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When pickup trucks are driven on concrete paved freeways, freeway hop shake is a major complaint. Freeway hop shake occurs when the vehicle passes over the concrete joints of the freeway which impose in-phase harmonic road inputs. These road inputs excite vehicle modes that degrade ride comfort. The worst shake level occurs when the vehicle speed is such that the road input excites the vehicle 1st bending mode and/or the rear wheel hop mode. The hop and bending mode are very close in frequency. This phenomenon is called freeway hop shake. Automotive manufacturers are searching for ways to mitigate freeway hop shake. There are several ways to reduce the shake amplitude. This paper documents a new approach using hydraulic body mounts to reduce the shake. A full vehicle analytical model was used to determine the root cause of the freeway hop shake.

Shudder vibration of a hydraulic power steering system during parking maneuver was studied with numerical and experimental methods. To quantify vibration performance of the system and recognize important stimuli for drivers, a shudder metric was derived by correlation between objective measurements and subjective ratings. A CAE model for steering wheel vibration analysis was developed and compared with measured data. In order to describe steering input dependency of shudder, a new dynamic friction modeling method, in which the magnitude of effective damping is determined by average velocity, was proposed. The developed model was validated using the measured steering wheel acceleration and the pressure change at inlet of the steering gear box. It was shown that the developed model successfully describes major modes by comparing the calculated FRF of the hydraulic system with measured one from the hydraulic excitation test.

The drum brake pulsation is an issue that may cause a major customer complaint. One of the root causes of the drum pulsation is the deformation of the drum to an out of roundness (OOR) shape during the wheel-drum-axle assembly process under the presence of the uneven wheel flatness. This paper summarizes the newly developed OOR simulation method using ABAQUS and the counter-measures to reduce the OOR, and subsequently pulsation, by identifying the drum design parameter effects on OOR.

Impact Harshness and Impact Shake are two related aspects of ride performance. Vehicle designs often need to meet the conflicting requirements between these two performance areas. The fundamental dynamics and general effect of vehicle and suspension design parameters need to be understood to reduce the cost and time associated with early vehicle development and ensure built-in quality. This study investigates the influence of the parameters in suspension and tire wheel systems on each of the performance metrics. Attempts are made to rank-order the relative sensitivity of each parameter on each of the metrics and propose approaches to improve ride quality.

This paper describes a front road wheel steer-by-wire system with two actuator motors on the rack and pinion assembly to move the road wheels. Dual actuators are used to provide actuator redundancy and to enhance the fault tolerance capability. When one actuator faults or fails, the other actuator is designed to work independently and maintain full system performance. The paper emphasizes control method to implement the motion control for the front road wheel steer-by-wire system with two actuators on the common load. The proposed dual servo synchronization motion control implements the angle tracking for the road wheel reference input by controlling two actuators synchronously and cooperatively. It includes two servo feedback control loops to track the common reference input. The angular position error between two feedback loops is compensated using a synchronized compensator.

In developing a direct injection gasoline engine, the in-cylinder fuel air mixing is key to good performance and emissions. High speed visualization in an optically accessible single cylinder engine for direct injection gasoline engine applications is an effective tool to reveal the fuel spray pattern effect on mixture formation The fuel injectors in this study employ the unique multi-hole turbulence nozzles in a PFI-like (Port Fuel Injection) fuel system architecture specifically developed as a Low Pressure Direct Injection (LPDI) fuel injection system. In this study, three injector sprays with a narrow 40° spray angle, a 60°spray angle with 5°offset angle, and a wide 80° spray angle with 10° offset angle were evaluated. Image processing algorithms were developed to analyze the nature of in-cylinder fuel-air mixing and the extent of fuel spray impingement on the cylinder wall.

In the automotive industry, vehicle durability analysis is based on test schedule encompassing multiple road surfaces (events) including rough roads, potholes, etc. Traditionally, in the Computer Aided Engineering (CAE) world, road load data for various road surfaces are measured/predicted and fatigue life is predicted for each individual road surface. Fatigue life for the complete test schedule is then calculated with Miner’s rule by summing fatigue damage for each road surface with an appropriate number of repetitions. A major pitfall of this approach is that it does not consider the effect of the largest rainflow range across the entire test schedule. The method described in this paper was developed to perform fatigue analysis of structures subjected to diverse road surfaces and also consider the case in which the maximum overall peak and minimum overall valley do not occur over the same road surface.

An algorithm, which determines the range of a preceding vehicle by a single image, had been proposed. It uses a “Range-Window Algorithm”. Here in order to realize higher robustness and stability, the pattern matching is incorporated into the algorithm. A single camera system using this algorithm has an advantage over the high cost of stereo cameras, millimeter wave radar and non-robust mechanical scanning in some laser radars. And it also provides lateral position of the vehicle. The algorithm uses several portions of a captured image, namely windows. Each window is corresponding to a predetermined range and has the fixed physical width and height. In each window, the size and position of objects in the image are estimated through the ratio between the widths of the objects and the window, and a score is given to each object. The object having the highest score is determined as the best object. The range of the window corresponding to the best object becomes an estimated range.

The intention of this work is to illustrate a method used to overcome limitations of tire models developed during an evaluation study of an Empirical Dynamic™ (ED) damper model. A quarter vehicle test system was built to support the evaluation, and a model of the test system was also developed in ADAMS™. In the model, the damper was represented by a polynomial spline function and by an ED model separately. Vehicle level comparisons between the physical measurements and the model predictions were conducted. The actuator displacement signal from the physical test was used to drive the virtual test system. Spindle acceleration, spindle force, and other signals were collected for comparison. The tire model was identified as a significant source of error and as a result, the direct vehicle level correlation study did not illustrate any advantage of the ED damper model over a spline damper model.

Steering Wheel Torsional Vibration (SWTV) at highway speed on smooth roads is one important attribute affecting vehicle refinement. To ensure desirable SWTV performance, achieve the best design compromises and minimize the development cost, specific design targets need to be defined and the proposed design needs to be assessed very early in the vehicle development cycle. In this paper, the fundamental dynamics of SWTV are analyzed and examples are given to demonstrate the strategies to reduce the SWTV response. Influence of design parameters on the SWTV response is predicted for four vehicle platforms. General guidelines for designing suspension and steering systems are discussed to ensure achieving SWTV targets.

Although not completely understood, rotor distortion due to bolt-up is an issue commonly found in conventional brake rotor design. In this paper, bolt-up is addressed by utilizing optimization and contact analysis methods. These methods give greater insight to the contributing factors that influence bolt-up distortion. In particular, the optimization method defines the approximate geometric shape required for a brake rotor based on optimizing one or more variables. By utilizing the non-linear contact analysis method, the results from the optimization analysis are validated. In general, the results show that bolt-up distortion is not significantly affected by changing design features, variables or combinations of design features and variables. However, significant improvement in bolt-up distortion is noticed when changes are made to the brake rotor and the wheel bearing hub.

Modern automobiles utilize stabilizer bars to increase vehicle roll stiffness. Stabilizer bars are laterally mounted torsional springs which resist vertical displacement of the wheels relative to one another. A stabilizer bar is constructed in such a way that it will meet package constraints and fatigue requirements. In order to design a robust stabilizer bar, Taguchi's “Design of Experiment method” is used. The objective of this paper is to develop a robust stabilizer bar design that will maximize the fatigue life and the roll stiffness while minimizing weight. This study is based on results obtained by CAE analysis.

The Milford Road Course is a new 2.9 mi (4.6 km), 20 turn, configurable closed course with 135 ft (41 m) of elevation change, constructed at the General Motors Proving Ground in Milford, MI, USA. This facility provides a convenient and safe venue for engineers to evaluate vehicle limit performance over extensive combinations of vertical, lateral and longitudinal acceleration at a wide range of speeds. This paper discusses the vehicle dynamics aspects of the facility design, simulation and construction.

A procedure was developed to predict suspension and cradle loads during a dynamic front wheel curb impact event. Previously, the only way to acquire these types of forces was to run a test. The procedure uses a multibody full vehicle ADAMS model. The impact between the tire and the curb was modeled using a simplified tire model. Specific structural suspension members were modeled with a proprietary method developed by GM to capture the elastic-plastic behavior. The analysis results showed good correlation with the test, and the procedure is now being used at GM.

An onboard vehicle-to-vehicle multi-hop wireless networking system has been developed to test the real-world performance of telematics applications. The system targets emergency and safety messaging, traffic updates, audio/video streaming and commercial announcements. The test-bed includes a Differential GPS receiver, an IEEE 802.11a radio card modified to emulate the DSRC standard, a 1xRTT cellular-data connection, an onboard computer and audio-visual equipment. Vehicles exchange data directly or via intermediate vehicles using a multi-hop routing protocol. The focus of the test-bed is to (a) evaluate the feasibility of high-speed inter-vehicular networking, (b) characterize 5.8GHz signal propagation within a dynamic mobile ad hoc environment, and (c) develop routing protocols for highly mobile networks. The test-bed has been deployed across five vehicles and tested over 400 miles on the road.

The era of the vehicle as a standalone non-connected entity is rapidly drawing to a close. The “Box” on four wheels is being opened to multiple communication channels based on consumer demand and expectations of the latest features, functions and content. Concurrently, automotive planners, marketers, engineers, and system architects are subject to increased complexity as a result of the rapidly evolving consumer electronics industry. This paper will discuss many of the limitations of existing automotive business models in attempting to successfully implement and meet consumer expectations. It will also propose a structural framework for automotive planners, marketers, engineers, and system architects to be able to better understand and predict consumer acceptance of electronics, multimedia features, and in-vehicle content access.

A multi vector design tool to accurately predict instrument panel obscuration was developed to insure that critical legal displays in vehicles are not obscured. The concept provides for a computer generated light source shaped to replicate the human eyes. The light source is then projected onto a 3D math based arrangement and the resultant shadows are visible on the instrument panel surface and its displays. Design studios require criteria for the placement of the instrument cluster gages and displays, various controls, switches, and steering column stalks before an interior theme can be completed. Therefore, instrument panel obscuration and visibility must be determined early in the design process. The obscured areas are a function of the instrument panel surface, steering wheel rim, hub, spokes, and the location of the driver's eyes. This light source method allows engineers and designers the ability to quickly determine obscured areas.

Recently published SAE Recommended Practice J2562 - SAE Biaxial Wheel Test standardized the terminology, equipment, and test procedure for the biaxial wheel test. This test was originally presented by Fraunhofer Institut Betriebsfestigkeit - LBF (Fraunhofer Institute for Structural Durability) in SAE paper 830135 “Automotive Wheels, Method and Procedure for Optimal Design and Testing”. The first release of SAE J2562 included a generic, scalable load file applicable to wheels designed for five to eight passenger vehicles with capacity to carry a proportional amount of luggage or ballast. Future releases of SAE J2562 would include two additional load files; one applicable to light trucks that have substantial cargo capacity and one for sports cars typically limited to two passengers and marginal luggage. This report details the process used to develop the SAE Biaxial Wheel Test Load File for passenger vehicles.

Hyundai Motor Company has combined physical and virtual testing tools to validate a full vehicle virtual prototype. Today a large number of physical tests are still required because the cycle of “design-build-test-change” relies on complex models of components and systems that typically are not easily validated. In order to shorten the development cycles, engineers perform multi-body simulations to dynamically excite components and systems and thereby estimate their durability under dynamic loads. The approach described herein demonstrates the feasibility of correlating the output from the corresponding physical and virtual prototype. Both synthetic and road load events are employed to excite physical and virtual vehicles, reveal difference in response, and ultimately improve the predictive capability of the model.

This paper presents a case study on reducing road noise of a passenger vehicle. SEA, insertion loss and sound intensity measurements were the tools used in the study. A SEA model was constructed to predict the primary paths (panels or area) contributing to the overall interior sound field. Insertion loss measurements were used to verify the primary contributing paths identified using SEA. To provide further details of the primary paths, intensity maps of identified panels were measured allowing detailed reconstruction of the contributory panels. The SEA model, insertion loss, and intensity maps aided in providing possible design fixes that will effectively reduce road noise. Finally, comparisons of predicted results versus actual results at both a subsystem and a full vehicle level are included in this paper.