noise levels. This combined approach helped us in reducing the overall noise level at certain constant speed by 4 dB(A) and also with great ease. All recommendations from this exercise are implemented |
Vehicle Airborne Noise Analysis Using the Energy Finite Element Method | The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration and the interior noise level of complex structural-acoustic systems by solving numerically governing differential equations with energy densities as primary variables. In this paper a complete simulation process for evaluating airborne noise in an automotive vehicle is presented and validated through extensive comparison to test data. The theoretical elements associated with the important paths of the noise transfer from the exterior of the vehicle to the interior acoustic space are discussed. The steps required for developing an EFEA model for a vehicle are presented. The model is developed based on the physical construction of the vehicle system and no test measurements are utilized for adjusting the numerical model. An acoustic noise source is placed at each one of four vehicle locations (engine compartment, front left tire patch, rear left tire patch, and exhaust) where typical exterior noise sources are present in an operating vehicle. The exterior acoustic field is evaluated numerically by the Energy Boundary Element Analysis (EBEA). The acoustic loading from each source is applied on all of the outer parts of the vehicle EFEA model and the interior noise level is computed in the frequency range of 200Hz - 8,000Hz. Predictions for the interior noise level (expressed in a noise reduction format) are compared with test results for all four excitations. The ability of the EFEA method to conduct a panel contribution analysis is used for identifying the panels which contribute the most to the power flow from the structure to the interior acoustic space. Such information is useful in making design decisions when implementing noise mitigation strategies. |
A Software Library for Active Control of Automotive Engine Noise | A general-purpose software solution for active control of engine noise within vehicle cabins is described. The feed-forward system, based on FxLMS algorithm, reduces engine orders below 150 Hz by emitting independent control signals from one or more loudspeakers in the cabin, and uses one or more microphones inside the cabin to monitor noise levels and adapt control filters. The software solution is a C/C++ callable library with floating-point and fixed-point versions, which would normally be ported to a DSP or application processor situated in the head-unit or power amplifier of the audio/infotainment system. We provide a comparative analysis of our integrated software library versus a mass-production solution in a Honda Odyssey, which shows that the software library, with a very reasonable computational complexity, provides a low-cost alternative to a dedicated ANC system whilst achieving comparable performance and robustness. |
Correlation of Dominant Noise Transfer Paths in Statistical Energy Analysis Vehicle Model from Test as Basis for Variant Vehicle Development | For purposes of reducing development time, cost and risk, the majority of new vehicles are derived strongly or at least generally from a surrogate vehicle, often of the same general size or body style. Previous test data and lessons learned can be applied as a starting point for design of the new vehicle, especially at early phases of the design before definite design decisions have been finalized and before prototype of production test hardware is available. This is true as well of vehicle NVH development where most new vehicles being developed are variants of existing vehicles for which the main noise transfer paths from sources of interest are already understood via test results and existing targets. The NVH targets for new vehicles are defined via benchmarking, market considerations, and other higher-level decisions. The objective is then to bridge the gap between test data from surrogate vehicles to direct support of the NVH development of new vehicle programs. Because of its strength in providing analysis predictions of the effect of design changes on vehicle NVH at higher frequencies, Statistical Energy Analysis (SEA) is an established tool for using available test data to correlate an SEA model that can be adapted for early design phase NVH development of new vehicles. The effect of changes to materials, gage thickness, sound package, source levels, or geometry changes on the interior noise levels can be predicted by SEA with good accuracy to support design decisions that must be made early in the program. This paper illustrates with a concrete example an idealized implementation of this process. The main test plan design considerations for a baseline surrogate vehicle are discussed. Some key test results and their uses are presented. The updating and correlation of an SEA model representing the baseline vehicle are shown. The objective methods for determining the effectiveness of the correlation are given using this vehicle as an example. Finally, the use of a correlated SEA model to effectively support the NVH development of several variant vehicle programs at an early phase of the design process is presented along with suggestions for the best use of this design tool, its advantages and limitations, and the most effective roles it can serve to support the overall vehicle design cycle. |
Ventilation Improvement in a Non-AC Bus | Ventilation is a crucial factor affecting passenger comfort in any vehicle. In a non-air-conditioned bus, ventilation caters to the dual requirement of fresh breathing air as well as providing a cooling sensation by enhanced evaporation of sweat. The higher the velocity of air around the passengers, the greater the cooling effect experienced by them. The ventilation mechanism of a non-air-conditioned bus is primarily the air flow through the windows due to relative motion between the bus and the air around it. This paper describes studies carried out to identify the right combination of open windows which would provide optimum air flow at the passenger head level plane in a bus. A bus model with 12 windows, 6 on each side is used for the study and air velocity at certain points in the head level plane, arising out of different combination of window openings is evaluated using CFD. The minimum value of velocity observed among the points, which is indicative of the minimum level of comfort provided by the combination, is compared for different combinations of openings and the optimum identified. Since a comparison of all possible combinations would involve evaluating 312 CFD runs, Design of Experiments (DOE) is used to obtain the optimum using a reduced number of analyses. Through this study it is attempted to place windows only at few strategic locations that would contribute to optimum air flow at all points within the bus by eliminating the non contributing windows without reduction in passenger comfort, thereby changing bus design philosophies and providing greater freedom in bus design. The optimum configuration of windows was found to provide ??7% reduction in window area. |
Active Noise Control for the 4.0 TFSI with Cylinder on Demand Technology in Audi's S-Series | To significantly increase fuel efficiency while keeping power and performance of its signature S models, AUDI developed a new 4.0 TFSI engine with Cylinder on Demand technology and introduced it with its new S6, S7 and S8 models. To manage upcoming NVH issues due to this new technology and keep the intended sporty V8 note of the engine under all operating conditions, a broad range of new and advanced technologies was introduced with these vehicles. This paper focusses on the Active Noise Control system and its development. It describes the ANC system from a control theory perspective in addition to the acoustical perspective. Special features of the system include the availability of multiple tunings (4/8 cylinder mode) to support the specific overall sound character and the fast switching process as switching between different cylinder configurations might be as fast as 300 ms. In addition, the system also includes specific features that allow an advanced audio system diagnosis. Last but not least, some aspects of the development process will be highlighted. |
Further Development of Velocity-based Airborne TPA: Scan & Paint TPA as a Fast Tool for Sound Source Ranking | The interior noise of a car is a general quality index for many OEM manufacturers. A reliable method for sound source ranking is often required in order to improve the acoustic performance. The final goal is to reduce the noise at some positions inside the car with the minimum impact on costs and weight. Although different methodologies for sound source localization (like beamforming or p-p sound intensity) are available on the market, those pressure-based measurement methods are not very suitable for such a complex environment. Apart from scientific considerations any methodology should be also ?쐄riendly??in term of cost, time and background knowledge required for post-processing. In this paper a novel approach for sound source localization is studied based on the direct measurement of the acoustic particle velocity distribution close to the surface. An airborne transfer path analysis is then performed to rank the sound pressure contribution from each sound source. The method called ?쏶can & Paint TPA??makes use of only one probe that is swept along the surface. The reciprocal transfer functions are measured by a second sweep with the same probe and a monopole sound source in the driving position. A new methodology for applying ?쏶can & Paint TPA??in a complex acoustic environment is given along with an experimental validation in a car interior. |
Functional Vehicle Design for Urban Mobility | When approaching new mobility solutions such as car-sharing, it soon becomes apparent that it may be necessary to develop specific vehicles for this application. In this paper, Applus IDIADA explains its experience in the development of the iShare, an electric vehicle conceived as a demonstrator of our complete vehicle development capabilities following the principle of ?쐂evelopment led by functionalities?? with the consideration that it would be used in open car-sharing fleets running according to the MIT's (Massachusetts Institute of Technology) ?쐌obility-on-demand??concept. This paper explains the process followed in order to reach the definition of the different parts, systems and components that are the result of the consideration of the Technical Functionalities, such as Active Safely, Passive Safely, Driveability, NVH, Fleet Management, Maintenance and Comfort, that in their turn result from the basic vehicle specifications defined from the analysis of the key functionalities of this vehicle that are suitability for the car-sharing business model and the mobility requirements of the potential customers. In particular, the paper includes details about the vehicle layout analysis and why a 4-wheel and 2-parallel seats configuration was chosen instead of 2- o 3-wheel or 2-tandem seats configuration, the powertrain, steering, suspension, braking, Passive Safety and energy efficiency concepts explored, the process allowing a customer to book and have access to a given vehicle without a physical key and finally the systems to allow the car-sharing operator to keep the cars in good conditions by replacing interior and exterior trims easily and inexpensively and recycling the materials to make new trims out of it. |
Seat Squeak Measurement and Diagnosis | BSR (Buzz, Squeak and Rattle) is one of the oldest concerns in automobiles which directly reflect the build, assembly and manufacturing quality of a vehicle. In a cabin all the areas where there is relative motion between two components, such as trims, instrument panel and seats, are prone to squeak. This paper explains the study of seat squeak measurement and diagnosis which is a major concern for one of the products which is already in the market. Since squeak is a friction induced non stationary phenomenon, lot of effort was required to generate squeak in both component as well as vehicle level. At component level, electrodynamic shaker was extensively used for generation of squeak signals. In Vehicle level, driving through different road patterns, pave track and forced excitation on four posters are performed for generation of squeak signals. In this paper usage of wavelet and Zwikker loudness are explained for the diagnosis of seat squeak to identify the problematic frequencies. Results in both pave track condition and in four poster excitation method are presented. |
Multidisciplinary Design Optimization of a Hatchback Structure | Lightweight automobile has an important role in saving the energy, improving the fuel economy and reducing the exhaust emission. However, reducing the mass of the automobile need to meet the structural and NVH (Noise, Vibration and Harshness) performance requirements. With the rapid development of Computer Aided Engineering (CAE) technology, more and more people tend to research the complex engineering application problem by computer simulation. An important challenge in today's simulation is the Multidisciplinary Design Optimization (MDO) of an automobile, including mass, stiffness and modal etc. This paper presents a MDO study in a minicar hatchback. The aim of the study is to minimize the mass of the hatchback while meeting the following requirements: (1) Structural performance. the bending stiffness is higher than the original data and the sagging residual deformation is less than the original data. (2) NVH performance. the lowest natural vibrational frequency is higher than the original data. The sample points are obtained by the Design of Experiment (DOE) with optimal Latin Hypercube and the approximation models of mass, modal, bending stiffness, sagging are established with polynomial response surface method. The thicknesses of the major components in the hatchback are selected as design variables. The approximation models are optimized by sequential quadratic programming method. A good agreement between the predictive values of the approximation and the results of finite element simulation with the error less than 5% is demonstrated. The predictive values of the approximation meet the engineering requirement. Consequently, the optimized results have higher accuracy. In the process of the optimization design, the weight of the hatchback reduced by 6.5% and the new hatchback meets all the prescribed requirements about structural and NVH performance. |
Effect of Glazing Thermal Conductivity on Cabin Soak Temperature | Previous papers by the present authors described use of computational fluid dynamics (CFD) to quantify the effect of glazing thermal conductivity on steady-state heating, ventilation and air-conditioning (HVAC) load under wide-ranging climate and state of motion scenarios, and to estimate the significance of this effect for electric battery performance. The CFD simulations yielded the total heat transfer between the ambient and the cabin of a model car, including radiative and convective heat transfer. The five-fold lower inherent thermal conductivity of polycarbonate relative to glass was found to reduce steady-state HVAC load by several percent in all scenarios, leading to reduced greenhouse gas emission or increased electric range, according to the type of vehicle. This paper complements the previous study by quantifying through simulation the effect of glazing thermal conductivity on cabin soak temperature, the latter reflecting a balance between radiative and convective heat transfer in a closed, unventilated, parked car with HVAC off, in a hot, sunny environment. Soak temperature has been a focus in the regulatory arena as an initial condition in proposed tests of air-conditioning contribution to tailpipe emissions. Two glazing configurations are simulated: a baseline configuration with glass at all locations, and a reduced thermal conductivity configuration with polycarbonate glazing substituted at the backlite and rooflite. A difference in soak temperature of less than 1째C is found for the two glazing configurations under the conditions of relatively high solar radiation and ambient temperature in Phoenix, Arizona at mid-day in June. This difference is small compared to both the soak temperature relative to the ambient and the variation in soak temperature found for a range of optical and heat transfer parameters for non-glazing elements of the cabin. The insignificance of glazing thermal conductivity for soak temperature is reconciled with its significance for steady state HVAC load in terms of air movement at the inside and outside glazing surfaces. |
A Development of Smart Ventilation System | There are some problems ?쐗indows fog up a lot??for ventilation system. We have Test Development Procedure to prevent the fog problems. But, Many fog problems occurred in the cars that we made. So in this paper, new ventilation system is needed and developed. The Smart Ventilation System automatically controls indoor air quality even though the blower motor is off. There are two sensors that is used for AutoDefogSensor system and CO2 CONTROL system.. The sensor is on when blower motor and heater control is off. We use these signals and make new ventilation logics. We evaluate this system in chamber & '13 winter test in USA. |
Development of an Acoustic Material Database for Vehicle Interior Trims | Characterizing the acoustic properties of sound-absorbing materials is costly and time consuming. The acoustic material database helps the automotive designers design their interior trims in accordance with target level for interior noise. In this paper, a two-microphone impedance tube was used to measure the normal sound absorption coefficient. The main parameters that are used in the theoretical model for interior noise level assessment are investigated. These parameters include thickness, airflow resistivity, porosity, tortuosity, viscous and thermal characteristics length. The measured results have been validated by the theoretical models. The validation of normal sound absorption coefficient was found to be in agreement with its corresponding measurement data. Finally, the sensitivity of the sound absorption coefficient which is related to the physical properties mentioned above is further analyzed. |
Optimal Design of Vehicle Dash and Floor Sound Package Based on Statistical Energy Analysis | An increasing demand for vehicle noise control has been proposed and at the same time, vehicle weight and fuel economy have become critical for the automotive industry. The methodology of statistical energy analysis (SEA) is used to balance both light weight and high noise insulation performance. In this paper, the vehicle dash and floor sound package systems, which are two of the major paths for vehicle interior noise, are studied and optimized by CAE and testing technology. Two types of sound packages which are the conventional insulation system and the lightweight one are chosen for the vehicle dash and floor system. The vehicle dash and floor systems are modeled by SEA and the transmission loss (TL) of the dash and floor system is analyzed, respectively. Several influence factors of the TL are also analyzed, such as sound package coverage, the leaks, etc. The results of the TL analysis show that under certain sound package coverage or leaks, the TL of the dash and floor system with the conventional sound package is a little larger than the TL with the lightweight one. However, the lightweight sound package system has better absorption property and the advantage of weight reduction. Meanwhile, the full vehicle SEA model is built up and the noise transfer path is analyzed. By using the full vehicle noise reduction tests, the full vehicle SEA model and the main noise transfer paths are validated. Then, the vehicle exterior sound pressure levels (SPL) are tested under several load cases inside a semi-anechoic chamber. By applying the vehicle exterior SPLs to the full vehicle SEA model, the correlations are performed between the simulation and tests. Finally, the sound package systems of the dash and floor are analyzed and optimized by the full vehicle CAE and testing analysis. |
Scientists Build Thinnest-Possible LEDs To Be Stronger, More Energy Efficient | Most modern electronics, from flat-screen TVs and smartphones to wearable technologies and computer monitors, use tiny light-emitting diodes, or LEDs. These LEDs are based on semiconductors that emit light with the movement of electrons. As devices get smaller and faster, there is more demand for semiconductors that are tinier, stronger and more energy efficient. |
SUPPLIER EYE | Are you innovating for NVH? I'll never forget the experience, as a kid, of lifting the massive steel hood of my father's 1971 Dodge Monaco and seeing nothing but V8 engine and a few rubber hoses. The vast compartment was so uncluttered, I could look straight down and see the pavement. By comparison, the view under today's vehicle hoods reveals a dense landscape of technologies aimed at acoustic control: covers, shields and insulators designed to keep injector clatter, induction honk and even pulley whirl muffled. Supplier innovations are central to winning the ongoing war with NVH-noise, vibration and harshness. The battle started decades ago and will certainly increase in the future. This is an engineering realm with numerous tradeoffs involving total piece cost, capital cost, stranded fixed capital, tooling complexity/count, system optimization, flexibility, intellectual property and even downstream warranty. But because NVH (more accurately, the lack of it) has direct impact on the end customer, it has become a commitment rather than an option across vehicle segments. |
Lincoln unveils Big-SUV future with Navigator concept | Intent on staying on its message of reinvigorating its brand under the banner of ?쐑uiet luxury,??Ford's premium-vehicle unit, Lincoln, used the 2016 New York auto show to reveal what almost certainly will be remembered as one of the most audacious concept cars ever, the Lincoln Navigator Concept. Two stupendously-sized gullwing doors lift to allow full access to the SUV's first and second seating rows, with 30-position adjustable seats ?쐄loating??on pedestal attachments that eliminate traditional seat tracks, full-length ?쐁oncertina??steps are power-deployed to create a waterfall of steps for entry and exit, and a ?쐗ardrobe management system??in the cargo area looks like something Tony Stark dreamed up to secure his Iron Man gear. |
Autonomous Robotic Manipulation (ARM) | Autonomous robotic manipulators have the potential to increase manufacturing efficiency, provide in-home care, and reduce the risk to humans in hazardous situations. The current challenge in autonomous robotic manipulation is to approach the capabilities of dedicated, one-off manipulators in known environments with versatile, inexpensive, and ubiquitous manipulator systems that can operate in a range of environments with only high-level human input. |
Dual-Compartment Inflatable Suitlock | There is a need for an improvement over current NASA Extravehicular Activity (EVA) technology. The technology must allow the capacity for quicker, more efficient egress/ingress, allow for ?쐓hirtsleeve??suit maintenance, be compact in transport, and be applicable to environments ranging from planetary surface (partial-g) to orbital or deep space zero-g environments. The technology must also be resistant to dust and other foreign contaminants that may be present on or around a planetary surface. The technology should be portable, and be capable of docking with a variety of habitats, ports, stations, vehicles, and other pressurized modules. |
The Thermal Hogan ??A Means of Surviving the Lunar Night | A document describes the Thermal Hogan, a new shelter concept that would be used on the Moon to moderate the extreme nighttime temperatures, allowing survival of equipment with minimal heater power. It is lightweight, has few mechanical parts, and would be relatively easy to deploy on the Moon. |
Dual-Compartment Inflatable Suitlock | A paper discusses a dual-compartment inflatable suitlock (DCIS) for Extra-vehicular Activity (EVA) that will allow for dust control, suit maintenance, and efficient EVA egress/ingress. The expandable (inflatable technologies) aspect of the design will allow the unit to stow in a compact package for transport. |
Wearable, Artificially Intelligent, Bionic Device | eLEGS is a wearable, artificially intelligent, bionic device that enables people with paralysis to stand up and walk again. The exoskeleton is battery-powered and rechargeable, fitting comfortably and securely over clothing. |
Microcontroller Based Low Cost Illumination Control and Warning System | This paper demonstrates the design, development and validation techniques for the vehicle illumination control system typically used for emerging market applications with limited program variable costs and more features needs to be packed in a controller module. The system, powered by an 8-bit RISC Harvard microcontroller, controls the in-car illumination by triggered time delay and a PWM controlled theatre-dimming effect for predefined duration. It further alarms the driver and co-driver if the exterior lamps are left ON and doors opened. The module is packed on a 30 mm square base with height 50 mm and mounted in the CJB. The paper concludes with a generic methodology for designing such robust systems for the cost and quality conscious automotive society. |
The Design of an Acoustics Laboratory for Off-Highway, Heavy Truck, and Recreational Vehicles | The new Blachford Acoustics Laboratory was designed specifically for acoustical testing of large vehicles, such as off-highway machines, recreational vehicles, and heavy trucks. While there are many automotive and architectural test laboratories for which a new laboratory can be based, there are very few acoustics laboratories capable of testing these larger vehicles. However, by drawing on the experience with the previous Blachford Laboratory, several off-highway manufacturers' test facilities, and the newer automotive manufacturer and supplier laboratories, a functional and cost effective design was developed. This design features indoor and outdoor test areas, including a large hemi-anechoic chamber equipped with a chassis dynamometer, a reverberation room with several transmission loss openings, work rooms, office areas, and a 10 meter radius outdoor drive-by pad. Special design considerations included door size, component test opening dimensions, dynamometer axle and floor loading capabilities, cooling and exhaust extraction flow rates, and special electrical connections. In addition, the site chosen for the laboratory also provided many challenges. |
Wavelet-Based Visualization, Separation, and Synthesis Tools for Sound Quality of Impulsive Noises | Recent applied mathematics research on the properties of the invertible shift-invariant discrete wavelet transform has produced new ways to visualize, separate, and synthesize impulsive sounds, such as thuds, slaps, taps, knocks, and rattles. These new methods can be used to examine the joint time-frequency characteristics of a sound, to select individual components based on their time-frequency localization, to quantify the components, and to synthesize new sounds from the selected components. The new tools will be presented in a non-mathematical way illustrated by two real-life sound quality problems, extracting the impulsive components of a windshield wiper sound, and analyzing a door closing-induced rattle. |
Interior Fittings ??A Global View | In today's global economy, the automotive design engineer's responsibilities are made more complex by the differences between regulatory requirements of the various global markets. This paper compares instrument panel head impact requirements of FMVSS 201 with its European counterparts, ECE 21, and EEC/74/60, Interior Fittings. It describes the similarities and differences between these regulations and explains the unique requirements for each market. It then compares processes for development and validation testing in both markets. It also covers related topics like self-certification, witness testing, radii, projections, and interior compartment doors. The cockpit design engineer will gain an understanding of the factors involved in ensuring that their design fully meets the requirements of the subject regulations. |
Use of Acoustical Holography for Efficient 3D Measurement in Car Interiors | A continuously growing demand comes from the automotive industry for optimization of materials and sound insulating product packaging inside the car, so as to propose the best acoustic performance at reduced costs. A new acoustical holography system provides part of the solution to meet such a demand. The capability of measuring the acoustic field inside a vehicle with high spatial resolution makes it an advanced tool for performing extensive studies of the acoustic transparency of car openings and interior components in various environmental conditions (acoustic chamber, on road, in wind tunnel). The method allows for: Detailed localization of noise sources or leaks, Knowledge of the acoustic energy distribution on elementary surfaces (such as doors, windscreen, roof, sealing components, ??, Reconstruction of the energy radiated by elementary surfaces in order to predict the acoustic pressure at driver's and passengers' ears, Introduction of local modifications on subsystems and components in order to predict their effect on the acoustic field. In conjunction with some numerical prediction methods, this technique will allow to apply integrated acoustic engineering design methods for a complete understanding and control of the large variety of components and systems involved in the car performance. |
Automotive Body Structure Enhancement for Buzz, Squeak and Rattle | Today, the interior noise perceived by the occupants is becoming an important factor driving the design standards for the design of most of the interior assemblies in an automotive vehicle. Buzz, Squeak and Rattle (BSR) is a major contributor towards the perceived noise of annoyance to the vehicle occupants. An automotive vehicle consists of many assemblies such as instrumentation panel, doors, sun/moon-roof, deck lids, hood, etc. which are the potential sources of BSR noise. The potential locations of critical BSR noise could be contained within such assemblies as well as across their boundaries. An extensive study is made regarding the overall structural behavior as well as their interaction under typical road loads to come up with enhanced design for improved quality from the BSR noise perspective. The alternative designs were comparatively evaluated for their relative noise level from buzz, squeak and rattle perspective using an analytical tool - N-hance.BSR. Critical noise sources both at the system as well as the assembly levels were identified and the relative noise levels were compared critically to determine the influence of the design changes on the BSR quality of the system and its assemblies. In this paper, a brief introduction is provided regarding the typical product background and the noise quality requirements, typical design changes that influence the BSR characteristics followed by a brief introduction to the software N-hance.BSR. The results of such a comparative design evaluation from N-hance.BSR are presented at the end. The observations of the critical squeak and rattle locations were confirmed by physical tests on the baseline and enhanced models. |
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