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Determination of an engine's inertial properties is critical during vehicle dynamic analysis and the early stages of engine mounting system design. Traditionally, the inertia tensor can be determined by torsional pendulum method with a reasonable precision, while the center of gravity can be determined by placing it in a stable position on three scales with less accuracy. Other common experimental approaches include the use of frequency response functions. The difficulty of this method is to align the directions of the transducers mounted on various positions on the engine. In this paper, an experimental method to estimate an engine's inertia tensor and center of gravity is presented. The method utilizes the traditional torsional pendulum method, but with additional measurement data. With this method, the inertia tensor and center of gravity are estimated in a least squares sense.

This paper summarizes a study on axle balance measurement and balancing strategies. Seven types of axles were investigated. Test samples were randomly selected from products. Two significant development questions were set out to be answered: 1) What is the minimum rotational speed possible in order to yield measured imbalance readings which correlated to in-vehicle imbalance-related vibration. What is the relationship between the measured imbalance and rotational speed. To this end, the imbalance level of each axle was measured using a test rig with different speeds from 800 to 4000 rpm with 200 rpm increments. 2) Is it feasible to balance axle sub-assemblies only and still result in a full-assembly that satisfies the assembled axle specification? To this end, the sub-assemblies were balanced on a balance machine to a specified level. Then with these balanced sub-assemblies, the full assemblies were completed and audited on the same balance test rig in the same way.

Tailor welded steel blanks have long been applied in stamping of automotive parts such as door inner, b-pillar, rail, sill inner and liftgate inner, etc. However, there are few known tailor welded aluminum blanks in production. Traditional laser welding equipment simply does not have the capability to weld aluminum since aluminum has much higher reflectivity than steel. Welding quality is another issue since aluminum is highly susceptible to pin holes and undercut which leads to deterioration in formability. In addition, high amount of springback for aluminum panels can result in dimension control problem during assembly. A tailor-welded aluminum blank can help reducing dimension variability by reducing the need for assembly. In this paper, application of friction stir and plasma arc welded blanks on a liftgate inner will be discussed.

A serpentine flow channel is one of the most common and practical channel layouts for a PEM fuel cell since it ensures the removal of water produced in a cell. While the reactant flows along the flow channel, it can also leak or cross to neighboring channels via the porous gas diffusion layer due to a high pressure gradient. Such a cross flow leads to effective water removal in a gas diffusion layer thus enlarging the active area for reaction although this cross flow has largely been ignored in previous studies. In this study, neutron radiography is applied to investigate the liquid water accumulation and its effect on the performance of a PEM fuel cell. Liquid water tends to accumulate in the gas diffusion layer adjacent to the flow channel area while the liquid water formed in the gas diffusion layer next to the channel land area seems to be effectively removed by the cross leakage flow between the adjacent flow channels.

In this study, a full vehicle with durability tire model established with ADAMS is applied to simulate the dynamic behavior of the vehicle under severe rough road proving ground events, where the shock force-velocity characteristics are modeled as nonlinear curves and multi-stage representations, respectively. The shock forces and velocities at each corner are resolved and through full factorial DOE, the shock forces and velocities response surface models are established to analyze the sensitivities of shock force and velocity to the shock damping characteristics.

In the development of several outside mirror designs for vehicles, a high frequency noise (whistling) phenomenon was experienced. First impression was that this might be due to another source on the vehicle (such as water management channels) or a cavity noise; however, upon further investigation the source was found to be the mirror housing. This “laminar whistle” is related to the separation of a laminar boundary layer near the trailing edges of the mirror housing. When there is a free stream impingement on the mirror housing, the boundary layer starts out as laminar, but as the boundary layer travels from the impingement point, distance, speed, and roughness combine to trigger the transition turbulent. However, when the transition is not complete, pressure fluctuations can cause rapidly changing flow patterns that sound like a whistle to the observer. Because the laminar boundary layer has very little energy, it does not allow the flow to stay attached on curved surfaces.

The objective of this paper is to investigate the effect of stamping process on oil canning and dent resistance performances of an automotive roof panel. Finite element analysis of stamping processes was carried out using LS-Dyna to obtain thickness and plastic strain distributions under various forming conditions. The forming results were mapped onto the roof model by an in-house developed mapping code. A displacement control approach using an implicit FEM code ABAQUS/Standard was employed for oil canning and denting analysis. An Auto/Steel Partnership Standardized Test Procedure for Dent Resistance was employed to establish the analysis model and to determine the dent and oil canning loads. The results indicate that stamping has a positive effect on dent resistance and a negative effect on oil canning performance. As forming strains increase, dent resistance increases while the oil canning load decreases.

Knowledge of the loads experienced by a leaf spring suspension is required for the optimal design of the suspension components and frame. The most common method of representing leaf springs is the SAE 3 link model, which does not give good results in the lateral direction. In this paper, a beam element leaf spring model is developed. This model is validated using data obtained from laboratory tests done on leaf spring assemblies. The model is then subjected to actual road load data measured on the Proving Ground. Lastly, results from the beam element model are presented and compared with results obtained from proving ground tests. Overall, the beam element model gives good results in all directions except in situations where it is subjected to high fore/aft acceleration and high reverse braking events.

In this paper, the effects of heat exchanger design parameters are investigated. The ease study being investigated here is the parametric analysis of automotive radiator where the hot fluid is the engine coolant and the cold fluid is the ambient air. Key parameters that are considered are the air density, fin thickness, fins height and air temperature. Effect of air density may be a concern since heat exchangers are usually designed, for automotive applications, under atmospheric pressure conditions. Changes in altitude will cause a change in air density. Therefore, the performance of cooling system may be affected by elevation. In this analysis, however, it is shown that the change in air density has very limited or no effect on the cooling system. The fin dimensions play a key role in the overall effectiveness of a heat exchanger. Some cost saving ideas may include reducing fin dimensions such as fin thickness or fin height.

Cam-phasing is increasingly considered as a feasible Variable Valve Timing (VVT) technology for production engines. Additional independent control variables in a dual-independent VVT engine increase the complexity of the system, and achieving its full benefit depends critically on devising an optimum control strategy. A traditional approach relying on hardware experiments to generate set-point maps for all independent control variables leads to an exponential increase in the number of required tests and prohibitive cost. Instead, this work formulates the task of defining actuator set-points as an optimization problem. In our previous study, an optimization framework was developed and demonstrated with the objective of maximizing torque at full load. This study extends the technique and uses the optimization framework to minimize fuel consumption of a VVT engine at part load.

Automotive electronics and software is getting complex day by day. More and more features and functions are offered and supported by software in place of hardware. Communication is carried out on the CAN bus instead of hard wired circuits. This architectural transition facilitates lots of flexibility, agility and economy in development. However, it introduces risk of unexpected failures due to insufficient testing and million of possible combinations, which can be created by users during the life time of a product. Model based development supports an effective way of handling these complexities during simulation and also provide oracle for its validation. Based on priorities and type of applications, test vectors can be auto generated and can be used for formal verification of the models. These auto-generated test vectors are valuable assets in testing and can be effectively reused for target hardware (ECU) verification.

Current engine development processes typically involve extensive steady-state and simple transient testing in order to characterize the engine's fuel consumption, emissions, and performance based on several controllable inputs such as throttle, spark advance, and EGR. Steady-state and simple transient testing using idealistic load conditions alone, however, is no longer sufficient to meet powertrain development schedule requirements. Mapping and calibration of an engine under transient operation has become critically important. And, independent engine development utilizing accelerated techniques is becoming more attractive. In order to thoroughly calibrate new engines in accelerated fashion and under realistic transient conditions, more advanced testing is necessary.

Exhaust durability is an important measure of quality, which can be predicted using CAE with accurate mount loads. This paper proposes an innovative method to calculate these loads from measured mount accelerations. A Chrysler vehicle was instrumented with accelerometers at both ends of its four exhaust mounts. The vehicle was tested at various durability routes or events at DaimlerChrysler Proving Grounds. These measured accelerations were integrated to obtain their velocities and displacements. The differences in velocities and displacements at each mount were multiplied by its damping and stiffness rates to obtain the mount load. The calculation was conducted for all three translational directions and for all events. The calculated mount loads are shown within reasonable range. Along with CAE, it is suggested to explore this method for exhaust durability development.

Studies in an Angular Stretch Bend Test (ASBT) have demonstrated that the failure location moves from the side wall to punch nose area. This occurs as the R/T ratio decreases below a certain limit and applies to most low carbon steels with the exception of Dual Phase (DP) steels. Such behavior in DP steels indicates that bending effects have a severe impact on the formability of DP materials. Therefore, the traditional criterion using the forming limit curve (FLC) is not suitable to assess the formability at punch radius areas for DP steels due in part to its uniqueness of unconventional microstructures. In this paper, a new failure criterion, ‘Bending-modified’ FLC (BFLC), is proposed by extending the traditional FLC using the “Stretch Bendability Index” (SBI) concept for the stretch bendability assessment.

In a gasoline engine, the unswept in-cylinder residual gas and introduction of external EGR is one of the important means of controlling engine raw NOx emissions and improving part load fuel economy via reduction of pumping losses. Since the trapped in-cylinder Residual Gas Fraction (RGF, comprised of both internal, and external) significantly affects the combustion process, on-line diagnosis and monitoring of in-cylinder RGF is very important to the understanding of the in-cylinder dilution condition. This is critical during the combustion system development testing and calibration processes. However, on-line measurement of in-cylinder RGF is difficult and requires an expensive exhaust gas analyzer, making it impractical for every application. Other existing methods, based on measured intake and exhaust pressures (steady state or dynamic traces) to calculate gas mass flowrate across the cylinder ports, provide a fast and economical solution to this problem.

This paper describes a lightweight magnesium intensive automobile body structure concept developed at DaimlerChrysler to support a high fuel-efficiency vehicle project. This body structure resulted in more than 40% weight reduction over a conventional steel structure while achieving significantly improved structural performance as evaluated through CAE simulations. A business case analysis was conducted and showed promising results. One concept vehicle was built for the purpose of demonstrating concept feasibility. The paper also identifies areas for further development to enable such a vehicle to become a production reality at a later time.

Mode management is an essential part of the design process for NVH performance. System resonances must be sufficiently separated to minimize interaction from source inputs and each other [1]. Such resonances are typically determined through experimental modal testing conducted in a lab environment under controlled and repeatable conditions. Global vehicle and suspension system response demonstrate soft nonlinear behavior, however. Their resonant frequencies may thus decrease under on-road input not reproducible in a lab environment. Subsequently, mode management charts derived from lab testing may not be representative of the vehicle's on-road dynamic response. This paper presents modal model determination methodologies, and examines suspension system and vehicle global dynamic response under lab modal test and operating conditions. Vehicle suspension modes measured under static and dynamic (rolling) conditions will be compared.

Crankshafts must be balanced statically and dynamically before being put into service. However, without pistons and connecting-rod assemblies, a non-symmetric crankshaft is not in dynamic balance. Therefore, it is necessary to apply equivalent ring-weights on each of the crankpins of the crankshaft when balancing it on a dynamic balancing machine. The value of the ring weight must be accurately determined, otherwise all advantages that are derived from balancing would be of no avail. This paper analytically examines the theoretical background of this problem. Formulas for calculating the ring weights are derived and presented. These formulas are applicable to a generic class of crankshafts of V-type engines with piston pin offset. Also, practical consideration, such as the design and manufacturing of these ring weights, the method of testing, and correction is addressed.

With the ever increasing popularity of SUV automobiles, studies involving driveline specific problems have grown. One prevalent NVH problem is axle whine associated with the assembled motion transmission error (MTE) of an axle system and the corresponding vibration/acoustic transfer paths into the vehicle. This phenomenon can result in objectionable noise levels in the passenger compartment, ensuing in customer complaints. This work explores the methodology and test methods used to diagnose and solve a field axle whine problem, including the use of cab mount motion transmissibility path analysis, running modes and a detailed MTE best-of-the-best (BOB)/worst-of-the-worst (WOW) study. The in-vehicle axle whine baseline measurements including both vehicle dynamometer and on-road test conditions, along with the countermeasures of axle whine fixes are identified and presented in this paper.

It is becoming increasingly difficult to obtain good repeatability from running lab vehicle correlation testing, since vehicle variability is so significant at the Low ULEV and SULEV emissions levels. These new emission standards are becoming so stringent that it makes it very difficult to distinguish whether a problem is a result of vehicle variability, test cell sampling or the analytical system. A vehicle exhaust emission simulator (VEES) developed by Horiba, can simulate emissions from low emitting gasoline vehicles by producing tailpipe flow rates containing emissions constituents ( HC, CH4, CO, NOx, CO2 ) injected at the tailpipe flow stream via mass flow controllers.