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Predicting the Acoustics of Squeak and Rattle | This paper discusses the development of a computationally efficient numerical method for predicting the acoustics of rattle events upfront in the design cycle. The method combines Finite Elements, Boundary Elements and SEA and enables the loudness of a large number of rattle events to be efficiently predicted across a broad frequency range. A low frequency random vibro-acoustic model is used in conjunction with various closed form analytical expressions in order to quickly predict impact probabilities and locations. An existing method has been extended to estimate the statistics of the contact forces across a broad frequency range. Finally, broadband acoustic radiation is predicted using standard low, mid and high frequency vibro-acoustic methods and used to estimate impact loudness. The approach is discussed and a number of validation examples are presented. |
TEST EQUIPMENT MAKER'S COOPORATIVE APPROACH TO THE MEASUREMENT NEXT GENERATION AUTOMOTIVES: COMPARISON OF NOISE AND VIBRATION CHARACTERISTICS BETWEEN ICE VEHICLE AND EV | The car's ride of electric vehicle (EV) is quite different from that of internal combustion engine(ICE)vehicle. Nonetheless, only limited discussion has held so far. We have carried out noise and vibration measurements using EV in order to compare to ICE vehicle. We have found that sound quality index in addition to sound pressure level are useful to evaluate distinguished sound of EV. Also, the characteristics of sound field in cabin are found to be quite different each other. |
Improving SEA Predictions with Experimental Data | Statistical Energy Analysis (SEA) has been used widely by industry and academia for more than 20 years to predict the mid-to-high frequency range behavior of complex acoustic systems. At Gulfstream Aerospace Corporation (GAC), SEA models have been developed to predict the interior cabin noise levels of completed Gulfstream aircraft. These models are also used for acoustic evaluations of design changes prior to implementation as well as a diagnostic tool for investigating noise and vibration issues. Throughout the development of the SEA models, extensive experimental testing in GAC's Acoustic Test Facility (ATF) was conducted on numerous aircraft components represented in the models. This paper demonstrates the importance of using experimental data to improve the accuracy of the SEA predictions by accurately adjusting the material properties and acoustic parameters of the SEA model to better match the ATF experimental data. This is particularly important for complicated SEA models with thousands of subsystems and junctions. |
Prediction of Vehicle Interior Sound Pressure Distribution with SEA | Statistical Energy Analysis (SEA) is the standard analytical tool for predicting vehicle acoustic and vibration responses at high frequencies. SEA is commonly used to obtain the interior Sound Pressure Level (SPL) due to each individual noise or vibration source and to determine the contribution to the interior noise through each dominant transfer path. This supports cascading vehicle noise and vibration targets and early evaluation of the vehicle design to effectively meet NVH targets with optimized cost and weight. A common misconception is that SEA is only capable of predicting a general average interior SPL for the entire vehicle cabin and that the differences between different locations such as driver's ear, rear passenger's ear, lower interior points, etc., in the vehicle cannot be analytically determined by an SEA model. However, because the interior acoustic energy distribution varies due to absorption and distance effects that can be modeled, an SEA model is capable of predicting the SPL at different interior locations with good accuracy at high frequencies. This paper discusses the SEA modeling assumptions used to generate a typical model of a vehicle cabin interior and surrounding structure. The distribution of acoustic absorption and its effect on the local interior SPL responses are addressed. Measurements of transfer functions to various points of the vehicle interior from exterior and interior acoustic sources and structureborne sources for a typical vehicle are presented and compared to SEA model predictions. Observations and recommendations about typical interior transfer function correlation, modeling limitations, and use of the SEA model as a design tool are given. |
SEA Wind Noise Load Case for Ranking Vehicle Form Changes | Vehicle manufacturers demand early design assessment of vehicle wind noise attribute so as to eliminate engineering waste induced by late design changes. Vehicle wind noise attribute can be simulated with a Statistical Energy Analysis (SEA) model using exterior surface turbulence pressure on the vehicle greenhouse panel as the wind noise load. One important application of SEA wind noise model is the wind noise assessment for vehicle form design. Vehicle form optimization for wind noise plays an important role in lightweight vehicle architecture, since that reduction in the wind noise load will compensate the loss of vehicle body acoustic attenuation caused by down-gauge glazing and body panels. In this paper, two SEA wind noise load cases currently used in vehicle SEA wind noise modeling have been analyzed and evaluated against vehicle measurements. Two types of evaluations have been made: prediction of the interior cabin noise level at driver's ear location and simulation of level change in the interior cabin noise corresponding to different exterior mirrors. The correlation result shows that current wind noise load cases over-predict the interior cabin noise and mis-simulate the level change in interior cabin noise in response to mirror shape change. A new SEA wind load case has been proposed. The prediction of the interior cabin noise from the proposed load case shows a good correlation with vehicle measurement. The correlation result shows that the proposed load case improves the simulation of change in the interior cabin noise in response to mirror shape change. Further effort is needed to improve the determination and representation of acoustic energy in the pseudo acoustic near field. |
An Efficient Modeling Approach for Mid-frequency Trim Effects | In traditional FE based structure-borne noise analysis, interior trims are normally modeled as lump masses in the FE structure model and acoustic specific impedance of the trim is assigned to the FE acoustics model when necessary. This simplification has proven to be effective and sufficient for low frequency analysis. However, as the frequency goes into the mid-frequency range, the elastic behavior of the trim may impose some effects on the structural and acoustic responses. The approach described in this paper is based on the structural FE and acoustic SEA coupling analysis developed by ESI, aiming to improve the modeling efficiency for a possible quick turnaround in virtual assessments. The idea is to reassemble the FE-SEA hybrid analysis results for the trimmed condition by combining radiated sound power from untrimmed body structure with trim component absorption, insertion loss data and other necessary information which can be extracted easily and quickly from an untrimmed FE model, and/or SEA model. |
Reconstruction of Vibro-Acoustic Responses of a Complex Vibrating Structure Using Helmholtz Equation Least Squares | This paper presents an experimental study on using the Helmholtz equation least squares (HELS) based nearfield acoustic holography (NAH) method for reconstructing the vibro-acoustic responses on the surfaces of arbitrarily-shaped structures. Specifically, we demonstrate the capability of HELS to reconstruct normal surface velocity (NSV) and perform panel contribution analysis. The test object is a hexagonal-shaped structure made of eight panels and frames that mimic a scaled automotive passenger compartment. The test was conducted inside a fully anechoic chamber with the structure excited by a point force using random input signals. The radiated acoustic pressures were measured via a linear array of microphones at a very close distance to the structural surfaces, and taken as the input to the HELS codes to reconstruct NSV and surface acoustic pressures (SAP). The first part of the study establishes the accuracy of the HELS reconstructions by comparing the reconstructed NSV to the benchmark NSV directly measured using a laser vibrometer. The second part is panel acoustic contribution examination (PACE) that utilizes the reconstructed NSV and SAP to determine the normal-component of the time-averaged acoustic intensity on the panel surfaces. The relative contributions from individual panels toward sound pressure level at any field point inside the compartment are determined by summing the acoustic power flow from individual panels to the field point. PACE enables one to establish the ranking of each panel for its contribution to the sound pressure level (SPL) at any field point, say, the driver ear position. The major advantage of using the HELS approach is that it can characterize the structure-borne noise on the source surface and surrounding fluid medium, as well as determine the panel contributions toward SPL values at any number of field points based on a single set of pressure measurements. |
Scan and Paint for Acoustic Leakage Inside the Car | Leakage ranking of vehicle cabin interiors is an important quality index for a car. Noise transmission through weak areas has an important role in the interior noise of a car. Nowadays the acoustic leakage inside a cabin can be measured with different techniques: Microphone array-based holography, Trasmission loss measurement, Beamforming analysis, Sound intensity P-P measurements and ultrasound waves measurements. Some advantages and limits of those measurement approaches for quantifying the acoustic performance of a car are discussed in the first part of this paper. In the second part a new method for fast leakage detection and stationary noise mapping is presented using the Microflown PU probe. This method is called Scan & Paint. The Microflown sensor can measure directly the particle velocity which in the near field is much less affected by background noise and reflection compared with normal microphones. This makes the sensor very suitable for measurements inside a complex and reactive environment like the interior of the car. A camera is used to film the sweep measurement procedure of some surfaces in the cabin interior of a Toyota Avensis. The audio data is processed and synchronized with the video data. A velocity or intensity colormap can be calculated for the different interior parts of the car under test. |
Improved Noise Source Identification Using Sound Quality Metrics Mapping in Vehicle Noise Measurements | A method of mapping a sound field using sound quality metrics has been investigated with an aim of identifying noise sources based on their sound characters rather than traditional measures such as sound pressure level (SPL) and intensity. The method having 11 metrics was implemented in four different array applications, namely near-field acoustical holography, planar beamforming, spherical beamforming, and patch acoustical holography. The sound quality metrics (SQ) mapping was applied to diesel engine measurements as well as vehicle interior measurements. In both applications, there have been a number of attempts to identify impulsive noise sources and therefore in this investigation an impulsiveness metric was developed. The proposed metric was validated against ideal impulses as a function of impulse repetition frequency, amplitude and duration of impulses. The results of noise source identification in both applications revealed that the proposed impulsiveness mapping enabled the detection of impulsive or rattling sources to be more effective compared to the use of SPL and intensity. Furthermore, a number of potential improvements on the SQ mapping are discussed. |
Sensation and Measurement of Low and Very Low Frequency Time-Varying Sounds in Accordance with the Very Short Impulse Response of Low-Frequency Human Hearing | Human hearing, with its active transducers, attention process and remarkable signal-processing abilities, challenges the transportation-product sound quality engineer to measure accordingly and has clearly given rise to the practice and tools of sound quality engineering. Transient events and/or level changes of various durations and magnitudes and over various frequency bandwidths are measurable with due care in the majority of ?쐒eal-world??acoustic time-signal histories, and frequently carry subjective importance. Inspired by recent work with wind-turbine sound situations, the focus of this paper is to suggest reconsideration of some low-frequency measurement methodologies in the transportation realm. Results will be presented coherent with the hearing system's unusually short impulse response at low and very low frequencies (principal magnitude within about 10 milliseconds, slight effect to about 75 milliseconds), which make low-frequency impressions not only sensitive to time variation, but even to very short-term transitory levels. Hearing-event evaluation is strongly weighted by short-term near-peak values not revealed in overall results and largely erased in conventional constant-percentage-bandwidth measures versus time such as 1/3-octaves. This sound quality concept is generally known and applied at mid and high frequencies, but would be productive to extend to low and very low-frequency sensation and measurement. |
Measuring Damping Loss Factors of High Performance LASD Coatings | One of the most effective NVH solutions used in the automotive industry to reduce structure-borne noise is to apply vibration damping treatments to the vehicle structure. These damping treatments need to meet increasing weight reduction targets, while offering the same or better damping properties. While Liquid Applied Structural Dampers (LASD) are now delivering high damping performance at lower densities, traditional damping measuring techniques are falling short in describing the performance of these extensional layers when applied onto more realistic test samples or real structures. This paper discusses the damping performance of LASD technology, in particular the newer generations of acrylic-based waterborne LASD materials, which through improvements in polymer architecture are achieving increased damping efficiencies together with reduced density. The paper further describes a test method for evaluating the composite damping loss factor (CDLF) properties of LASD treatment layers applied to metal panels used as test samples. The panel test method is based on the calculation of the reverberation time as determined from the initial decay rate of the band filtered impulse response functions. The damping data determined by using this test method is found to be in good agreement with similar data measured independently by using power injection methods (PIM). Correlations between damping performance of LASD treatments measured by using panel testing, one dimensional beam testing, and body-in-white testing methods are also discussed. The damping measurement technique described was used as a validation tool for the latest generation, lower weight, high performance, LASD materials. Panel measurements correlate well with existing test techniques and provide useful information on damping performance, in a high modal density environment, which can be used as input into advanced NVH modeling techniques. |
Damping Mass Effects on Panel Sound Transmission Loss | The primary function of damping treatment on a vibrating panel in a vehicle is to reduce vibration levels or radiated sound power by the dissipation of energy. However, in automotive applications the mass effects of damping materials should not be ignored, especially with regard to airborne noise performance. In this paper, a Finite Element-Statistical Energy Analysis (FE-SEA) hybrid analysis is used to evaluate the mass effects of applied damping materials on Sound Transmission Loss (STL). The analysis takes into consideration effects on both the elastic properties and modal mass of the panel. It is shown that while uniformly distributing the mass of the damping material over the panel generally over-estimate the mass effects on STL, an area weighting approach underestimates the effects. Results are confirmed by laboratory testing. A nomogram is generated to show the total effect of the mass of the damping material on STL. |
Simulation of Noise Reduction in Passenger Trains Using Metal Foams | One of important problems in railway transportation systems is control of noise and vibration. Metal foams are very good medias for absorbing noise. So in this paper, noise of motion of a train is simulated by MATLAB software and the reduction of noise level in a compartment of passenger car that is equipped by metal foam sheets is considered. Commonly, the sound absorption coefficients are obtained experimentally and they are available in datasheets and references. The different parameters that influence on the capability of this equipment were considered. For example the microstructure, thickness, magnitude of compaction, relative density and etc of metal foam is effective parameters. High porosity has good effect on the performance of absorber sheet. By increasing of compaction ratio, in frequency domain we will have enhancing of absorption of the noise. Compaction process is done by two different ways: one is direct and else is progressively. Relative density has inverse relation with reduction of sound pressure level. So with these considerations the absorption ability of metal foams is less than glass wool as one of the best available noise absorbers in industry. But by changing the microstructure such as rolling, compaction and derailment and also increasing area of used metal foam, we can achieve to high level performances. |
Spirit AeroSystems Acoustics Lab: Measurement and Analysis Capabilities | Previously part of a larger OEM, Spirit AeroSystems became a standalone company 5 years ago and is currently a Tier One supplier of aerostructures. Products include fuselage components, wing structures, engine struts and nacelles, and at the request of various OEMs, fully stuffed fuselages and podded engines where all of the wiring, heating, duct work, etc. is installed prior to delivery. While operating as part of the Propulsion Structures and Systems Business Unit, the design, testing and analysis services provided by the acoustics lab potentially impact all programs at all stages of development because of increasing noise regulations and material certification requirements for implementation in high noise environments. In order to address these issues, the acoustics lab has three main objectives: support design and development of engine nacelle lining technologies, ensure components meet structural fatigue requirements and ensure aircraft interiors meet noise regulation exposure limits. Historically, the primary focus of the lab has been the development and testing of acoustic liners and their components and qualification of assemblies and materials that will be exposed to high level noise environments. One objective of this paper will be to discuss the methods used to design, develop, and verify the performance of an acoustic liner and the structural integrity of not only the acoustic liners but any assembly or material installed in a high level noise environment. A second objective will be to discuss the development of new testing and analysis capabilities that arose from the relatively recent requirement to address structural acoustic and interior noise requirements. |
A Pragmatic Approach to Production NVH Test of Seat Adjusters | A powered seat adjuster is a complex mass-produced assembly that is heavily optimized for low cost and light weight. The consequence is an inevitable degree of uncontrolled variation in components, subassemblies, and final product. Automakers are driving an exceptional focus on quality and the showroom experience of the car buyer is paramount. Therefore, any seat adjuster with the potential to not satisfy the customer's expectation is likely to be screened on the production line. This paper describes NVH metric design in the context of automated production line detection of seat adjuster defects. A key requirement of the production environment is that the metrics offer intuitive explanations of possible defects and are based on industry-standard formulations. The metric set is a hybrid of objective and subjective parameters with a focus on ensuring a robust sorting process that maximizes detection while minimizing the possibility of failing acceptable product. As a set, the metrics are therefore capable of correlation to human subjective impression of the seat track sound as well as direct indication of specific defects that may fail one or more objective metrics. |
Practical Considerations of Driveline Vibration and Acoustic Test Cell with Case Study of McLaren's Driveline Dynamometers | Test Facilities for Vibrations and Acoustics can be very complicated. With the addition of necessary high power motor dynamometers for load application, the complexity of the test cell increases dramatically. The motors and subsequent additional fixtures and shafts necessary to apply loading conditions can produce additional source noises that would interfere with test measurements. In addition, facility interfaces can dramatically influence the test cell setup and reduce the measurement capabilities. This paper addresses common considerations needed in considering a new test cell for driveline vibration, acoustics, efficiency, and durability testing using motored dynamometers. In addition to outlining common design points, a practical application of 2 new dynamometers utilized for vibration, acoustics, efficiency, and durability testing and their subsequent capabilities are outlined. |
VALIDATE - Basis for New Sophisticated Research Platform for Virtual Development of Vehicle Systems | The Stuttgart Driving Simulator currently under construction at the University of Stuttgart makes out the main component of the University's new automotive research platform. The facility will be one of the largest of its kind in Europe. The simulator is based on a powerful eight axes motion system to realistically recreate the linear and rotary motion as perceived by the driver during a real trip. To add further value to the driving simulator, it is designed to house a real vehicle which can be easily exchanged - from small passenger cars up to large luxury sedan vehicles as well as SUVs. To assure a sound testing environment, the driving simulator features a realistic graphical and acoustic representation of the vehicle environment such as roadway, environment, and traffic. This is achieved through a complex surround visualization system with very high level of detail as well as an advanced spatial acoustic noise generator. Additional to this, high-quality dynamic force feedback systems at the control elements (pedals, steering wheel, gear stick, etc.) ensures a realistic vehicle and driver milieu. The research platform currently set up is predominantly specialized for energetic topics within the automotive research and development and hence well suited for contemporary topics like sustainable mobility. A major research topic will cover the field of driver influences. With the measurement vehicle, as a further component of the research platform, a first, for German conditions representative study, has been conducted. The acquisition of the driving resistances and power flows in IC, the onboard electrical system, auxiliaries, exhaust system, and cooling system during real drives confirms the strong influence of the driver on the fuel consumption and thus the CO??emissions. On average, the driver accounts for a 6.5% fuel consumption variation and in a standard situation variations in fuel consumption up to 65% due to driving style have been measured. Based on the knowledge about the saving potential in various driving situations, appropriate assistance systems can be designed and qualitatively and quantitatively tested and verified in the new driving simulator environment. |
Optimum Constraint Strategy for Liftgates | The present study defines the functional requirements for a liftgate and the body in order to avoid rattle, squeak, and other objectionable noises. A Design For Six Sigma (DFSS) methodology was used to study the impact of various constraint components such as bumpers, wedges, and isolated strikers on functional requirements. These functional requirements include liftgate frequency, acoustic cavity frequency, and the stiffness of the liftgate body opening. It has been determined that the method of constraining the gate relative to the body opening has a strong correlation to the noise generated. The recommended functional performance targets and constraint component selection have been confirmed by actual testing on a vehicle. Recommendations for future liftgate design will be presented. |
Experimental Analysis of the Filter Element Influence in A/C System | The study objective is to evaluate the thermal comfort and vehicle safety emphasizing on air-conditioning system. Several aspects of automobiles thermal comfort are associated with security issues as the windows defogging and defrosting, and air quality inside the vehicle. For the automotive industry, constant air flow in the vehicle is the reason of continuous research on the improvement of the stream and quality of the air that reaches the occupants. This work presents flow bench and vehicle experimental tests results ass an evaluation of the possibilities of the filter element improvement, for the flow, air filtering and temperature adjustment optimization inside the vehicle. Comfort and safety evaluations were made by the air stream inside the vehicle and experimental tests in a climatic chamber. All the tests were made in the same vehicle. Local head losses were evaluated at the flow bench and the vehicle conditioning at the climatic chamber. The pressure inside the vehicle was analyzed during the flow variation, to ensure a comfortable condition for vehicle occupants. |
Door Latch Strength in a Car Body Environment | Federal Motor Safety Standard (FMVSS) 206 regulates the minimum strength of side door latches in passenger carrying vehicles. The purpose of the standard's requirements is ?쐔o reduce the likelihood of occupants being ejected from vehicles in real world accidents.??Investigation of unwanted door openings during accidents has revealed various types of latch failures that do not produce latch and/or striker damage consistent with that found in Federal Motor Vehicle Safety Standard compliance testing. An intersection collision in which a striking vehicle contacts the struck vehicle aft of the affected door has for many years been considered the ?쐌ost critical to door latch performance??(1). This type of car to car collision will often result in structural separation of the door end panel, ?쏝??post striker panel or latch/striker assembly. These structural failures combine tensile and shear loading on the latch/striker assembly. This paper defines the state of the industry with regard to vehicle door latch strength using a simple testing method that produces door latch separations more consistent with common intersection side impact collisions. The test methodology simultaneously applies both longitudinal and lateral loads as the vector sum of the FMVSS 206 defined loads. To place the test findings in perspective, results are normalized using the existing 206 requirements. |
Development of Cabin Air Quality System | In recent years, concern among car users regarding air quality has been steadily increasing. Pollen and diesel vehicle exhaust gases entering the cabin and smoke from fellow passengers not only reduce the quality of experience for everyone in the car, but are also harmful to the health. Therefore, we developed: 1 A low pressure loss, dust-removing, selectively deodorizing filter that effectively absorbs malodor from diesel vehicle exhaust gas, without affecting A/C performance. 2 An automatic intake door control system that excludes outside exhaust gas 3 An optic catalytic air purifier with germ removal and long life deodorizing functions. We here report on the system combining these functions. |
Effects of Vehicle A-pillar Shape on Local Mean and Time-Varying Flow Properties | Separated flow is the main generator of aerodynamic noise in passenger vehicles. The flow around the A-pillar is central to the wind noise as many modern vehicles still have high fluctuating pressures due to flow separations in this region. Current production vehicle geometry is restricted due to the amount of three dimensionality possible in laminated windscreen glass (and door opening etc). New materials (e.g., polycarbonate) offer the possibility of more streamlined shapes which allow less or no flow separation. Therefore, a series of experimental investigations have been conducted to study the effects of the A-pillar and windshield geometry and yaw angles on the local flow and noise using a group of idealised road vehicle models. Surface mean and fluctuating pressures were measured on the side window in the A-pillar regions of all models at different Reynolds numbers and yaw angles. Flow visualisation was also used to see the flow structure and supplement the surface mean and fluctuating pressure data. Frequency based analysis was conducted. The studies show that depending upon the curvatures of A-pillar and windshield, the fluctuating pressure coefficients can be reduced significantly. Reynolds number sensitivities were minimal and the surface mean and fluctuating pressures can be scaled if no feedback mechanism is present. A relationship between the surface fluctuating pressure coefficients and local A-pillar radii was established. |
System Design Parameters in Determining Automotive Sidelite Glazing Performance | A study has been conducted to develop design criteria for materials for use in glazing systems and to identify the parameters affecting actual intrusion-resistance. The intent is to be able to provide the automotive consumer with enhancements in occupant security and safety through incorporation of enhanced protective glass (EPG) in body glass locations. Based on actual sidelite attacks and measurements of human applied forces, an appropriate and comprehensive test methodology has been developed. The test method extends beyond simple impact by providing a measure of the applied force or energy to gain entry to the vehicle through the sidelite as installed in a vehicle. Tests have revealed that the performance level depends not only on the particular glazing type utilized, but how it engages with the door system which in turn controls the in-service performance. Information generated by this methodology has compared favorably with time-to-vehicle-entry obtained from direct human attack. This type of comprehensive testing has provided valuable information for guiding glazing development and outlining parameters for proper design of door systems. The sidelite testing and product evaluation has also provided insight into factors which relate to occupant interaction and safety when occupant contact with body glass occurs. Many of the relationships overlap between occupant security and safety, such that, if a reasonable degree of intrusion-resistance is provided, there will be a commensurate benefit in occupant safety (c.f., ejection-mitigation). |
ISS Crew Refrigerator Freezer Rack - Comparing EcosimPro and ESATAN Modeling | The Crew Refrigerator/Freezer Racks (RFR) are being developed and built at Astrium Friedrichshafen under ESA contract. The RFR will provide conditioned storage volume for astronaut food during transport in the MPLM and on board the ISS. To support the design of the RFR a thermal model has been established at Astrium in the early project phase using the ESATAN software which is the ESA standard thermal analysis tool. This model has been extended to allow full operational simulation of the RFR during a typical mission scenario. For demonstrating the capabilities of EcosimPro, a state of the art tool to address Environmental Control and Life Support analysis, the same model is built up with EcosimPro. The results are validated by comparing them to those from the ESATAN simulation. Three simulation cases are investigated: steady state operation mode, 8 hours passive period with increase of ambient temperature from 30째C to 49째C and recovery, door opening every 3 hours for up to 30 seconds at ambient temperature of 30째C. |
?쏛 Dry Aircraft is a Safer Aircraft ??Beating Condensation by Using Dry Air??"The airline industry seems to be providing more leisure features on planes like inflight entertainment | Internet access and Digital TV |
Peugeot Fractal demonstrates a new take on sound design | Peugeot used the 2010 SR1 concept to introduce its i-Cockpit touchscreen-based system, designed to control heating and ventilation, navigation, audio, connectivity, and the trip computer. The first-gen system entered production in the 2012 Peugeot 208. The company took the i-Cockpit concept one stage further in the Fractal electric urban coupe concept at the 2015 IAA Frankfurt Show, to include sound. The concept plays a ?쐓ound signature,??created by DJ and sound designer Amon Tobin, which is triggered when the driver opens the car using the smart watch remote locking system. ?쏝ehind this concept of an electric car-that is not really new, there was this question that electric cars emit no sound,??explained Matthias Hossann, Head of Concept Cars and Advanced Design at Peugeot. |
Momentum, the Magazine for Student Members of SAE International 2010-09-01 | High-speed education @ formula hybrid event Annual competition provides a hands-on learning experience for undergraduate and graduate engineering students. Body-shaped for supermileage Six different single-occupant vehicles designed and built by teams of collegiate engineering students snared four-digit fuel economy at Eaton Corp.'s Marshall, MI, test track during the 31st annual SAE Supermileage competition in June. Mercedes-AMG goes with the current flow Opening the doors on new technology. First flight approaches for 'disruptive' new UAV engine An earlier iteration of UAS' Nightwind 2 in flight, powered by an off-the-shelf industrial engine. Three resume tips for college grads Employers often hire recent graduates to mold new hires to their own corporate culture and work philosophy, leading some employers to look more for potential than for specific experience. SAE, Deere announce 'learn twice' initiative Students involved in SAE International's Collegiate Design Series can get their team's registration fee reimbursed by working with local elementary and high school teachers to teach science, technology, engineering, and math concepts through the "A World In Motion" curriculum. EngineerXChange being launched to help attract younger members With the launch of EngineerXchange in October, SAE is hoping to communicate with young engineers via the Web and social media. |
Automotive Engineering: March 2021 | Engineering Ford's future Product platform and operations chief Hau Thai-Tang on navigating the microchip shortage, compact-unibody trucks, EV and AV challenges, and driving engineering efficiencies amid the lockdown. NAWA aims for 5-minute EV charge A new nano-based carbon electrode is key to reducing electric-vehicle charging time. Hemphill's mission: Support the innovation ecosystem Schaeffler America CTO Jeff Hemphill brings impressive technical chops and well-honed communication skills to his new role as 2021 SAE International president. Editorial The legacy of the pioneering, controversial EV-1 SAE Standards News Help wanted: SAE tech standards committee, task force seeks new members SUPPLIER EYE Electrification and the Two-Cycle Imperative Electrified Corvettes in development German OEMs flex 3D manufacturing muscle ZF builds 'middleware' to address vehicle software escalation TDK unveils power-generating wheel sensor Bosch consolidates computing talent in new mobility division Ford F-150 Raptor goes 4-door only; R version next year Q&A Celina Mikolajczak, VP of battery technology for Panasonic Energy of North America, discusses The relentless pace of EV battery development and manufacturing |
Momentum, the Magazine for Student Members of SAE International 2012-10-31 | The Nano in retrospect A senior graduate student in the Department of Mechanical Engineering at the Indian Institute of Technology looks at the development of the world's cheapest car and its effect on Indian car users. A different riff on your basic two-seat electric car Markus Lienkamp, Chair of Automotive Engineering at the Technical University of Munich, is leading the Visio.M project, a German government-supported R&D effort to produce a low-cost, high-utility electric car that might attract the interest of the middle European mass market. Materials lead the way to vehicle mass reduction Reducing a vehicle's mass opens the door for a downsized engine and transmission, a lighter cradle and body structure, smaller wheels and brakes, as well as a weight-slimmed suspension. The start point for this ripple effect is materials. |
Momentum: October 2014 | Buckeye Current's TT triumph The Ohio State University reprised its third-place finish in the 2014 TT Zero for all-electric motorcycles, beating some of the pros on the world's toughest race circuit. Kettering FSAE team improved as season progressed Lowest priced may not mean the best, but certainly not the worst. Leveling the field: getting #girlsinstem Despite facing the brunt of gender segregation, women are forging ahead and dramatically improving STE M, both academically and professionally. Mercedes-AMG's SLS departure opens door to new GT Powering the car is an all-new biturbo 4.0-L V8 available with two power levels: hot (GT) at 340 kW (456 hp) and exceedingly hot (GTS) at 375 kW (503 hp). |
Analytical and Experimental Approach to Acoustic Package Design | The interior noise signature of passenger vehicles is a significant contributor to a customer's perception of quality. The vehicle acoustic package can be an important piece to the acoustic signature, and can be utilized not just to reduce the sound levels inside the vehicle but also to shape the sound such that it meets the expectations of the customer. For this reason the definition, design, and development of an acoustic package can be vital to meeting vehicle-level acoustic targets. In many situations this development is conducted experimentally, requiring the availability of prototype vehicles and acoustic package components. Of more value is the ability to develop components early in the design phase, leveraging analytical tools to define component-level requirements and targets to meet the vehicle-level targets, and ultimately meet the final customer expectations. This paper presents efforts made to further combine the benefits of experimental and analytical approaches to acoustic package design. The benefits of which include the ability to predict interior sound levels for alternative acoustic package configurations early in the design phase, allowing for listening studies to verify component and vehicle-level targets. Additionally, the performance of alternative designs can be quantified in the frequency domain and using sound quality metrics, while minimizing the necessity for physical testing. A current market vehicle was utilized for this development, in which experimental measurements were developed and conducted for optimum cooperation and utilization of analytical tools. The acoustic package was characterized to predict the sound levels for alternate acoustic package designs, listening studies were performed and metrics were calculated for each configuration to verify performance against the vehicle-levels targets, and developed solutions were verified through experimental testing. |
A CFD/SEA Approach for Prediction of Vehicle Interior Noise due to Wind Noise | For most car manufacturers, aerodynamic noise is becoming the dominant high frequency noise source (> 500 Hz) at highway speeds. Design optimization and early detection of issues related to aeroacoustics remain mainly an experimental art implying high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the development of a reliable numerical prediction capability. The goal of this paper is to present a computational approach developed to predict the greenhouse windnoise contribution to the interior noise heard by the vehicle passengers. This method is based on coupling an unsteady Computational Fluid Dynamics (CFD) solver for the windnoise excitation to a Statistical Energy Analysis (SEA) solver for the structural acoustic behavior. The basic strategy is to convert the time-domain pressure signals generated by CFD everywhere on the panels into structural power inputs, which in turn are used as input to an SEA model leading to the noise inside the cabin. This approach quantifies the windnoise contribution coming from different panels (e.g. side windows, windshield) at various locations inside the vehicle (driver and passenger headspace). In this paper the key technical and numerical aspects of the approach are presented, and interior noise predictions corresponding to real automotive cases are compared to experimental measurements. As examples of the usage, a vehicle exterior shape design study and an acoustic package optimization study are presented. |
A Systematic and Disciplined Process for Developing Drive Files for Squeak and Rattle and Durability Tests in the Lab | The pressure to shorten vehicle product development time-to-launch means more in-lab tests must be performed earlier, and before vehicle prototypes are available for road or test track evaluations. Squeak and Rattle (S&R) evaluations of subsystems/modules and components must be performed using realistic road excitation conditions. How S&R performance degrades as the vehicle, module or component accumulates customer miles or kilometers must be assessed before the design is frozen. Durability tests must be performed earlier in the design/development timeline as well. All these pressures point to having a systematic, disciplined and streamlined methodology or protocol for acquiring and processing road vibration data useful for S&R and durability tests. The protocol must comprehend data acquisition, sampling, and signal processing; properly editing acceleration time histories for either in-lab replication as time histories or as PSD random vibration; creation of drive files that replicate multiple road surfaces; combining multiple road surfaces and speeds into fewer (if not one) tests that replace one-test-for-one-road-condition approaches; selecting overall vibration amplitudes for composite multiple roads; and performing such tests in order to satisfy S&R and durability experts, design/release engineers seeking design validation, and multiple other stakeholders. This paper presents such a protocol based on the expertise from different engineers working on a multitude of vehicle development programs from different companies in different countries over many years. |
A Generic Model for Analysis and Optimization of Fuel Filler Door with Torsional Spring | A mathematical model was developed for the analysis of a fuel filler door with a torsional spring. The model calculates performance indices such as opening and closing forces, kinetic energy during opening and closing and the maximum spring stress. The model was integrated with an optimization program. Two types of optimization problems were formulated: the traditional problem which does not include the effects of random design parameters, and the stochastic type optimization, which does. An example shows how the mathematical model, in conjunction with optimization techniques, can help determine fuel filler door designs. |
Modelling the Dissipative Effect of Seal Air Hole Spacing and Size on Door Closing Effort | Door weather strip seals are designed with ventilation holes spaced at regular intervals along the seal system to expedite the flow of air from the seal system during the door closing process. The flow of air through the ventilation holes represents a nonlinear damping mechanism which, depending upon hole size and spacing, can significantly contribute to door closing effort. In this study we develop one- and two- dimensional versions of a nonlinear damping model for seal compression load deflection (CLD) behavior which incorporate the effects of seal damping response due to air flow through the ventilation holes. The air flow/damping models are developed from first physical principles by application of the mass and momentum balance equations to a control volume of entrapped air between consecutive air ventilation holes in the seal system. Both model formulations indicate that the damping component of seal force per unit length generated during seal compression is directly proportional to , where L and D represent, respectively, the spacing distance and diameter of the air ventilation holes. Numerical predictions for the damping force at a section in a production vehicle door seal system during closing are made using the two models and results compared. |
Door Structural Slam Durability Inertia Relief Approach | The automotive industry faces many competitive challenges including weight and cost reduction to meet CAFE standards. In particular, a thin door panel optimized for weight reduction can cause high manufacturer warranties and durability problems. Traditionally, the assessment of door slam durability is accomplished by tests rather than using computer aided techniques. Many simple CAE techniques such as simple linear static and dynamic analyses have been used to evaluate the door structural integrity. However, the door slam event requires complex analysis due to the transient impact phenomenon. To solve this complex door slam event with a computer based technique is a challenging and interesting problem for CAE engineers. However, a simplified technique has been developed to anticipate the potential durability problem in the door. This technique involves the use of the computer- based finite element method incorporating inertia relief and fatigue life prediction. Actual testing validated the analytically predicted results. This method provides an inexpensive way of predicting door slam durability reducing development time and product cost. As a result, the new approach aided the door design robustness. |
Research on the Application of Aluminum Door Beams for Automobiles | The effect of cross-section and type of alloy on the performance of aluminum extrusions as door beams was investigated. As a result, aluminum door beams were developed which have bending properties comparing favorably with those of door beams made of high tensile strength steel with a tensile strength of 1470 N/mm2. Furthermore, a technology to design door beams with the required performance and bending properties dealing with various car models was developed by making the most of the versatility of aluminum extrusions produced in various types of cross-sections. |
Response of the Eurosid-1 Thorax to Lateral Impact | The Eurosid-1 dummy was subjected to a series of lateral and oblique pendulum impacts to study the anomalous ?쐄lat-top??thorax deflection versus time-histories observed in full-scale vehicle tests. The standard Eurosid-1, as well as two different modified versions of the dummy, were impacted at 6 different angles from -15 to +20 degrees (0 degrees is pure lateral) in the horizontal plane. The flat-top deflections were observed in the tests with the standard Eurosid-1, while one of the modified versions reduced the flat-top considerably. Full scale vehicle tests with the standard and modified Eurosid-1 suggest similar reductions. A second series of tests was conducted on the modified Eurosid-1 to investigate the effect of door surface friction on the shoulder rotation and the chest deflection. The data suggested that increasing the friction on the door surface impeded shoulder rotation and ultimately reduced the chest deflection in the Eurosid-1. |
An Investigation of Vehicle HVAC Cabin Noise | Noise and vibration have an important influence on a customer's perception of vehicle quality and cabin interior noise levels are a key criteria. The interior sound levels of automobiles have been significantly reduced over the years, with reductions in power train, tire and external wind noise. One of the highest in-cabin noise levels now arises from heating, ventilating and air conditioning systems, generated by the air-rush noise at various HVAC settings. Thus quieter climate control systems are desired by car manufacturers. A systematic benchmarking study was performed to investigate the in-cabin noise of vehicles. 21 passenger cars including compact, mid-size, full-size, and a truck were selected. Tests were conducted on relatively new production vehicles in various conditions. A binaural head system was used in front passenger seat to measure noise levels. The methodology used and the experimental results were presented in this paper. It was found that the design of the HVAC system has a major influence on the vehicle in-cabin acoustic performance. The size/price of the vehicle may not correlate to the cabin quietness due to the complexity of acoustic effects in the HVAC system. |
Class A Application/Definition | This SAE Information Report will explain the differences between Class A, B, and C networks and clarify through examples, the differences in applications. Special attention will be given to a listing of functions that could be attached to a Class A communications network. |
Investigation on Wiping Noises and NVH Design Consideration in a Wiper System | As automobiles become increasingly quieter, the wiper operation noise becomes more noticeable by the customer. This paper deals with the experimental approach and the methodology to investigate the Friction induced wiping noise. Role of design in a wiper system plays a very imperative task in meeting the performance of wipers but at the same time it does not cater to the NVH issues. Some of the important design parameters which affect the NVH properties of the wiper system are highlighted in this paper. For better understanding of the system some of the best in class vehicles for SUV category were tested and compared with our test vehicle. In this study more importance given to analytical part which is more important to investigate and in depth study of the friction induced noise. For analytical study some techniques such as time frequency domain i.e. Wavelet transforms, frequency domain and time domain where extensively used. Finally ranking of the NVH design factors based on the criticality are stated in this document. These factors may be helpful during design of wiper system for better NVH, without deteriorating the functional performance. |
Sound Absorbers in Small Cavities | The automotive industry is often interested in controlling noise radiated from trim pieces in the passenger cabin. In general, there is a small air gap that separates these trim pieces from the sheet metal that is the actual source of the noise. It is common practice to place an acoustically absorbent material in this space to reduce radiated noise. In this paper the in situ noise control performance of a variety of materials is examined by placing them in a test fixture that simulates the sound field in the vicinity of vehicle pillar trim. In this fixture a noise source is positioned behind a piece of sheet metal. A flat plastic sheet that is similar in composition to pillar trim is placed a small distance away from the sheet metal. The sides and rear of the fixture are sealed so that the plastic sheet is the only significant radiator of the sound radiated from the sheet metal. The random incidence and normal incidence performance of a variety of absorbers are compared to their performance in this test fixture. In addition, the theory that relates the acoustic absorption of a material to its ability to decrease noise levels will be considered. |
Application of an Elastomeric Tuned Mass Damper for Booming Noise on an Off-highway Machine | NVH is gaining importance in the quality perception of off-highway machine performance and operator comfort. Booming noise, a low frequency NVH phenomenon, can be a significant sound issue in an off-highway machine. In order to increase operator comfort by decreasing the noise levels and noise annoyance, a tuned mass damper (TMD) was added to the resonating panel to suppress the booming. Operational deflection shapes (ODS) and experimental modal analysis (EMA) were performed to identify the resonating panels, a damper was tuned in the lab and on the machine to the specific frequency, machine operational tests were carried out to verify the effectiveness of the damper to deal with booming noise. |
A New Modeling Technique of Large Trim Part Air Passages for An Accurate Acoustic Model | Finite element models based on the design drawing information are widely applied in the early development stage in the automotive industry. During this stage, the performances of noise and vibration of a vehicle are evaluated by the calculation using FE models. Therefore, it is extremely important to secure the accuracy of the calculation by FE models. Otherwise the problem does not solved with the countermeasures implemented in FE models. To predict sound pressure levels in the passenger compartment, an acoustic model for the compartment must be precisely created. Experimental analysis have shown in the past that narrow air gaps between interior trim parts or between a trim part and a body structure have a high impact on the acoustic transfer functions even in the low frequency range where the issues on booming noise and road noise are often addressed. However, the narrow gaps are usually not modeled in FE models because a lot of small finite elements are needed to express the narrow gaps and much resource is required for the calculation. In this study an acoustic leakage element is proposed to model the narrow air gaps. This element consists of one hexahedral element representing air gaps and several rigid elements connecting adjacent acoustic fields. Specifications for the hexahedral element are experimentally identified by using Helmholtz resonator. The proposed method is verified by the comparisons between the measured and calculated acoustic transfer functions of a vehicle. |
Brake Grind Noise Reduction Potential on Vehicle Level - A TPA Study | Rust accumulated on disc rotor surfaces causes brake judder and excessive grind noise. This low frequency noise phenomenon is audible especially at low vehicle speed without masking from other noise sources like wind and road noise or power train sound. This often leads to customer complaints resulting in significant warranty costs. Alternative drive systems like hybrid or full electric power trains will emphasize this problem. Most studies concentrate on optimization of the brake system to reduce low frequency brake noise. In this work, the potential for optimization on vehicle level was investigated. The most effective NVH optimization can be achieved by improving and matching the acoustic properties of the vehicle and the brake system. In a first step, the main structure borne noise transfer paths have been identified by means of Transfer Path Analysis. A detailed analysis of the relevant transfer paths shows critical sound transmission of the suspension system and its attachments to the vehicle body. The potential of this approach for brake noise optimization is demonstrated by an example. As a second step, the radiating body surfaces contributing to the perceived brake noise have been identified using panel contribution analysis. This helps to optimize the vehicle body structure and trim package. The potential for improvements has been predicted using a modified interior noise synthesis model. The results have been verified experimentally by principal modifications to the vehicle. |
Operational Modal Analysis Techniques used for Global Modes Identification of Vehicle Body Excited from a Vehicle in Idle Engine | With the purpose to identify the root cause of increased levels of vibration felt at idle speed in a popular vehicle prototype a study was conducted using techniques for analysis of vibration transmission between components of a vehicle, using Mechanical Vibrations Analysis and Operational Modal Analysis, for the analysis of the operational modes was used ODS - Operational Deflection Shape technique which is possible only see the shapes related to probable modes. The experimental results were compared with results for the modal analysis by Finite Element Method (FEM). The vehicles used are identical prototypes, but with different levels of vibration. Therefore, to study there is a vehicle with satisfactory levels and a second with unsatisfactory levels. This study demonstrates the methodology used to identify the cause of the different behaviors between cars and also discuss the improvements made in the body according to the results of the numerical experimental confrontation. |
CHARACTERISATION OF PASSENGER VEHICLE IN-CABIN NOISE USING OMA AND SOUND QUALITY TECHNIQUES - AN INTEGRATED APPROACH | In the recent past, interior noise quality has developed into a decisive aspect for the evaluation of overall vehicle quality. The paper discusses the effect of structural modes of vibration caused in a passenger car during its operational conditions and its effect of noise inside the cabin. In order to characterize the body modes under road operation, OMA is used and the Interior noise quality of car cabin is judged by the Sound quality tools. Based on the jury evaluation, the problem is identified and problem area is identified with operational modal analysis techniques to take the countermeasure and verification of the study is done. The relation of body modes is established to overall cabin noise performance and improvements are checked with use of Modification Prediction tool after identifying the critical areas. This study is helpful in developing the new vehicle modal faster and also to analyze and to take countermeasure at earlier stages of developments. |
Acoustic-Structural Sensitivity Analysis and Optimism of Car Body Multilayer Panels | Acoustic-structural sensitivity analysis for coupled acoustic-structural systems can be conveniently and quickly used in dynamic modifications of car body panels to reduce interior sound pressure level. In practice, car body panels are multilayered structure which consists of the outside skin, the interior trim, and the air gap or absorbent layer between them. The vibration characteristics and the capability of sound insulation of multilayer panels are very important factors which dominate acoustic response in car cavity. A simplified car body model is made to investigate the effects of multilayer panels on interior sound levels. With the model, the relation between the acoustic response of the cavity and the property of multilayer panels are achieved. The validity of theoretical analysis is verified through a comparison between the experiment and the numerical simulation results. Finally, acoustic-structural sensitivity analysis of car body multilayer panels is evaluated synthetically. The panels??structure is optimized, and car interior sound level is improved. |
Modeling Airborne Noise Transmission in a Truck using Statistical Energy Analysis | Statistical Energy Analysis (SEA) was used during the design of a new heavy duty truck. This paper provides an overview of the building and validation process of an airborne SEA model of a typical commercial vehicle. Predictions of interior noise levels are compared against tests. A noise path contribution analysis is presented, demonstrating how the impact of potential design changes on the interior sound levels can be evaluated with an SEA model. |
Vehicle Airborne Noise Analysis Using Boundary Element and Finite Element Energy Based Methods | 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 governing differential equations with energy densities as primary variables. A finite element approach is employed for the numerical solution of the governing differential equations. Results from EFEA simulations have been compared successfully with test results for Naval, automotive, and aircraft structures. The Energy Boundary Element Analysis (EBEA) has been developed for conducting exterior acoustic simulations using the acoustic energy density as primary variable in the formulation. EBEA results have been compared successfully to the test results in the past for predicting the exterior acoustic field around a vehicle structure due to external noise sources. In this paper, the EBEA and EFEA methods are combined for predicting the interior noise levels in a vehicle due to exterior acoustic sources. The EBEA is employed for computing the acoustic field around a vehicle structure due to exterior acoustic noise sources (i.e. tire source, engine source, etc.). The computed exterior acoustic field comprises the excitation for the EFEA analysis. The vehicle structure, the acoustic treatment, and the interior acoustic volumes are represented in the EFEA model. The interior noise level in the vehicle is computed by the EFEA. Predictions for the interior noise level (expressed in a noise reduction format) are compared favorably with test results for two separate types of excitation. A generic case study is presented for computing the interior noise due to exterior acoustic excitation from a transmission and a driveline. |
Acoustics Inside the Space Shuttle Orbiter and the International Space Station | The acoustics environment in enclosed habitable space vehicles and modules is important to mission safety, crew health, and efficient operations. Noise is unwanted sound that can interfere with crew communications and sleep, creating habitability concerns, hearing loss, or other health issues. This paper discusses the acoustic environment and the noise control efforts in the Space Shuttle Orbiter and the International Space Station, and the lessons learned from these efforts. Included is the need to apply the design discipline of acoustics early in the design process, to establish reasonable acoustic limits and ?쐂esign them into??vehicles/modules, and to apply noise control to ensure that limits are met. Program management needs to be supportive of these efforts. |
Optimization of Sound Packages for Commercial Vehicles Using Panel Contribution Analysis | Microphone array-based Panel Contribution Analysis (PCA) is a new technique used for Sound Package design optimization for commercial vehicles. The technique allows for noise control performance and cost optimization. This technique ranks the contribution of fully trimmed structural panels (e.g. floor, roof, etc.) and leaks in a vehicle cabin to the noise levels experienced by a driver while the vehicle is in cruising operation. Often the noise and vibration sources (engine, transmission, exhaust, aerodynamic noise, tires, etc) cannot be easily modified, thus the only practical action to solve noise problems is to design the noise control treatments applied to the vehicle panels. Panels that have a large contribution to the noise levels at the driver's ear are heavily treated with noise control materials, whereas panels with low contribution get little to no treatment. This paper describes a microphone array-based PCA technique, and the results of a successful application of it to optimize the interior noise level performance of a new commercial vehicle. The application results clearly indicated the dominant contributing panels to the sound pressure levels at the driver's ear. |
A PU Probe Array Based Panel Noise Contribution Analysis Whilst Driving | This paper presents new developments on hot wire anemometer based panel noise contribution analysis. The used sensor allows the direct measurement of particle velocity. Some historical remarks are given and the latest developments of the technique are reported. Four steps are required to determine the panel noise contribution of the interior of a vehicle and to visualize the results in 3D. In a first step the probes are positioned on the interior surfaces and their x, y, z coordinates are measured. Based on these data a 3D geometry model is created. The geometry data are acquired using a specially designed 3D digitizer. The second step is a measurement in a certain mode of operation. This step can be done in a laboratory but it is also possible to perform the measurement whilst driving the vehicle on the road. Stationary as well as non stationary running conditions like e.g. run ups are accessible and do not limit the applicability of the method. The third step is the determination of the transfer paths from the panels to a certain listening position. This measurement is done reciprocally. In a fourth and last step the transfer paths are linked with the operational data gathered in step two. The results are then visualized using the 3D geometry model. This paper describes the measurement of a conventional car with a resolution of 180 panels. Since an array of 45 probes was used step 2 and step 3 had to be repeated 4 times. The complete measurement typically takes approximately 3 days. |
Mapping 3D Sound Intensity Streamlines in a Car Interior | Sound source localization techniques in a car interior are hampered by the fact that the cavity usually is governed by a high number of (in)coherent sources and reflections. In the acoustic near field, particle velocity based intensity probes have been demonstrated to be not susceptible to these reflections allowing the individual panel contributions of these (in)coherent sources to be accurately determined. In the acoustic far field (spherical) beam forming techniques have been used outdoors in the free field, which analyze the directional resolution of a sound field incident on the array. Recently these techniques have also been applied inside cars, assuming that sound travels in a straight path from the source to the receivers. However, there is quite some evidence that sound waves do not travel in a straight line. The Maritime Institute of Stetting in Poland made numerous 3 D sound intensity measurements demonstrating an erratic pattern of sound intensity streamlines [1], [2] His approach was transferred from a lab to an actual car cabin upon request of a larger European car manufacturer. At 900 positions inside the car the 3D intensity is measured with a 3 D sound intensity probes using three particle velocity sensors. Such a probe is not susceptible to the pressure-intensity index. Several speakers that are driven in sequence are used as controlled sound sources. The results demonstrate that even with a single sound source, the 3D intensity streamlines are strongly bending, suggesting that far field techniques do not point towards the sound source. |
A Balanced Approach for Wind Noise Control | A balanced approach for wind noise control is presented in this paper. This approach is focused on improved sound insulation and low mass. Initially, the Sound Transmission Loss (STL) of tempered, standard laminated and acoustic laminated glasses for different thicknesses was measured in a STL suite. The critical frequency range was identified from in-vehicle noise measurements. These STL data and in-vehicle results provided the relevant information for a proposal with better acoustic performance and lower mass. The efficiency of this proposal was confirmed with new in-vehicle measurements. |
Ultrasound Techniques for Leak Detection | Leak detection of vehicle cabin interiors is an important quality inspection phase that typically has been handled with various time consuming, or potentially product damaging techniques. Leak detection in tank or pressure vessel applications is almost always a concern for gas or fluid containment in vehicles and in many other industries. Numerous techniques exist for the detection of leaks in these and other types of structures. When testing is required in a production environment, often the speed of leak detection is very important if all samples must be tested. The use of several ultrasound based methods for leak detection in vehicle cabins and pressure vessel applications is presented here. Ultrasound waves are typically classified as having spectral content greater than 20 kHz. In the case of leak detection in a production environment, frequently the ultrasonic spectrum is largely free from background noise content that dominates the audible spectrum. The method for the response measurement of ultrasonic signals presented here is with the implementation of high frequency microphones. The excitation methods presented here are an active method utilizing an ultrasonic emitter, a passive method relying on the passing of air through leak locations, and a vibro-acoustic method utilizing a small electro-dynamic shaker. The methods presented here have been tested for the existence of leaks in some structures, but have not been tested in this paper for the existence flaws and defects that may potentially lead to leaks in some structures after prolonged use. |
Shearplate ??A New Innovative Approach to Reduce Powertrain Noise | This Paper is evaluating the development and effectiveness of using a Shearplate, a new and innovative approach to reduce powertrain noise and vibrations. The results show that the approach is offering monumental improvements in terms of reduced noise and vibrations. Sound quality evaluations also show very clearly that the approach is an effective countermeasure to the targeted problems. With the knowledge gathered during the development and with what is partly presented in this paper we now have an additional tool that car manufacturers can deploy in their efforts to design more fuel efficient and cleaner burning engines without sacrificing NVH performance. |
How Advances in On-Road NVH Simulator Technology Have Enabled Firm Targets for Delivery at the Concept Phase | One of the great challenges of the NVH development process is to ensure that customers and stakeholders in the vehicle team are involved in sound quality decision making throughout a new vehicle programme. Recent developments of interactive NVH simulators have enabled a cost-effective customer-focused method for capturing the opinions and decision making processes of people who are not NVH experts. This paper describes the latest enhancement to the NVH Simulator approach which allows the sounds of virtual vehicles to be evaluated whilst driving on-road. The sounds are created and presented to the driver in such a way that they appear totally natural and the assessor is not aware that they are synthesized. Since the subjective evaluations are performed on normal roads, key decision makers can understand, sign up with confidence to, and appreciate the value of the proposed sounds. The main emphasis of this paper is a recent case study in which the ?쏰n-Road??and ?쏡esktop??simulators were used at the concept stage to deliver an exciting sound to enhance and compliment a new B-segment vehicle. The paper explains how the tools were used to: Set vehicle level sound quality targets to enhance the appeal of the vehicle, including customer surveys and the use of the On-Road Simulator for final sign off at target confirmation drive events. Understand the path and source contributions of a donor vehicle and key competitor. Create and demonstrate a strategy for practical realisation of the vehicle level target. The paper concludes with a discussion of the benefits of the approach and summarizes the next steps in the development of the technology and process. |
Use of SEA to Support Sound Package Design Studies and Vehicle Target Setting | Statistical Energy Analysis (SEA) vehicle models are well-accepted tools for predicting the high-frequency interior acoustic effects of a design change to the structure or sound package of the vehicle. [1] SEA models do not strongly depend on geometric details, which allows SEA to be uniquely used as an analysis tool very early in the vehicle design phase to identify potential Noise, Vibration, and Harshness (NVH) issues caused by proposed changes to acoustic or vibration source levels, component materials, construction details, or sound package details of the vehicle. SEA models can also be used to suggest alternatives while the vehicle is still in the development stages to compensate for a predicted or known degradation to NVH in a vehicle due to a design or source level change. This paper presents a case study in which validation testing and an SEA model were combined to obtain recommendations for the most effective sound package changes to meet NVH targets. The motivation behind this study and the role and benefits of the SEA model are presented. An overview of standard uses of SEA for vehicle design for component-level and full-vehicle level is given. SEA model validation methodology and results are discussed. A description of the measurement test plan and methodology is provided. The use of the SEA model to predict combinations of sound package changes to compensate for changes and to reach NVH targets for a new vehicle and the corresponding results are presented. Conclusions from the work are summarized. |
In Situ PU Surface Impedance Measurements for Quality Control at the End of an Assembly Line | With PU probes the sound pressure and acoustic particle velocity can be measured directly. Over recent years, the in situ surface impedance method, making use of such a probe, has proven to be an alternative to Kundt's tube measurements for product development type of work. The in situ method can also be used for the purpose of quality control on the acoustic material, be it during manufacturing or assembly, ensuring the best possible way to monitor the practical effectiveness of the acoustic package designed earlier on. In order to assess the variance of the acoustic package material leaving the assembly line, a relevant number of samples were taken over time. The quality of both the headliners, and the passenger seats were measured, of 25 cars of the same type. The robustness of the measurement method will be discussed, and the results will be presented. |
Squeak and Rattle Prevention in the Design Phase Using a Pragmatic Approach | Squeaks and Rattles (S&R) today are one of the main issues leading to a down ranking in quality perception of interiors in vehicles. Being annoyed by these types of noises, customers are driving up warranty and goodwill cost to many billion per vehicle model on lifetime. Still most of the problems are solved by automotive manufacturers and suppliers after they appear in hardware testing. Usually expensive solutions like felts and oil/grease are selected to solve the problem. However prevention is the key to eliminate unwanted Squeaks and Rattles early in the design phase based on CAD data and material information. This paper shows a pragmatic approach to support the design engineer to create a virtually S&R free CAD-model. |
Modeling of In-Cabin Climate and Fogging of Windshield | Passenger safety is considered as the central issue in vehicle design. One of the important factors that strongly affect driving safety is visibility through the windshield. Present model is mainly focused on the problem of fogging of windshields including the effects of latent heat and humidity. Model was studied for different climatic conditions like hot humid climate and cold climate. The effect of surface parameters like static contact angle, on defogging was also studied. Further, the effect of AC on in-cabin climate was also studied. Experimental results for condensation on a glass plate very well resembled with the glass-model results. The model helps in predicting fogging and understanding the actual thermal parameters leading to it and hence can be useful in optimizing these parameters so as to reduce fogging. It serves as a useful tool in optimizing the performance of an air conditioner. |
A Review and Analysis of the Performance of Laminated Side Glazing in Rollover Accidents | Advanced glazing has been investigated as a means by which to reduce occupant ejection in rollover accidents. However, most testing on these advanced glazing materials has not effectively captured the occupant kinematics typically seen in actual rollover accidents, and as a result, passing these tests does not ensure occupant retention. While current work has attempted to characterize the dynamic (impact) and static (push-out) material properties necessary for understanding the containment performance of advanced glazing, most testing has consisted of single impacts. Rollover accidents typically include multiple impacts and potentially long duration centrifugal forces on the side glazing. As such, there is little test and/or simulation data to support the theory that advanced glazing would substantially reduce the risk of occupant ejection in rollover accidents. The risk of head injury due to occupant impacts may not be significantly different between tempered and laminated glazing, but higher neck forces have generally been reported for laminated glazing. The laceration potential of laminated glazing may also be significant. This paper reviews the existing literature and testing in the area of automotive glazing materials, with specific emphasis on the containment potential of advanced glazing. We also present an analysis of the centrifugal forces on side window glazing due to occupant contact during rollover accidents. These forces most likely exceed the containment potential of laminated glazing. |
Reducing a Sports Activity Vehicle's Aeroacoustic Noise using a Validated CAA Process | Developing a low interior noise level of vehicles is a big challenge - even a greater one if one thinks about aeroacoustics. Aeroacoustic noise and its origins are usually identified with the help of prototypes when exterior design changes or the replacement of exterior parts like side mirrors are very limited. However, computational aeroacoustic (CAA) methods in virtual project phases offer more design options for the vehicle's geometric shape. The early consideration of aeroacoustic relevant design changes helps to keep project costs low by avoiding tool changes. This paper describes MAGNA STEYR's virtual aeroacoustic process starting from standardized model generation and simulation of wind noise, including the validation of computational results via comparison with measurement data gathered in an acoustic wind tunnel. The simulations are carried out using the commercial CAA code ?쏱owerFLOW??(Exa) based on the Lattice-Boltzmann method. CAA post-processing results with the aim to detect hot spots and to derive effective measures are presented. As a typical application, a design modification example is highlighted: Pressure fluctuations on a vehicle's side window are influenced strongly by the design of the a-pillar. Improvement potential was identified by analyzing simulations results and a-pillar modifications were developed which led to a validated interior noise reduction of 1 dB(A). |
Vibro-Acoustic Simulation of Side Windows and Windshield Excited by Realistic CFD Turbulent Flows Including Car Cavity | Nowadays, the interior vehicle noise due to the exterior aerodynamic field is an emerging topic in the acoustic design of a car. In particular, the turbulent aerodynamic pressure generated by the air flow encountering the windshield and the side windows represents an important interior noise source. As a consequence PSA Peugeot Citro챘n is interested in the numerical prediction of this aerodynamic noise generated by the car windows with the final objective of improving the products design and reducing this noise. In the past, several joint studies have been led by PSA and Free Field Technologies on this topic. In those studies an efficient methodology to predict the noise transmission through the side window has been set up. It relies on a two steps approach: the first step involves the computation of the exterior turbulent field using an unsteady CFD solver (in this case EXA PowerFlow). The second step consists in the computation of the vibro-acoustic transmission through the side window using the finite element vibroacoustic solver Actran. The present paper extends this methodology for the handling of multiple windows, i.e., the two front side windows and the windshield. The complete car cavity is modeled as well. First, a complete description of the method and the finite element model is provided, from the boundary conditions to the different components involved, like the windows, the seals and the car cavity. The total wind noise level results and the relative contributions of the different windows are then presented and compared to measurements for a real car model. The influence of the flow yaw angle (0째 versus 10째 orientation) is also assessed. |
Studies on Neutral Gear Rattle in Early Stage Design | In today's competitive automobile market, customers have become more sensitive towards NVH behavior of the vehicle than ever. The noise generated by gear rattle is one of the main contributors towards customer's overall NVH perception. This paper adopts a model based design approach towards gear rattle phenomenon to predict the tendency of gear rattle at a very early stage of design. This up-front understanding of gear rattle will potentially reduce the expensive design changes and iterations at later stages. A single unloaded gear pair is modeled in AMESim software, which is then extended to the complete gearbox in neutral condition. The sensitivity of rattle index for different input parameters is studied. Analysis on uncertainty propagation is carried out to find the rattle index distribution for Gaussian variation of input parameters. A novel rattle index based on Jerk is proposed and compared with the existing index. Both the indices are later predicted for the complete gearbox and the contribution of each pair towards rattle is analyzed. |
Design Optimization of Acoustic Enclosure for Noise Reduction of Diesel Generator Set | Diesel engine generator (DG) sets used in industrial plants and residential/official buildings cause serious noise problems if not (canopised) properly. Generally, DG set engines used are with rotational speed of 1500 rpm. In present study automotive diesel engine with 3000 rpm speed was converted for Genset application. Due to higher speed, engine noise levels and its cooling requirements were quite high. Objective of the study was to optimize the design of an enclosure for the said DG set to meet requirements of low noise and proper ventilation to comply MoEF legislative limits. A detailed Noise Source Identification (NSI) was carried out to identify and rank different noise sources. A Hybrid approach which consists of experimental DOE and simulation based on Boundary Element Method (BEM) was used for enclosure design. Design variables like enclosure dimensions, sound absorbing materials and louvers were used in optimization study. Final validation was done on modified enclosure prototype for noise level and internal temperature. Substantial noise level reduction of 8 dB was achieved with appropriate ventilation. |
Road Test Measurement and SEA Model Correlation of Dominant Vehicle Wind Noise Transfer Paths | In order to effectively use CAE to meet wind noise NVH targets, it is important to understand the main wind noise transfer paths. Testing confirmation of these paths by means of acoustic wind tunnel test is expensive and not always available. An on-road test procedure including a ?쐗indowing??method (using barriers) was developed to measure wind noise contribution at important higher frequencies through the main transfer paths, which were shown by test to be the glasses at a typical operating condition in which wind noise was dominant. The test data was used to correlate a full-vehicle SEA (Statistical Energy Analysis) model that placed emphasis on the glass properties, main noise transfer paths, and interior acoustic spaces while simplifying all other transmission paths. A method for generating wind noise loads was developed using measured glass vibration data, exterior pressure data, and interior acoustic data. The individual glass paths were correlated and a baseline model was developed including the noise contribution of all glass paths and a lumped non-glass flanking path. Design studies of the glass properties were performed, especially to explore the overall acoustic performance potential of laminated glasses, individually and in combination, which have potential to reduce vehicle weight. These results and recommendations of how this technique and baseline model can be extended to other vehicle body styles and conditions are presented. |
Can You Hear It Now? Time-Domain Source-Path-Contribution Applied To a Diesel Engine | Source-Path-Contribution (also known as transfer path analysis or noise path analysis) comprise a well-known set of techniques that have traditionally been performed in the frequency domain. With advancements and modern techniques, these same principles can be applied accurately in the time-domain. Foremost among the benefits of this are an ability to analyze transient events, and the ability to listen to the contributions from various sources instead of merely viewing them. This paper demonstrates the analysis of a diesel engine vehicle utilizing time-domain source-path-contribution techniques. |
Influence of the Gyroscopic Effects on Friction Induced Vibration in Aircraft Braking in System | Aeronautical brakes are subject to non-linear unstable vibrations. In particular, two modes appear and present a risk for the structure. Firstly, the whirl modes consist of a rotating bending motion of the axle out-of-phase with the brake torque tube. It is due to a coupling of two bending modes of the axle in orthogonal directions. Secondly, the brake squeal mode resulting from stick-slip or sprag-slip phenomena consists of a rotational motion of the brake around the axle. Those vibrations are not resulting from an external excitation but are friction-induced self-excited. Hence, they are dependent on tribological phenomena specific to carbon disks and are in particular controlled by the friction coefficient 關. In order to take into account the dynamical aspect in brake design, Messier-Bugatti-Dowty wants to simulate modes and acceleration g's levels. This article deals with the improvement of such a model. A finite element of the brake exists. It is able to reproduce whirl modes and squeal mode. In order to improve it, physical phenomena must be introduced. Here, the impact of gyroscopic effects is evaluated. For this, an analytical model is built to determine the consequences on frequencies and stability. |
A Study of Experimental Acoustic Modal Analysis of Automotive Interior Acoustic Field Coupled with the Body Structure | The accuracy of the vibro-acoustic coupled system model for the low frequency range depends on how accurately modal characteristics are represented at the input, output, and the structure-acoustic coupling surface. This study focus on extracting the detailed acoustic mode shapes on the coupling surface for the improvement of the model accuracy. In order to extract the acoustic mode shapes on the coupling surface from an experimental test, the applied method is initially evaluated by FE model results. As the next step, the same procedure in the previous step is applied to the test data of an actual vehicle for the purpose of extracting the detailed acoustic mode shapes at the coupling surface of the body structure and cabin interior acoustic field. |
Vehicle Mid-Frequency Response Using the Superelement Component Dynamic Synthesis Technique | This paper presents the Component Dynamic Synthesis (CDS) superelement creation, which contains the loading frequency information and is much faster than the Component Mode Synthesis (CMS) method in the residual run. The Frequency Response Functions (FRFs) are computed using the direct frequency response method and the inversion of dynamic stiffness matrix is done using the singular value decomposition (SVD) method for every discrete frequency in the frequency range of interest. The CDS will be very efficient and economical for design of experiments and robust optimization, where hundreds of runs are required. The CDS super element can be used when there is a large number of residual runs on a very large vehicle model at higher end of the frequency range of study. For the residual analysis to run as fast as possible, all components, except very small ones, need to be converted into CDS superelements. Numerical results demonstrate the efficacy of the CDS method for the prediction of mid-frequency responses for vehicle vibration and noise. |
Method for Detecting Planar Surfaces in Outdoor Urban Environments | The ability to detect and recognize buildings is important to a variety of vision applications operating in outdoor urban environments. These include landmark recognition, assisted and autonomous navigation, image-based rendering, and 3D scene modeling. The problem of detecting multiple planar surfaces from a single image has been solved with this technology. |
Practical Loop-Shaping Design of Feedback Control Systems | An improved methodology for designing feedback control systems has been developed based on systematically shaping the loop gain of the system to meet performance requirements such as stability margins, disturbance attenuation, and transient response, while taking into account the actuation system limitations such as actuation rates and range. Loop-shaping for controls design is not new, but past techniques do not directly address how to systematically design the controller to maximize its performance. As a result, classical feedback control systems are designed predominantly using ad hoc control design approaches such as proportional integral derivative (PID), normally satisfied when a workable solution is achieved, without a good understanding of how to maximize the effectiveness of the control design in terms of competing performance requirements, in relation to the limitations of the plant design. |
Safely Stopping Motion Using Discrete Wiring | Functional machine safety using discrete wiring is an established way to protect workers from injury, and protect companies from the expense associated with accidents and downtime. |
SOFIA Closed- and Open-Door Aerodynamic Analyses | Work to evaluate the aerodynamic characteristics and the cavity acoustic environment of the SOFIA (Stratospheric Observatory for Infrared Astronomy) airplane has been completed. The airplane has been evaluated in its closed-door configuration, as well as several open-door configurations (see figure). Work performed included: acoustic analysis tool development, cavity acoustic evaluation, stability and control parameter estimation, air data calibration, and external flow evaluation. |
EDITORIAL: The unforgettable pyramid on the hood | If you're old enough to remember 1990, you may recall the best television ad of the year. It showed the front end of the all-new Lexus LS400 sedan against a black background. A multi-level pyramid of champagne glasses glistened in the center of the car's hood. It was demonstration time, and the demo was all about Noise, Vibration and Harshness-and the lack of it. |
How a Tier 2 tackles NVH | Saint-Gobain invested in anechoic testing so small components can make a big NVH difference. Saint-Gobain is a company that understands how vital NVH R&D is for perceived quality. Unwelcome noise is a major challenge in premium cars, but it is the minor components that matter. For Saint-Gobain that means particularly its bearings and tolerance rings. The French company, founded in the 17th century, has become so determined these components can assist with reducing vehicle NVH that it has built its own semi-anechoic chamber, hardly a routine investment for a Tier 2 supplier. Until recently, Saint-Gobain used facilities at European universities and a specialist test site in Germany for NVH development, but its own chamber in the U.K. will help the company to better understand OEMs' systems and improve performance. The ISO 3745- and 3744-compliant facility in Bristol was established with support from Southampton University's Institute of Sound and Vibration Research (ISVR Consulting) and by Br체el & Kjaer, with headquarters near Copenhagen, Denmark. |
Compact, Lightweight, CMC-Based Acoustic Liner | In the wake of recent developments that have reduced fan and jet noise contributions to overall jet-engine noise, aircraft designers are turning their attention toward reducing engine core noise. Innovators at NASA?셲 Glenn and Langley Research Centers are developing a compact, lightweight acoustic liner based on oxide/oxide ceramic matrix composite (CMC) materials. |
2017 Pacifica is first hybrid minivan, rides on all-new FCA platform | Despite the popularity of SUVs and CUVs, nothing beats a minivan for its combination of interior flexibility, ingress/egress, passenger comfort, cargo hauling and, in some cases, fuel efficiency. While the segment isn't as large as it was in 2000, when sales peaked at 1.37 million deliveries in North America, about 500,000 minivans are still sold annually-ample profit-spinning volume that analysts expect will be sustained through at least 2020. As millions of customers would likely attest, the minivan is ?쐓till the best transportation ?쁳ool??for families,??observed Tim Kuniskis, head of FCA's passenger car brands, when he pulled the cover off Chrysler's 2017 Pacifica-the company's sixth generation minivan. It was shown to Automotive Engineering and other media on embargo prior to the car's official debut at the 2016 North American International Auto Show. |
Enhancing Image Clarity in the SWIR | A chromatic or color-corrected lenses for use in the visible portion of the electromagnetic spectrum have been addressed in literature, textbooks, and industry journals as early as the 18th Century. Many of these accounts by scientists and optical designers detail a method of selecting two dissimilar materials to form an achromatic pair or doublet with the ability to greatly counter image blurring resulting from the dispersive nature of refractive optical elements. Whether these tried and true optical formulae produce equally successful results in wavelengths beyond the visible range warrants further examination. |
Using Fan-poled Crystals to Tune Ti:S Lasers | Titanium:Sapphire (Ti:S)-based laser systems have revolutionized ultrafast research from biological imaging to high energy physics. Ti:S has a very broad gain bandwidth (680-1080 nm) but many applications require even broader tuning ranges covering UV, visible, and longer IR wavelengths. Frequency doubling, tripling, and quadrupling extend access to the 190-540 nm range. Ultrafast optical parametric oscillators (OPOs) pumped by Ti:S lasers reach beyond 1080 nm and fill in the ?쏷i:S gap??(540 to 680 nm). |
Experimental Sensitivity Studies on Glass Bonding Urethanes | This paper investigates the sensitivities of glass bonding adhesives to the dynamic characteristics of automotive body structures. Experimental modal analysis was conducted to study the damping, response amplitude, and stiffness of different adhesives to a door assembly and a vehicle body. Three different glass bonding adhesives were used in this study. Performance advantages of using these adhesives are given. |
Design and Construction of a Small Reverberation Chamber | As a manufacturer of a complete line of acoustical materials American Acoustical Products needed to construct a laboratory that would allow the characterization of the acoustical properties of its materials. Reference panels of materials were available that had been previously measured for absorption in a full scale reverberation chamber. A design for a small reverberation chamber was developed based on the Toyota Specification TSL 0600G-4 which includes a small transmission window for STL measurements. This design has the advantage of being constructed with no parallel surfaces, is tall enough to walk into and is optimized for measuring samples between 9 and 30 square feet in surface area. In order to allow the facility to function effectively several innovative techniques have been employed. To maximize the reverberation time the walls were constructed using constrained layer damped and mass loaded sheetrock on a timber frame. The walls and roof were constructed without cavities to avoid resonances and all the internal surfaces including the door and transmission window sealing panel were tiled with ceramic tiles for maximum reflectivity. The room's external surfaces were lined with sound absorbing foam to improve the sound transmission loss measurements. To generate a diffuse sound field, the chamber was excited by a NXT짰 Distributed Mode Loudspeaker which has virtually no directivity. To measure the room response, pressure zone microphones were placed in the corners of the room where all the resonant modes have pressure maxima. Finally the analysis of the RT60 sound decay was measured by a two channel real time analyzer using a studio mixing desk to switch between microphones. Results from the small reverberation room will show how closely the measurements agree with the full scale tests carried out to ASTM C423 at the Hudson Valley Acoustics Laboratory12 |
N-Hance: Software for Identification of Critical BSR Locations in Automotive Assemblies using Finite Element Models | Today's highly competitive automotive industry is constantly looking for ways to improve the perceived quality of its vehicles. Perceived quality defined as the sense of touch, feel and sound that the customer perceives in a vehicle is seen as one of the areas with maximum potential for increasing customer satisfaction. Buzz, Squeak and Rattle (BSR) is one of the major contributors towards the perceived quality in a vehicle. Almost all of the annoying noises that the customer hears can be classified into a buzz, squeak or rattle. Traditionally BSR in subsystems and components of a vehicle have been identified and rectified through extensive hardware testing. With the auto companies and suppliers being challenged to cut structural costs, eliminate costly hardware builds, and bring products to market faster by reducing development cycles, increasing math analysis of subsystems and components for such perceived quality issues is desirable. In line with the needs of the industry to perform math-based analysis and to improve the perceived quality of vehicles, Lohitsa and GM partnered to validate N-hance. BSR. N-hance.BSR is a software tool developed exclusively to identify BSR critical-locations, for the finite element model that is subjected to a vibration profile of interest. The software has been fully automated to rank order the issues based on their severity and thus enables analysis and interpretation of the results, with minimum user input. N-hance.BSR is a fully contained software including pre and post processors, user friendly GUI and report generating capabilities. The tool was used to predict critical-locations on two different subsystems and the results from the analysis were then correlated to BSR issues identified through hardware testing. In both cases the correlation was greater than 75%, taking into account only those issues from hardware components that were adequately represented in the finite element model. An overview of the method is presented followed by results from the BSR evaluation of an instrument panel and a door. |
Solution for Direct Solar Impingement Problem on Landsat-7 ETM+ Cooler Door During Cooler Outgas in Flight | There was a thermal anomaly of the landsat-7 Enhanced Thematic Mapper Plus (ETM+) radiative cooler cold stage during the cooler outgas phase in flight. With the cooler door in the outgas position and the outgas heaters enabled, the cold stage temperature increased to a maximum of 323 K when the spacecraft was in the sunlight, which was warmer than the 316.3 K upper set point of the outgas heater controller on the cold stage. Also, the outgas heater cycled off when the cold stage was warming up to 323 K. A corrective action was taken before the attitude of the spacecraft was changed during the first week in flight. One orbit before the attitude was changed, the outgas heaters were disabled to cool off the cold stage. The cold stage temperature increase was strongly dependent on the spacecraft roll and yaw. It provided evidence that direct solar radiation entered the gap between the cooler door and cooler shroud. There was a concern that the direct solar radiation could cause polymerization of hydrocarbons, which could contaminate the cooler and lead to a thermal short. After outgas with the cooler door in the outgas position for seven days, the cooler door was changed to the fully open position. With the cooler door fully open, the maximum cold stage temperature was 316.3 K when the spacecraft was in the sunlight, and the duty cycle of the outgas heater in the eclipse was the same as that in the sunlight. It provided more evidence that direct solar radiation had entered the gap between the cooler door and cooler shroud. Cooler outgas continued for seven more days, with the cooler door fully open. The corrective actions had prevented overheating of the cold stage and cold focal plane array (CFPA), which could damage these two components. They also minimized the risk of contamination on the cold stage, which could lead to a thermal short. |
MAGDOOR - Magnesium in Structural Application | The objectives of the project is to contribute to reduced emissions by weight reduction, which in this study is made by replacing the inner door steel structure with cast magnesium. Weight target is 55 % relative steel, implying vehicle lightening by more than 25 kg, hence saving 200 litre fuel during the life of the vehicle. A magnesium door concept is expensive in high volumes, and the risks include incomplete die filling, multimetal incompatibility and low strength. Cost efficiency implies to design for integration and commonality. Ductile alloys, correct ingate shape and optimized wall thickness is necessary to meet the impact and quality requirements of the door structure. Joining Al to Mg is mainly limited to adhesives and promising Mg surface treatment alternatives to chromateing have been evaluated. |
Localized Nonlinear Model of Plastic Air Induction Systems for Virtual Design Validation Tests | Plastic air induction system (AIS) has been widely used in vehicle powertrain applications for reduced weight, cost, and improved engine performance. Physical design validation (DV) tests of an AIS, as to meet durability and reliability requirements, are usually conducted by employing the frequency domain vibration tests, either sine sweep or random vibration excitations, with a temperature cycling range typically from -40째C to 120째C. It is well known that under high vibration loading and large temperature range, the plastic components of the AIS demonstrate much higher nonlinear response behaviors as compared with metal products. In order to implement a virtual test for plastic AIS products, a practical procedure to model a nonlinear system and to simulate the frequency response of the system, is crucial. The challenge is to model the plastic AIS assembly as a function of loads and temperatures, and to evaluate the dynamic response and fatigue life in frequency domain as well. This paper presents a modeling procedure for nonlinear plastic products, such as AIS assemblies, by using an array of locally linearized systems, for virtual design validation tests. The measurement results of physical DV tests are first presented to quantify the basic nonlinear response behaviors of the plastic AIS products. The proposed finite element modeling method is then evaluated based on correlation with the measured test results. The localized nonlinear model is thus employed to simulate the frequency response of the plastic AIS products and to identify weak spots of the design. Durability evaluation of the AIS product is then conducted in terms of estimated life, based on the simulated dynamic stresses and material fatigue properties. The presented procedure has helped the engineering team to identify potential durability design problems without a prototype, and to guide the design changes and modifications. |
Standard Metrology for Vehicular Displays | The scope of this SAE Standard is to provide methods to determine display optical performance in all typical automotive ambient light illumination - with focus on High Ambient Contrast Ratio, which is critical for display legibility in a sunshine environment. It covers indoor measurements and simulated outdoor lighting. It is not the scope of this document to set threshold values for automotive compliance, however some recommended values are presented for reference. |
Effects of Brake Pad Boundary Contact Surfaces on Brake Squeal | The disc brake corner assembly is comprised of several subsystems (brake pad, caliper, rotor etc.) which have interfaces between two or more of these structures. The brake pad assembly as the subsystem connecting the rotor to the caliper has specific areas of contact which influence the onset and potential to control brake squeal. The primary excitation interface occurs between the friction pad and rotor surface. The contact is initiated by the piston apply force on the brake pad insulator. Contact interface reaction forces, displacements and deformations are generated and form the natural and geometric boundary conditions of the overall system. Brake squeal characteristics are strongly affected by these conditions. The study focuses on brake system dynamic response to interface contact conditions. The brake insulator and pad assembly interacting with the brake piston as well as caliper are evaluated. Modifications that change the system dynamics through these interfaces are also assessed by dynamometer testing. Properties including compliance, interface friction and traction, damping, decoupling and isolation are discussed with respect to their potential impact on mechanisms leading to brake squeal. Three practical solutions that have been proven to decrease brake squeal via interface modifications are demonstrated at two interface areas 1) Piston to insulator modifications via changes in friction level as well as decoupling and damping 2) Caliper assembly interface with the backing plate incorporating friction level changes with decoupling and damping at the attachment point. Comparative test results indicating the effect of these modifications are presented. |
Improvement in Noise Transmission Across Firewall of a Passenger Car | Firewall of a car separates the engine compartment from the cabin and acts as a barrier for engine noise entering the passenger compartment. Hence noise transmission through the firewall plays an important role in determining the interior noise of a car. Noise Reduction measurement technique is useful to evaluate existing and potential acoustic treatments of the firewall of a car. This paper presents two systematic measurement approaches for quantifying the acoustic performance of firewall insulation materials across the firewall of a car. First a Volume Velocity Source was placed in the passenger compartment and noise reduction was measured across the firewall with different configurations of firewall acoustic treatments. Similar exercise was repeated by installing an actual vehicle firewall in a sound transmission loss suite and measuring the noise reduction across the firewall. Measurement techniques such as leakage detection and sound intensity mapping were used to enhance the understanding of the noise transmission paths through the firewall and to rank the dominant leakage areas. Based on the above, appropriate modifications to the car have been carried out and evaluated for reducing the noise transmitted through the firewall of the car. To assess the influence of improvement in noise reduction across the firewall on the interior noise of the car, in cab noise measurements were carried out with the engine running on the test track. |
Brake NVH: Testing and Measurements | As other vehicle systems have become more refined, more attention must be placed on brake NVH issues because they can cause a negative customer experience. From the laboratory to the road, the use of technology as well as further study by engineers is helping to lessen noise, judder, and vibration in cars. This book provides readers with a fundamental understanding of current practices for measuring and testing brake NVH. From coverage of basic definitions and concepts to in-depth analysis of on-road testing procedures, it will serve as a comprehensive reference guide for brake test technicians, test engineers, lab managers, and others who work on making brakes quieter, smoother, more refined, and more reliable. Readers will learn how to test for brake noise, what tools to use, and which recent standards and practices have led to the successful measurement of brake noise and vibration. Topics covered include: ??Common brake noise and vibration issues ??Instrumentation, transducers, and other technical details ??Measurement practice for laboratory and on-road testing ??Brake pad damping and natural frequencies ??Current trends in brake noise and vibration measurements |
Principles of Vibration Analysis with Applications in Automotive Engineering | This book, written for practicing engineers, designers, researchers, and students, summarizes basic vibration theory and established methods for analyzing vibrations. Principles of Vibration Analysis goes beyond most other texts on this subject, as it integrates the advances of modern modal analysis, experimental testing, and numerical analysis with fundamental theory. No other book brings all of these topics together under one cover. The authors have compiled these topics, compared them, and provided experience with practical application. This must-have book is a comprehensive resource that the practitioner will reference time and again. |
Dispersion of Test-Based NVH Characteristics at Various Trim Levels | A broad measurement campaign was run at Volvo aiming at the evaluation of dispersion in test-based NVH characteristics of a car body and at the derivation of reference data for judging the accuracy of CAE predictions. Within this work 6, nominally identical, vehicles were tested. Tests included operational noise on Complete Vehicle (CV) level (road noise, engine noise and idling noise), NTF, VTF & Acoustic FRF measurements in CV, Trimmed Body (TB) & TB-Stripped (TBS) configurations. Additionally, modal analysis and NTF, VTF, AFRF tests were carried out on 4 BIPs of the same vehicle type. Further, limited tests were carried out on 28 vehicles of the same type. The aim of the work was to study the development of dispersion with increasing complexity of the test object, from the BIP to TB and CV. In this respect this study is unique - there has been several studies regarding the dispersion in test results but the studies that trace the dispersion between different levels of complexity of the test object are scarce if not non-existent. In parallel with this, CAE activities were carried out in order to create CAE models corresponding exactly to the test objects, for all trim levels. Even the boundary conditions were modeled with great detail. In this way, it was possible to study the development of CAE prediction accuracy with increasing complexity of the test object. Further on, several classes of measurement points' locations were studied. In the paper the dispersion results will be presented and some comments regarding prediction accuracy and its assessment will be given. |
Influence of Tire Air-borne Noise on Vehicle Loudness Predicted during Design Phase Based on Hybrid Internal Noise Contribution Model | The development of new technologies that reduce engine size and improve performance, combined with the introduction of hybrid and electric vehicles, make tire noise critically important for the new generation of automobiles. Tire noise transmission into the passenger compartment can be classified as either air-borne or structure-borne sound. Both of these mechanisms are very complex to predict because tires are highly non-linear, subject to large static, dynamic and centrifugal loads; they suffer from impact, stick and slip forces; and the pumping of air in the tire grooves is complicated. Customers today demand more sophistication of products in terms of interior noise; thus, sound quality metrics have earned an important role during the design phase allowing human perception of noise to be predicted and improved with reduced cost in a way that addresses consumer preferences. Of the various metrics, loudness has been shown to be the most important metric due to consideration of masking effects on human hearing. This paper discusses global loudness assessment of a vehicle during its design phase for two different types of tires through a hybrid internal noise contribution model with the following inputs: i - powertrain forces (surrogate data); ii - tire radiated noise (measured from a carryover vehicle through of a chassis roll dynamometer within a hemi-anechoic chamber), iii - noise transfer functions (simulated using FEM), iv - acoustic noise reduction functions (simulated using SEA). |
Automotive Electronics Testing for Conductive Coated Heat Reflective Windows | The electromagnetic interference between the conductive coating in heat reflecting automotive glass and vehicle electronics can limit the application of such technology. A number of methods are available to maintain electromagnetic compatibility and the function of RF electronics in the passenger compartment, while accruing the heat load reduction benefits of the coating. This paper provides detailed test data showing the antenna performance differences resulting from the conductive windshield transmission of RF signals. |
Engineering Moveable Glass Window Seals of Automotive Door Using Upfront CAE | The traditional moveable glass window seal development process has relied heavily on physical prototypes for design verification. Due to frequent styling changes and an overall reduction in design time, physical prototypes for the glass window seals have proven to be inadequate. Utilization of computer aided engineering (CAE) tools is necessary in order to shorten lead time. CAE tools will help to decrease expensive prototyping, free up valuable manufacturing line time, and improve overall quality. A cross functional approach has been applied to expand the scope beyond traditional methods of moveable glass window seal design, such as wedged boarding, into new computerized modeling methods. The CAE was used to address major requirements of the glass window seals including glass velocity, glass stall force, sealing-ability, seal durability, seal assembly, seal appearance, and regulator motor current. A systematic process is used for the glass window system design development using CAE to insure that production parts will meet all functional and assembly process objectives. |
Dimensional Management Process Applied to Automotive Door Systems | The processes utilized in building-up and installing automotive door assemblies to a body are required to address a complex interaction of dimensional requirements. The Dimensional Management Process is employed to arrive at the optimum design and process to achieve the many functional and appearance related requirements of the door system. This paper will demonstrate the application of the Dimensional Management Process to the typical automotive door system and the use of integrated three-dimensional tolerance analysis to compare different door assembly and installation methods for the purpose of achieving an optimum appearance and functionality of the door system. |
Testing of New Composite Side Door Concepts | Car side doors are one of the most complex parts of the body, because this component has to meet a lot of requirements. Independent of the material - steel, aluminum, magnesium, or fiber-reinforced plastics (FRP) - there are multiple important requirements. In this paper, testing methodologies for self-supporting car side doors made from FRP are presented based on different conceptual design studies using these innovative materials. These doors and related testing methodologies have been developed in joint research and pre/advanced-development projects with different partners, car manufacturers as well as suppliers. The importance and benefit of benchmarks, advanced experimental material analysis, substructure and full-size component testing in the product development process is discussed. Furthermore important links to the CAE-process are referred and the significant value on the whole development process is demonstrated. Test data for new composites car side doors based on different conceptual design are presented and methodologies for further improvement of the development process suggested. |
Analytical Robust Door Hinge System Design Taguchi Approach | The automotive industry faces many competitive challenges including weight and cost reduction to meet CAFE standards. In particular, a non robust door hinge optimized for weight reduction may cause high warranty and durability problems in the field. Many analytical techniques such as optimization and sensitivity analysis have been widely used in a hinging system design. However, none of the techniques include robustness and the design variation in the analysis. This paper presents an application of finite element method coupled with the parameter design using Taguchi's design of experiment. This approach identified the hinge design variables in the pillar-hinge-door system and improved the robustness of vertical rigidity performance. |
Subsets and Splits