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Viewing 1 to 22 of 22
1998-11-16
Technical Paper
982824
Shan Shih, Scott Kuan, Chris Keeney, Ragnar Ledesma
The uniqueness of heavy and medium duty vehicle powertrain design, compared to that of passenger cars, is two fold: vast variations exist from vehicle to vehicle because of mission requirements, and powertrain components are sourced from a diverse group of suppliers. Vehicle powertrain design involves selection of the appropriate major components, such as the engine, clutch, transmission, driveline, and axle. At this design stage the main focus is on power matching, to ensure that the vehicle's performance meets specifications of gradability, maximum speed, acceleration, fuel economy, and emissions[1, 2, 3, 4 and 5]. The general practice also demands that the durability of the drivetrain components for the intended vocation or application be verified. Equally important but often neglected in the design phase is the system's NVH (Noise Vibration and Harshness) performance, such as torsional vibration, U-joint excitation, and gear rattle.
2005-11-01
Technical Paper
2005-01-3609
Ramesh Edara, Shan Shih, Nasser Tamini, Tim Palmer, Arthur Tang
Virtual proving ground (VPG) simulations have been popular with passenger vehicles. VPG uses LS-DYNA based non-linear contact Finite Element analysis (FEA) to estimate fully analytical road loads and to predict structural components durability with PG road surfaces and tire represented as Finite elements. Heavy vehicle industry has not used these tools extensively in the past due to the complexity of heavy vehicle systems and especially due to the higher number of tires in the vehicle compared to the passenger car. The higher number tires in the heavy vehicle requires more computational analysis duration compared to the passenger car. However due to the recent advancements in computer hardware, virtual proving ground simulations can be used for heavy vehicles. In this study we have used virtual proving ground based simulation studies to predict the durability performance of a trailer suspension frame.
2006-10-31
Technical Paper
2006-01-3576
Yenkai (Brian) Wang, Shan Shih
Welding has been used extensively in automotive components design due to its flexibility to be applied in manufacturing, high structural strength and low cost. To improve fuel economy and reduce material cost, weight reduction by optimized structural design has been a high priority in auto industry. In the majority of heavy duty vehicle's chassis components design, the ability to predict the mechanical performance of welded joints is the key to success of structural optimization. FEA (finite element analysis) has been used in the industry to analyze welded parts. However, mesh sensitivity and material properties have been major issues due to geometry irregularity, metallurgical degradation of the base material, and inherent residual stress associated with welded joints. An approach, equilibrium-equivalent structural stress method, led by Battelle and through several joint industrial projects (JIP), has been developed.
2006-10-31
Technical Paper
2006-01-3573
Jia Li, Shan Shih
To validate the integrity of a commercial vehicle's exhaust system's structural design is a challenging job. An integrated approach to use both simulation/modeling and hardware testing must be employed to reduce product development cost. In addition to the considerations of the geometry and configuration specs of 70-90 parts and joints as well as material's thermal and mechanical property data in model development, representative loading must be used. For base excitation type of loading, such as the one experienced by the vehicle's exhaust system, one must decide whether to conduct the time domain transient analysis or frequency domain random vibration analysis. Although both methods are well known, few discussions can be found in the literature regarding their effective use in the framework of product design and development. Based on our study, the random vibration method should be used first for identifying high stress locations in the system and for design optimization.
2006-10-31
Technical Paper
2006-01-3546
Wangquan (Winston) Cheng, Scott Kuan, Shan Shih
This paper describes an analytical process for the design of a brake shoe assembly that consists of the linings, shoe table, webs, and rivets. One fundamental performance requirement for the brake shoe assembly is that the linings will not lose clamp force within the desired service life. Key elements of the analytical process involved developing an FEA model with given loading conditions and developing a mathematical model to study the influence parameters of the forces acting on the lining.
2004-03-08
Technical Paper
2004-01-1547
Ramesh Edara, Shan Shih
Multibody Dynamics Simulation (MDS) studies are valuable in providing guidance in suspension systems design and reduce product development cost and time. These studies are used in various stages of suspension system design and development. In both concept study and detailed design the subsystem kinematics, dynamics and full vehicle dynamics studies are used. In this paper, four case studies for suspension system performance optimization using MDS studies are presented.
2003-11-10
Technical Paper
2003-01-3436
Shan Shih, Scott Kuan, Dale Eschenburg
Engineering specifications, i.e. test bogeys, are criterion for determining the success or failure of durability designs in the product development process. Considerations in the development of the specifications for vehicle structural components, such as axle housings and suspension torque rods, have been presented in a previous SAE paper [1]. This paper has been prepared because the factors on the same subject for vehicle drive train components, such as gears and bearings, are quite different. The center of this study is on “how to define equivalent duty cycles for lab test”. Several issues distinguish this task for drive train components: High cycle fatigue, high accelerated tests, competitive failures and failure modes, empirical component load-life data, loading, field correlation, and system level tests.
2007-05-15
Technical Paper
2007-01-2258
Ragnar Ledesma, Shan Shih
A simple ADAMS model was developed for simulating one possible mechanism that causes low-frequency (less than 1 kHz) noise in disc brake assemblies for heavy-duty and medium-duty trucks. The model consists of: truck tire, axle housing, torque plate, caliper, push rods, inner pad, outer pad, and rotor. Only one component (the torque plate) was modeled as a flexible body (using a finite element model), while all other parts are considered as infinitely rigid. A lumped parameter representing the suspension wrap-up stiffness resists the axle pitch motion. When the brakes are not engaged, the system has two distinct modes of vibration, namely, the axle pitch mode which is governed by the suspension wrap-up stiffness, and the caliper transverse (side-to-side) mode, which is governed by the stiffness of the torque plate (out-of-plane deflection of the torque plate) and by the suspension lateral stiffness.
1999-09-13
Technical Paper
1999-01-2812
Rajesh Somnay, Shan Shih
The effectiveness of computer simulation modeling for product development support is evidenced by its wide-spread usage. For example, finite element analysis (FEA), has been found indispensable for reducing product development cycle time and cost as well as enhancing product quality. Along with other pertinent information, accurately defined loads are necessary for conducting effective FEA for product design optimizations. FEA results using rough estimated loads often do not provide a good basis for design improvement. A better approach is to define loads through system simulation modeling. The development of such a model involves the synthesis of a wide range of product design knowledge along with a systematic process for model correlation. As the technology becomes matured, there is a strong drive to make the process more efficient by integrating the different types of simulation techniques. Two examples are given in this paper.
1999-09-13
Technical Paper
1999-01-2813
Shan Shih, Yenkai Wang, Patrick Cadaret
Contact stress analysis or surface fatigue life prediction is a subject frequently encountered in powertrain component designs. Examples are the design of gears, bearings, cams, and load ramps. In many cases, design evaluations rely on simple analysis, component supplier's suggestions, and prototype testing. One viable technology trend in modern engineering, however, is to use computer simulation and analysis as a design guide. It is universally acknowledged that up-front computer-aided-engineering (CAE) will reduce the product development cycle time and cost, and improve product quality. In addition, this approach provides a good platform for technology growth. Scattered examples on surface durability analytical modeling techniques are available in the literature. But, the most suitable engineering tools for routine product design support are yet to be developed. Currently, a semi-empirical approach is widely used in the industry.
1999-11-15
Technical Paper
1999-01-3745
Shan Shih, Scott Kuan, Jerry Tou, Fred Huscher
Although the methodology of straight bevel gear tooth form generation has been known for quite some time, few references are available in the literature. Presented in this paper are the general numerical procedures of spherical involute and octoid tooth form generations. We have proven that a tooth form generated from the latter approach, by simulating the rotation of a crown gear, matches exactly with the one from the former approach of unwraping a wire from a base circle. The advantage of using general numerical procedures rather than closed form equations is the flexibility of generating both standard and modified gear tooth profiles. In making the forging die, the gear tooth form must be developed with considerations of both the theoretical optimal geometry, and the dimensional compensation for heat treatment distortion.
2000-09-11
Technical Paper
2000-01-2641
Shan Shih
Automotive transmission design quality is generally judged by the vehicle's performance. Its acceleration, gradeability, maximum speed, terminal speeds, fuel economy and emissions provide these measures. These performance characteristics are optimized through the design process. This process, however, is iterative in nature and requires informed decision making to produce a design that is cost effective and excels in quality. In modern engineering, computer simulation plays an important role in the product design and development process. This paper provides a case study of the design and analysis of a heavy truck automatic transmission. It demonstrates the use of computer simulation models in generating and evaluating innovative design ideas.
2001-03-05
Technical Paper
2001-01-0335
Dale A. Frank, Shan Shih
Although computer models for vehicle and sub-system performance simulations have been developed and used extensively in the past several decades, there is currently a need to enhance the overall availability of these types of tools. Increasing demands on vehicle performance targets have intensified the need to obtain rapid feedback on the effects of vehicle modifications throughout the entire development cycle. At the same time, evolution of the PC and development of Web-based applications have contributed to the availability, accessibility, and user-friendliness of sophisticated computer analysis. Web engineering is an ideal approach in supporting globalization and is a cost-effective design-analysis integration business strategy. There is little doubt that this new approach will have positive impacts on product cost, quality, and development cycle time. This paper will show how Microsoft Excel and the Web can be powerful and effective tools in the development process.
2000-12-04
Technical Paper
2000-01-3467
Scott Kuan, Dean House, Tomaz Varela, Shan Shih
In recent years, several transit agencies have tested buses equipped with hybrid powertrain systems. It has been reported that hybrid powertrains have significant advantages over conventional diesel engine systems, in the area of emissions and fuel economy performance. Presented in this paper are engineering issues and suggestions from an auto component supplier point of view in the design of such a powertrain system. The particular system being considered consists of a downsized diesel engine, a generator, a battery package, two identical AC induction motors, and gearbox systems for the left and right driven wheels. The assembly is supported by an H-shaped suspension sub-structure uniquely designed to achieve the “ultra-low floor” configuration. Our discussion covers the system performance, as well as the durability issues. In particular, the presentation focuses on the durability and the design layout of the gearbox and suspension substructure.
2000-12-04
Technical Paper
2000-01-3417
Shan Shih, Rajesh Somnay, Robert Hannon, Joseph Kay
Effective linear and nonlinear drum brake system FEA (finite element analysis) models have been developed. Such models can help engineers understand many drum brake related issues, such as lining wear and mechanical and thermal instability. The pressure distribution at the drum and lining interface is an important piece of information in drum brake design. Besides the accurate prediction of the shoe factor, the models can be used to guide designs for improving brake efficiency, reducing component weight and enhancing durability. Progress is also being made in developing hybrid models that integrate FEA models with other analysis techniques. This approach offers engineers easy-to-use design tools. The integrated design and analysis approach will help product design and development by reducing cycle time, cost and improving product quality.
2002-11-18
Technical Paper
2002-01-3124
Shan Shih, Scott Kuan, Rajesh Somnay
Only products with high quality, low cost, and short concept-to-customer time will continue to have a high market share. For this reason, auto parts suppliers must strive to gain superior engineering capability. One key step in this pursuit is to implement widespread CAE (Computer-Aided-Engineering) in PDP (product development process) [1]. FEA (Finite Element Analysis), in particular, has been identified as a subject that deserves concentrated effort. Specifically, FEA needs to be used broadly and effectively in every phase of PDP ranging from concept evaluation and prototyping, to pre-production design and troubleshooting. However, resource requirement and process quality assurance are major issues in this undertaking [2, 3]. As a counter-measurement, developing product specific FEA guidelines has been identified as a priority strategic initiative. The focus of our presentation is on how to develop standard FEA procedures to guide FEA jobs.
2002-11-18
Technical Paper
2002-01-3139
Rajesh Somnay, Shan Shih
A method for predicting the propensity of a drum brake system to produce noise is presented. The method utilizes finite element models of the individual components of the drum brake system, which have been assembled into the system model of the brake assembly. An important step in this process is the tuning of the dynamic characteristics of the FEA model to ensure validation with experimental tests. Friction is the key element, which defines the behavior of the drum brake system. The system FEA model is assembled by coupling the lining and drum at the contact interface to simulate the friction interaction. This process produces an asymmetric stiffness matrix. A complex eigenvalue analysis identifies the system dynamic characteristics such as the frequency and damping for each vibration mode. The damping values reveal which modes are unstable and therefore likely to produce noise.
2002-03-04
Technical Paper
2002-01-1046
Shan Shih, Ward Bowerman
Since 1983 the Torsen® differential has been employed in the powertrain of more than two-dozen sedans, SUVs, and military vehicles. This differential device is renowned for its unique high torque bias capacity. Torque bias has long been recognized as a desirable drivetrain characteristic that enhances both a vehicle's drivability and stability. Since the generation of torque bias relies on friction, the know-how in achieving balanced design of torque bias and efficiency is crucial. Presented in this paper is an analytical evaluation of the performance of Torsen differential with respect to these parameters. The mathematical model provides effective guidance in design optimization. The performance predictions were found to correlate well with experimentally measured data. In an effort to explore the theory behind the Torsen differential design, the general subject of speed differentiation and torque bias generation is reviewed.
2001-11-12
Technical Paper
2001-01-2732
Ragnar Ledesma, Shan Shih
The effect of kingpin inclination angle and wheel offset on various vehicle performance metrics such as steering effort, vehicle handling, and steering system vibration is described in this paper. A simple ADAMS model of a medium-duty truck has been developed for this study. The front axle consists of an idealized solid axle suspension with suspension system components represented by rigid bodies. The tire model used in this study is a linear tire model, and estimates of tire force coefficients were obtained as an average of several published estimates of medium-duty truck tires. Experimental design procedures (DOE) have been conducted to determine the effects of kingpin inclination angle and wheel offset on various steering system performance measures. For each performance metric, a 2-variable (KPIA and wheel offset), 5-level DOE was performed using the full factorial matrix for a total of 25 tests for each performance metric.
2001-11-12
Technical Paper
2001-01-2728
Rajesh Somnay, Shan Shih, Paul Johnston
This paper presents a methodology for predicting drum brake performance using FEA (finite element analysis) models considering both the mechanical-structural compliance and thermal effects. The methodology for brake torque prediction with FEA models considering the structural flexibility of the brake components alone has been established [1]. The frictional heat generated during braking causes thermoelastic distortion that modifies the contact pressure distribution at the drum-lining interface. In order to capture this thermal effect, a transient thermal analysis is conducted to predict the transient temperature distribution on the brake components. In the thermal analysis, the heat generated at the drum and lining interface is based on the pressure distribution from the compliant mechanical model. Also, the mechanical properties of the brake components as well as the lining friction are dependent on the temperature distribution.
2001-11-12
Technical Paper
2001-01-2809
Shan Shih, Jacinto Yruma, Phil Kittredge
Conducting effective drivetrain NVH (Noise, Vibration and Harshness) troubleshooting is difficult because its execution requires commanding knowledge and experience on complicated vehicle system interactions. This is especially true for commercial vehicles due to the wide variety of available powertrain and chassis configurations and broad spectrum of vehicle applications. Furthermore, access to revenue producing commercial vehicles is often limited. Problem solving must be carried out within a tight schedule. Under these circumstances, a practical drivetrain NVH troubleshooting guide will come in handy. The objective of this paper is to document the “know-how” we have learned. Subjects covered in the discussions are underlying physics, problem diagnosis, solutions, and problem avoidance.
1992-11-01
Technical Paper
922481
Christopher S. Keeney, Shan Shih
Powertrain torsional vibration has become a subject of increasing concern for the heavy duty truck industry in recent years. This is due in part to truck and diesel engine developments, and to drivetrain system trends. A computer simulation is an effective tool in analyzing this problem. A powertrain vibration analysis program has been developed by the authors. It has been used extensively in the evaluation and optimization of powertrain system performance. In this paper, first the heavy duty powertrain is characterized as a vibrating system. Its natural frequencies, mode shapes and frequency response characteristics are reviewed. Second, the theory of torsional vibration and its application in the simulation are described. The drivetrain is described as a discreet model. An undamped modal analysis is given as an eigenvalue problem.
Viewing 1 to 22 of 22

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