Paragraph
stringlengths 6
919
| Details
stringlengths 6
4.93k
|
|---|---|
Crew Protection, Contingency EVA and the Crew Exploration Vehicle | The proposed NASA Crew Exploration Vehicle (CEV) has been labeled ?쐍ot as a repetition of Apollo, but instead what Apollo should have been.??While this designation is certainly ripe for debate, there is no debating that the space suit community has, up to this point, had limited or no input into the on-going design of the CEV. However, it is important that the community take the opportunity to influence the configuration of the proposed CEV so as to optimize its orbital and planetary/lunar EVA capability, flexibility and safety. This ?쐗indow of opportunity??will not remain open for long, as the CEV?셲 configuration is rapidly congealing. This paper covers: 1. Brief space suit configurations, employment and history. 2. Brief descriptions and comparisons of IVA, EVA and IEVA space suits. 3. How history can be a guide to optimize EVA for the Crew Exploration Vehicle. |
System Dynamics and Ride Quality Assessment of Automobile | Ride quality analysis involves the study of three topics: ride excitation sources, system dynamics of a vehicle, human perception and tolerance of vibration. In this study, we establish an integration analysis procedure including the system dynamics analysis and the ride quality evaluation. The dynamic responseof a passenger car was simulated by a multi-body model with ADAMS software. The calculated acceleration responses of seats coincide with the field measured ones. The effect of damping ratio (C), stiffness coefficient (K), vehicle speed and seating location on the acceleration response are also investigated. The ride quality analysis was conducted following the ISO 2631 standard. A LabVIEW computer code was developed to provide fast and convenient assessment of the comfort. A 3-axis translational accelerometer was installed on the seat. The responses of a passenger car traveling on the long wave road, asphalt uneven road and stepped joint road of proving ground in ARTC (Automotive Research & Testing Center in Taiwan) were collected. A satisfactory agreement was observed between the comfort index obtained on the experimental data and dynamic simulation. |
Development of a Lightweight Sound Package for 2006 Brand-New Vehicle Categorized as C | This paper describes an effective method of developing a soundproof package, which balances both light weight and high noise insulation performance. Since it is required to propose design of sound insulator in the early stages of the development, the hybrid statistical energy analysis (SEA) modeling method is applied, which is practical for high frequency analysis. Also an acoustic characteristic estimation technique of the multi layer structures is used. As a result of applying these effective methods, the 2006 brand-new vehicle categorized as C has enhanced in road noise quietness and decreased in weight as compared with the previous model. |
The Armageddon Device Part II | Applying good engineering practices to software-intense automotive systems can save automakers millions of dollars in warrantee costs, lost customer loyalty and lawsuits. Carefully crafted development testing could expose non-robust software that fails intermittently when the customer activates the function. The chances are very good the service technician will replace the ECU when the customer brings the vehicle in for repair of the intermittent behavior. These electronic parts are sent to the supplier for analysis. Upwards of 60% of all ECUs analyzed are TNI (Trouble Not Identified) related. This paper elaborates on a method of developmental testing that provides these cost savings. This paper continues to build on concepts discussed in the SAE paper, ?쏷he Bus Crusher and The Armageddon Device Part I?? [1] The experiment of subjecting an ECU to several electrical disturbances is explained in detail. The objective of an embedded system is to have a predictable output for any combination of input sequences. If the operation of the embedded system is viewed as a big state diagram, testing verifies that the embedded system operates in acceptable states and that transitions between states are all known and predictable. The stress-testing concept described in this paper generates sequences of stimuli that can?셳 normally be planned for (the number of combinations is massive). The embedded system must always remain in a known acceptable state, regardless of the stimulus. The testing techniques described allows for the creation of a stimulus to verify the robustness of the embedded system. Experiments were conducted on electrical breadboards, which were subjected to RF (Radio Frequency) noise, periodic network initialization, communication bus failures, intermittent ground open, and repeated cycling of the locking function. The hypothesis of the experiment was to stress the ECU?셲 operating environment by causing events that seldom occur, and make them happen with high regularity. The electrical noise level is below the ECU design limit, e.g., the task monitoring the ECU voltage range will ignore voltage drops of less than 15 msec (milliseconds). Subjecting the ground circuit to an interruption of less than 15 msec should result in no humanly perceivable behavior change. Methods to stress the software are the focus of this document. Described are: 1. Building the RF Blaster 2. Building the Armageddon Breakout box 3. Introducing new noise factors; ground lift and periodic network initialization 4. Lock-Unlock Cycle test 5. Results of the tests |
Investigation of the perceived sound quality of an automotive HVAC system | The noise emitted by the heating, ventilation and air conditioning system (HVAC) has a great influence on the car acoustical comfort and quality perception. To improve its sound quality, physical properties which determine the subjective perception have to be identified. The HVAC-noise of twelve cars in different arrangements of fan speed and direction of air flow was recorded for later objective and subjective analysis. All cars were of the same model, but with three different types of HVAC-systems, and had just been manufactured. Objective analysis with sound quality software and subjective evaluations was carried out. Using multiple linear regressions on the subjective data, relations between subjective results and psychoacoustic metrics were determined and models to predict subjective response to HVAC sounds are proposed. It is shown that the annoyance caused by the HVAC-noise can be satisfactorily described by Zwicker's stationary loudness model. |
In-Vehicle Panoramic Noise Source Mapping | For many years engineers in the automotive market have struggled to find ways to accurately and efficiently map the noise sources found inside a vehicle. Many techniques, both theoretical and measurement based, have been proposed and used, but there has always been a trade off between accuracy and efficiency. Techniques like sound intensity mapping and Statistical Energy Analysis have proven to be accurate when mapping noise sources in vehicle, but require a large investment in time and money to create a simple, easy to interpret picture showing where dominant noise sources come from. In this paper the authors will introduce and demonstrate a novel technique, spherical beamforming, which can overcome the issue of test time and produce fast, accurate noise maps from the interior of a vehicle. |
Investigation on the Acoustic Performance of Current Trunk Load Floor Solutions | Different solutions for trunk floors recently presented on the market have been collated and investigated in order to better define the possible features integrated and the acoustic performance of trunk load floors. A description protocol has been devised and applied to systematically categorize the whole set of features potentially characterizing a trunk floor, and the wide range of solutions used with respect to materials, processes and design configurations. The acoustic performance has been specifically addressed with the evaluation of the acoustic absorption on both sides and a specific testing procedure to evaluate the noise insulation capability provided by actual parts. The results of the actual parts acoustic performance measurement campaign show that a substantial improvement in the acoustic function of the trunk floor module can be achieved by the systematic choice of materials, processes, and of the geometry of the part, in compliance with the standard OEMs requirements Some solution trends for vehicle architecture and segment are highlighted, and recommendations to enhance the acoustic performance and the functionality of trunk floors are provided. |
FEA Design of a Vibration Barrier to Reduce Structure Borne Noise | In the low frequency range, mechanical vibrations propagate into the car body by structure borne transmission. In order to limit this transmission, an original system called ?쏺ibration Barrier??has been developed. It reduces the vibrations propagating into the hollow body network (the transmission path) using a cavity part and the high damping foam technology. This paper describes the general concept and the FEA design process of a Vibration Barrier part. An example is given for a full car body. The best compromise of the tested designs leads to a significant reduction of the structure borne noise using a lightweight part. |
Combining an Energy Boundary Element with an Energy Finite Element Analysis for Airborne Noise Simulations | The Energy Boundary Element Analysis (EBEA) has been utilized in the past for computing the exterior acoustic field at high frequencies (above ??00Hz) around vehicle structures and numerical results have been compared successfully to test data [1, 2 and 3]. The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration of complex structures at high frequencies and validations have been presented in previous publications [4, 5]. In this paper the EBEA is utilized for computing the acoustic field around a vehicle structure due to external acoustic noise sources. The computed exterior acoustic field comprises the excitation for the EFEA analysis. Appropriate loading functions have been developed for representing the exterior acoustic loading in the EFEA simulations, and a formulation has been developed for considering the acoustic treatment applied on the interior side of structural panels. In order to demonstrate how the new developments can be combined in airborne noise applications, a case study is presented. |
Tire Noise Reduction with Fiber Exterior Wheel Arch Liners | Tire noise reduction was evaluated with acoustically designed exterior wheel arch liners. The wheel liners were made with a fiber blend selected to meet acoustical requirements, process demands, and durability challenges. Fiber liners were installed in a vehicle and noise level measurements were made under a range of operating conditions. The results show the reduction in tire noise that can be achieved at the source and in the vehicle. A critical part of this evaluation was a rapid analysis technique to select metrics that correlated with subjective assessments. The analysis techniques also helped quantify the improvements over a baseline condition. |
Microcellular Ceramic Foams: Manufacturing and Study of Acoustical Properties | A novel processing method for fabricating high porosity microcellular ceramic foams for sound absorption applications has been developed. The strategy for fabricating the ceramic foams involves: (i) forming some shapes using a mixture of preceramic polymer and expandable microspheres by a conventional ceramic forming method, (ii) foaming the compact by heating, (iii) cross-linking the foamed body, and (iv) transforming the foamed body into ceramic foams by pyrolysis. By controlling the microsphere content and that of the base elastomer, it was possible to adjust the porosity with a very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9 횞 108 - 1.6 횞 109 cells/cm3) and desired expansion ratios (3 - 6 folds). Sound absorption testing has been performed using ASTM C-384 standard test. The preliminary results show that ceramic foams are candidate sound absorption materials. |
Evolution of Fiber Felt Technologies and Composites Enhancing Vehicle Acoustics | For generations, fiber felt technologies have been used as a building block in the development of various absorbers and decoupler composites used for automotive acoustics. This development has led to a variety of felt components with increasing complexity in their differentiations. This paper will review the evolution of three generations of felt technologies. Generation 1 and 2 will discuss needled, resinated, and thermoplastic fibers bonded felts by comparing various performance indexes from physical parameters of raw materials, manufacturing processes, product applications and physical characterization along with acoustic properties. Generation 3 will introduce strategies, technologies, and approaches to further simplify the multitude of fiber felt innovations. |
Product Sound Quality of Vehicle Noise ??A Permanent Challenge for NVH Measurement Technologies | Sound quality of vehicle is more and more an important product feature which significantly influences the perceived product quality. Over recent years, the broad variety of new models, which resulted in increased competition, has lead to rising customer demands with regard to NVH (Noise, Vibration and Harshness) aspects. Apart from the indispensable troubleshooting, the acoustic engineer's scope of work is extended to NVH design engineering. Thus, innovative, ambitious measurement technologies were developed to meet these new, challenging tasks and to maintain a competitive advantage. |
Calculations of Wind Tunnel Circuit Losses and Speed with Acoustic Foams | The GM Aerodynamics Laboratory (GMAL) was modified in 2001 to reduce the background noise level and provide a semi-anechoic test section for wind noise testing. The walls and ceiling of the test section were lined with acoustic foam and foam-filled turning vanes were installed in the corners. Portions of the wind tunnel circuit were also treated with fiberglass material covered by perforated sheet metal panels. High skin drag due to roughness of the foam surfaces, along with high blockage due to the large turning vanes, increased the wind tunnel circuit losses so that the maximum wind speed in the test section was reduced. The present study calculates the averaged total pressure losses at three locations to evaluate the reductions in skin drag and blockage from proposed modifications to the circuit, which were intended to increase the test section wind speed without compromising noise levels. The effect of foam roughness, characterized by measurement of the boundary layer displacement thickness, was incorporated into CFD models with effective-viscosity and inner-wall-log roughness models. The mathematical correlation of the reduction of total pressure loss with the increase of test section speed is presented to justify the proposed circuit modifications. The projected reduction in the circuit total pressure loss coefficient from 0.54 to 0.44 is in good agreement with the tests. |
Dynamic Door Component Test Methodology | This paper describes the development of a Dynamic Door Component Test Methodology (DDCTM) for side impact simulation. A feasibility study of the methodology was conducted using a MADYMO computer model by taking parameters such as door pre-crush, door-to-SID (Side Impact Dummy) contact velocity and the deceleration profile into consideration. The prove-out tests of this methodology was carried out on a dynamic sled test facility. The DDCTM has been validated for various carlines. In addition, various existing dynamic component test methods are reviewed. In our approach, a pre-crushed door, mounted on a sled, strikes a stationary SID at a pre-determined velocity. A programmable hydraulic decelerator is used to decelerate the sled to simulate the barrier/door deceleration pulse during door-to-SID contact period. This test procedure provides excellent correlation of the SID responses between the component test and the full-scale vehicle test. The DDCTM significantly reduces the time and resources required for developing improved side impact protection systems, including new door/trim, side air bag systems and padding material evaluation. This methodology has been applied to the development of the Ford Deploying Trim System. |
Glazing Effects of Door or Frame Deformations in Crashes | 1990 Geo Prism front door side tempered glass windows 3 mm thick were slowly bent, or shock loaded, to failure, with the glass clusters and fragments then found as large as 13 x 10 cm, weight to 42 grams, with some sharp points and slivers, and speed of release from the glazing surface of intermediate size pieces to 23 km/h. The fracture patterns of the tempered glass bent or shock loaded to failure were often oblique rather than perpendicular, in comparison to the patterns of an unloaded tempered glass broken by a locally applied sharp pointed object. This explains the sharpness and many lacerations of tempered glass shattered in road crashes, often under conditions of bending or shock loading of the edges of the glazing before it fails. Modification of Federal Motor Vehicle Safety Standard 205 to include fragment studies and laceration effects are suggested. |
Front and Side Brake Lights | Most applications in the ever-expanding automobile safety arena can be categorized in one of two ways: (a) accident prevention and (b) occupant protection. This is for accident prevention. With this application there will be 360 degree brake lights on a vehicle; two units mounted on the front of the vehicle below the vision of the operator, one on each side and a unit mounted on the right and one mounted on the left side of the vehicle in front of the front door and behind the front fender well (preferred location). All of the rear (red), front (blue), and both sides (blue) are energized to emit light 360 degrees when the brake system is applied. |
Seamless Passenger Side Air Bag Doors | Passenger side air bags have been rapidly accepted by the public for the protection they provide; however, in exchange, they have created an issue with fit and finish detracting from the harmony and flow-through styling presently in vogue in vehicles. With the current plethora of materials and processes used to manufacture separate passenger side air bag doors and the inability to build components to a line on line fit, attempts to tune all these factors is a lesson in frustration. In 1992, a design and development team from Textron, Chrysler, Dow, and Allied Signal were given the assignment of making the 1996 Voyager/Caravan the industies first fully integrated seamless passenger air bag (PAB) door. Several critical factors had to be addressed: 1) split seam appearance 2) pab deployment at all temperatures 3) instrument panel integrity 4) customer abuse 5) head impact 6) manufacturability 7) foam retention As a result of their effort, a padded surface instrument panel without any visible seams over the PAB, was implemented into production on the 1996 Chrysler Voyager and Plymouth Caravan models. A vinyl skin is cast with a preferentially weakened section to allow predictable tearing during air bag deployment. The shell is processed using conventional means to provide an instrument panel with a mid-mount PAB canister and an insert molded plastic/steel door that has no distinguishing features to indicate where the bag will deploy. This provides a seamless flow-through appearance, optimizing color, gloss, grain and dimensional match. |
Aerodynamic Simulations by Using Discontinuous Interface Grid and Solution Adaptive Grid Method | Aerodynamic simulations of automobiles with an airflow type rear spoiler (a spoiler that guides part of the flow on the roof onto the rear window of a one-box or two-box car to reduce the adhesion of snow or dust on the rear window) using a discontinuous interface grid method and around a rear view door mirror using a solution adaptive grid method are presented. These new methods have made it possible to capture the detail phenomena around equipment items such as spoilers and door mirrors, thereby improving the accuracy of the CFD (Computational Fluid Dynamics) simulations and shortening the time required. |
A Sound Quality System for Engineers | In the eighties, the main concern in the automotive industry from a designer's standpoint was a level issue. In the nineties, the market has put more stringent requirements on the automotive industry with respect to noise in general and psychoacoustics. The governments have imposed lower limits with respect to pass-by noise standards. Customers are spending more time in their car than in the past and are demanding acoustical comfort. All of this is leading to an environment where a sound quality system is becoming a daily tool in the design and trouble-shooting world. This paper describes what should be looked for in a sound, how to quantify these properties and what tools are needed. These steps are then applied in a case study. |
The Perfectly Silent Car - An Engineering Goal? | A look at the car development of today shows that even strictly cost oriented cars try to give their customers comfort and calm riding. High value cars explain themselves as a substitution for your home when you are on the road. Even from the environmental point of view, people, governments and many associations claim for more reduction of the noise emitted by vehicles. So can it be really a question that the main scope of engineering should be the development of cars as silent as possible? Noise or sound is something that is present even if it seems to be silent. Information are exchanged and emotions controlled. The answer to the above question is not only a technical one but also is touched by marketing and political issues. On the way through the global vehicle noise vibration and harshness (NVH) the following lecture shows that sound design and engineering, acoustic quality, customers expectations and noise legislation are the important areas to define the noise behavior of a car. |
Development of a Power Window Switch with Improved Ergonomics | This paper explains a methodology to develop a Power Window Switch (PWS) that is easy to operate. Many PWS knobs use a pivot movement. The most popular shapes are: 1.Pull-up/Push-down, 2.Rocker, and 3. Toggle. In the Pull-up/Push-down PWS, the knob motion matches the window motion. Since the design of the knob prevents an object or a part of clothing from catching, and pulling the knob up, potential injury from the window coming up is avoided. The knob top surface of the pull up PWS is pushed down to open the window, and the knob front surface is pulled up to close it. One weakness of this design is that the operating finger posture changes each time the window direction changes, the finger will often become tired with the repetitive posture changes. Another weakness of the Pull-up/Push-down PWS is the flush top surface of the knob to the bezel. The size of the knob and corresponding finger well limits the size of the finger and length of the fingernail. |
Design for Automotive Glass Removal Using Active Disassembly | Active Disassembly is a well researched technique for creating assemblies or casings that can break themselves apart for recycling using a heat trigger. ?쁂hiodo??has applied this principle to consumer electronic goods since the mid nineties. In response to pending EU legislation, the scope of active disassembly has broadened to include automotive disassembly. The first automotive demonstrators produced have been to make self-disassembling window glass retaining channels that enable easy glass removal for recycling. This waste glass can then be used in coastal defences as an alternative to landfill. Both shape memory alloy and shape memory polymer solutions have been examined. The shape memory alloy solution has been successful. Optimisation for the polymer solution is required. |
Glazing for Vehicle Interior Noise Reduction | As noise levels within vehicle cabins continue to be reduced, wind noise and traffic noise transmitted through the glazing increase in importance in the quest to achieve further reduction. With consumers ranking cabin noise as an important factor in vehicle purchase decisions, and with the projected increase in vehicle telematics, including speech recognition systems, the need for even quieter interiors will continue. NVH engineers have not recognized that vehicle glazing offers an effective option for noise reduction; often, only monolithic glass has been considered, where the only option for improvement has been to increase the mass (increasing the thickness and the vehicle weight). This paper presents sound pressure loss data for laminated glass compared to the tempered glass typically used for side, rear and roof glazing today. The sound pressure loss results show a significant opportunity for improvement in the 2000 to 6000 Hz region, a key range for human conversation and the key range for wind noise. Along with this acoustic improvement is a reduction in mass of the glazing. |
Increasing Performances by Using Multi-Thicknesses Blanks | Multi-thickness blanks (MTB) enable the dimensional optimization of steel parts by modulating thickness and mechanical properties. Traditionally, this is done by the addition of reinforcement to the basic part after the drawing of both. With MTBs, we first assemble the two flat blanks to obtain a single blank, which is then drawn without further assembly. MTBs comprise the Tailored Welded Blank (TWB), already widely used in automobiles, and a new category ?쏱atchwork?? The TWB is a butt-welded assembly of two blanks with neither overlap nor superimposition. The patchwork blank is made by either the adhesive bonding or welding of a blank onto the surface of the base blank, at the point to be reinforced. These products enable the increase of performance objectives (impact, rigidity, vibration and fatigue resistance, etc.) whilst permitting weight reduction and thus adding to the potential of high resistance steels. They also enable, in numerous cases, the reduction of overall costs. Examples of applications are; side members, shock towers and pillar reinforcements. Illustration of design principles permitting the better understanding and exploitation of MTB potential are shown in this paper. |
3D Inside Vehicle Acoustical Holography | A continuously growing demand comes from the automotive industry in order to get an experimental tool allowing for the optimization of materials and sound insulating products implementation inside the car, so as to propose the best acoustic performance at reduced costs. The acoustical imaging system LORHA provides part of the solution and its demonstrated capability of measuring the acoustic field inside a vehicle makes it an advanced tool for performing extensive studies of the acoustic transparency of car openings. This paper focuses on the methodology and recent operational results obtained within the tight collaboration established between METRAVIB RDS, its partner HUTCHINSON and well known car manufacturers. |
Trends and developments in Automotive Glass Encapsulation with PUR materials | The encapsulation of automotive glassparts started mid '80. It was a step forward in an attempt to supply ready-to-mount glass parts to the automotive production lines. These encapsulated glassparts have a moulded gasket all-around the periphery. Encapsulation can be done with different materials. In this lecture we will focus on the use of polyurethane (PUR) - more specific aliphatic polyurethane - and make a comparison with other materials such as PVC, TPE and EPDM. Since that time, encapsulation has really evolved from the original design function, towards a medium where more and more other elements can be integrated into the window. This can be combined with the fact that today large, complex and even laminated windows need to be encapsulated. Due to these functional integration opportunities the overall cost can be reduced combined with a much larger freedom of design and esthetics. |
Welding of Energy Management Systems and Air Duct Systems to Headliner | This paper reviews the use of vibration welding for joining crash impact pad's and air duct systems to headliner. Increasing government regulation and the evolution of automotive safety are demanding a new innovative welding technology for crash impact pad's as well air duct systems to the headliner. Vibration welding is an approved welding technology to join both similar and dissimilar materials and is used in many automotive applications is an innovative solution for such headliner applications. Driven by customer needs, energy management is an important consideration in protecting the occupants of a vehicle from injury in a crash situation. Air ducts are becoming more and more important to distribute air to the rear passenger. In this case both are placed between the headliner and the roof of the vehicle. Not only does vibration welding produce major cost savings, which is related to no consumables (no adhesive required), but also improves product quality, which means no smelling (no fogging through adhesive), and also provides higher pull off strength without variance with temperature is important in competition. |
?쏛ctive Mass Absorber??at a 4횞4 Transmition System | The extensive use of rotative machines in the diverse branches of the modern world has made the rising undesirable mechanical and acoustic vibration levels to be a problem of special importance for the machines normal operation as for the communities that are each time more affected by the problem. It makes the study of vibration and acoustic phenomena also to be even more important and the applications of its concepts more sophisticated. Several are the concepts used for decreasing vibration levels, like common dampers, hydraulic dampers, active dampers, natural frequencies changes and others. The choice of use of one or another depends greatly on the engineering possibilities (weight, energy, physical space, other components functional interference, vibration levels, etc.) as well as the cost of implementation of each one. As a general rule, normal dumpers is usually the best method to decrease vibration levels, because of the smaller prices and not often collateral undesirable effects. In this work is presented a problem of vibration of the powertrain system of a 4횞4 car that could not be easily solved by the use of normal dumpers and therefore another vibration-decreasing concept has been used: the ?쏛ctive Mass Absorber?? ?쏡ynamic Absorber??is a concept based on a phenomenon related to one specific vibration absorption by one auxiliary vibrating system attached to the main system, which the vibration level is wanted to be decreased. It works as it was draining the vibration movement of one specific frequency, so the main system vibration level decreases and the attached system (active mass damper) vibrates. In a normal car there are several exciting vibration and acoustic sources, such as the engine, tires, road roughness, air intake and exhaust system. The active mass absorber concept, which is designed for one only frequency absorption, is not an effective approach for the general vibration and acoustic problem solution. In the present study, however, the second order engine vibration was detected to be transmitted to the rear part of the car by the driveshaft and resonating in the back seats area. This resonation caused high sound pressure levels inside the vehicle and could not be decreased by normal dampers between the rear differential and the vehicle body. The solution proposed to this problem was attaching an active mass damper to the rear differential that absorbs part of the vibration energy before it flows to the car body. |
Application of LIN Network Interface for Ford South America Vehicles | Some communication buses are too powerful and expensive for simple digital on/off operations such as activating lights, wipers, windows, etc. For these applications the LIN bus is currently the most promising communication protocol across the world's automotive industry. This paper addresses a study using LIN (Local Interconnect Network) for Ford South America vehicles. This will propose a new electrical architecture designed with LIN network, which will be replacing the conventional rear and front lights cables in Trucks, where other higher protocols, such as CAN, are not cost effective. LIN is a new low cost serial communication system intended to be used for distributed electronic system that will allow gaining further quality enhancement and cost reduction on cables, connectors and switches. |
NVH Highlights and (Pot)Holes 1972-2001 | The NVH performance of motor vehicles has been improved dramatically during the 1972-2001 period. The paper identifies the main advances made, i.e. the development highlights and indicates a number of points where a lot of work still needs to be done (Holes or with and automotive flavor ?쏱otholes??. The paper is structured as indicated below. 1 Introduction 2 Highlights 2.1 Vehicle 2.1.1 Body rigidity 2.1.2 Body leakage 2.1.3 Engine efficiency and vibration isolation 2.1.4 Suspension systems 2.2 Noise Control proper 2.2.1 Passby noise treatment and Aerodynamics 2.2.2 Interior treatment simulation and optimization 2.2.3 Noise Control material improvements 2.2.4 Multi-functional parts 2.2.5 Dissipative treatment packages 2.2.6 Noise Quality engineering 2.2.7 Development Methodology: Benchmarking 3 (Pot)Holes 3.1 Modeling car subsystems 3.2 Optimization; application to ever-larger subsystems 3.3 Simulation and Optimization of Passby Noise 3.4 Diagnostics 3.5 Materials and Shapes 3.6 Understanding the vehicle development process |
Improved Methodology for Dynamics of Orbiter Payload Bay Doors | The Payload Bay Door Dynamics Simulation (PBDS) computer program simulates the mechanical behavior of the space-shuttle payload bay doors and their latching and driving mechanisms during opening, closing, latching, and unlatching. PBDS was developed to replace an older program that was computationally inefficient and that simulated the door hinges incorrectly. In PBDS, the large system of dynamical equations of the payload-bay-door system is decomposed into smaller systems of dynamical equations at the mechanism level. This decomposition involves decoupling through neglect of the inertial parameters of the driving and latching mechanisms, which are small relative to those of the doors. The equations of motion of the doors, which are flexible, are derived by use of a Cartesian flexible-body formulation. The equations of motion of the mechanisms are derived by use of an efficient recursive formulation. Though decoupled dynamically, the door and the mechanisms are coupled kinematically. In solving the mechanism equations, the responses of the door at points where the door is attached to the mechanisms are fed as inputs to the mechanism equations. The outputs of the mechanism equations are forces and torques, which are fed back to the door equations to complete the computational cycle. |
Ford looks to spread Corning's new lightweight Gorilla Glass beyond the 2017 GT | While many supercar enthusiasts have ?쐅one ape??over the Ford 2017 GT, the program development engineers have done the same for a new lightweight glazing solution. Called ?쏥orilla Glass,??the three-layer laminate is claimed by its supplier, Corning Inc., to deliver more than five times the strength, pound for pound, of conventional automotive glass while offering significant mass reduction. In the case of the GT, more than 12 lb (5.4 kg) was saved by using Gorilla Glass in three areas: the windshield (first use for a production vehicle), the rear window, and in an acoustic separator in the rear bulkhead. It also helped reduce the car's center of gravity by 3 mm (0.12 in). |
Opel designs a new Astra | Opel launched the fourth-generation Astra at the 2015 IAA (Frankfurt Motor Show). The car is more compact than the model it replaces and weighs up to 200 kg (440 lb) less. A five-door hatchback and five-door Sports Tourer estate were on display at the show. The Astra (a Vauxhall in the U.K.) will be the first vehicle to feature General Motors' OnStar Connectivity system in Europe and comes with the option of matrix LED headlights, which Opel claims is the first time this feature has been offered on a European C-segment car. |
Automotive Engineering International 2005-03-01 | Production preview from Detroit Attendees of the 2005 North American International Auto Show in the "Motor City" this January were treated to nearly 70 vehicle introductions, 24 of which were worldwide production cars and trucks. AEI editors present the technical highlights of some of the more significant 2005 and 2006 production vehicles. Significantly this year, the cars we've highlighted outnumber trucks by more than two to one. DSPs start progressing Math processors will help to provide more functionality in the cabin and improve motion contorl throughout the vehicle. Sliding doors the Toyota way Door openings are about more than hinges and pillars, according to the Japanese automaker. Accelerating technology Hybrid technology is gaining in popularity, broadening its scope to embrace performance, and driving industry collaborations. SAE 2005 World Congress preview General Motors is host company of the April 11-14 event, and has high expectations for its success in SAE's centennial year. Design "demarqueation" PSA's new design center will improve collaboration between teams while preserving individual brand identity, according to the company. Connected SAE 100 Future look: When an automotive designer is asked to envision a vehicle of the future, the response is likely to be, "Define the society of the future and I can create a vehicle responsive to that society." Tomorrow's smart car will make drivers better, smarter SAE 100 Future look: Driving on today's expressways is as dangerous as ever. Drivers face the daily challenges of extremely congested roads and distractions from cell phones, passengers, and even in-vehicle DVD systems. Powertrain electronics: a systems evolution SAE 100 Future look: Market forces, driven by consumer and regulatory demands, coupled with advances in technology, have created tremendous opportunities for engineering innovation. Telematics to focus on OEM ROI SAE 100 Future look: It is no secret that a couple yearas ago many in the automotive industry wrote off telematics as a dead issue. That chapter has long since passed, and what you will see emerge in the coming years is a reborn telematics industry that has little resemblance to what we have seen in the past. A gateway to the connected car SAE 100 Future look: Each generation of cars has not only brought drivers sleeker designs and more powerful engines, but also more advanced electronics in the form of features such as satellite radio and navigation. Testing resources This special edition of Product Briefs highlights some of the latest equipment used to develop cleaner, quieter, and safer vehicles. |
Improved Design for Manufacture in Minivan Body Systems | The design for manufacturability process has been recognized as a very effective method for improving the overall quality in mechanical product design. The first part of the paper deals with an extended DFM which encompasses all the various Quality issues in product development. The importance of the three major elements quality, cost and timing are highlighted in the mathematical model for Design for Quality (DFQ). The second part of the paper describes the application of DFQ in the design and development of minivan body and interior systems. The best value of the DFQ is recognized when the process is used proactively during the early stages of the development cycle. Such is the case of the applications discussed in this paper which covers the following systems: hood assembly, seamless door system, sliding door system, instrument panel and message center installation, and fuel filler door-and-housing system. |
Comparison of Airbag-Aggressivity Predictors in Relation to Forearm Fractures | Four unembalmed human cadavers were used in eight direct-forearm-airbag-interaction static deployments to assess the relative aggressivity of two different airbag modules. Instrumentation of the forearm bones included triaxial accelerometry, crack detection gages, and film targets. The forearm-fracture predictors, peak and average distal forearm speed (PDFS and ADFS), were evaluated and compared to the incidence of transverse, oblique, and wedge fractures of the radius and ulna. Internal-airbag pressure and axial column loads were also measured. The results of this study support the use of PDFS or ADFS for the prediction of airbag-induced upper-extremity fractures. The results also suggest that there is no direct relationship between internal-airbag pressure and forearm fracture. The less-aggressive system (LAS) examined in this study produced half the number of forearm fracture as the more-aggressive system (MAS), yet exhibited a more aggressive internal-pressure performance. Both the peak-internal pressure and the initial-inflation rate of the LAS were higher than for the MAS, but the PDFS, ADFS, and axial column loads of the LAS were lower. This inverse relationship between internal-airbag pressure and airbag aggressivity prompted an investigation of the LAS and MAS design characteristics. The closed-module design of the LAS, coupled with longer, thicker tear seams, results in higher peak-internal pressures and greater rates of pressure increase when compared to the MAS. Therefore, more inflator energy must be used to achieve bag egress from the LAS module, making less energy available to be imparted to a forearm. The reduced and more distributed mass and size of the LAS doors may assist in the reduction of focused energy transfer to a forearm and the less-aggressive-tank-test characteristics compared to the MAS inflator. A combination of these factors causes a reduction in the level of fracture predictors, such as PDFS and ADFS, when using the LAS, and a reduction in the incidence and severity of forearm fractures. |
Preliminary Studies on the Effects of Injection Rate Modulation on the Combustion Noise of a Common Rail Diesel Engine | The present work deals with tests on a DI Diesel engine equipped with two different types of Common Rail injectors, the second one allowing a ?쐓moother??fuel rate in the first stage of injection. The work aims at understanding how injection parameters and different injection rates may affect the combustion process in terms of in-cylinder pressure, noise and vibrations of the engine block. The tests performed for the same engine torque generally showed that engine speed, injection pressure and pilot injection duration are the most significant parameters that affect engine noise emissions. As regards the injection rate modulation, experiments showed that it is possible to reduce combustion noise at low engine speeds if the initial rate of injection is lower during the first stage of injection. |
Friction-Induced Vibrations of Window Sealing Systems | The problem of squealing from vehicle windows opened or closed in partly wet conditions has been investigated. Experiments were conducted using a glass-run seal sample and a tangentially moving glass piece installed on a test bench. The instantaneous velocity of the glass was measured along with the total dynamic frictional force for varying normal static loads and sprayed-water distributions. The characteristics of squeal vibrations and the influence of normal load and water distribution are discussed. The relation between friction force and speed was also investigated. An idealized model consisting of a one-dimensional continuous rod excited by a moving frictional point force was then investigated. The method of averaging was applied to solve the nonlinear equations of motion. The response became unstable when the magnitude of the negative slope and the normal force were large regardless of boundary conditions. Frequency jumps appeared in the numerical simulations due to the variation of the modal amplitudes according to the position of the contact force on the rod. The model provided an adequate qualitative description of many of the trends observed in the experiments. |
Door Courtesy Switch | This SAE Recommended Practice defines the test conditions, procedures, and performance requirements for 6, 12, and 24 V Door Courtesy Switches which are intended for use in motor vehicles. |
Automotive Manufacturing Task Analysis: An Integrated Approach | Automotive manufacturing presents unique challenges for ergonomic analysis. The variety of tasks and frequencies are typically not seen in other industries. Moving these challenges into the realm of digital human modeling poses new challenges and offers the opportunity to create and enhance tools brought over from the traditional reactive approach. Chiang et al. (2006) documented an enhancement to the Siemen's Jack Static Strength Prediction tool. This paper will document further enhancements to the ErgoSolver (formerly known as the Ford Static Strength Prediction Solver). These enhancements include integration of: Jack's Low Back Analysis tool; a modified Rohmert equation for muscular fatigue analysis; strength scaling equations to account for frequency and duration; the initial HUMOSIM Framework (Reed et al., 2006) for standing posture prediction; an automated measuring tool for common human-related measurements; vision windows and head/eye behavior settings; and Excel and PowerPoint reporting capability. Some of the functionality integrated into the ErgoSolver is existing Jack functionality. The goal of integrating these features was to ease the learning curve and increase efficiency for new and experienced users alike. Attempts were made to bring together, organize and present commonly used functionality in a fashion targeted towards the assembly ergonomics professional. Where functionality gaps were found in Jack, new functionality was created and integrated. While some of these features are pure usability features (i.e. shortcut methods for performing routine tasks), others are based on new and emerging research. |
Development of a Broad Delta Airframe and Propulsion Concepts for Reducing Aircraft Noise around Airports | This paper describes the impact of noise on the civil aircraft design process. The challenge to design ?쁲ilent??aircraft is the development of efficient airframe-engine technologies, for which integration is essential to produce an optimum aircraft, otherwise penalties such as higher fuel consumption, and, or noise are a concern. A description of work completed by Cranfield University will cover design methodologies used for a Broad delta airframe concept, with reference to future studies into alternate concepts. Engine cycle designs for ultra-high bypass ratio, constant volume combustor, and recuperated propulsion cycles are described, with a discussion of integration challenges within the airframe. |
Analytical Simulation of the Effects of Noise Control Treatments on an Excavator Cab using Statistical Energy Analysis | The objective of this study was to utilize Statistical Energy Analysis (SEA) to simulate the effects of a variety of noise control treatments on the interior sound pressure level (SPL) of a commercial excavator cab. In addition, the effects of leaks on the SPL of the excavator cab were also investigated. This project was conducted along with various tests that were used to determine the inputs needed to accurately represent the loads that the cab experienced during operation. This paper explains the how the model was constructed, how the loads were applied to the model, the results that were obtained from application of treatments, and a study of the effects of introducing leaks to the cab structure in the SEA model. |
ECoustics -- Vehicle Sound Package Inspired by Environmental Design | The environmental issues are mounting for a global automotive industry associated with ever-increasing output. Major issues include fuel consumption, vehicle emissions, consumption of non-renewable materials, and recycling of waste materials. This paper provides an overview of recent advances in new acoustic materials based on recycled and sustainable sources for ?쐃nvironmental??vehicle sound packages that address NVH and trim acoustics requirements. Thanks to new eco-design standards, both the OEM and suppliers can increase and improve eco-friendly aspects such as recycling end of life vehicles. The use of end of life materials in a new car includes: automotive shredded residue (ASR) such as tire fibers included in damping materials, chips foam from seats for acoustical shields, and automotive shredded residue for acoustical dash insulators. |
SEA Modeling of Vehicle Wind Noise and Load Case Representation | Vehicle wind noise is becoming increasingly important to customer satisfaction. Early wind noise assessment is critical to get things right during the early design phase. In this paper, SEA modeling technique is used to predict vehicle interior noise caused by the exterior turbulence. Measured surface turbulence pressures over vehicle greenhouse panels are applied as wind noise load. SEA representation of wind noise load case is investigated. It has been found that current SEA wind noise load case over-estimates at frequencies below window glass coincident frequency. A new concept of noise source pole index is introduced and a new wind noise load coupling has been developed. Comparison with vehicle wind tunnel measurements shows that the proposed load case significantly improved prediction accuracy. |
Experimental Characterization of the Unsteady Flow Field behind Two outside Rear View Mirrors | The unsteady flow fields behind two different automobile outside side rear view mirrors were examined experimentally in order to obtain a comprehensive data base for the validation of the ongoing computational investigation effort to predict the aero-acoustic noise due to the outside rear view mirrors. This study is part of a larger scheme to predict the aero-acoustic noise due to various external components in vehicles. To aid with the characterization of this complex flow field, mean and unsteady surface pressure measurements were undertaken in the wake of two mirror models. Velocity measurements with particle image velocimetry were also conducted to develop the mean velocity field of the wake. Two full-scale mirror models with distinctive geometrical features were investigated. |
Sound Quality of Exhaust Pipes Through Semi-Active Noise Control | Due to the increasing demands on NVH levels Sound Quality has become a major issue for the vehicle development. This includes the care taken with the internal noise levels as well as with the way noise is perceived. A different issue relates to the sensation the vehicle leaves through the type of noise coming from the engine to the car exterior. A major part of this sensation comes from the exhaust system through the mufflers which also contribute to the interior noise to some extent. In situations involving one-dimensional wave propagation as in engine exhaust systems, the use of active noise control is a strategy with increasing interest. Nevertheless, considerable restrictions due to the actuators and to the computational power needed for an active control system reduce the possible practical applications. The design and implementation of a semi-active noise control system for ducts based on Helmholtz resonators are presented in this work, in order to overcome these shortcuts. The engine speed, related to predominant frequency components of the noise, is used as reference for an active tuning of the passive, dynamical characteristics of a Helmholtz resonator by varying parameters like resonator volume through a computer controlled mechanism. The practical implementation of the system and an experimental setup are discussed together with the necessary procedures for the system. |
Tackling NVH ONE dB PER DAY | New tools and technologies are helping engineers reduce vehicle Noise, Vibration and Harshness. The vehicle chief engineer did not like what he was hearing on this recent evaluation ride. He was reviewing a new transmission scheduled for production in his company's iconic sporty car. But the marriage of transmission and platform was generating unacceptably high cabin-noise levels. The CE wasn't pleased. His design and manufacturing engineers explained that the new gearbox featured a thin-wall aluminum case for reduced mass. However, the lightweight case was the noise transmitter. |
Foam for NVH solutions | New innovations for a wide variety of sound-deadening applications. |
Nissan targets cabin NVH with big investment in Sentra upgrade | Significant updates to the seventh generation Sentra make the 2016 model Nissan's quietest and most dynamic-driving compact sedan to date. The automaker invested more than three times its typical outlay for a mid-cycle refresh on Sentra, according to Chris Schwerkoske, senior product planner. The 2016 model contains more than 550 new parts involving the exterior, interior, suspension, and steering systems, Schwerkoske told Automotive Engineering. |
Armored Response Vehicle for Bomb Disposal Teams | Lenco Industries Pittsfield, MA 413-443-7359 |
Analysis and Optimization of a Window Latch Effort Problem | A mathematical model was first developed for the opening effort analysis of vehicle side window latch. The model was then linked to an optimization program to perform optimization studies. The optimization parameters are the coordinates of key joints and the shifts of contact surface profile. Both deterministic and random optimization problems were formulated and solved. Results of the optimization studies were compared and conclusions were drawn from the results. |
Cabin Interior Noise Acoustic Assessment under the Influence of Air Intake System: Simulation and Experimental Investigation | This paper presents an assessment of the cabin interior noise under the influence of the AIS (Air Intake System). The AIS is one of the four main noise sources present in the vehicle and is therefore necessary to evaluate its contribution and thus improve its noise emission levels. It is also important to achieve the acoustics targets during the development phase, as noise and vibration are still amongst the main causes for problems at the last design and even pre-release stages. In order to assess the vibroacoustic behaviour and reduce the extent of the virtual prototype phase, durability and acoustic models was integrated. Using these models, stress and fatigue were checked. Modal and structural analyses were performed, orifice noise and radiated noise evaluated. Also SPL (Sound Pressure Level) was computed at the driver and passenger's ear location. Fluid/structure interaction analyses verify the AIS and cabin coupled response effects in the interior noise. Following that, simulation and experimental measurements were compared. The comparison shows the AIS structural frequencies that have significant contribution to the interior sound pressure level. These analyses also show the advantages of the integration between durability and acoustic numerical models, reducing cost and time during the project virtual phase. From now this paper gives a brief description on how to perform cabin interior noise analyses under the influence of AIS. |
On Simulating Passenger Car Side Window Buffeting | Side window buffeting is simulated for a passenger car using unstructured mesh and a finite volume based CFD solver. We first provide a description of the analysis method. Two vehicle configurations are considered: front window open and rear window open. The accuracy of RNG k-琯 and LES turbulence models is evaluated for this application by comparing predicted buffeting frequency spectrum with corresponding experimental measurements made in a wind tunnel. Further, the effects of several parameters on buffeting frequency and amplitude are studied. They include vehicle speed, yaw angle, inlet turbulent intensity, observer location inside the passenger compartment, presence of exhauster and side view mirror design. Simulation results prove to follow the trends observed in the experiments. |
Experimental Verification of Residual Compression in Tempered Automotive Glass with Holes | Tempered float glass is commonly used for both side windows and backlites in the automotive industry. The success of such products is primarily attributed to high level of residual compression, following tempering, which provides abrasion resistance as well as 3X higher functional strength to sustain mechanical, vibrational and thermal stresses during the vehicle's lifetime. Certain applications of tempered glass, however, require mounting holes whose surface-finish must be controlled carefully to withstand transient tensile stresses during tempering. Simultaneously, the nature and magnitude of residual compression at the hole must provide sufficient robustness to bear mounting, vibrational and thermal stresses throughout the life of the vehicle. This paper presents (i) analysis of residual compression at the hole, (ii) measurement of biaxial strength of annealed glass with hole at center, and (iii) measurement of biaxial strength of tempered glass with hole at center. Both fractographic analysis and the biaxial strength data of annealed and tempered glasses are used to deduce the magnitude of residual compression at the hole. These data show excellent agreement between analytical solution for residual compression and that inferred from biaxial strength. The nature of residual stresses at the hole, which differs considerably from that of classical tempering, is highlighted. |
Influence of Cabin Modal Density on Vehicle Interior Noise | The increasing trends towards smaller power units running at high speeds together with the increasing use of diesel engines in passenger vehicles have resulted in higher vehicle interior noise and vibration levels. The customer awareness towards comfort of vehicle specifically with reference to perceived noise levels has become a selling point for vehicle manufacturers. In this paper experimental and analytical techniques used to study the influence of cabin related parameters on interior noise are presented. These techniques were applied to study interior noise of truck cabins. The noise and vibration signals were measured at body panels and at Operators Ear Location (OEL) for different engine speeds. The natural frequencies of body panels were identified by using frequency response function measurements. The modal analysis of acoustic cavity was carried out using finite element technique. |
New Cockpit Human-Machine-Interface Concept | More and more features in today's vehicles put increasing demands on the driver's ability to process information, operate functions and simultaneously concentrate on driving. This necessitates simplifying and optimizing the human-machine-interface (HMI). Therefore, Siemens VDO has developed a cockpit study, ?쏝reeze?? showing a new, ergonomic HMI concept in an attractive design. The number of switches is minimized by implementing a force feedback switch, allowing intuitive operation of several functions via a menu system displayed on a 10 inch monitor. Specific driver functions are operated by mulit-function keys in the steering wheel with a secondary display. The turn indicator is operated by squeezing the steering wheel grips. Vibration elements are activated in dangerous situations to alert the driver. Additional features include flat panel loudspeakers and instrumentation with 3D-effect Many technical details are presently under development, however, some solutions are already in production. |
Reduction of Road Noise by the Investigation of Contributions of Vehicle Components | The mobility technique is used to analyze the transfer functions of road noise between the suspension and the body structure. In the previous analyses, the suspension system and the body structure are altogether modeled as subsystems in the noise transfer path. In this paper, the mobility between the suspension and the body structure is analyzed by the dynamic stiffness at the connecting points. The measured drive point acceleration FRF at the connecting point in the transfer path was used to estimate the contributions of subsystems. The vibration modes of tire, the acoustic noise of tire's interior cavity, the vibration modes of the car's interior room, and the vibrations of body structure and the chassis are also considered to analyze the coupling effects of the road noise. Analyzing the measured results, direction for modification of car components is suggested. The road noise around 250Hz in car's interior room is reduced by the modifications of the housing panel near the rear suspension. |
An Analysis of Idling Vibration for a Frame Structured Vehicle | A finite element model for an entire frame-structured sports utility vehicle was made to evaluate the characteristics of the idling vibrations for the vehicle. The engine exciting forces were determined by Souma's method to simulate the idling vibrations. The modeling of the power plant and the entire vehicle was verified by the reasonable agreement of the experiment and calculation results. Attention was focused on the frequency of the first-order vertical bending mode for the frame. It has become clear that the idling vibration level of the vehicle is lowered by decreasing the frequency of the first-order frame bending mode. |
Micro Step vs. Full Step - A Quantitative Competition | Stepper motors are used in a wide range of automotive applications. High reliability at low cost, low power dissipation, and low noise are the main requirements for those applications. Compared to full stepping, micro stepping has better performance concerning reliability, accuracy, low-noise, and also on wear out. With micro stepping, a low resolution low cost stepper motor may have the same or better performance then a more expensive stepper motor with higher resolution with full stepping. To decide either to realize micro stepping or full stepping, quantitative criteria are required for the competition. This article gives those criteria based on the physics of the stepper motor. |
Evaluation of Aerodynamic Noise Generated in Production Vehicle Using Experiment and Numerical Simulation | Aerodynamic noise generated in production vehicle has been evaluated using experiment and numerical simulation. Finite difference method (FDM) and finite element method (FEM) are applied to analyze the flow field, and Lighthill's analogy is employed to conduct acoustic analysis. The flow fields around front-pillar obtained by numerical simulations agree with those by experiment for two cases with different front-pillar shape. Moreover, the distribution of acoustic source predicted by FEM is consistent with that obtained by experiment. Present study ascertained the feasibility and applicability of FEM with SGS model towards prediction of aerodynamic noise generated in production vehicle. |
Development of a Luxury Vehicle Acoustic Package using SEA Full Vehicle Model | Interior noise has become a significant performance attribute in modern passenger vehicles and this is extremely important in the luxury market segment where a quiet interior is the price of entry. With the elimination of early prototype vehicles to reduce development costs, high frequency analytical SEA models are used to design the vehicle sound package to meet targets for interior noise quality. This function is important before representative NVH prototypes are available, and later to support parameter variation investigations that would be cost prohibitive in a hardware test. This paper presents the application of an analytical full vehicle SEA model for the development of the acoustic package of a cross over luxury utility vehicle. The development concerns addressed were airborne powertrain noise and road noise. Power flow analysis was used to identify the major noise paths to the interior of the vehicle. The SEA model allowed the performance of alternative designs to be assessed, the reduction of the power input from the major noise paths to be quantified and optimization of the acoustic package for both road noise and powertrain noise to be completed. The SEA model was used to drive acoustic package design to meet not only acoustic targets but also the mass and costs targets and deliver an optimized package. The other major benefit of the full vehicle model that this paper will present are the impacts of not meeting sub-system requirements that are usually rolled down to the supplier. This is invaluable as it informs the vehicle design team what the impact is on the sound pressure level at the ?쐂rivers ear??of not meeting subsystem requirements, for example the ?쐃ngine compartment absorption or front of dash transmission loss requirement?? It is concluded that the use of a detailed SEA model is a highly valuable design tool to support ?쁀??to ?쁁??design and material comparisons, to identify major noise paths, and to provide direction to the program. |
Power Steering Pump Sound Quality and Vibration - Test Stand Development | The quietness of the interior of automobiles is perceived by consumers as a measure of quality and luxury. Great strides have been achieved in isolating interiors from noise sources. As noise is reduced, in particular wind and power train noise, other noise sources become evident. Noise reduction efforts are now focused on components like power steering pumps. To understand the contribution of power steering pumps a world-class noise and vibration test stand was developed. This paper describes the development of the test stand as well as it's objective to understand and improve the sound quality of power steering pumps. |
Squeak and Rattle Behavior of Elastomers and Plastics: Effect of Normal Load, Sliding Velocity, and Environment | The use of plastics and elastomers, for interior and exterior automotive components, presents a risk of frictionally incompatible materials contacting each other, resulting in squeaks, ticks, chirps??Ford's NVH S&R Department, and MB Dynamics have developed a tester (Figures 1 and 2) that can measure friction, and sound, as a function of sliding velocity, normal load, surface roughness, and environmental factors that allows us to provide up-stream engineering information to Forward Model Design Engineers. When material pairs undergo sliding contact, friction forces can cause elastic deformation adjacent to the contacting surfaces. The elastic deformation is a mechanism for storing energy and sound is produced when the energy is released. The sound that we hear may be a squeak or squeal (multiple stick-slip) or a tick (single stick-slip). However if the sliding material composition (e.g. coatings, low friction additives?? and the structure (surface roughness or stiffness/compliance) of the sliding components is properly selected, we can avoid or minimize noise by minimizing elastic deformation and therefore the release of stored elastic energy. The release of the stored elastic energy can occur when the kinetic friction is less than the static friction. This difference can be duplicated during single excursion events or when undergoing sine or random vibration. In the case of thermoplastics, cold temperatures can have a major influence on acoustic properties by reducing chain mobility (Tg) at the sliding contact surface leading to an increase in the surface contact stiffness and therefore changing the elastic deformation properties. |
Wind Noise and Drag Optimization Test Method for Sail-Mounted Exterior Mirrors | An L18 Taguchi-style Design of Experiments (DOE) with eight factors was used to optimize exterior mirrors for wind noise and drag. Eighteen mirror properties were constructed and tested on a full size greenhouse buck at the Lockheed low-speed wind tunnel in Marietta, GA. Buck interior sound data and drag measurements were taken at 80 MPH wind speed (0째 yaw angle). Key wind noise parameters were the fore/aft length of mirror housing and the plan view angle of the mirror housing's inboard surface. Key drag parameters were the fore/aft length of the mirror housing, the cross-section shape of the mirror pedestal, and the angle of the pedestal (relative to the wind). |
Identification of Annoying Noises in Vehicles | During its initial use the vehicles go through a period of adjustment, in which the structure and moving parts show their problems of looseness, tightness, stress, excess or lack of torque by emitting characteristic noises of different intensity and frequency. These noises are bothersome for the user. Car manufactures and private companies have specially-trained personnel who are able to identify the source of those noises simply by listening to them. Once the source is identified, the problem is often solved by tightening the moving parts and/or using polymer materials. For the companies that provide the service of elimination of annoying noises inside the cabin, however, this dependence on such specially trained people is a problem. As an alternative, there is a proposal to develop a system that measures the noise patterns inside the cabin during dynamic tests, subtracts the engine noise, identifies the annoying noise, obtains the frequency spectra of the detected noise by using the Fourier and Hilbert transforms, compares these spectra with the spectra of the most frequently annoying noises found inside cabins of vehicles and, finally, reports the potential sources of the annoying noise detected. This paper describes the system assembled for this purpose and its performance in the elimination of annoying noises inside vehicle cabins. |
A Case Study on Airborne Road Noise Reduction of a Passenger Vehicle | This paper presents a case study on reducing road noise of a passenger vehicle. SEA, insertion loss and sound intensity measurements were the tools used in the study. A SEA model was constructed to predict the primary paths (panels or area) contributing to the overall interior sound field. Insertion loss measurements were used to verify the primary contributing paths identified using SEA. To provide further details of the primary paths, intensity maps of identified panels were measured allowing detailed reconstruction of the contributory panels. The SEA model, insertion loss, and intensity maps aided in providing possible design fixes that will effectively reduce road noise. Finally, comparisons of predicted results versus actual results at both a subsystem and a full vehicle level are included in this paper. |
The Rattle Trap | This paper addresses the fundamental mechanisms associated with Buzz, Squeak and Rattle (BSR) sounds and the analysis of their acoustic signatures. These sounds will be generated and analyzed individually with a conventional popular metric in the presence of typical background sound. Baseline computations of the background will be performed for comparison. This paper will present a look at the sensitivity of the current popular metrics ability to identify BSR specific sounds in the presence of background noise levels. This understanding of the measurement and quantification of the specific BSR sound signatures can be the basis for design target setting with respect to specific BSR phenomena. As well, this can lead to a better understanding of whether or not it is appropriate to quantify these phenomena together or if there is a need for a ?쏳attle Trap??metric, a ?쏝uzz Trap??metric or a ?쏶queak Trap??metric. |
Vehicle Panel Vibro-Acoustic Behavior and Damping | Damping treatments are widely used in passenger vehicles, but the knowledge of damping treatments is often fragmentary in the industry. In this study, vibro-acoustics behavior of a set of vehicle floor and dash panels with various types of damping treatments was investigated. Sound transmission loss, sound radiation efficiency as well as damping loss factor were measured. The damping treatments ranged from laminated steel construction (thin viscoelastic layer) and doubler plate construction (thick viscoelastic layer) to less structural ?쐀ake-on??damping and self-adhesive aluminum foil-backed damping treatments. In addition, the bare vehicle panels were tested as a baseline and the fully carpeted floor panel was tested as a reference. The test data were then examined together with analytical modeling of some of the test configurations. As expected, the study found that damping treatments add more than damping. They also add mass and change body panel stiffness. Each of the three factors affects different aspects of noise and vibration of vehicle panels. |
Motorhome Acoustical Issues: An Overview | Motorhomes or recreational vehicles (RV's) are unique vehicles in that they pose many interesting design challenges to acoustical engineers. This type of vehicle has many of the typical NVH (Noise Vibration and Harshness) issues seen in passenger cars and heavy trucks; however, there is an entire arena of NVH issues that are not seen in these other products. The issues are not present in these other markets; because a motorhome, not only serves as a means of transportation, it also serves in a secondary role as a home. The dual role of the coach creates many residential noise concerns. Some of these issues include managing generator sound levels while the coach is either parked in a campsite or on road, controlling engine noise levels for designs where the bed serves as the engine cover, and controlling wind noise to improve speech communication between the driver and passengers. Complicating these issues is the fact that each unit is semi-customized. In many cases the owner also has a choice of chassis, generator, engine and drivetrain along with appliances and other amenities that affect the acoustics. With the high cost of these vehicles, owners demand low noise levels and high sound quality in all aspects of vehicle operation. This paper presents an overview of numerous Class A motorhome sound quality studies and presents typical sound levels and techniques for controlling undesirable sounds. |
A Comparison of Seven Different Noise Identification Techniques | Today's NVH engineers have at their fingertips a myriad of different noise source identification techniques available with which to locate noises. Unfortunately, with so many different techniques available, it is not always clear which technique is the best for a specific application. Should one use Sound Intensity? Or is Acoustic Holography a better tool? But if there are noises above 5kHz, which technique works then? And what is Beamforming? Would that work? With so many choices, it is required to know before the test which technique is the best choice. This paper will give an overview of 7 popular techniques to help the practicing NVH engineer decide which technique is the best for a specific application. A practical explanation along with a real life example will be given to help make clear where and how a technique can be used. |
Windshields With New PVB Interlayer for Vehicle Interior Noise Reduction and Sound Quality Improvement | Noise transmission through automotive windshields is the subject of extensive laboratory acoustic and full scale high-speed track NVH evaluation. Standard windshields transmit structure-borne noise through resonances at low frequencies, and wind noise and airborne noise due to coincident effect at high frequencies. Approaches to enhance windshields NVH performance and to improve vehicle interior noise quality are explored. The study shows that the most effective approach is to design a new interlayer for windshields. This leads to the development of an acoustic grade PVB interlayer. To quantify the noise reduction by windshields with the new PVB interlayer, Solutia commissioned NVH testing of the windshields installed on cars, comparing these with factory-equipped standard windshields. Dynamic responses of the windshields were studied in laboratory on a dynamometer and resulting frequency response functions measured. A considerably high damping of resonant vibrations and significant reduction of structure-borne noise were noted. Further studies on the windshields for enhanced noise reduction, in particular wind and road noise, were conducted with several vehicles on high-speed test tracks. Test results show that the use of the windshields with new PVB interlayer results in 2 - 6 dB reduction in the cabin noise in high frequency range and up to 2 - 3 dB reduction in low to mid frequency range. Both subjective and objective results indicate that these windshields can greatly improve the vehicle wind noise and road noise performance and noise quality within the cabin, and result in the quieter passenger compartment. |
Exhaust System Robustness Analysis Due to Flex Decoupler Stiffness Variation | The function of flex decoupler is to reduce the vibration transferred from the engine to the vehicle body. The stiffness of the flex decoupler is a key parameter in the vibration control. This paper deals with decoupling exhaust hot end and cold end to minimize vibration transfer. A computer aided engineering (CAE) based design of experiment (DOE) is used to investigate the coupling stiffness. A finite element model is built to analyze the exhaust vibration responses. Robustness of the exhaust system is analyzed. The analysis reveals that vertical stiffness of the flex decoupler is the key parameter for the hanger force response. The main control factors for exhaust vertical and lateral bending frequencies are vertical and lateral stiffnesses of the decoupler, respectively. |
Light-Weight Localized Structural Reinforcements for Structural and NVH Applications | The use of adhesively bonded localized reinforcements is a relatively new concept in the automotive industry. Although use of this reinforcement method is in its early stages, these reinforcements are now used for a variety of applications in the automotive industry including crash worthiness, fatigue resistance, and NVH. This approach can provide relatively fast, easy, non-intrusive, and cost effective solutions for OEM's when compared to traditional reinforcement methods. Also overall weight can be simultaneously reduced since the reinforcement is placed only where it is needed instead of filling an entire section with foam or changing the metal thickness along an entire body member. Materials and concepts have been developed that can be used to improve the structural stiffness and the resulting NVH performance of the vehicle. This paper will discuss the use of localized reinforcements including materials, applications, and potential uses and the benefits. |
Improved Acoustics Through Perforated Plastic Panels | In an effort to further reduce noise inside the passenger compartment of automobiles, a new approach has been made to incorporate parts not traditionally considered to be acoustic in nature. Through use of patented technology, the acoustic improvement can even be tuned to specific audible ranges to quiet background noise and improve audio clarity for devices such as hands free cellular phone devices. This paper will discuss the theory of using perforations for acoustic applications, demonstrate how the acoustic response can be tuned with flat sample development and illustrate actual invehicle data showing potential improvement of perforated plastic components. |
Portable NVH Dynamometers | Noise Vibration and Harshness (NVH) characteristics have become a key differentiator between ?쏥ood??vehicles and ?쏝est-In-Class??vehicles. While all OEM's and most Tier 1 suppliers have on-site in-ground chassis dynamometers, a need was identified to design, develop and bring to market, a fully capable portable NVH full vehicle chassis system. The original concept entailed a device, which could be brought to the customer's location, be fully self contained, requiring no external power, and provide data acquisition using transducers that would not contact the vehicle. With traditional instrumentation taking several hours to install, non-contacting lasers would be used to provide significant timesaving, and prevent any possible damage to the vehicle from pinched wires. The new methodology should provide data acquisition in as little as 20 minutes. Analysis would be accomplished immediately following testing, with hard copies available before the next vehicle was ready to run. Full vehicle NVH root cause analysis, including system balancing would be done in minutes, at the customer's location, assembly plant, engineering center, or Visteon site. Along with the NVH capabilities, performance data would also be available including horsepower, fuel testing, etc. This paper presents history, design, development, implementation, use, and future developments for the Visteon Portable NVH/Performance Dynamometers that are now in service. Showcasing how the portable dynamometers support a vehicle level NVH design methodology is presented, which seeks an optimum balance of system design criteria. This is possible by providing bumper-to-bumper NVH root cause analysis, driveline imbalance sensitivity to first order forces, driveline imbalance cross-talk analysis, wheel/tire imbalance and force variation sensitivity, system resonance identification, and dynamic mount transmissibility analysis. |
Acoustic Sources localization: Application to Wiper Aerodynamic Noises | The reduction of aerodynamic noise sources is today an important topic in automotive industry. In order to localize the different sources on the arm and blade, a 48 microphones acoustic antenna coupled with a software based on the beam-forming imaging method has been used. Obtained results are validated inside the car on track. Aerodynamic numerical simulations are compared to aerodynamic measurements. The turbulent kinetic energy distribution obtained from the simulations is then compared with measured sound sources localization maps: the results are presented and commented for two wiper configurations. |
Vehicle Retention Methods for Four-Wheel Chassis Dynamometer Testing | Four-Wheel Anechoic Chassis dynamometers are an established and valuable tool used extensively in the development of noise control systems for the automotive industry. Variations in vehicle platforms, exterior styling, as well as, increases in vehicle test load condition ranges have changed the methods required to secure vehicles to chassis dynamometers. This paper will investigate two methods used to retain vehicles for four-wheel chassis dynamometer testing. These methods affect the acoustic signature of the test vehicle and can influence the measured performance of acoustic treatments. The performance of a typical acoustic interior system will be measured and analyzed under different vehicle retention methods as well as the influence of retention force variation. Best practice recommendations are then discussed. |
Collision Performance of Automotive Door Systems | Historically, most safety related improvements to door systems have involved retention of occupants within the vehicle. However, such improvements have not been without some safety trade-offs. The recent update to FMVSS 214 (Side Impact Protection) has focused attention on increased occupant protection in side impacts. The standard essentially increases vehicle side strength requirements in order to reduce intrusion into the occupant space. The safety consequences associated with strengthening vehicle side structure will be evaluated with respect to various impact configurations. Energy management considerations of current as well as conceptual door systems during a collision will also be discussed. Individual latch and hinge component testing as currently required by FMVSS 206 does not completely evaluate the collision performance of the door as a system. From field collision evaluation, it has been seen that doors and surrounding side structure must act as a system to efficiently manage collision forces and distribute occupant loads. Procedures for evaluating current and future door systems by means of revised laboratory testing procedures will be evaluated. |
Application of Experimental Design in the Steady State Particulate Exposure Levels in a 1992 International School Bus | A steady state mobile test was developed to measure the concentration of breathable particles that can enter the cabin of a school bus. The principles of experimental design were used to identify the experimental conditions for the test and to analyze the data. The design consisted of a series of steady-state tests using a 1992 International school bus. The testing was performed on a closed three mile track at the Army Test Center in Aberdeen, MD. The mass concentrations of particles smaller than 2.5 microns were measured at three locations inside the bus and at the air intake into the engine. The number concentration of particles was measured at the tailpipe. Three factors were varied at three levels in a Box-Benhken design. The steady state speed was set at 5, 30, and 55 mph. A load was applied to the engine with a mobile dynamometer to simulate a 0, 0.67% and 1.33% road grade. Tests were performed with three window configurations: all windows open, all windows closed, and all windows half open. Steady state averages for PM2.5 mass concentrations inside the bus ranged from 2.2 關g/m3 to 111 mg/m3. An analysis of variance indicates that there was a significant difference in the concentration of particles inside the bus as a result of the varying speed and windows conditions. At the 95% confidence interval the factors of speed and windows had a significant effect on the particle mass concentration. Furthermore, the effect of speed on the particle concentration was dependent on the window configuration used. |
An Efficient Light Weight all Plastic Dual Rack and Pinion Window Lift Mechanism for Automotive Vehicles | In the latter half of 2004, a new concept of window lift mechanism will be supplied to a major OEM for a high volume passenger car in the North American market. This new concept of window lift mechanism, marketed by Dura Automotive Systems, Inc. as the Racklift?? was jointly developed in conjunction with an independent inventor. The Rack Lift mechanism is essentially an all-plastic construction, which results in a very light weight unit. Plastic gears are driven along each side of an injection molded unitary dual rack providing a quiet and efficient operation. The higher efficiency of this mechanism, compared to traditional designs, allows use of smaller, lighter and lower output electric motors. The plastic mechanism is greaseless and thus produces a constant efficiency over the required operating temperature range. The combination of high efficiency, lightweight and robustness to temperature makes this an ideal concept for automotive applications. |
Comparison of Indoor Vehicle Thermal Soak Tests to Outdoor Tests | Researchers at the National Renewable Energy Laboratory conducted outdoor vehicle thermal soak tests in Golden, Colorado, in September 2002. The same environmental conditions and vehicle were then tested indoors in two DaimlerChrysler test cells, one with metal halide lamps and one with infrared lamps. Results show that the vehicle's shaded interior temperatures correlated well with the outdoor data, while temperatures in the direct sun did not. The large lamp array situated over the vehicle caused the roof to be significantly hotter indoors. Yet, inside the vehicle, the instrument panel was cooler due to the geometry of the lamp array and the spectral difference between the lamps and sun. Results indicate that solar lamps effectively heat the cabin interior in indoor vehicle soak tests for climate control evaluation and SCO3 emissions tests. However, such lamps do not effectively assess vehicle skin temperatures and glazing temperatures. |
On The Causes of Image Blurring in External Rear View Mirrors | Effective rear view vision from external mirrors is compromised at high speed due to rotational vibration of the mirror glass. Possible causes of the mirror vibration are reviewed, including road inputs from the vehicle body and a variety of aerodynamic inputs. The latter included vibrations of the entire vehicle body, vibrations of the mirror ?쐓hell?? the turbulent flow field due to the A-pillar vortex (and to a lesser extent the approach flow) and base pressure fluctuations. Experiments are described that attempt to understand the relative influence of the causes of vibration, including road and tunnel tests with mirrors instrumented with micro accelerometers. At low frequencies, road inputs predominate, but some occur at such low frequencies that the human eye can track the moving image. At frequencies above about 20Hz the results indicate that at high speeds aerodynamics play a dominant role. When the vehicle is yawed, significantly greater aerodynamic inputs arise from the leeside vortex than from the vortex on the upwind side. However since the mounting of the mirror glass is part of a complex dynamic system the results are configuration specific. |
LIN Protocol -Technology Review and Demonstration in Power Window Application | This paper describes and investigates the possibilities and the advantages of using LIN as a multiplexed electrical system in a vehicle. LIN is a communication protocol designed for controlling simpler electrical components in a vehicle, like for example switches, sensors and actuators. Investigations have been done concerning the technique behind LIN as well as the recourses needed in order to implement LIN-communication between components on the power window of a Maruti Suzuki's ZEN car. Clearly the benefits of using LIN are low cost to feature ratio and at the same time reducing harness costs and enabling higher reliability of the vehicle functions. |
?쏞lear Vision??Automatic Windshield Defogging System | The present paper describes the system design for the Clear Vision auto defog system and the improvements made to the Integrated Dew Point and Glass Temperature (IDGT) sensor. The Clear Vision auto defog system has been implemented on a 2000 Cadillac DeVille. Preliminary validation tests demonstrate satisfactory performance. |
New Procedure for Noise Source Mapping During Pass-By Noise Measurements | Acoustic source identification is an important issue in both early and prototype validation stages of NVH design. OEMs and suppliers need to assess the entire description of vehicle noise emission, to understand and address interior comfort and exterior radiation issues. Today, none of the existing methods allow engineers to get a quick snapshot of sources contributing to the external pressure level affecting pass-by noise emission compliance, requiring long and arduous testing projects with & without physically masked components. A new acoustic imaging technique provides an important solution. The method is based on a microphone array. Like a camera, but unlike current holographic methods, the software delivers focused, near-realtime 2D colour snapshots and movies, corresponding to the sound pressure level at the region of interest. Typically, the entire side of a vehicle can be analysed during one pass-by run. Examples are given to demonstrate the time-space or frequency-space resolution of mappings, using one data set for numerous configuration analyses in a very short time. The technique is also being used successfully for trains, aircraft, trucks, tractors, and other vehicles for optimising exterior sound radiation characteristics |
Nonlinear Model Validation for Automotive Seat Cushion-Human Body Combined Structure | In this paper, a nonlinear dynamic model for automotive cushion-human body combined structure is developed based on a nonlinear seat cushion model and a linear ISO human body model. Automotive seat cushions have shown to exhibit nonlinear characteristics. The nonlinear seat cushion model includes nonlinear stiffness and nonlinear damping terms. This model is verified by a series of tests conducted on sports car and luxury car seats. The transfer functions from the tests for human body sitting on an automotive seat changes with the vibration platform input magnitudes. This indicates that the combined structure possesses nonlinear characteristics. The nonlinear model is validated by the transfer functions from the test. The paper discusses the influence of the parameters of the nonlinear structure on the design of seat and assessment of human body comfort. |
Automotive Buzz, Squeak and Rattle (BSR) Detection and Prevention | Recent advances in automotive noise control engineering have reduced the general level of noise in the passenger car compartment and focused more attention on irritating noises. Buzz, Squeak and Rattle (BSR) have surfaced as major concerns. Customers increasingly perceive squeak and rattle as direct indicator of vehicle build quality and durability as revealed from the J. D. Power surveys. The high profile nature of squeak and rattle has motivated the manufacturers to pay attention during early phase of vehicle development program. Traditional methods of prevention and elimination of squeak and rattle have been found to be no longer sufficient to develop acceptable products in shortened product development cycle. Basic causes, design guidelines and validation technique using laboratory simulation and digital data acquisition have been successfully developed to push the BSR prevention process upstream in the development cycle. A test procedure to map the vehicle BSR performance with the use of laboratory simulation and digital data acquisition tools has been developed. The vehicle BSR performance is evaluated based on the subjective rating system. As commitment towards customer to meet his expectations in quality right from purchase till the useful life of vehicle, the vehicle BSR performance is monitored till the end of life. Lab simulation technique allow determination of sub-system or prototype vehicle degradation much early in the development process. Simulation is used to map the progression of noise with respect to vehicle life and usage conditions. Targeting at reducing noises after durability exposure, effectively later in the vehicle life, is crucial in ensuring new vehicle quality. |
Vehicle Interior Noise Source Identification and Analysis for Benchmarking | The acceptance criterion of any vehicle in terms of user comfort invariably depends on the vehicle interior noise and vibration characteristics. The levels of sound energy and structural excitation inside the vehicle compartment measures the amount of annoyance in terms of quality and comfort. For vehicle interior noise abatement and noise treatment, it is desirable to quantify the noise sources by determining the sound power contribution from each vehicle component/panel, acoustic leakages inside the vehicle, body panel vibrations, gearshift lever and steering wheel vibrations. Many a times, it is necessary to arrive at benchmarks or targets for the various sources of noise in order to refine the systems. The present paper describes a methodology for interior noise source identification and its analysis for benchmarking. Two different vehicles of the same class but of different makes were compared and evaluated for interior noise and vibration levels. Intensity mapping of the complete interior of both the vehicles was carried out and compared. Similarly, the vibration and sound pressure levels were measured and compared at selected locations and at anti-node points. The effectiveness of the firewall, silencers and engine mounts were also checked and compared. The sound intensity measurements at stationary condition with different engine speeds inside the vehicle helped in computing the sound power from different vehicle panels, and identifying sources and their contribution. The correlation between pressure and vibration levels of different sources with acoustical and structural transfer paths were studied. The modal behaviour of the acoustic cavity and the structural panels were studied using finite and boundary element techniques, to predict the sound pressure levels at selected locations and the contribution of different vehicle panels. This provided benchmarking - sourcewise, acoustic as well as structural and system noise-engine, firewall, different panels, silencers, etc. enabling to set individual system targets. |
Vibration Testing and Modal Analysis of Airplanes ??Recent Advances | The paper will introduce some recent advances in vibration testing and modal analysis of airplanes. Recently, a very promising parameter estimation method became available, that has the potential to become the new standard. The main advantage of this so-called PolyMAX method is that it yields extremely clear stabilization diagrams even for broadband and high-order analyses. The method will be applied to two aircraft cases: a Ground Vibration Test using broadband shaker excitation on a small composite aircraft and in-flight data using natural turbulences as excitation. These two data sets allow illustrating both the classical Frequency Response Function based as well as the operational output-only modal analysis process. |
Dynamic Modal Analysis and Optimization of a Mechanical Sensor Arm Deployment System for a C-130 Aircraft | During structural engineering design two of the most overlooked design facets of a finished product is understanding the behavior characteristics of how the product will react when resonated at its natural frequencies and actually defining and understanding the overall vibration profile responsible for the excitation of the structure. A C-130 mechanical arm/pod system has been developed to accommodate 1,000-pounds of sensor payload deployable in flight from a C-130 Hercules military aircraft (variants B thru J). The mechanical arm/pod system will be subjected to a profile of vibration from numerous sources during deployment and while in the final operating position. A general vibration profile for the mechanical arm/pod will be compiled from the plane?셲 four T-56-A-15 turboprop engines, the atmospheric turbulence and random gust loads. A pitot-accelerometer sensor probe was used to obtain vibration data of the C-130 ramp during a zero-light turbulence category flight for indicated airspeeds of 130 knots and 150 knots. The mid/low frequency values with worse case scenario magnitudes induced by buffeting, flutter and gust loads were computed. A formal vibration analysis was conducted utilizing the Finite Element Approach and Modal Analysis using Pro/ENGINEER and Pro/MECHANICA software packages. The natural frequency modes for the mechanical arm/pod system was computed in the x, y and z directions with three different geometrical configurations of the structural cross-member supports. |
Vibro-Acoustic Modeling of Aircrafts Using Statistical Energy Analysis | The Statistical Energy Analysis ??SEA is one of the main methods used to study the vibro-acoustic behavior of systems in the aeronautic, automotive and naval industries. The principal advantages of this method are the possibility of analysis in the mid and high frequencies range, the reduced computational costs when compared with other methods (like Finite Element Method or Boundary Element Method) and ease modeling of different sources of noise and vibration. As a statistical method, SEA provides results associated with average values in time, space and in an ensemble of similar structures. In aerospace applications, where the noise and vibration sources are usually random, SEA is particularly indicated. SEA also allows the straightforward modeling of the noise control treatments used in commercial aircraft and the further optimization of these treatments, reducing weight and costs. In this work, the steps followed at the development of an EMBRAER aircraft SEA model are presented. The hypotheses adopted during the subsystems definitions are discussed. The noise and vibration sources considered at the model are described and the calculations of the power inputs are demonstrated. Finally, some results obtained through the model are shown and some possibilities of analysis using the model are explored. |
Analytical Design of Cockpit Modules for Safety and Comfort | This paper reviews the state of the art on analytical design of cockpit modules in two most crucial performance categories: safety and comfort. On safety, applications of finite element analysis (FEA) for achieving robust designs that meet FMVSS 201, 208 and 214 requirements and score top frontal and side NCAP star-ratings are presented. On comfort, focus is placed on Noise, Vibration and Harshness (NVH) performance. Cutting-edge analytical tools for Buzz, Squeak and Rattle (BSR) avoidance and passenger compartment noise reduction are demonstrated. Most of the analytical results shown in this paper are based on the development work of a real-life application program. Correlations between the analytical results and physical test results are included. Examples of Computational Fluid Dynamics (CFD) analysis for climate control are also included. At the end, the road map toward 100 percent virtual prototyping and validation is presented. |
Part Design and Material Selection for Single Shot Injection Molded Passenger Airbag Deployment Doors | The passenger airbag (PAB) deployment door is a very critical component of the passenger airbag restraint system because of the many demands put upon the door. As an aid to those in the field who lack technical expertise and experience, this paper is intended to be a somewhat indepth set of guidelines for the part design and material selection for single shot injection molded PAB deployment doors. Disadvantages and advantages of this type of door are discussed. In regards to part design, some areas covered are size, hinge, tear seam, gap hiders, and surface. Environmental factors, mechanical properties, structural factors, and processing parameters -- all of which are important for material selection -- are defined and described. |
HVAC Vacuum Duct Door | The duct door (also referred to as ?쐖alve??or ?쐄lap?? which is used to regulate the air flow in a vehicle's HVAC system (Figure 1), has undergone a significant technological evolution since the early eighties. During the past decade, this evolution has centered on the raw materials used and on the manufacturing processes in order to gain in reliability and quality as well as in weight and cost reduction. Following the review of this evolution, we will present a new development: the vacuum duct door (?쏺DD??. This patented concept consists in activating the rotation of the door by creating an air depression, thereby doing away with the mechanical components utilized up until now for that purpose |
Measurement of Aeroacoustically Induced Door Glass Vibrations Using a Laser Vibrometer | Work has been performed to study side glass vibrations of a typical automobile using a scanning laser vibrometer. The objective of this work was to achieve better understanding of the source and path mechanisms for aeroacoustically generated wind noise. As a tool for measuring aeroacoustically generated vibrations, the laser vibrometer presents many advantages over traditional methods. These advantages, discussed in this paper, include rapid setup, full field imaging, high spacial resolution, non-contact operation, and wide dynamic and frequency ranges. |
Calculating the Loudness of Impulsive Sounds | In this paper, a procedure for calculating the loudness of impulsive sounds is presented. Impulsive sounds are defined as short duration (< 500 msec), high energy sounds usually caused by an impact. Each of the six steps in this procedure are discussed in some detail. Validation of the method is obtained by psychoacoustic testing using both loudness matching and modified Levitt (up-down) techniques. The implementation of the impulsive loudness metric is then illustrated for door closing and power lock sounds. |
Vehicle Closure Sound Quality | This paper describes an investigation into the sound quality of passenger car and light truck closure sounds. The closure sound events that were studied included side doors, hoods, trunklids, sliding doors, tailgates, liftgates, and fuel filler doors. Binaural recordings were made of the closure sounds and presented to evaluators. Both paired comparison of preference and semantic differential techniques were used to subjectively quantify the sound quality of the acoustic events. Major psychoacoustic characteristics were identified, and objective measures were then derived that were correlated to the subjective evaluation results. Regression analysis was used to formulate models which can quantify customers perceptions of the sounds based on the objectively derived parameters. Many times it was found that the peak loudness level was a primary factor affecting the subjective impression of component quality. In several other cases, however, factors such as the length of the sound, the existence of multiple impacts, and sharpness proved to be more important for subjective preference. The resulting regression models can be used to quantify the sound quality of future closure hardware changes and guide engineers in the design of closure systems with optimal sound quality. |
New Material for Supplemental Inflatable Restraint Doors | New specialty urethane foams have been developed for use in composite type air bag doors (doors which consist of a vinyl skin, a foamed urethane core, and a supporting substrate). These air bag door foams are characterized by: high strength and tear resistance (much greater than typical instrument panel (IP) foam), good low and high temperature physical properties (required for varied deployment conditions) excellent heat aged physical properties (required for long life in vehicle service), and low vinyl staining rivaling good IP foam. Detailed descriptions of the air bag door foam physical properties are presented along with recent developments. |
Aerospace Engineering 2004-09-01 | Marotta turns things around The valve-making company used to have trouble getting product out the door on time, but it has improved its turnaround dramatically via lean thinking. A view from the factory Manufacturing techniques and materials used in other industries may be debuting at aerospace factories near you. Reverse engineering Using digital processes accelerates design and increases manufacturing quality. Fine-tuning aerodynamics The aerospace industry relies on massive amounts of computing power to continually simulate, test, and optimize vehicles for reliability and accuracy. |
Subsets and Splits