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A task group within the SAE Automotive Corrosion and Protection (ACAP) Committee continues to pursue the goal of establishing a standard test method for in-laboratory cosmetic corrosion evaluations of finished aluminum auto body panels. The program is a cooperative effort with OEM, supplier, and consultant participation and is supported in part by USAMP (AMD 309) and the U.S. Department of Energy. Numerous laboratory corrosion test environments have been used to evaluate the performance of painted aluminum closure panels, but correlations between laboratory test results and in-service performance have not been established. The primary objective of this project is to identify an accelerated laboratory test method that correlates with in-service performance. In this paper the type, extent, and chemical nature of cosmetic corrosion observed in the on-vehicle exposures are compared with those from some of the commonly used laboratory tests

General Motors (GM) recently purchased an acoustic holography system based on the Helmholtz Equation Least Squares (HELS) methodology. Typically acoustic holography has utilized planar transformation of the Fourier acoustic equations. General Motors conducted a variety of experiments on a simple well understood structure. This enabled us to understand the setup parameters and confirm the manufacturer's claims for accuracy. Measurements on the structure were taken using the HELS based equipment and a laser vibrometer. Conclusions are drawn on how to set up the equipment for future testing on vehicles.

The need for improved axle NVH integration has increased significantly in recent years with industry trends toward full-time and automatic four wheel drive (4wd) systems. Along with seamless 4wd operation, quiet performance has become a universal expectation. Axle gear-mesh noise can be transmitted to the vehicle passenger compartment through airborne paths (not discussed in this paper) and structure-borne paths (the focus of this paper.) A variety of mounting configurations are used in an attempt to provide improved axle isolation and reduce structure-borne transmission of gear-mesh noise. The configuration discussed in this paper is a 4-point vertical mount design for an Independent Front Drive Axle (IFDA). A significant benefit of this configuration is improved isolation in the range of drive torques where axle-related NVH issues typically exist.

The objective of this paper is to propose a new model in the identification of a contributing factor to the generation of Radio Frequency Interference (RFI) due to the operation of a spark-ignited engine. This model incorporates parameters in the electrical operation of the ignition system components and their interaction with the engine mechanical structure, which is also used as a circuit component (the ignition system “ground”). T he model was developed as a result of analysis of numerous studies that have been conducted over the years in an attempt to identify why RFI characteristics can differ when using identical components on different engines, or locating the components in different locations on identical engines. This situation is a problem due to the resulting uncertainty with respect to the determination of what is the optimum vehicle ignition system configuration to meet all electrical and RFI or electromagnetic compatibility (EMC) requirements.

This paper discusses radio usage habits observed during analysis of 700 hours of video sampled from the 100-Car Naturalistic Driving Study database. Analysts used large-scale printouts of each vehicle's radio faceplate and recorded interactions based on video analysis of hand movement and location (without the assistance of audio recordings). The duration and specific manipulations or adjustments were recorded for each interaction. The results summarize the length and type of interactions, most often-used controls, and total percentage of time drivers interacted with the radio.

The need for accurate virtual prototyping prediction is well documented in the literature. For welded body structures one notable shortcoming has been the ability for finite element analysis (FEA) to accurately predict the failure of welded joints due to cyclic loading. A new approach to representing spot-welds for durability evaluation in automotive sheet metal structures is presented here. Excellent correlation with spot-weld failures in actual tests have been observed through this modeling approach. We present a method of representing spot-welds using the finite element method. This method has shown to be able of predicting the behavior of spot-welds prior to the build of any prototypes or testing. Further, for spot-weld failures we present evidence that reveals which radial quadrant of the spot-weld will contain the failure. This method also allows engineers to determine the mechanism of failure. This paper describes in detail the spot-weld modeling method.

The GM Aerodynamics Laboratory (GMAL) was modified in 2001 to reduce the background noise level and provide a semi-anechoic test section for wind noise testing. The walls and ceiling of the test section were lined with acoustic foam and foam-filled turning vanes were installed in the corners. Portions of the wind tunnel circuit were also treated with fiberglass material covered by perforated sheet metal panels. High skin drag due to roughness of the foam surfaces, along with high blockage due to the large turning vanes, increased the wind tunnel circuit losses so that the maximum wind speed in the test section was reduced. The present study calculates the averaged total pressure losses at three locations to evaluate the reductions in skin drag and blockage from proposed modifications to the circuit, which were intended to increase the test section wind speed without compromising noise levels.

The unsteady flow fields behind two different automobile outside side rear view mirrors were examined experimentally in order to obtain a comprehensive data base for the validation of the ongoing computational investigation effort to predict the aero-acoustic noise due to the outside rear view mirrors. This study is part of a larger scheme to predict the aero-acoustic noise due to various external components in vehicles. To aid with the characterization of this complex flow field, mean and unsteady surface pressure measurements were undertaken in the wake of two mirror models. Velocity measurements with particle image velocimetry were also conducted to develop the mean velocity field of the wake. Two full-scale mirror models with distinctive geometrical features were investigated.

Fast-running metamodels (surrogates or response surfaces) that approximate multivariate input/output relationships of time-consuming CAE simulations facilitate effective design trade-offs and optimizations in the vehicle development process. While the cross-validated nonparametric metamodeling methods are capable of capturing the highly nonlinear input/output relationships, it is crucial to ensure the adequacy of the metamodel error estimates. Moreover, in order to circumvent the so-called curse-of-dimensionality in constructing any nonlinear multivariate metamodels from a realistic number of expensive simulations, it is necessary to reliably eliminate insignificant inputs and consequently reduce the metamodel prediction error by focusing on major contributors. This paper presents a robust data-adaptive nonparametric metamodeling procedure that combines a convergent variable screening process with a robust 2-level error assessment strategy to achieve better metamodel accuracy.

The methodology of predicting analytical fatigue life of automotive body structures using two commercially available computer codes, NASTRAN and NCODE is described. Modal transient durability simulations are improved with use of residual vectors incorporating inertia relief basis functions. Simulations consisting of hundreds of thousand finite elements and hours of road loads are routine.

For the assessment of vehicle acoustics in the early design stages of a vehicle program, the use of full vehicle SEA models is becoming the standard analysis method in the US automotive industry. One benefit is that OEM's and Tier 1 suppliers are able to cascade lower level acoustic performance targets for NVH systems and components. Detailed SEA system level models can be used to assess the performance of systems such as dash panels, floors and doors, however, the results will be questionable until test data Is available. Correlation can be accomplished with buck testing, which is a common practice in the automotive industry for assessing the STL (sound transmission loss) of vehicle level components. The opportunity to conduct buck testing can be limited by the availability of representative bodies to be cut into bucks and the availability of a transmission loss suite with a suitably large opening.

Interior noise has become a significant performance attribute in modern passenger vehicles and this is extremely important in the luxury market segment where a quiet interior is the price of entry. With the elimination of early prototype vehicles to reduce development costs, high frequency analytical SEA models are used to design the vehicle sound package to meet targets for interior noise quality. This function is important before representative NVH prototypes are available, and later to support parameter variation investigations that would be cost prohibitive in a hardware test. This paper presents the application of an analytical full vehicle SEA model for the development of the acoustic package of a cross over luxury utility vehicle. The development concerns addressed were airborne powertrain noise and road noise. Power flow analysis was used to identify the major noise paths to the interior of the vehicle.

Over the years different methods of vehicle interior noise development have been used by car companies. During my 38 plus years of experience with General Motors' Noise and Vibration Laboratory and Advanced Vehicle Development Center, I have worked with varying methods, and when looking back, these methods have fluctuated between the application of highly subjective analysis and highly objective analysis. Stepped up efforts to reduce overall vehicle engineering design and development time have intensified the use of computer modeling techniques. Iterations of acoustic package content proposals once done experimentally can now be accomplished, to some degree, with computer analysis. To achieve appropriate sound1 character that meets consumer expectations will require both subjective analysis and objective testing and analysis early in a vehicle program.

The paper presented a correlation work between the GM and Goodyear acoustical laboratories to determine the tire noise load cases used for vehicle tire noise allocation and high-frequency airborne noise analysis. A large group of tires with different sizes were tested in the two labs to examine the lab-to-lab load cases differences in terms of near-field sound intensity and far-field sound power. A good agreement was found for the noise ranking between the two labs by 1/3 octave band and overall A-weighted sound intensity and sound power. The correction factors could be determined from one lab to another as well as from the near-field sound intensity to the far-field sound power. The discrepancies were investigated by comparing the two fixtures and two dyno shell profiles. The differences in 1/3 octave band sound measurement between the two labs were found to be contributed mainly by the shell profiles.

This paper will examine the regulatory development process, discuss the technical principles of the Economic Commission for Europe (ECE), R51.03 test, and discuss the overall objectives of the ECE R51.03 noise emission regulation. The development of this global noise emission regulation was a multi-stakeholder process which has resulted in new test procedures and new noise emission regulation principles. New test procedures based on ISO 362-1:2015 move the test basis to representative in-use noise emission, independent of vehicle propulsion technology. As part of the regulatory development, a monitoring program was conducted by the European Union to assess the applicability of the proposed test to provide representative vehicle noise emission results. The monitoring results also provided the basis to determine equivalent stringency between the test procedures of ECE R51.02 and R51.03.

Powertrain mounting systems design and development involves creating and optimizing a solution using specific mount rates and evaluation over multiple operating conditions. These mount rates become the recommended “nominal” rates in the specifications. The powertrain mounts typically contain natural materials. These properties have variation, resulting in a tolerance around the nominal specification and lead to differences in noise and vibration performance. A powertrain mounting system that is robust to this variation is desired. The design and development process requires evaluation of these mounts, within tolerance, to ensure that the noise and vibration performance is consistently met. During the hardware development of the powertrain mounting system, a library of mounts that include the range of production variation is studied. However, this is time consuming.

In order to reduce the number of head injuries sustained by pedestrian accidents, safety engineers are developing pedestrian friendly hood systems through gauge optimization of the hood inner panel. In this study, the clinch method was employed to assemble a pedestrian friendly hood with a 0.5mm thick inner panel. Static and dynamic analyses were carried out to determine the clinch experiencing the highest loads and to understand the fatigue behavior of a clinched hood during a slam event. The macroscopic failure modes of clinched joints by hood slam were studied by means of a scanning electron microscope. A simple equation was derived to correlate the hexahedron spot weld model as a substitute for clinching in order to obtain an equivalent stiffness for a clinched joint within the linear region of an F-D curve. The F-D curve was obtained by lap shear testing.

In recent years several variants of lightweight multi-layered acoustic treatments have been used successfully in vehicles to replace conventional barrier-decoupler interior dash mats. The principle involved is to utilize increased acoustic absorption to offset the decrease in insertion loss from the reduced mass such that equivalent vehicle level performance can be achieved. Typical dual density fibrous constructions consist of a relatively dense cap layer on top of a lofted layer. The density and flow resistivity of these layers are tuned to optimize a balance of insertion loss and absorption performance. Generally these have been found to be very effective with the exception of dash mats with very high insertion loss requirements. This paper describes an alternative treatment which consists of a micro-perforated film top layer and fibrous decoupler layer.

It has the aim to discuss the evolution of electronics components, integrated circuits, new transistors concepts and associate its importance in the automotive modules. Today, the challenge is to have devices which consume less power, suitable for high-energy radiation environment, less parasitic capacitances, high speed, easier device isolation, high gain, easier scale-down of threshold voltage, no latch-up and higher integration density. The improvement of those characteristics mentioned and others in the electronic devices enable the automotive industry to have a more robust product and give the possibility to integrate new features in comfort, safety, infotainment and telematics modules. Finally, the intention is to discuss advanced structures, such as the silicon-on-insulator (SOI) and show how it affects the electronics modules applied for the automotive area.

As more wireless services such as satellite radio (SDARS), navigation systems, OnStar, and mobile telephones are installed on GM vehicles, there is a need to make quick and accurate vehicle antenna pattern measurements. The interaction between vehicle and antenna must be included to ensure accurate vehicle antenna measurements. This implies that the size of the effective antenna should include both the antenna and vehicle interaction dimensions. For the frequency range of 500 MHz to 6 GHz, one solution is to use a spherical near-field system. The Satimo rapid probe array technology was selected to develop a vehicle antenna test system (ATS), which minimizes test time and maintains data accuracy. The ATS was designed to operate inside of an existing GM electromagnetic compatibility (EMC) anechoic chamber equipped with a nine-meter turntable.