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Model Based System Development in Automotive | The paper presents a major part of the STEP-X project (Structured Development Process by the example of X-By-Wire-Application in the automotive), namely a seamless, model based software development process in automotive engineering. Our process is model based and supported by a tool chain. The tool DOORS is used for requirements management and engineering whereas the CASE tool Artisan RtS based on the Unified Modeling Language (UML) and the CASE tool Ascet SD are used for specification and design purposes. Each of these tools has its particular strength in a certain design phase. We propose designing rules and modeling guidelines for the development of state based behavior which conforms to seamless model transformation in our tool chain. The rules are checked by an embedded rule-checker. Additionally we illustrate our approach in a case study on a subsystem of the Volkswagen car electronics. The case study is characterized by state-oriented and concurrent behavior as well as time and value-discrete information processing. |
Challenges in Vibroacoustic Vehicle Body Simulation Including Uncertainties | During the last decades, big steps have been taken towards a realistic simulation of NVH (Noise Vibration Harshness) behavior of vehicles using the Finite Element (FE) method. The quality of these computation models has been substantially increased and the accessible frequency range has been widened. Nevertheless, to perform a reliable prediction of the vehicle vibroacoustic behavior, the consideration of uncertainties is crucial. With this approach there are many challenges on the way to valid and useful simulation models and they can be divided into three areas: the input uncertainties, the propagation of uncertainties through the FE model and finally the statistical output quantities. Each of them must be investigated to choose sufficient methods for a valid and fast prediction of vehicle body vibroacoustics. It can be shown by rough estimation that dimensionality of the corresponding random space for different types of uncertainty is tremendously high. Therefore, a substantial reduction of the dimensionality is crucial. Next important step is to choose a proper method to model uncertainties and include them in the FE model. Here, many different methods are available: From well-known sampling based methods like Monte-Carlo to more sophisticated spectral methods like generalized Polynomial Chaos. Finally, the output of these simulations is not a single deterministic value but rather completely new results like mean value, variance and probability distribution. Therefore, the mindset has to change from comparing single deterministic curves and values to an evaluation of stochastic quantities and their relations. This new kind of output requires dealing with new demands as well as a new mindset from simulation engineers. |
Concept Study on Windshield Actuation for Active Control of Wind Noise in a Passenger Car | The windshield is an integral part of almost every modern passenger car. Combined with current developments in the automotive industry such as electrification and the integration of lightweight material systems, the reduction of interior noise caused by stochastic and transient wind excitation is deemed to be an increasing challenge for future NVH measures. Active control systems have proven to be a viable alternative compared to traditional passive NVH measures in different areas. However, for windshield actuation there are neither comparative studies nor actually established actuation concepts available to the automotive industry. This paper illustrates a comparative conceptual study on windshield actuation for the active control of wind noise in a passenger car. Making use of an experimental modal analysis of the windshield installed in a medium-sized vehicle, a reduced order numerical simulation model is derived. Possible actuation concepts are briefly recapitulated and a comparative, preliminary study assists the selection of possible actuation positions of the windshield. Two basic actuation concepts (i.e. an electrodynamic inertial mass actuator as well as windshield actuation by means of piezo-electric stack actuators) are investigated in detail and generalized design requirements are derived for both actuator types. |
High Frequency Vibration Transmission Analysis on Agricultural Tractor by Using Combined Dynamical Energy Analysis and Transfer Path Analysis Approach | Dynamical Energy Analysis (DEA) has recently been introduced as a mesh-based high frequency method modelling structure borne sound for complex built-up structures. Using DEA, the structure-borne sound of an assembled agricultural tractor was calculated and good agreement between measurement and DEA calculations has been shown. However, it is still difficult to model a solid structure as currently DEA is based on wave-transmission calculations through plates and plate-to-plate junctions. Additionally, it is often difficult to generate accurate FE meshes of assembled complex structures because of welds, bolts, and rubber brushes between components. In this paper, we propose a novel method to generate DEA elements based on measurement data in order to model solid parts of a complex structures. The method of Advanced Transfer Path Analysis (ATPA) is employed to extract energy-transmission characteristics of a structure. Firstly, Frequency Response Functions (FRFs) are measured between interface points on a structure. Then the direct transfer functions between all interface points are calculated using ATPA. Finally, DEA elements connecting interface points are calculated. They are based on the ATPA result and therefore represent energy-transmission characteristics of the structure. the proposed method is applied to an agricultural tractor structure in order to generate DEA-TPA elements of a gear casing demonstrating the effectiveness of the proposed method. |
Vibration Energy Harvesting Damper in Vehicle Suspension | The road roughness is one of the main sources of a severe undesired vehicle vibration. The vehicle suspensions are the front lines of defense protecting the passengers and vehicle equipment from harsh vibrations caused by the ground road roughness. The recent tendency is to combine the process of vibration mitigation and additional electrical power generation. It allows scavenge the power from a vehicle?셲 vibrations and convert these vibrations into electrical power for use in vehicle systems. New Vibration Energy Harvesting Damper (VEHD) is based on author?셲 US Patents and consists of two main components: Tuned Mass Damper with automatic self-tuning properties and Generator of Electricity. The analysis of dynamical performance and effectiveness of developed rectilinear VEHD for Jeep Sport Wrangler vehicle suspensions is presented. Mathematical model of dynamical behavior is developed and the simulation analysis illustrates the direction of optimal parameter?셲 selection for getting VEHD with minimal mass. Test results demonstrate the efficiency of proposed VEHD and some new opportunities for their applications in vehicle suspensions. |
Evaluation and Improvement of Greenhouse Wind Noise of a SGMW SUV using Simulation Driven Design | At SAIC-GM-Wuling (SGMW) the greenhouse wind noise performance of their vehicles has gained a lot of attention in the development process. In order to evaluate and improve the noise quality of a newly developed SUV a digital simulation based process has been employed during the early stage of the design. CFD simulation was used for obtaining the flow induced exterior noise sources. Performance metrics for the quality were based on interior noise levels which were calculated from the exterior sources using a SEA approach for the noise transmission through the glass panels and propagation to the driver?셲 or passenger?셲 head space. Detailed analysis of the CFD results allowed to identify noise sources and related flow structures. Based on this analysis, design modifications were then applied and tested in a sequential iterative process. As a result an improvement of more than 2 dB in overall sound pressure level could be achieved. |
CFD Water Management Design for a Passenger Coach with Correlation | Side window clarity and its effect on side mirror visibility plays a major role in driver comfort. Driving in inclement weather conditions such as rain can be stressful, and having optimal visibility under these conditions is ideal. However, extreme conditions can overwhelm exterior water management devices, resulting in rivulets of water flowing over the a-pillar and onto the vehicle?셲 side glass. Once on the side glass, these rivulets and the pooling of water they feed, can significantly impair the driver?셲 ability to see the side mirror and to see outwardly when in situations such as changing lanes. Designing exterior water management features of a vehicle is a challenging exercise, as traditionally, physical testing methods first require a full-scale vehicle for evaluations to be possible. Additionally, common water management devices such as grooves and channels often have undesirable aesthetic, drag, and wind noise implications. Being able to detect water management issues such as A-pillar overflow, as well as to develop strategies to resolve them in parallel with early design cycle exterior aerodynamic development, is highly desirable for this reason. This paper details a collaborative effort where a CFD method is first validated against on road testing and then applied to a design study. The Lattice Boltzmann code based results presented show an excellent correlation with on-road test data. One successive design variants is created, with the design process being driven by the understanding provided by the CFD results. |
Enhancing Driver Awareness Using See-Through Technology | This paper presents a real-time application of see-through technology using computer vision (e.g., object detection) and Vehicle-to-X (V2X) communication (e.g., Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I)). Each access point (AP) was connected to Chattanooga?셲 fiber optics internet, supporting a data transfer rate up to 10-Gbps. Using a 5Ghz frequency, vehicular communications were set up with a seamless handover for transferring real-time data. Two web cameras acting as clients were mounted on the windshield of two of three vehicles to send image data to the offsite server. Using multi-threaded programming, both image feeds were processed simultaneously. Once the server received the images, it performed an object recognition algorithm on each image using a convolutional neural network (CNN). Post- identification, the images from the second vehicle were sent and overlaid dynamically to the third vehicle?셲 image. This repetitive overlapping of images allowed the third vehicle to ?쐓ee-through??the second vehicle in real-time. This experiment was showcased during the US Ignite Smart Cities Summit in June 2017 to emphasize the benefits of drivers being able to ?쐓ee-through??the car in front to make more intelligent decisions when passing a vehicle, stopping for a pedestrian, or seeing an upcoming detour due to construction before the view is within their line of sight. Using V2X communication with computer vision gives the driver a higher level of awareness and allows better decision making in the case of a roadway conflict, ultimately increasing the level of safety on our roadways. |
Application of CAE (Computer Aided Engineering) Superelement Technique for NVH (Noise, Vibration and Harshness) Attributes on a Trimmed-Body Vehicle Structure in Order to Assist Supplier Commodity Development Based Also on NVH Requirements | The business environment is ever changing, several innovations have allowed companies to transcend borderlines and become global entities. While the opportunities are numerous so are the challenges. In this fiercely competitive global marketplace, success requires companies to pay closer attention to supplier relations. The relationship between an automotive industry and its suppliers is an example of it, so the application of CAE (Computer Aided Engineering) superelement technique may improve, in terms of NVH (Noise, Vibration and Harshness), the vehicle development efficiency, without compromising confidentiality directives. Most of NVH requirements must be tracked through Transfer Functions (TFs) analyses at response points located on the Trimmed-Body Finite Element Model (FEM), as for example: Point Mobility, Vibration Transfer Function (VTF) and Acoustic Transfer Function (ATF). As the Trimmed-Body is an assembly of sub-systems, some of them developed in-house and other by external suppliers, FEM and TFs must be cascaded to all sub-system developers, including external suppliers. Confidentiality directives do not allow FE models sharing with external suppliers, precluding commodities development by suppliers to be driven by NVH attribute targets and requirements. Although the Global Static Stiffness is not a TF analysis, it is also considered part of NVH requirements. This paper shows how to obtain the static and dynamic reductions of the stiffness, damping, fluid-structure coupling, load and mass matrices of the Trimmed-Body FEM in order to generate a superelement representation with all design variables, as geometries, materials and properties hidden, with no reversal engineering possibility. It will allow external suppliers to develop their own sub-assemblies, considering NVH attribute targets and requirements. It is also part of this paper to propose the inclusion of superelements use on the engineering statement of work (SOW) in order to integrate the suppliers to all phases of new vehicle programs. |
Restoring and Upgrading of a Ford Motor Company Reverberation Room Test Suite | This paper presents the upgrades and improvements needed to bring an old and seldom used reverberation room test suite up to current standards. The upgrades and improvements included eliminating a below-floor pit that was open to the reverberation room, improving the acoustical diffusion within the room, enlarging the opening between the reverberation room and an adjacent anechoic chamber, renovating the anechoic receiving chamber, constructing an innovative sound transmission loss test fixture, and installing of a high power reverberation room sound system. |
Evolution of Trim Modeling with PEM for Structureborne Noise Prediction in Full Vehicle | The need in the automotive industry to understand the physical behavior of trims used in a vehicle is high. The PEM (poro-elastic method) was developed to permit an explicit representation of the trims in the FEM full vehicle models and to give tools to diagnose the effect of the trims and test design changes (porous material property, geometry, etc.,). During the last decade, the evolution of software and hardware has allowed the creation of models with highly detailed trim description (porous material using Biot parameters, plastic trims, etc.,). These models can provide good correlation up to 400Hz compared to measurements in contrast to classical NSM (Non Structural Mass) methodology which shows limitations. This paper will first introduce the classical method using non-structural masses, local masses and high values of acoustic damping to represent the trim which shows limitations for predicting the response above 200Hz and does not allow a detailed analysis of the effect of trims on the vibro-acoustic behavior of the vehicle. A review of the literature of the evolution of the modeling techniques for full vehicles with PEM representation of the trims is presented from early models with only some porous trims represented as PEM to the latest ones where most of the trim parts ranging from acoustic porous trim (dash insulator, absorbers, etc.,) to the elastic plastic parts (dashboard, pillar trims, etc.,) are included in the model. The influence of modeling accurately the coupling conditions between the trims and the inner cavity or the structure will be discussed. The different results available to diagnose the problems and the influence of the design improvements and visualize them via methods such as intensity contour plots will be introduced. |
Non-Linear Dynamic Analysis of a SuperPlug??Door Module Response to a Door Slam Event | The SuperPlug??door module is a new Delphi innovation. It is a one-piece composite structure, which integrates several door components into one assembly. This reduces the total part count, simplifies the vehicle level assembly process, and reduces labor cost (see the Appendix). The door slam durability test is an important factor in door module design. As more hardware is integrated into the SuperPlug, this subsystem performance in a door slam test becomes important. Therefore, the correct placement of components and the supporting structure is critical. Currently, the evaluation of door slam durability for the SuperPlug is a process of build then test. This is time consuming and costly due to a long testing lead-time and the expense of tooling a new mold. It was realized that a numerical process for assessing the effect of door slam would be required. This process would compute the dynamic response using finite element analysis (FEA). The first attempt within the Doors Systems group to simulate door slam used static FEA [1]. It was based on the assumption that the maximum dynamic loads could be modeled as point forces at the center of gravity of each component. This approach had the advantage of producing results quickly. However, the results are not considered realistic because factors like inertia, time and contact were not included in the analysis. It was then recommended to apply dynamic FEA methods that can consider these factors. This paper is a summary of a master?셲 degree thesis work on door slam [1]. It will describe how dynamic FEA was used to determine the response of a SuperPlug to a door slam. Discussion on how the FEA results compare with door slam tests will be presented. |
Autoliv?셲 Sound and Vibration Laboratory for Automotive Safety Component Development | The new sound and vibration laboratory at Autoliv?셲 Ogden Technical Center (OTC) was purpose-built with a focus on automotive safety restraint product development (air bags, seat belts, steering wheels, etc.). The laboratory requirements stem from the continued industry trend of quieter vehicles which drives the need for components with extremely low levels of rattle noise. The laboratory at OTC complements similar Autoliv testing facilities around the world. Test articles range from several cubic inches up to approximately one cubic foot and contain varying degrees of moving elements. With the new laboratory at OTC, Autoliv can test new product designs earlier in the development process and obtain test results and feedback faster. The function of the OTC test lab is vibration-induced rattle noise; shake components with a known input and measure the resulting noise. To provide an acceptable signal to noise ratio, the new laboratory was designed to have a 25 dBA re 20 關Pa noise floor, reasonable Transmission Loss though the various partitions, modest internal reverberation control, and an ultra-quiet electrodynamic shaker. Achieving these goals required a site acoustic and vibration survey during the project planning phase, the results of which were compared to the performance criteria to drive the various architectural decisions. The resulting facility is capable of generating, recording, and analyzing the target sounds without concern for noise contamination. With this high quality vibro-acoustic information, design decisions can be made early in the product design cycle. |
The Noise and Vibration Response of Eight Light Vehicles on Sinusoidal and Conventional Rumble Strips | Noise and vibration measurements were conducted on eight light vehicles ranging from small compact passenger cars to a large sport utility vehicle on and off shoulder rumble strips of two different designs to assess the input to a vehicle operator when the vehicle departed from the travel lane. The first design was a more conventional design, consisting of cylindrical indentions ground into the pavement at regular 30 cm intervals, and a continuous sinusoidal profile with a peak-to-peak length of 36 cm. Triaxial vibration measurements were made at six locations, including the steering wheel and column, the seat cushion and track, and the front and rear spindles. Interior noise was measured at six locations, one at the operator?셲 outward ear and five at the front seat passenger (three in the fore/aft locations of the seat and at outboard and inboard ear locations). In addition to the in/on vehicle measurements, pass-by noise levels were made. The measurements were performed at 97 km/h and 72 km/h. The primary purpose of the measurements was to develop a recommendation for a standard rumble strip evaluation procedure that could be implemented by transportation agencies to assure comparable results when considering rumble strip designs that produce minimal exterior noise while maintaining sufficient warning input to the vehicle operator. This research did reveal some markedly different results between the test vehicles in both interior noise and vibration as well as pass-by noise. In this paper, these results are presented, and initial draft test procedures are reviewed. |
Practical Uses for Road Noise Cancellation | Today?셲 automotive customers have come to expect luxury and electric vehicles to be quiet and refined pieces of machinery. As customers have come to expect powertrain cancellation in most vehicles today, they are also increasingly looking for a reduction in road noise to improve their overall perception of luxury and electric vehicles. While the field of noise cancellation is ever expanding, several auto makers are exploring the possibility of introducing a real time Road Noise Cancellation (RNC) system to meet these customer expectations. An RNC system can be integrated into the vehicle infotainment system and be utilized to either noticeably reduce or shape the vehicle noise floor. This paper will look at the current traditional Noise and Vibration (N&V) methods of reducing road noise and then also the benefits associated with actively controlling the amount of road noise using an RNC system. |
Human Resources Integration Master Plan: A Response to Revolving Door Management | Taylor (1999) reported the effects of national cultures on the work values of aviation mechanics and Patankar (1999) reported the effects of their professional and organizational cultures. Taylor and Patankar (1999) found effects of national and professional cultures on the outcomes of maintenance human factors programs. Considering those effects, this paper focuses on a strategy that would encourage the champions of human factors programs to develop a human resources master plan and integrate it with the organizational culture. |
Structural Modules with Improved Crash Performance Using Thermoplastic Composites | A new group of composite materials ?쏛dvanced GMT??which are used for the economic production of light weight complex shaped parts in the automotive industry are presented. Advanced GMT consist of a combination of different technical textiles such as woven or stitched fabrics and non-woven mats which are impregnated with a polypropylene resin to a laminate. The laminate is flow molded to complex shaped components with a total cycle time of 30 to 60 seconds using standard equipment. The use of advanced GMT for weight saving and performance improvement of structural modules is discussed. Examples of such modules include hatchback or side door modules, front-end modules, bumper beams with integrated energy absorbers (crash cones) or spare wheel wells and structural elements in the power train. Common for all these type of modules or components is the need for geometric freedom in the design, crash worthiness including high specific energy absorption and ductile failure behavior, structural stiffness and economic production of large series. A case study of a side door module is presented. Aspects of the functional integration is shown with the complex features of the part allowing mounting of several elements such as side window railings, the lock, speakers etc. The versatility of advanced GMT is shown by a comparison in the crash behavior of the door module. The addition of local reinforcement of advanced GMT to a GMT structure increased the crash energy absorption with 300%, without weight increase. |
A Discussion On Using A Pendulum as a Method for Impact Testing Vehicle Sub-Systems | The purpose of this paper is to discuss the use of a pendulum as a repeatable method for impact testing vehicle subsystems and components. Tests on three different vehicle subsystems are presented as examples of impact testing that has been performed using a pendulum. Impact testing on two different roll bar designs to compare effectiveness, impact testing on various van side cargo doors to compare door latch integrity, and impact testing on various fuel tanks to compare the integrity of the fuel tank with and without shields installed. These tests were not intended to replicate the forces, energy, or impact pulse on the vehicle in the actual collision but rather evaluate how the vehicle subsystem reacted to impacts that were similar to that which occurred in the collision. Using proper instrumentation, it can be used to determine the forces or energy required to cause a localized failure or event, determine if an engineered solution has corrected the problem, and used to compare one design to another. |
Material and Design Innovation Techniques for Expanded Polypropylene (EPP) Products Used in Automotive Interior Applications | The use of Expanded Polyolefin foams including Expanded Polypropylene (EPP) material for interior applications has grown over the years to include applications throughout the vehicle. The demand for weight and cost reduction has forced designers to seek out the most versatile material available to satisfy the need for performance, durability, as well as design flexibility. The role of light-weight materials such as EPP has expanded. As such, the design challenges have also enabled the use of EPP in applications requiring energy management, as well as structural, acoustic, and storage/stowage functions. This paper will review the design guidelines that enable EPP to be used in numerous automotive interior applications. As EPP foam becomes more widely specified, and as the applications become more multifunctional, it is important to understand the potential solutions available to satisfy all aspects of design, performance, quality, and safety. Recent material developments and innovations allow for EPP to be specified in a wide range of densities, and with a variety of surface finishes and textures, as well as surface properties that allow it to be used in applications subject to NVH (Noise, Vibration and Harshness) requirements, and those requiring material compatibility. Technical innovations now allow for material optimization, which enable EPP to conform to the stringent performance requirements and BSR (Buzz, Squeak and Rattle) guidelines for today's automotive interiors. Performance can be affected using either mechanical or chemical solutions to satisfy OEM requirements. This paper will also highlight current production examples of EPP applications and their latest design and performance characteristics. Examples of recent performance studies will be cited; including graining and textured surfaces, acoustic enhancements, low friction solutions, and molded part operational and attachment methods. |
Advanced Source Localization Techniques Using Microphone Arrays | Microphone arrays used in vehicle acoustics are mainly designed for fast setup and basic evaluation (e.g. using delay-and-sum beamforming) resulting in a restriction to free field environments. Applications in vehicle interiors require advanced source localization techniques taking into account the reflections at the different panels appearing as mirror sources. Coherence filtering techniques allow for the detection of these mirror sources. An additional sensor is placed as a reference close to the main source. This reference signal is used to filter the array signals increasing the overall dynamic range of the acoustic source mapping. The discrimination of the original source and the reflections is obtained by manipulating the impulse responses between the reference signal and all microphone signals. Other advanced signal processing techniques can be used to increase the limited dynamic range of conventional beamforming such as principal component analysis removing the dominant sources. An implementation allowing for online application based on spatial filters will be presented. In addition the production requirements of large scale arrays, for example wind tunnel measurements and pass-by or fly-over measurements, are discussed. Manufacturing a large scale array with an appropriate precision for the microphone positions and the video system would be very expensive. A very efficient solution turns out to be a combination of a small calibrated camera module (consisting of a video system plus a small number of microphones with high-precision positioning) and a large scale array containing microphones with low-precision positioning. Array measurements using a standard loudspeaker for excitation serve as input for nonlinear optimization techniques to identify the positions of all microphones based on the orientation of the camera module. The techniques also allow for combining small arrays to increase the spatial resolution. This paper describes the theoretical background of different source localization techniques based on microphone arrays. Application examples are used to illustrate not only their advantages but also their potential drawbacks. |
Evaluation of Ground Vehicle Wind Noise Transmission through Glasses Using Statistical Energy Analysis | The contribution of wind noise through the glasses into the vehicle cabin is a large source of customer concern. The wind noise sources generated by turbulent flow incident on the vehicle surfaces and the transmission mechanisms by which the noise is transmitted to the interior of the vehicle are complex and difficult to predict using conventional analysis techniques including Computational Fluid Dynamics (CFD) and acoustic analyses are complicated by the large differences between turbulent pressures and acoustic pressures. Testing in dedicated acoustic wind tunnel (AWT) facilities is often performed to evaluate the contribution of wind noise to the vehicle interior noise in the absence of any other noise sources. However, this testing is time-consuming and expensive and test hardware for the vehicle being developed is often not yet available at early stages of vehicle design. In addition, modifications of the vehicle exterior geometry that may be beneficial to interior noise are often difficult to implement during the testing or to evaluate properly via test. This paper describes a test-based approach to measuring and understanding the contribution of exterior wind noise to the interior cabin noise through the individual glasses and the development of a correlated Statistical Energy Analysis (SEA) model capable of predicting the effect of a design change to any combination of thickness or material changes to the glasses. AWT testing was performed with interior microphones, accelerometers on the glasses, and arrays of flat exterior pressure transducers to establish the acoustic and structural-acoustic transfer functions to the interior. An underbody skirt, extensive taping of exterior gaps, and ?쐀locker??parts on the interior of the glasses were used in order to isolate the noise contribution through individual glasses. Two versions of the front side glass -monolithic and laminated - were tested to compare the effect of the glass material and damping on transmitted wind noise and to provide a reference from which the wind noise load at this important location could be inferred. The data set from this testing was processed and used to correlate an SEA model of the test vehicle capable of being used for design studies of the effect of the glasses on the interior wind noise. |
Progress in Aeroacoustic and Climatic Wind Tunnels for Automotive Wind Noise and Acoustic Testing | There has been significant progress in developing test facilities for automotive wind noise and automotive components since the early 1990s. The test technology is critical to the development of modern vehicles, and essentially every major automotive manufacturer owns and operates their own aeroacoustic wind tunnel, or has rental access to one and conducts a significant amount of wind noise testing. The current status for climatic wind tunnels is that many new CWTs are being defined with acoustic test requirements. These test capabilities in AAWTs and CWTs will continue to enable the development of vehicles with better wind noise attributes, fewer problems with sunroof ?쁞ooming?? and lower noise levels for HVAC and auxiliary systems. In the future, it is expected that the test demand for AAWTs and CWTs with low acoustic background noise will continue to increase as customers expect better automotive products, especially across more of the product line. The objective of this work is to present some of the progress and challenges involved in designing wind tunnels with low background noise in order to meet the requirements of automotive companies for their product development needs. |
Miga Aero Actuator and 2D Machined Mechanical Binary Latch | Shape memory alloy (SMA) actuators provide the highest force-to-weight ratio of any known actuator. They can be designed for a wide variety of form factors from flat, thin packages, to formmatching packages for existing actuators. SMA actuators can be operated many thousands of times, so that ground testing is possible. Actuation speed can be accurately controlled from milliseconds to position and hold, and even electronic velocity-profile control is possible. SMA actuators provide a high degree of operational flexibility, and are truly smart actuators capable of being accurately controlled by onboard microprocessors across a wide range of voltages. |
Automotive Engineering: January/February 2021 | Gearing EVs for greater efficiency Ingear, an innovative 2-speed transmission born in Canada, aims to unlock electric-vehicle performance and efficiency. Built-in Google vehicle apps arrive Android Automotive OS opens the door, cautiously, for third-party developers. Riding on air: Activated carbon aims at autos An old piece of science is set to bring new applications across the mobility spectrum. Allison builds a testing powerhouse Allison Transmission's new Vehicle Environmental Test center in Indianapolis is open for business for external and in-house customers alike. The VET has everything vehicle development teams need to improve testing efficiencies. Editorial The EVs are coming. Now what? SAE Standards News SAE J3178 Information Report for battery adhesives, sealants available Supplier Eye On my 2021 radar What We're Driving CES 2021: GM creates BrightDrop electrified delivery and logistics company Magna execs warn of impending EV complexities Hyperscreen brings new meaning to 'widescreen' display Dana's twin-clutch axle boosts Ford Bronco Sport's off-road cred Sparkling RWD platform underpins Genesis GV80 Nissan's 2021 Rogue is a COVID beater |
Noise, Vibration and Harshness of Electric and Hybrid Vehicles | The noise, vibration, and harshness (NVH), also known as noise and vibration (N&V), is a critical feature for customers to assess the performance and quality of vehicles. NVH characteristics are higher among factors that customers use to judge the vehicle's quality.This book sets out to introduce the basic concepts, principles, and applications of the NVH development and refi nement of Battery Electric Vehicles (BEV), Hybrid Electric Vehicles (HEV), and Fuel Cell Electric Vehicles. Each type comes with its own set of challenges. |
Passive Noise Reduction Possibilities for Trucks | Passive noise reduction decreases the transmission of noise and vibrational energy without altering or changing the noise generating components and mechanisms. The lessening of the transmission of noise and vibrational energy is achieved through the use of noise control materials and parts which provide vibration damping, insulation, or sound absorption. Noise sources radiate sound power and vibrate. The airborne noise propagates to the exterior and causes a particular maximum ?쏛??weighted level to be measured during pass-by tests. Exterior or pass-by noise, and interior or in-cab noise are the two major noise problems for trucks. The major tasks of soundproofing a truck include the definition of treatments for exterior and interior noise and the choice and application of damping insulation and absorption materials in the cabin and engine compartment. |
The Building and Test-Track Evaluation of an Aluminum Structured Bertone X1/9 Replica Vehicle | A vehicle build and evaluation program to demonstrate the feasibility of Alcan's Aluminum Structured Vehicle Technology (ASVT) is described. Five replica Bertone Xl/9 sports cars have been built on the production manufacturing facilities of Carrozzeria Bertone in Turin. The all-aluminum alloy body structures were produced with strength and stiffness equivalent to production steel bodies but with a weight reduction of approximately one third. Modes and frequencies of vibration, interior noise characteristics and 30 mph barrier test results for vehicles with aluminum and steel bodies are compared. High load input, 1000 mile pave and accelerated corrosion tests have proved the vehicles' durability. |
Analysis of the Sound Field in an Automobile Cabin by using the Boundary Element Method | A method of analyzing the three-dimensional sound field in a full-size automobile cabin was studied. The acoustic resonant frequency and the acoustic mode of the cabin were calculated by using the boundary element method (BEM), and were then compared with an experiment conducted on a full-size cabin model made of plaster. The calculated resonant frequencies agreed with measured ones to within about 3% below 170 Hz, and the calculated modes and frequency response curves were in good agreement with experiments when the cabin wall was rigid. In the case of a wall partially lined with absorbing materials, the calculated resonant frequency and the damping ratio were approximately the same as the experimental ones. From these studies, it is concluded that the BEM is useful for analyzing the sound field in a full-size automobile cabin. |
Insulating Glazing in Side Windows | The main problem with the car climate while running is thermal asymmetry on the human body. This asymmetry is caused by solar radiation, drafts from cold air and drafts due to radiation from cold surfaces. During winter, the cold surfaces of the side windows are a major source of discomfort, not only because of the above-mentioned cold radiation towards the outer upper body parts, but also as a result of the air stream needed for demisting the windows. This air stream has a very low temperature when reaching the B-pillar, where it easily deflects, hitting the driver's/passenger's shoulder. In order to avoid these problems, tests have been carried out with side-lights consisting of two hermetically sealed panes with a small air space in between. It was found that the surface temperature is significantly raised, by some 15째C, at low ambient temperatures. Not only are the heat losses reduced, but mist formation is also prevented. Negative aspects are weight and cost. For future development, chemically tempered glass might create possibilities for lighter solutions. |
Environmental Influence on the Acoustic Performance of OEM Automotive Loudspeakers | Automotive audio systems and loudspeakers are typically designed, evaluated, and optimized, for best acoustical performance under indoor laboratory testing conditions. Review of the current loudspeaker engineering test standards, including those published by the car manufacturers, confirms this. Environmental testing is limited primarily to accelerated life tests which are subjective in analysis and often destructive. Although there are some post environmental test requirements for irreversible changes to acoustical performance, there are no requirements on how much the acoustical performance of loudspeakers may change while exposed to either high humidity or non - temperate temperature conditions. The effect of humidity and water on the acoustical performance of today's ?쐗aterproof??automotive loudspeakers is shown to be potentially audible. Recommendations are made for designing more environmentally robust automotive loudspeakers. |
Time Delay Imaging for Automotive Sound Systems | Delayed arrivals of a stereo source are manipulated to suppress undesirable vehicle cabin acoustics and replace them with optimum acoustics for reproduction of commercial recordings. These optimum playback acoustics are derived from concert hall and listening room measurements. An experimental vehicle sound system implementing these concepts is described. |
Towards an Objective Estimate of the Subjective Reaction to Diesel Engine Noise | A microcomputer-based analyser is being developed to estimate subjective reaction to noise from diesel-powered road vehicles. An interactive technique is envolving to match certain combinations of objective measurements to the subjective preferences of individuals, using a control signal from the microcomputer. For a pilot experiment on diesel engine noise at cold idle conditions, the sound stimuli were obtained from engine surface vibration signals. The pilot experiment results suggest that the impulsive characteristic of the sound could be more important than the overall level. |
Applications of Shape Memory Alloys in the Transportation Industry | Shape memory alloys (SMAs) - which have the ability to change from a ?쐂eformed??state to an original ?쐒emembered??state when triggered thermally - offer engineering properties available in no other material. Their potential has not been fully exploited. Existing applications for SMAs in the transportation industry include electric fog lamp louvers and a device to reduce rattling noise in manual transmissions. Future applications in the transportation industry include the use of high density, zero insertion force electric connectors, which are capable of withstanding extreme shock and vibration. |
New Concepts for Acoustic Material Selection | Significant developments in moldable noise reduction materials will allow design engineers of off-highway equipment to incorporate molded parts concepts into their design schemes for both the cab and engine compartments as their use of contoured shapes continues to increase. When properly designed, and used in conjunction with complementary treatments which have been carefully selected on the basis of proven acoustic test criteria, molded sound barriers and sound absorption parts are more cost effective than the oft seen overkill of conventional materials. |
Aerodynamic Characteristics of Subaru XT | In recent years much more attention is being paid to aerodynamics, resulting in vehicles that are far more highly refined aerodynamically emerging one after another. SUBARU's belief is that aerodynamic design of such vehicles should be well balanced with engine cooling, aerodynamic noise, field of view, dirt splash and other aspects and should not impair roominess, driving comfort, safety, and other requirements while properly controlling aerodynamic force. At SUBARU, vehicle aerodynamic design usually takes the following steps. First, 1/5-scale models are built and the aerodynamic characteristics of the actual vehicle are evaluated mainly based on such models. This is followed by building full-scale models with which equipment, underfloor, and other details are subjected to further evaluation, and thus development is promoted. |
Experimental Research on Vibratory Properties of an Engine Hood | A method and measurement system are developed for the experimental determination of vibratory properties of complex structures and applied to the determination of the engine hood for the passenger car ?쏾ASTAVA?? Using a mechanical transfer impedance, the vibratory properties and damping factors are determined. The driving force at one point and the velocities at different points of the engine hood are measured. The vibratory properties of the engine hood have been analyzed and compared with regard to the stages of production completion: (1) engine hood without reinforcements, paint, and anti-rumble material; (2) engine hood without paint and anti-rumble material; and (3) engine hood complete. In all cases the engine hood was mounted on the nude car body for testing. Three levels of constant sinusoidal vibration force were applied in the middle point of the engine hood. The results are given in the form of velocity-frequency curves (velocity spectrum) for different measured points, force levels and different assembly stages in production. The hood reinforcements resulted in decreased output velocity levels of a factor between 2.0 and 2.5. On the other hand, the increase of the stiffness of the engine hood structure shifts the resonance frequencies and extends the peak outputs toward lower frequencies. A method for determination of the damping factor and relative damping are presented. By applying the anti-rumble material noise levels decreased by 1.0 to 1.5 dB(A). The output vibration levels decreased as well. |
Acoustic Analysis of a Light Truck Cab | Acoustic analysis of a Light Truck cab in the frequency range of 0 to 140 Hz was performed by utilizing an analytical method combined with experimental data. The structural and acoustic modes of the cab were determined by utilizing the MSC/NASTRAN dynamic analysis capability. Chassis, powertrain, and suspension components were simulated with the experimental modal data, acquired from dynamic testing of an actual vehicle. Triaxial transfer functions were obtained at all six cab-mount locations due to shaker excitation at the pinion nose and the 4 spindles, as well as neutral engine run-ups. The overall system model was constructed by combining analytical structural and acoustic modes with the experimental modal data using the modal synthesis technique and an in-house developed computer code called MOTRAN. The acoustic mode shapes, response at critical cab-structure locations, and interior sound level at the driver's ear were obtained. After the validity of the model was shown, the model was used to improve the acoustic response of the cab structure in terms of noise-related problems such as boom and drone. A new post processing method was developed to identify and determine the effects of "panel deadening" on the acoustic response of the vehicle. After extensive analytical iterations, an effective set of structural improvements were determined, and the recommended design modifications implemented on the vehicle. Subjective and objective evaluations were conducted to verify that the noise characteristics of the cab structure were indeed improved with the proposed design change. |
Effect of Glass Angles on the Cooling Loads of Automobile Air Conditioners | The characteristics of the directional total transmissivity of solar insolation through the glass panels of windshield, backlight and windows of automobiles are presented. The effect of the glass angles on the interior air temperature of the automobiles and the cooling loads of their air conditioners are discussed. |
Car Crash Tests of Ejection Reduction by Glass-Plastic Side Glazing | 1983 ejection statistics are reviewed; half of the passenger car ejections, some 36,000 people of whom 5,346 died, are through glazing areas. Previous work has shown the remarkable strength of thin plastic coatings, developed for windshield anti-laceration applications, when applied to the inside of tempered glass side windows, in reducing ejection. In the present work, two tests were made, each with the NHTSA Moving Deformable Barrier (MDB) at 39 mph and all four wheels turned at 26 degrees, striking a stationary Volkswagen Rabbit in a perpendicular impact. The Alfred I. DuPont de Nemours Company provided the plastic coating on tempered glass side windows. The plastic layer extended beyond the sides and top of the glass to be wrapped around steel strips bolted to the window frame. On vehicle impact, the tempered glass broke, but the pieces were held in place by the plastic layer, which then deformed outward as a ?쐓afety net??with head contact. In the first test, with a low and short striking vehicle hood line simulation, the top of the door bent out as the bottom was pushed in, and the head bulged the glazing out to hit the elevated base plate of the MDB, although the ?쐓afety net??held. In the second test, with a more typical vehicle hood line effect simulation, the ?쐓afety net??again held, giving a HIC of 616. A window design to allow window up and down motion with the plastic layer movably secured with a ?쏷 edge??in the window channel is under construction. An eight inch sphere Glazing Test Device is being developed, with a skin simulation / chamois coat on the lower hemisphere for laceration measurement, accelerometers for Head Injury Criterion (HIC) measurement, and a weight variable from 10 to 20 to 40 pounds, for ejection reduction measurement. This paper presents the views of the authors, and not necessarily those of the National Highway Traffic Safety Administration (NHTSA). The numbers in parentheses are the references, listed at the end of the paper. This paper is dedicated to the memory of Henry H. Wakeland, late of the National Transportation Board, who was instrumental through his work in New York in establishing government efforts to build experimental safety cars, and to the memory of William Haddon, Jr., M.D., late of the Insurance Institute of Highway Safety, who taught the world that automobile safety is one of the most important areas of preventive medicine, and that cars could be built, passively, not to harm. Both of these giants of automobile safety research died in early 1985. |
Ground Testing Approach for the B-1B Bomber | Existing methods for production ground testing the B-1B would create an undesirable and cumbersome work environment. The noise generated by the equipment along with hoses, cables and ducts on the floor produce a safety hazard. The information presented here deals with a new approach to meet the aircraft delivery rate requirement. Goals were established and a review of existing methods provided the ?쐓tepping stones??to the solution. The use of high technology computer applications is discussed along with the equipment types used on the B-1B bomber. This is the first automated approach to ground testing and checkout of complex aircraft mechanical systems. |
The NCSU Low Speed Boundary Layer Wind Tunnel | Procedures employed for the design of a new low speed boundary layer wind tunnel are described. The tunnel is a semi-open circuit facility for the study of large scale two-dimensional boundary layers with or without pressure gradients, A large plenum box is used as a replacement for a diffuser, 90 degree turn and noise attenuation chamber. The modular test section is seven meters long and capable of velocities from 5 to 33 m/sec. Experimental data to evaluate the tunnel performance are also described. |
An Application of Structural-Acoustic Analysis to Car Body Structure | In order to calculate efficiently the characteristics of car body vibration and the acoustic characteristic of the passenger compartment, a structural-acoustic analysis system, ?쁂AD-B?? was developed. This system divides the body into three components - front body, main cabin and rear body. The characteristics of front and rear body vibration are expressed in modal parameters. The vibration characteristic throughout the car body is then calculated through the building block approach, while the main cabin remains in finite elements. A good agreement in eigen pairs was seen between this approach and the conventional finite element method. As for the passenger compartment, it is divided into finite elements and its eigen pairs are calculated. Then by linking body vibration with the acoustic characteristic of the passenger compartment, sound pressure in the passenger compartment is calculated. Since in the CAD-B system, the contribution of each panel vibration to sound pressure is calculated and displayed, the parts of the panel to be deadened are derived quickly. This approach has been applied to the problem of road noise reduction, and resultantly, interior noise could be reduced by using only a small quantity of sound deadening material. Some floor panel modifications to reduce noise were also made. |
Hem Flange Evaluation of Corrosion Performance | Field or service testing is the best procedure for evaluating the corrosion resistance of any material. However, in the development of a new product, complete service testing and long atmospheric exposure are impracticial due to the time required to develop data. Historically, the accepted method for accelerated testing has been the ASMT-B117 Salt Fog Test. Unfortunately, many investigators have found that salt fog test results do not correlate with field performance. For example; a light weight electro galvanized steel would be unacceptable based on only salt fog results, while field experience shows it to be marginally acceptable for a three to five year period. With a goal of approximating the conditions inside a car door, an investigation was undertaken to modify the current exterior paint scab cycle test to more closely match actual field conditions. This paper will cover how we developed our cycle test and correlation of our results with actual automotive performance. |
A Study of Vehicle Interior Noise Using Statistical Energy Analysis | The noise and vibration of an automotive vehicle is studied using Statistical Energy Analysis (SEA). Three sources of interior noise - the engine, tires, and air flow - have been measured and used as inputs to the SEA model. The flow of acoustic energy through various structural components is calculated in order to determine the dominant paths of noise transmission to the passenger compartment. The predicted interior noise levels are compared to those measured under different operating conditions. The SEA model also evaluates the expected variation of the interior noise as the result of changes in the design configuration of the vehicle. |
Unconstrained Layer Damping and the Use of Modified PVA as a High Efficiency Lightweight Material | A lightweight polymeric visco-elastic sheet material has been developed called ?쁃edpan??(thickness 600 micron, surface weight 1.25 Kg/m2). It exhibits excellent vibration damping performance when used as an unconstrained layer on sheet metal panels. Geiger plate decay rates of 26 dB/sec have been measured. The sheet is flexible, non-toxic, and meets automotive and building flammability specifications. The material composition is stable under paint stoving conditions (temperature up to 200째C), and the product has a tendancy to drape form to underlying structures when hot. These properties make it ideally suitable for the vibration deadening of automobile body panels. |
Motorist Head and Body Impact Analysis, Methodologies and Reconstruction | Motorist impact marks and embossments provide valuable data relating to evaluation of injury, crash energy management, occupant positioning and collision severity. Research techniques presented enable analysis of these impacts. Biomechanical techniques for motorist head impact analysis are presented along with static crush calibration and dynamic impact replication of passenger compartment head dents. Evaluation and identification of occupant induced marks on restraint systems are discussed as well as determination of who was driving. Ejection findings of the fifties and sixties are clarified by case studies that show how vehicle design changes may switch the portal of ejection from doors to windows. |
Evaluation of Vibration with Respect to Human Response | Methods of quantifying vibration with respect to human response are fully defined. The procedures may be applied to all types of vibration: multiple-axis and multiple-input motions which are steady-state, random or transient. The procedures are based on experimental research and have been applied to predict the discomfort, annoyance, health risks, interference with activities and motion sickness associated with vibration measured in a wide range of environments. The general method involves the assessment of 12 axes of vibration (the 3 translational and 3 rotational axes on a seat surface, the 3 translational axes at the seat back and the 3 translational axes at the feet). The method may be simplified so as to include only those axes of interest in specific environments. A scale of approximate discomfort, an ?쁝ction level??guide to the prevention of health effects, magnitudes of vibration which may interfere with activities, and a means of predicting the probability of motion sickness are provided. In all cases the frequencies, axes, locations and durations of the motions responsible for adverse effects can be identified. The application of the procedures to evaluate measurements in vehicles, assess computer predictions of vehicle vibration and optimise seat dynamics is described. |
Occupant Comfort Requirements for Automotive Air Conditioning Systems | This paper will describe - 1. Occupant comfort levels of 7 production vehicles when evaluated under ?쐒eal world??owner test conditions, 2. Effect of film on glazing surface for interior vehicle temperature. The stylist who designs vehicles to sell must consider what imposition they have placed upon the a/c engineer. Tumble home glass surfaces and large areas increase the greenhouse effect on passenger comfort, whether it is in Michigan or the Southwest desert. Today, the automotive industry is a world market and the products must meet the demand of the owner. Sun Test Engineering has run an a/c evaluation program to determine their level of performance on various a/c products in Phoenix. Arizona the last several years. In the summer of 1985, 17 vehicles were evaluated for customer usage test and the results of 7 vehicles are present in this paper. Additional test programs were conducted on the effect of film applied to the glazing surface. |
A Free-Flight Headform Impact Device for Evaluating the Energy- Absorption Characteristics of Vehicle Interiors | This paper reports on the design, development, and use of a test rig that enables the analysis of the aggressivity of vehicle interiors to the heads of occupants. The equipment comprises a pneumatically controlled free-flight headform device. It can be positioned inside the passenger compartment of any passenger car via any normal window or door aperture. The device fires a simulated headform prescribed in SAE J984 at speeds for 10 to 30 mph. The enormous degree of flexibility in positioning enables impacts to be conducted on almost any part of the vehicle interior. Currently, energy-absorbing characteristics of the interior of passenger cars are assessed using drop rigs or pendulums, which necessitate the dismantling of the vehicle body. This has implications for representativeness in terms of the validity of the stiffness characteristics of the section of the vehicle being tested. The results of testing standard specimens, using all three test devices, are presented and discussed. |
Materials Substitution in Automotive Interiors | Automotive interiors are evolving in the direction of increased: Luxury Passive occupant crash protection Acoustic and vibration isolation Electronic instrumentation Warranty life |
The Future of Random Vibration Screening and Testing in Automotive Engineering | Emphasizing stimulation (using random vibration and thermal shock), this paper first examines ESS (environmental stress screening), a relatively recent electronics production tool. Then it emphasizes simulation (of over-the-road random vibration), environmental laboratory testing during development. While different in their immediate objectives, the two subjects have a common goal: increasing the reliability of vehicles and their onboard electronic and other assemblies. |
An Overview of Automotive Interior Glass Light Scattering Film | Light Scattering Films (LSF) on automobile interior glass surfaces were studied on 35 vehicles. The principal chemical compounds that caused the LSF were identified along with the primary sources for these chemicals. The LSF composition and amount found on the windshields exhibited extreme variability. The causes of this variability are discussed. The health and safety of the occupants exposed to the extremely low levels of volatile airborne precursors of the LSF were also studied. Finally, the techniques are presented to: Measure the tendency of a material to contribute to the LSF. Characterize the composition of the LSF. Minimize the LSF in future automotive interiors. |
Simulation of Road Crash Facial Lacerations By Broken Windshields | The facial laceration test has been proposed as an addition to the dummy injury criteria of Federal Motor Vehicle Safety Standard 208. To better understand laceration conditions as they actually occur, three road crashes of increasing severity, all involving facial laceration by the broken (cracked) windshield and one involving partial ejection, have been simulated physically and analytically. The physical simulations used vehicle test bucks, the Hybrid III head with the chamois facial coverings of the facial laceration test, and a piston - constrained Head Impactor. Computer simulations of the three crashes were also carried out using the CALSPAN 3D ?쏞VS??and the 2D ?쏡RISIM??computer programs. The computer simulations provide insight into the effective mass of the head and body on windshield contact, and the forces, velocities, and accelerations involved. The computer simulations show how the impact velocity and effective mass of the head can be much higher than expected, due to body kinematics and loading of the head by the body during windshield contact. These simulations help explain accidents in which the windshield was broken by head contact in a 7.5 km/hr (5 mph) crash, and in which the head was partially ejected in a 21 km/hr (13 mph) crash. The physical simulations approximated the damage observed in the three accidents. In addition, the reduced laceration and potentially reduced ejection by the use of glass-plastic glazing was demonstrated. This paper presents the views of the authors, and not necessarily those of the National Highway Traffic Safety Administration. |
Interior Noise Control of the Saab 340 Aircraft | A comprehensive development program was performed on the Saab 340 aircraft, with the goal of reducing sound levels at the passenger seats in the plane of the propellers. The test program included in-flight sound measurements and operating deflection shape measurements on the fuselage structure, for various propeller speeds and synchrophase angles, and structural frequency response tests. The noise control approach developed was to reduce the low-order fuselage response with the addition of viscoelastic tuned dampers to the fuselage frames in the plane of the propellers. |
20 Questions About Acoustics in Industry | The potential contributions of acoustical technology to manufacturing companies pervade nearly all of its functions from marketing and product planning to design engineering and quality control. Despite this, however, companies generally feel uneasy when they embark on programs to use acoustics in their operations because the technology seems complicated and somehow harder to ?쐅et a handle on??than it is in other cases. But the issues of product sound, and the benefits of acoustics on a diagnostic tool are too important to ignore, so in this paper we discuss these issues in a ??0 questions??format to help planners, engineers and managers as they proceed to implement acoustical technology in their organizations. |
Acoustical Measurements for Automotive Sound System Evaluation Using Time Delay Spectrometry | Over the last few years significant emphasis has been placed on the design of automotive sound systems having proper spectral and spatial performance. But often the frequency response of such a system is subjectively perceived as unbalanced. This paper investigates the direct sound field's frequency response in the car and the effect of the early reflections upon the total sound field. In-car acoustics and subjective test methods are discussed as well. |
A Wind-Tunnel Method for Evaluating the Aerodynamic Noise of Cars | In this paper a test method for measuring the car aerodynamic noise in the Fiat wind tunnel is reported. Through this method measurements of vehicle interior noise in the test section generated by air flow are performed. The separation between interior aerodynamic noise and background noise (fan noise, self generated noise in the tunnel, etc.) is performed by simulation of the last one with loudspeakers without air flow. The present method allows also to separate the shape noise contribution from aspiration wind noise and to localize the most critical acoustical areas into the car. By means of this method it is possible to optimize the car shapes and seals in order to improve the vehicle acoustical comfort. |
Automotive Convenience Products Trends and Prospects | The purpose of this paper is to describe the growth and the trends of automotive convenience products. These products contributed to make the driving experience more pleasurable. Electronics have contributed to this growth since the sixties, and its contribution and prospects will be the prime focus of this paper. With the continuing advance of electronic products in the consumer and industrial sectors, the consumer wants' and expectations are changing, especially with the ?쏝aby Boom??generation. More new convenience features will be developed by the prudent use of electronics. The development of these future products require a thorough understanding of consumer wants and needs through market research, careful adaptation of the emerging technology to avoid gimmickry, and dedicated application of engineering know how to design package efficient, cost effective and reliable products. |
A New Dimension in Automotive Trim | Colamco has developed new technologies which have many advantages for automotive soft interior trim applications. The process is particularly suited to molded seat production but has proven to be flexible enough for use on any interior surface. The process combines standard polyether urethane foam with fabric or vinyl and any desired backing material to achieve highly styled parts both in 3-dimensional shaping and embossed designs. Products may also exhibit further characteristics such as softness, multi-densities, full breath-ability, and high durability, as well as noise reduction and acoustical insulation. In the report we will discuss Colamco Technology, materials requirements, automotive seat molding, inherent differences between the Colamco technology and other processes, and special applications of the technology. Emphasis will be on automotive molded seating. |
A Baseline Design for the Space Station Habitat | A baseline design has been selected for the Space Station Habitat (HAB) element. The HAB provides the primary living space to support man's permanent presence in space. The HAB element is designed to provide an environment that maximizes safety and human productivity. This paper outlines some of the current design features including the common core elements and the man-systems hardware. The HAB is arranged in three areas based on crew activity and acoustical considerations. The first area is the quiet zone, which contains the crew quarters. The second area is a buffer zone for noise suppression, where the stowage, medical facilities, and personal hygiene facilities are located. The third area is the active zone which contains the galley/wardroom, laundry and exercise facilities. Each of these three areas will be discussed together with the applicable requirements, the common utility elements, and the man-systems hardware furnishings. |
The Rolls-Royce Civil Engine Family - Today and into the Future | Rolls-Royce Civil Engine strategy calls for technology development for derivative engine programs and application to longer term new propulsion concepts. In the near future, further development of the turbofan for the next generation of derivative aircraft is planned. Reductions in fuel consumption, noise, weight, and cost will be achieved with engine cycles in the range currently in service and by refinements to component efficiency and application of advanced materials and manufacturing techniques. This derivative approach is likely to continue until the relationship between first and operating cost changes dramatically. As fuel prices rise, or the demand for more rapid travel develops, changes to the basic engine cycle will be necessary. For long range, high subsonic speed operation, substantial increases in turbofan bypass ratio will be needed to realize further fuel burn reductions. For intermediate ranges the propfan may have limited application, but economics will probably dictate retention of a more conventional powerplant for short range aircraft. |
Strength Problems of Low-Floor Urban Buses | The main characteristics of up-to-date urban buses are the low floor level, high capacity, and the many large-size doors. The longitudinal bending load bearing elements of the frame structures of thin window and door supports, suitable for today's popular line design pattern, are the sidewalls and beams without door openings. The main torsional load bearing element, on the other hand, is the master beam made up of the longitudinal beams by means of the floor cover and the lattice joint of the latter's lower flanges. Since the structural height of the longitudinal beams playing the critical role in load bearing is governed, at a certain minimum free height provided for, by the height of the floor level, reduction of the latter will have to be associated with that of their dimensions as well |
Improved Laminated Windshield with Reduced Laceration Properties | A new laminated automobile windshield called Triplex ?쏷en-Twenty,??fabricated from two thermally stressed glass plies of 2.3 mm soda-lime float glass laminated with a 0.76 mm HPR polyvinyl butyral interlayer, has been biomechanically evaluated by Triplex Safety Glass Co., Ltd., using a dropping headform and a skull impactor, and by Wayne State University, using a 50th percentile anthropomorphic dummy on the WHAM III sled test facility. The results of these evaluations at velocities up to 60 km/h are expressed in terms of Gadd index, head injury criterion, and various laceration scales including the new Triplex laceration index (TLI). Some details are also given of other properties of the windshield. The results of the evaluations indicate that the Ten-Twenty windshield offers a reduction of about two units on the TLI scale equivalent to one of the following: 1. A 99% reduction in the number of cuts when the length and depth of cuts remain unaltered. 2. A 90% reduction in the length of cuts when the number and depth of cuts remain unaltered. 3. A change in depth of cuts from one layer of skin simulation to another, but in particular a 78.5% reduction in the depth of cuts into the polyvinyl chloride base layer when the number and length of cuts remain unaltered. In practice, the length, number, and depth of cuts all change together so that one typical example taken from the test program of a two-unit reduction in TLI is: 1. A 62% reduction in the average depth of cuts into the polyvinyl chloride base. 2. A 27% reduction in the average length of cuts. 3. No increase in the total number of cuts. On the basis of these results, Ten-Twenty is a much safer laminated automobile windshield than those now commercially available due to decreased laceration to the occupants during a collision. |
European Legislative Requirements for Agricultural Tractors and Farm Machinery | This paper outlines the structure and interrelationships of the numerous European standards making organizations, with particular reference to agricultural machinery. Because many of the standards being developed by these organizations are becoming part of legislation in the various Common Market countries, their work is of great interest to the machinery manufacturers. Covered are the highway code-constructional requirements, safety constructional requirements, test codes, and engineering standards. The current status of requirements for lighting, tractor cabs (including structural tests, noise, and emissions), maximum speed limits, brakes, hitches, and safety in the various contries are discussed. |
The Design of a Cost-Effective Quiet Diesel Truck | This paper reports the results of a project whose aim was to develop a quiet truck in a cost-effective manner. In the paper a method of approach to identification of noise sources and diesel truck noise control is presented, along with a demonstration of noise control techniques and the results obtained. The final drive-by noise level, as measured by SAE J366a procedures, was 72 dB(A). The approach was to take a standard production truck and modify its exhaust system, fan, transmission, and cab enclosure. Although no modifications were made to the engine, a quieting kit consisting of dampening panels was fitted to it. |
The Environmental,Commercial and Regulatory Implications of SAE Recommended Practice J57a for Truck Tire Sound Levels | There can be no control over environmental pollution without methods for measuring how the environment is being affected by mankind. Consequently, when traffic noise was identified in 1964 by communities as an important form of pollution, it became necessary to measure the amounts of noise present and to assign relative importances to various sources in vehicular traffic. Truck tires were identified as being significant contributors and engineers from the tire and truck manufacturing industries acting under the auspices of the SAE set about to develop a test procedure that satisfied the immediate need - to initiate control over truck tire noise. This paper is a review of the outcome of that effort by one who participated in the earlier work on the testing standard. How well the method works, and how well it serves to meet the objectives now on the horizon are the preliminary topics of this discussion. The paper contains a discussion of the accumulated experience in testing tire noise and the current indications for a meaningful test procedure. |
Photovoltaic Glazing for Automotive Applications | A computer simulation of an automobile has been prepared which enables the spectral characteristics of the glass windows, semitransparent photovoltaic sunroofs, and special solar control coatings and films to be incorporated into the thermal analysis. This paper presents the resultant interior temperatures for three vehicle configurations when subjected to various ventilation flow rates, convection conditions, and solar control coatings. |
A Comprehensive Programme for Hearing Conservation and Noise Control | Emphasis is placed on noise control at source in the hearing conservation programmes in the U.K. factories of Lucas companies, especially when new plant is ordered. This paper briefly describes the overall plan and Company standards with five case studies to illustrate how they work in practice. It concludes with a summary of the key steps in the Company strategy. |
A Unique Approach to Mobile CB | A new 40-channel CB Radio System has been developed by a major automotive manufacturer as a regular production option for a number of its 1978 cars and trucks. To maximize theft resistance, the system uses a remote chassis, detachable microphone, and a tri-band antenna. The factory-installed CB features a uniquely styled power microphone, digital channel display, automatic scan, switchable noise blanker, memory for emergency channel 9, automatic noise limiter, and extensive vehicle noise suppression. Vehicle speaker(s) are time-shared with the entertainment system. This state-of-the-art system is presented here in terms of component functions, design development, manufacture, and test equipment and procedures. |
Quiet Tires-An Overview | Vehicle and tire manufacturers are currently working to produce quiet commercial vehicles and tires. While much time has been spent by both government and industry to gather data to cut vehicle noise, it seems that industry and government now wish to interpret this data and make use of it in a short period of time. But this cannot be done without consideration of cost. We must consider the initial investment of new tires, the labor involved and importantly the national availability of these products as replacements are needed. Only with the full cooperation of government, manufacturers, and the transportation industry can this be accomplished. |
S-65-200 Commercial Compound Aircraft Design for Maintenance | In the design of the S-65-200 Commercial Compound Aircraft - a 230 knot, 86 passenger transport - maximum consideration was given to meeting a high dispatch reliability goal and to ease of performing maintenance. This paper describes how maintenance and reliability of this compound helicopter is enhanced by use of new and improved technology. Use of built-in test equipment reduces electronic component maintenance by approximately 43%. An airborne integrated data system reduces line level maintenance by approximately 16% and provides trend information for detection of incipient malfunctions. A newly developed rotor head bifilar vibration absorber reduced aircraft vibration levels, thereby reducing airframe and structure maintenance by almost 15%. A modularized engine allows for minimum disassembly at intermediate levels of maintenance. New and high grade materials, such as composites and vacuum-melt steels, improve life characteristics of structure and dynamic components. The ability to inspect subsystems is increased, and all components are readily removable. Almost 95% of all maintenance actions are performed from outside the aircraft. The cumulative result of these features of the S-65-200 Commercial Compound Aircraft is a predicted 0.98 dispatch reliability. Direct maintenance is estimated at 9.3 maintenance manhours per flight hour for all levels of aircraft maintenance. |
Development and Analysis of Door Side-Impact Reinforcements | A door side-impact reinforcement beam has been developed that allows efficient use of material in resisting side crush loads. The beam section can be roll formed, thus permitting further economies in fabrication. Analytical techniques have been developed that evaluate and handle bending, buckling, and crippling in beam design. This paper covers the development that led up to these results and includes a detailed description of how to apply the analytical methods. |
Importance of Acoustical Leaks in Passenger Car Bodies | In its treatment of acoustical leaks in passenger car bodies, this paper considers the general principle of noise control in a passenger compartment, the concept of acoustical leaks, examples of such leaks, and design guidelines for acoustical isolation. The paper states that the basic problems can actually be designed into vehicles through lack of understanding of acoustical principle, and various examples are given in illustration. Remedies for some of these deficiences are also proposed. Finally, design principles formulated to eliminate acoustic leaks are presented. |
System Engineering - A Window System | Many of the formal system engineering procedures and techniques developed in the aerospace industry have convenient informal application to the analysis, evaluation, and qualification of new automotive design. This paper describes such ?쐓ystemization??from a product engineering viewpoint in the development of a hardtop window project. The project is traced through its several design and development stages; and the advantages of the system engineering approach, as well as some of the problems encountered, are explored. The paper concludes with a discussion of additional controls that would have been required to yield the full information recording/retrieval capability demanded for complete system integration on larger projects. THE COMPLEXITY OF the present-day automobile is as evident in its door window systems as it is beneath the hood. Current usage of curved glass, repeatably positionable at superhighway speeds in a frameless or hardtop application, has posed new challenges for the designer. Additional emphasis on sealing capability, reduced operator effort, and low noise levels has compounded the design challenge. The designer has met these challenges by producing systems much more sophisticated than those in earlier cars. Optional hardware configurations that can be added or deleted from the system and partial modification of existing systems with during-model-run effectivity points are routine. Also, the cost of both materials and the labor associated with assembly, adjustment, and service are receiving additional emphasis today. All of these factors combine to make the product engineer's task in verification testing of window systems more difficult, and at the same time more important than it was previously. |
Consumer Acceptance of the Volvo Passive Belt System | Consumers' acceptance of and attitude toward a passive three-point belt system have been studied and evaluated in a personal interview investigation of 325 people. These participants were provided with the opportunity to try out the belt system in two demonstration cars-2-door and 4-door sedans. The method of selecting the respondents complied very well with the requirements of public representation. The results of the inquiry are presented in the full survey as related to driver, passenger, age, sex, etc. The main question in the study-the convenience when entering or leaving the demonstration car-was very positively judged. The most frequent opinion on a 7-point evaluation scale was as high as 7 (most positive); the average value of 6.2-5.9 was given for wide- and half-open doors, respectively. |
An Update on Noise Control at International Harvester | International Harvester has testified to the Environmental Protection Agency about present noise levels and has stated what it considers to be reasonable goals. Noise control work is progressing, especially in the area of environmental noise on lawn and garden equipment and operator noise on larger tractors. The engineering community must take every opportunity to present the case for cost-benefit considerations in noise control. |
Comparison of Three Types of Front Body Construction of Sub-Compact Cars | Three different types of front suspension and the corresponding body construction configurations were selected for comparison among unitary constructed sub-compact cars with a weight range between 2,500 lb and 3,000 lb and which are being manufactured by Toyota. These were compared and evaluated in terms of weight, productivity, noise and vibration characteristics, and crashworthiness. The pros and cons of each type were analyzed and the results of this analysis are presented in this paper. From these results, it has been concluded that when only the front body is considered, these three types of front body design are preferable in the following order. 1. McPherson type. 2. Double wishbone type with upper and lower arms installed on the fender apron. 3. Double wishbone type with upper and lower arms mounted on the suspension member. |
180 Cu Yd Stripping Shovel | Because of the size and weight of the various components going into the machine, new approaches were used to solve the practical limitations of manufacturing facilities, shipping clearances, and erection procedures. Although the general appearance of the machine is similar to previous units, there are a number of new design features incorporated in the unit. This paper will be limited to the major design considerations as follows: adaption to stripping two seams of coal simultaneously; dipper with two doors; computerized hydraulic steering maintaining Ackerman correction; double end drive crawlers and belt tensioning; and electrical innovations. |
Noise Abatement of Vibratory Feeders | Three principal noise-generating mechanisms were identified in the vibratory feeder as structural vibrations, interaction between the conveyed parts and the track surface and radiation from the bowl cavity. Treatment of the track surface based on theoretical analysis of the vibration-stimulated conveyance, structural damping treatment of the bowl and ?쐓ee through, load through, reach through??acoustical screen have been developed. These treatments lead to 20??5 dBA reduction of the sound pressure level accompanied by substantial reduction of part delivery time. |
Past, Present and Future of Elastomeric Body Sealers in Automotive Application | Automotive body sealing has progressed from the time when the internal combustion engine replaced the horse on the buggy, which had no windshield, windows or doors, to the present time when every effort is made to make the passengers as comfortable as possible by isolating them from heat, cold, wind, water and noise. This pursuit of comfort has not only been made possible by but has also created the need for new developments in designs, materials, manufacturing procedures and tooling. |
Metal Stamping Presses Noise Investigation and Abatement | Noise generating mechanisms connected with steel-blanking operation has been identified and their engineering treatments developed and tested. Use of rubber-metal laminates proved to be successful for cushioning impacts in kinematic pairs and joints. Use of plastic for the stripper plate construction was recommended. The ?쐂ie stiffener??concept was developed to reduce main noise peak associated with punch breakthrough. Screening of the die cavity by a transparent curtain of overlapping PVC strips was shown to be effective. A pulse load simulator with adjustable load rate and amplitude has been developed to facilitate testing of presses. |
Optimum Subsonic, High?밃ngle?뱋f?밃ttack Nacelles | Many proposed advanced aircraft - but especially tilt-nacelle, subsonic-cruise, V/STOL aircraft - require nacelles that operate over a wide range of aerodynamic conditions. The optimum design of such nacelles and their inlets is described, including how the inlet low-speed design conditions are selected, the conditions for which the various regions of the inlet are designed, and appropriate criteria of merit. For low-speed operation the optimum internal surface velocity distributions and skin friction distributions are described for three categories of inlets: those without boundary-layer control (BLC), those with BLC, and those with blow-in door slots and retractable slats. Experimental results are presented that show the performance of the various types of inlets. At cruise speed the effect of factors that reduce the nacelle external surface area and the local skin friction is illustrated. These factors are cruise Mach number, inlet throat size, fan-face Mach number, and nacelle contour. The interrelation of these cruise-speed factors with the design requirements for good low-speed performance is discussed. Finally an inlet design without BLC and an optimized inlet design with slots and slats are compared to illustrate the possible reductions in nacelle size. |
Energy Conservation Aircraft Noise, and the Bottom Line | The established distribution system is in the process of being restructured to combat the effects of high cost energy, inflation and environmental restrictions. As a part of this system, the air freight industry, also, must re-examine its options in equipment, energy reduction, financial risk and services offered. In the area of investment and energy reduction a cost effective solution is already available. That is, equip a portion of the existing cargo fleet with new technology, quiet, fuel efficient engines. Ten airlines have stepped up to this solution and are re-engining their fleets of DC8 aircraft with CFM56 engine. |
A General Aviation Operator Views His Equipment | Each new model change usually brings improvements over earlier models. From the point of view of increasing window area and designing more pleasing appointments, there have been significant advances. With regard to engine reliability and time between overhauls, significant advances have also been made. Solutions to some of the other problems, however, have made little gains. Examples are pilot sitting position and ease of seeing outside the cockpit area; noise level for effective verbal communications between instructor and student; and shoulder space for instructor and student in trainers. An area where major strides are yet to be made is in panel, cockpit, instrument, and control layout and function. A continuing concern expressed by pilots is the transition time from one aircraft to another or the problems of regularly operating in two or more aircraft. This suggests that there is a need to provide more commonality between airplane layouts. Since the hourly maintenance labor costs are increasing, the original design should consider labor-saving methods during routine inspections such as accessible location of battery. Performance data and aircraft systems descriptions should be more uniform between manufacturers. |
Airport Noise, Sonic Booms, and Public Health | Different adverse effects of noise are treated in the context of defining public health problems posed by exposure to sonic booms and to operational aircraft noise around airports. These aircraft sounds can affect states of social and mental well-being through masking speech communication or other desired sounds, disrupting behavior and subjective feelings, and interfering with needs for privacy, rest, and sleep. Such adverse effects fall short of what may be called mental disorders, but the long-term cumulative impact of these noise disturbances remains to be fully evaluated from the standpoint of mental as well as physical health. There may, however, be some potential risk of hearing loss caused by the maximum current aircraft noise exposures in neighborhoods bordering airports. Evidence for other physical ailments connected with exposures to aircraft sounds intruding in airport communities is suggestive at present and requires more medical verification. The most pressing research needs are for retrospective and prospective studies of the physical and mental health status of communities subjected to different amounts of aircraft noise and sonic booms. |
Sound Attenuation After the Fact | The noise levels of earthmoving equipment, in the operator's cab and outside the machine, are discussed. Ways and means of lowering the dB ratings for increased operator and by-stander comfort are taken into account. Suggestions are made for ways of mounting the cab itself and lessening vibratory reactions from the engine, including rubber engine and cab mounts, plus acoustical material for reducing inside the cab noise. |
The Economic Necessity of Viable Door to Door Air Cargo Service | Air freight is and will continue to be a small shipment business. The rapid increase in the amount of freight carried has induced a state approaching chaos on the ground. The result is delay, losses, and damage to shipments. The air cargo industry must now develop a sophisticated door to door capability offering improved service and lower costs to the user. Satellite air freight depots, with perhaps several airlines in a single building, must be developed in major commercial areas. Door to door container usage, at present faltering, should be encouraged. A new rating system, with door to door prices that taper with distance, should be devised. |
A Passive Safety Belt System | The geometry and behavior of several front-seat passive belt configurations have been studied and evaluated. General design criteria are discussed. The preferred solution is a three-point belt with two ends attached to the door. The belt straps automatically, and for comfortable exit, the occupant may make a slight manual operation. Crash tests indicate that the belt performs approximately as a standard three-point belt. Door strength, retractor strength, strap strength and tension, seat influence, etc., have been tested. Curves are given for recorded and computed data, including old and new severity index. |
One-Wire Automotive Electrical Systems | A single-wire vehicle electrical control system is applied to the various vehicle electrical functions. The resultant three-wire system (signal, power, ground) reduces wire bulk in the floor, door, instrument panel, and engine compartment of the vehicle. Increased control switch and component complexity, due to the additional solid-state components required, may affect overall reliability. Improved power bus and signal bus protection must be added to the control system. Failure of the entire single-wire control system, due to accidental grounds or opens, limits application to certain noncritical vehicle electrical systems. |
Summerization of Construction Equipment | This paper discusses some of the problems encountered in ?쐓ummerizing??or air conditioning a cab used on construction equipment. The environmental conditions of high temperature and high relative humidity combined with severe dust shock and vibration conditions affect the design of components. Components discussed are compressors, condensers, evaporator coils, filters, air ducts, air diffusers and heaters. Installation for ease of maintenance and replacement is emphasized. |
Evaluation of Aircraft Internal Noise | From the standpoint of marketing as well as safety, control of aircraft interior noise is of considerable interest to the manufacturers of business aircraft. The interior acoustics engineer in the industry, having no fund of accumulated experience or research to draw from in the industry itself, has to piece together a working design procedure from a knowledge of boundary-layer theory, jet noise, random vibrations, and architectural acoustics to meet an acceptable cabin noise criterion for the small aircraft. In this paper, methods are outlined to calculate the cabin noise levels due to the three main noise sources-the boundary-layer pressure fluctuations, jet exhaust, and internal equipment. Formulas for quick estimation of overall noise levels due to these sources as well as methods to obtain octave band levels are given. The paper also discusses manufacture or service-related noises and methods for identifying their sources. |
Window System Design Using Computer Analysis | Soon after the styling door surface, glass drop, and belt height are determined, the placement of window system components is critical in effecting a smooth operating window system with low effort. For single arm - single post window systems, a computer analysis technique has been developed to position the post and regulator in the most optimum location. The computer program used displays results through the use of computer graphics. This graphic output allows instantaneous evaluation of how variations in geometry effect the window system operation. |
A Consideration of Vehicle's Door Shutting Performance | Many papers have mentioned, in passing, a phenomena that is known as ?쏿irtightness?? which is one factor that hinders automobile doors from closing. It also causes the eardrums of any passengers in the vehicle to be temporarily pressurized when the door is closed. However, few documents have considered this phenomena in detail. In this paper, we investigate the magnitude of ?쏿irtightness??as it affects ear pressure and examine its relationship to such factors as the volume of the passenger compartment, door's opening area and its inertial moment. Finally, we utilized estimation methods to predict its influence on the force required to close the door and the amount of the resultant air draft. |
Development of Door Guard Beams Utilizing Ultra High Strength Steel | Door guard beams have been developed through the utilization of ultra high strength steel (tensile strength>100 kg/mm2). At first, the sheet metal gauge was reduced in proportion to the strength of the ultra high strength without changing the shape of the beam section. This caused beam buckling and did not meet guard beam specifications. Analyzing this phenomena in accordance with the buckling theory of thin plates, a design criteria that makes effective use of the advantages of ultra high strength was developed. As a result, our newly designed small vehicle door guard beams are 20% lighter and 26% thinner than conventional ones. This makes it possible to reduce door thickness while increasing interior volume. |
Vibration Analysis by Double Pulsed Laser Holography | The use of a giant pulse laser with 30 ns double pulses makes it possible to holograph different phases of an object vibration within time intervalls from 100 關s to 1 ms onto the same plate. The vibration phases into which the first and second laser pulse are fired can be exactly preselected by means of an electronic trigger system. The simultaneous reconstruction of the holograms taken by the first and the second laser pulse generates on the object surface a system of interference fringes which are loci of equal displacement. Adjoining fringes correspond to displacement differences of half a wavelength of the laser's light. In this way, it is possible, for instance, to visualize the vibration pattern of car bodies and drive units excited by the running engine. The method of measurement and a hologram camera especially constructed for making double pulsed holograms of automobiles are described. Several examples of application are quoted in order to illustrate this technique. |
Development of an Indoor Noise Test Procedure for Trucks | An alternate, indoor, noise test procedure for truck exterior noise is being developed in order to overcome the weather problems associated with the presently employed outdoor test method. The feasibility of a reverberation room measurement of sound power level has been demonstrated through a series of comparative indoor and outdoor measurements for several vehicles. An indoor test procedure has been broadly defined and an experimental effort is continuing to complete its development and to demonstrate its equivalence to the outdoor passby test. |
Aircraft Noise Control Practices Related to Ground Transport Vehicles | Aircraft noise control practices which may have application to ground vehicles are presented. Noise sources, design criteria, prediction methods and test facilities are described. Recent application of aircraft noise control methods in the use of sound insulation, structural damping, air conditioning and engine noise are discussed. The overall technical approach (design process) to solving airplane noise problems is emphasized. |
Materials for Noise Control | The purpose of this paper is to present a basic overview of the technology and materials available for controlling airborne noise and structural vibration. The paper will be oriented to the truck industry. Materials and applications will be presented with this bias. The paper will cover technology of absorption, reflection and vibration damping. Material properties, availability and practical considerations to selection will be presented. Typical applications for materials in the truck market will be briefly highlighted. |
An Example of Noise Control Treatment for Construction Machinery Cab Interiors | The effect of noise on the operator has become of increasing concern to manufacturers of construction machinery in recent years. Although the noise generated by heavy duty construction equipment is much greater when compared to other types of machines such as the passenger car, the problems are similar. Many of the lessons learned in reducing interior noise within the automobile can be used to reduce noise within the operator's cab of construction machinery. This paper represents the results of a joint effort between Fiat-Allis Construction Machinery, Inc., and Globe Industries, Inc. to apply these lessons to reduce the noise within the cab of a medium sized crawler tractor. |
Durability of Rubber Modified SMC | A carboxylated butadiene-styrene elastomer has been developed as a low profile modifier for polyester resins used in sheet molding compounds. The elastomeric modifier will provide Class A surfaces with low long-term wavi-ness, energy absorbing characteristics and zero shrinkage. Especially outstanding results are obtained when molding large, thin, flat panels such as roof, door, hood and tailgate panels from rubber modified SMC. Surface appearance properties are subjective, but properties such as radial bend, tension testing, high impact and reverse impact tests are shown to demonstrate the energy absorbing and toughening characteristics imparted by the modifier. |
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