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This study aims to provide a set of reference post-mortem human subject tests which can be used, with easily reproducible test conditions, for developing and/or validating pedestrian dummies and computational human body models against a road vehicle. An adjustable generic buck was first developed to represent vehicle front-ends. It was composed of four components: two steel cylindrical tubes screwed on rigid supports in V-form represent the bumper and spoiler respectively, a quarter of a steel cylindrical tube represents the bonnet leading edge, and a steel plate represents the bonnet. These components were positioned differently to represent three types of vehicle profile: a sedan, a SUV and a van. Eleven post-mortem human subjects were then impacted laterally in a mid-gait stance by the bucks at 40 km/h: three tests with the sedan, five with the SUV, and three with the van.

This paper demonstrates the benefit of using simulation and robust optimization for the problem of balancing vehicle noise, vibration, and ride performance over road impacts. The psychophysics associated with perception of vehicle performance on an impact is complex because the occupants encounter both tactile and audible stimuli. Tactile impact vibration has multiple dimensions, such as impact hardness and memory shake. Audible impact sound also affects occupant perception of the vehicle quality. This paper uses multiple approaches to produce the similar, robust, optimized tuning strategies for impact performance. A Design for Six Sigma (DFSS) project was established to help identify a balanced, optimized solution. The CAE simulations were combined with software tools such as iSIGHT and internally developed Kriging software to identify response surfaces and find optimal tuning.

At the early design stage it is easier to achieve impacts on the brake noise. However most noise analyses are applied later in the development stage when the design space is limited and changes are costly. Early noise analysis is seldom applied due to lack of credible inputs for the finite element modeling, the sensitive nature of the noise, and reservations on the noise event screening of the analysis. A high quality brake finite element model of good components’ and system representation is the necessary basis for credible early noise analysis. That usually requires the inputs from existing production hardware. On the other hand in vehicle braking the frequency contents and propensity of many noise cases are sensitive to minor component design modifications, environmental factors and hardware variations in mass production. Screening the noisy modes and their sensitivity levels helps confirm the major noisy event at the early design stage.

The work presented in this paper outlines the development of a simulation model to aid in the design and development of a compliant sprocket for balancer drives. A design with dual-mass flywheel and a crank-mounted compliant chain sprocket greatly reduces interior noise levels due to chain meshing. However, experimental observations showed the compliant sprocket can enter into resonance and generate excessive vibration energy during startup. Special features are incorporated into the compliant sprocket design to absorb and dissipate this energy. Additional damper spring rate, high hysteresis and large motion angle that overlap the driving range may solve the problem during engine start-up period. This work develops a simulation model to help interpret the measured data and rank the effectiveness of the design alternatives. A Multibody dynamics system (MBS) model of the balancer chain drive has been developed, validated, and used to investigate the chain noise.

Robust assessment using standardized signal-to-noise (SS/N) is a Design For Six Sigma (DFSS) methodology used to assess the mating quality of USCAR electrical connectors. When the insertion force vs. distance relationship is compared to a standard under varying environmental and system-related noise conditions, the ideal function is transformed into a linear relationship between actual and ideal force at the sample points acquired during the mating displacement. Since the ideal function used in the robust assessment of competing designs has a linear slope of 1 through the origin, the SS/N function used is of the form 10 log (1/σ2), also known as nominal-the-best type 2. Using this assessment methodology, designs are compared, with a higher SS/N indicating lower variation from the standard.

It is well known that lining reduction through wear affects contact pressure profile and noise generation. Due to high complexity in brake noise analysis, many factors were not included in previous analyses. In this paper, a new analysis process is performed by running brake “burnishing” cycles first, followed by noise analysis. In the paper, brake lining reduction due to wear is assumed to be proportional to the applied brake pressure with ABAQUS analysis. Brake pads go through four brake application-releasing cycles until the linings settle to a more stable pressure distribution. The resulting pressure profiles show lining cupping and high pressure spots shifting. The pressure distributions are compared to TekScan measurements. Brake noise analysis is then conducted with complex eigenvalue analysis steps; the resulting stability chart is better correlated to testing when the wear is comprehended.

This paper presents four methodologies for modeling gear mesh excitations in simple and compound planetary gear sets. The gear mesh excitations use simplified representations of the gear mesh contact phenomenon so that they can be implemented in a numerically efficient manner. This allows the gear mesh excitations to be included in transmission system-level, multibody dynamic models for the assessment of operating noise and vibration levels. After presenting the four approaches, a description is made regarding how they have been implemented in software. Finally, example models are used to do a comparison between the methods

The work presented in this paper outlines the design and development of a compliant sprocket for balancer drives in an effort to reduce the noise levels related to chain-sprocket meshing. An experimental observation of a severe chain noise around a resonant engine speed with the Dual-Mass Flywheel (DMF) and standard build solid (fixed) balancer drive sprocket. Torsional oscillation at the crankshaft nose at full load is induced by uneven running of crankshaft with a dual-mass flywheel system. This results in an increase of the undesirable impact noise caused by the meshing between the chain-links and the engagement/disengagement regions of sprockets, and the clatter noise from the interaction between the vibrating chain and the guides. This paper evaluates and discusses the benefits that the compliant sprocket design provided. A multi-body dynamics system (MBS) model of the balancer chain drive has been developed, validated, and used to investigate the chain noise.

A numerical investigation of automobile sunroof buffeting on a prototype sport utility vehicle (SUV) is presented, including experimental validation. Buffeting is an unpleasant low frequency booming caused by flow-excited Helmholtz resonance of the interior cabin. Accurate prediction of this phenomenon requires accounting for the bi-directional coupling between the transient shear layer aerodynamics (vortex shedding) and the acoustic response of the cabin. Numerical simulations were performed using the PowerFLOW code, a CFD/CAA software package from Exa Corporation based on the Lattice Boltzmann Method (LBM). The well established LBM approach provides the time-dependent solution to the compressible Navier-Stokes equations, and directly captures both turbulent and acoustic pressure fluctuations over a wide range of scales given adequate computational grid resolution.

This work discusses the development of SAE procedure J2747, “Hydraulic Pump Airborne Noise Bench Test”. This is a test procedure describing a standard method for measuring radiated sound power levels from hydraulic pumps of the type typically used in automotive power steering systems, though it can be extended for use with other types of pumps. This standard was developed by a committee of industry representatives from OEM's, suppliers and NVH testing firms familiar with NVH measurement requirements for automotive hydraulic pumps. Details of the test standard are discussed. The hardware configuration of the test bench and the configuration of the test article are described. Test conditions, data acquisition and post-processing specifics are also included. Contextual information regarding the reasoning and priorities applied by the development committee is provided to further explain the strengths, limitations and intended usage of the test procedure.

This paper examines the aerodynamic forces on the open hood of a stationary vehicle when another large vehicle, such as an 18-wheel semi-truck, passes by at high speed. The problem of semi-truck passing a parked car with hood open is solved as a transient two-vehicle aerodynamics problem with a Dynamic Moving Mesh (DMM) capability in commercial CFD software package FLUENT. To assess the computational feasibility, a simplified compact car / semi-truck geometry and CFD meshes are used in the first trial example. At 70 mph semi-truck speed, the CFD results indicate a peak aerodynamic force level of 20N to 30N on the hood of the car, and the direction of the net forces and moments on the hood change multiple times during the passing event.

Since 2000, an Aluminum Cosmetic Corrosion task group within the SAE Automotive Corrosion and Protection (ACAP) Committee has existed. The task group has pursued the goal of establishing a standard test method for in-laboratory cosmetic corrosion evaluations of finished aluminum auto body panels. A cooperative program uniting OEM, supplier, and consultants has been created and has been supported in part by USAMP (AMD 309) and the U.S. Department of Energy. Prior to this committee's formation, numerous laboratory corrosion test environments have been used to evaluate the performance of painted aluminum closure panels. However, correlations between these laboratory test results and in-service performance have not been established. Thus, the primary objective of this task group's project was to identify an accelerated laboratory test method that correlates well with in-service performance.

This paper presents the hybrid technique application in identifying the noise transfer paths and the force transmissibility between the interfaces of the different components in the vehicle. It is the stiffness based formulation and is being applied for the low to mid frequency range for the vibration and structure borne noise. The frequency response functions such as dynamic compliance, mobility, inertance, and acoustic sensitivity, employed in the hybrid method, can either be from the test data or finite element solution or both. The Source-Path-Receiver concept is used. The sources can be from the road surface, engine, transmission, transfer case, prop-shaft, differential, rotating components, chain drives, pumps, etc., and the receiver can be driver/passenger ears, steering column, seats, etc.

A novel longitudinally sliding overhead video screen monitor was developed to address consumer needs for vehicles equipped with rear seat entertainment and long length sunroofs. Long length sunroof openings in vehicles are causing engineers to mount video screen monitors in locations other than the overhead. Typically, they are mounted on the floor console or on the back of front seat head restraints. Floor console mounted video screen monitors generally do not provide a comfortable viewing distance or angle for second and third row occupants. Head restraint mounted video monitors cause issues with seat shake and two monitors adds to the vehicle cost unnecessarily. The mountable sliding video monitor assembly comprises of a video display screen, brackets for mounting the monitor, a pair of tracks that are movable with respect to each other, a series of ball bearings, and a roof mounting bracket. The inner main track is adapted for mounting the pair of tracks to the vehicle.

The Hood ajar sensing system provides customer feedback regarding the latch positional state of hood. If the sensing system is not robust to variation due to manufacturing, thermal conditions, and assembly, diagnostic failures can result. Executing various elements of the design for six sigma process can reduce the potential for diagnostic failures. This paper presents a method for achieving quality improvements by developing transfer functions, and using them for sensitivity and variance analysis. Control parameters were optimized to minimize non-conformal situations in the presence of various noise conditions.

The main objective of this paper was to determine if the vehicle performance can be maintained with a reduced mass cradle structure. Aluminum and magnesium cradles were compared with the baseline steel cradle. First, the steel chassis alone is analyzed with the refined finite element model and validated with experimental test data for the frequencies, normal modes, stiffnesses and the drive-point mobilities at various attachment mount/bushing locations. The superelement method in conjunction with the component mode synthesis (CMS) technique was used for each component of the vehicle such as Body-In-White, Instrument Panel, Steering Column Housing & Wheel, Seats, Cradles, CRFM, etc. After assemblage of all the superelements, analysis was carried out by changing the front and rear cradle gauges and the material properties. The drive-point mobility response was computed at various locations and the noise (sound pressure) level was calculated at the driver and passenger ears.

This paper presents a pioneer work and first time application of Multi Objective Robust Optimization to analytically improve Idle Shake Performance. The method is developed to obtain a robust design with multiple objectives under consideration along with managing material property variation. It was a Robust Optimization on top of Multi Objective Genetic Algorithm, Robu-MOGA. The design variables in the study included the nominal values and tolerances of Sound Transmission Loss property, and interior material Absorption property. The analytical objective was not only to minimize the peak airborne noise at each specified frequency, but also to reduce the total cost and the total mass of the materials. In the study, AutoSEA (statistical energy analysis) from ESI Software, Inc. was used as the solver. AutoSEA was integrated with iSIGHT from Engineous Software, Inc.

Appropriate road noise levels are critical to perceived quality in today's highly competitive automotive industry. Tire noise is often one of the dominant sources. In order to provide effective noise control schemes it is imperative to fully define the noise paths. In this paper, a case study of an experimental lab method is presented that allows definitive understanding of the structure-borne and airborne spectral contributions of tire noise. For this study, interior noise data were collected using a 10 ft road wheel. Data were collected for the front and rear tires. These measurements contained both the structure-borne and airborne contributions. The same test was performed with the tire physically disconnected from the vehicle structure. This measurement contained only the airborne contribution. The structure-borne contribution was then calculated as the difference in noise levels between the two cases.

The International Organization for Standardization (ISO) has developed a new measurement procedure, ISO362:200X, for vehicle exterior noise. This proposed standard covers motorcycles, light duty vehicles, and heavy-duty vehicles. The intent of the new procedure is to measure vehicle noise consistent with typical urban operation. SAE has conducted a cooperative research program to evaluate the new ISO procedure for light duty vehicles with regard to the intent of the procedure, technical, and practical considerations. The results of the cooperative research program indicate the new ISO procedure meets the intent of measuring typical traffic noise and does so in a technically correct and practically achievable manner.

The Door system is one of the major paths for vehicle interior noise under a variety of load conditions. In this paper we consider the elements of the door lower (excluding glass) in terms of noise transmission. Passenger car doors are comprised of the outer skin, door cavity, door inner sheet metal, vapor barrier, and interior trim. Statistical Energy Analysis (SEA) models must effectively describe these components in terms of their acoustic properties and capture the dominant behaviors relative to the overall door system. In addition, the models must interface seamlessly with existing vehicle level SEA models. SEA modeling techniques for the door components are discussed with door STL testing and model correlation results.