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Journal Article

Reducing Power Demand for Heavy Suspension Tests

2008-04-14
2008-01-0690
Competitive pressures, globalization of markets, and integration of new materials and technologies into heavy vehicle suspension systems have increased demand for durability validation of new designs. Traditional Proving Ground and on-road testing for suspension development have the limitations of extremely long test times, poor repeatability and the corresponding difficultly in getting good engineering level data on failures. This test approach requires a complete vehicle driven continuously over severe Proving Ground events for extended periods. Such tests are not only time consuming but also costly in terms of equipment, maintenance, personnel, and fuel. Ideally multiple samples must be tested to accumulate equivalent millions of kilometers of operation in highly damaging environments.
Technical Paper

Virtual Manufacturing of Automotive Body Side Outers Using Advanced Line Die Forming Simulation

2007-04-16
2007-01-1688
As a virtual manufacturing press line, line die forming simulation provides a full range math-based engineering tool for stamping die developments of automotive structure and closure panels. Much beyond draw-die-only formability analysis that has been widely used in stamping simulation community during the last decade, the line die formability analysis allows incorporating more manufacturing requirements and resolving more potential failures before die construction and press tryout. Representing the most difficult level in formability analysis, conducting line die formability analysis of automotive body side outers exemplifies the greatest technological challenge to stamping CAE community. This paper discusses some critical issues in line die analysis of the body side outers, describes technical challenges in applications, and finally demonstrates the impact of line die forming simulation on the die development.
Technical Paper

From Algorithms to Software - A Practical Approach to Model-Driven Design

2007-04-16
2007-01-1622
The value of model-based design has been attempted to be communicated for more than a decade. As methods and tools have appeared and disappeared from a series of different vendors it has become apparent that no single vendor has a solution that meets all users’ needs. Recently standards (UML, MDA, MOF, EMF, etc.) have become a dominant force and an alternative to vendor-specific languages and processes. Where these standards have succeeded and vendors have failed is in the realization that they do not provide the answer, but instead provide the foundation to develop the answer. It is in the utilization of these standards and their capability to be customized that companies have achieved success. Customization has occurred to fit organizations, processes, and architectures that leverage the value of model-driven design.
Technical Paper

A Method for Overcoming Limitations of Tire Models for Vehicle Level Virtual Testing

2006-04-03
2006-01-0499
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.
Technical Paper

Tuning Guide for Deflected-Disc Suspension Dampers

2006-04-03
2006-01-1380
This paper presents an empirical-based model which explains the force-deflection characteristics of disc stacks commonly used in automotive suspension dampers. The model provides tools for comparing different disc stacks to understand their effect on damper performance. Load-deflection data is presented on a variety of discs and combinations of discs. The data is analyzed to show how the diameter, thickness and relative position of discs in a stack can affect the stack stiffness throughout the range of disc deflections. A model is developed to show how changes in the disc stack will affect damper performance at different velocities. An example is provided that shows predicted changes in disc stack force-deflection characteristics and the resulting changes in a damper force-velocity curve. Ride results are also presented that confirm the validity of the model.
Technical Paper

Custom Real-Time Interface Blockset Development in Matlab/Simulink for On-Target Rapid Prototyping

2006-04-03
2006-01-0169
In GM R&D Powertrain/Engine Control Group, rapid prototyping controller (RPC) systems with Matlab/Simulink are used extensively to design, simulate and implement advanced engine control algorithms and models. However, those RPC systems use powerful microprocessors with large amounts of RAM contrary to engine control modules (ECM) in production vehicles. Therefore, a thorough analysis on the comparatively much more complicated algorithms and models cannot be performed during the research stage, since there are not enough tools to enable the smooth transition from Matlab/Simulink to the production type processor. The Real-Time Interface (RTI) Blockset for a production like microprocessor would close the transition gap between rapid prototyping controller systems and production type microprocessors by leveraging the power and popularity of Matlab/Simulink in control engineering world and automatic code generation tools.
Technical Paper

Music Analogy: An Alternative Strategy for Sound Quality Requirements

2005-05-16
2005-01-2477
In recent years a predominant strategy for setting sound quality (SQ) requirements has been the sensory correlation approach (also called sensory evaluation or sensory science). Some users of this approach have reported their progress in numerous papers. Other SQ practitioners have made presentations on specific topics that show the linkage to music and musical notation. These specific links point to an alternative general strategy - “the Music Analogy for Sound Quality.” This paper begins by comparing the general methods of the music analogy and sensory correlation. Some major differences will be identified and implications discussed. Some existing specific tools for the music analogy will be identified as well as some gaps that need to be filled. Finally, reasons will be presented concerning why the music analogy should be considered when developing sound quality requirements.
Technical Paper

Model-Driven Product Line Software Development Process

2005-04-11
2005-01-1288
The past 10 years have created such buzzwords as “model-based development” and “auto-code generation”. Conveniently absent from the tool literature on model-based development are the equally, or more important concepts of Software Architecture and Process. When developing product line software, the process and architecture form a critical foundation to base reusable products and components. The development process can no longer be viewed as “model-based”, but rather as “model-driven”, due to the reliance on the models as the source artifact as opposed to the creators of the source artifacts. A model-driven product line software development process allows capturing of behavior, for commonality across different products, and having a different implementation for a specific product release.
Technical Paper

A Subsystem Crash Test Methodology for Retention of Convenience Organizer Equipment System in Rear Impact

2005-04-11
2005-01-0735
Any equipment system or vehicle component like the Convenience Organizer storage system needs to be retained within the cargo compartment without intruding into the passenger compartment for occupant safety during a high speed impact. This paper outlines a test method to evaluate the retention of such a system in a rear impact environment. The method utilizes a low speed barrier to simulate a high speed RMB (Rear Moving Barrier) impact. The content of the low speed RMB impact test setup was developed utilizing DYNA3D analytical simulation results from a full vehicle model subjected to high-speed RMB impact. The retention of the equipment developed through this test method was confirmed on a full scale rear impact test.
Technical Paper

Supplementation of Measured Vehicle Road Loads to Study Vehicle Configuration Changes

2005-04-11
2005-01-1403
Measured vehicle loads, taken during durability events, are commonly used to drive in-lab vehicle subsystem validation testing. The use of measured loads can be problematic due to (a) off-nominal characteristics of the test vehicle, (b) post-test changes to vehicle tuning - bushings, springs, and shocks for example, (c) scheduling, timing and weather requirements, (d) modification of vehicle characteristics by the inclusion of transducers and (e) the cost of executing tests. A general process for supplementing and rationalizing measured vehicle data through the use of correlated multi-body dynamic simulations is presented. Difficulties in modeling tires and other components, as well as difficulties in model correlation for abusive load events are also discussed.
Technical Paper

A Multi-hop Mobile Networking Test-bed for Telematics

2005-04-11
2005-01-1484
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.
Technical Paper

Predicting Tire Handling Performance Using Neural Network Models

2004-03-08
2004-01-1574
Recent studies have shown that complex vehicle components such as shock absorbers, rubber bushings, and engine mounts can be accurately modeled by combining laboratory measurements with neural network technology. These nonlinear dynamic blackbox models (also known as Empirical Dynamics1 models) make it possible to predict nonlinear and hysteretic component behavior over wide ranges of amplitude and frequency. The models can handle realistic input waveforms as well as multiple inputs and multiple outputs. These techniques have now been applied to rolling pneumatic tires, to enable high accuracy predictions of tire and vehicle handling behavior. Models that predict high amplitude force components (three forces and three moments) using up to four randomly-varying inputs (radial deflection, slip angle, and camber angle, and slip ratio) have been successfully generated, using data obtained from MTS Flat-Trac III tire test equipment.
Technical Paper

e-Thermal: A Vehicle-Level HVAC/PTC Simulation Tool

2004-03-08
2004-01-1510
This paper describes a vehicle-level simulation model for climate control and powertrain cooling developed and currently utilized at GM. The tool was developed in response to GM's need to speed vehicle development for HVAC and powertrain cooling to meet world-class program execution timing (18 to 24 month vehicle development cycles). At the same time the simulation tool had to complement GM's strategy to move additional engineering responsibility to its HVAC suppliers. This simulation tool called “e-Thermal” was quickly developed and currently is in widespread (global) use across GM. This paper describes GM's objectives and requirements for developing e-Thermal. The structure of the tool and the capabilities of the simulation tool modules (refrigeration, front end airflow, passenger compartment, engine, transmission, Interior air handling …) is introduced. Model data requirements and GM's strategy for acquiring component data are also described.
Technical Paper

Integration of Physical and Virtual Tools for Virtual Prototype Validation and Model Improvement

2003-10-27
2003-01-2813
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.
Technical Paper

A Case Study on Airborne Road Noise Reduction of a Passenger Vehicle

2003-05-05
2003-01-1407
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.
Technical Paper

Brake Groan Simulation for a McPherson Strut Type Suspension

2003-05-05
2003-01-1627
Brake groan noise and vibration occurs in a stopped vehicle by the simultaneous application of torque to the wheel and the gradual release of brake pressure. Eventually the torque load breaks the friction between pad and rotor causing slippage and energy release. If the torque load is not large enough to maintain slippage, a sustained stick-slip vibration, called groan, can occur which transmits a low frequency noise to the vehicle interior. In some cases the noise levels caused by groan can be objectionable, thus procedures for developing remedial designs are needed. To this end, a project was performed to analytically simulate groan vibration in a vehicle with a McPherson strut type suspension. The goal was to demonstrate that analytical models could be used to simulate groan behavior and to identify suspension components that affect the groan behavior. The ADAMS software was used to model a brake/suspension system.
Technical Paper

Tools for Integration of Analysis and Testing

2003-05-05
2003-01-1606
The automotive vehicle design process has relied for many years on both analytical studies and physical testing. Testing remains to be required due to the inherent complexities of structures and systems and the simplifications made in analytical studies. Simulation test methods, i.e. tests that load components with forces derived from actual operating conditions, have become the accepted standard. Advanced simulation tools like iterative deconvolution methods have been developed to address this need. Analytical techniques, such as multi body simulation have advanced to the degree that it is practical to investigate the dynamic behavior of components and even full vehicles under the influence of operational loads. However, the approach of testing and analysis are quite unique and no seamless bridge between the two exists. This paper demonstrates an integrated approach to combine testing and analysis together in the form of virtual testing.
Technical Paper

A Practical Implementation of ASAM-GDI on an Automated Model Based Calibration System

2003-03-03
2003-01-1030
The paper addresses the connectivity issues related to integrating an Automated Model Based Calibration System (MTS Atlas) to a dynamometer test bed data acquisition system using an ASAM-GDI Interface. The GDI (Generic Device Interface) implementation was chosen over other ASAM interfaces due to its real-time capabilities and the ability to host new GDI drivers as these drivers become available. A structured migration process is developed showing how a new interface standard can be implemented that integrates with legacy test equipment, yet provides a simple low cost mechanism allowing replacement of old or redundant equipment.
Technical Paper

Brake and Cruise System Integration using Robust Engineering

2003-03-03
2003-01-1095
This paper presents a project that was done to solve an integration problem between a brake system and a cruise control system on a GM vehicle program, each of which was supplied by a different supplier. This paper presents how the problem was resolved using a CAE tool which was a combination of formulated MS/Excel spreadsheet, Overdrive (GM internal code), and iSIGHT of Engineous Software Inc, which is a process integrator and process automator. A sensitivity study of system reliability was conducted using iSIGHT. The most sensitive factor was found through the sensitivity study. Thereafter, a Robust design was obtained. The recommended Robust Design was implemented in the vehicle program, which led to a substantial cost saving. The CAE software tool (the combination) developed through the problem solving process will be used to ensure quality of brake and cruise system performance for future vehicle programs.
Technical Paper

Accurate Shock Absorber Load Modeling in an All Terrain Vehicle using Black Box Neural Network Techniques

2002-03-04
2002-01-0581
This paper presents the results of a study of using a neural network black box model of a shock absorber of an ATV (All Terrain Vehicle, four wheel drive, off road, single person vehicle) for accurate load modeling. This study is part of a larger investigation into the dynamic behavior and associated fatigue of an ATV vehicle, which is conducted under the auspices of the Fatigue Design and Evaluation Committee of SAE of North America (www.fatigue.org). The general objectives are to develop new correlated methodologies that will allow engineers to predict the durability of components of proposed vehicles by means of a “digital prototype” simulation. Current state of the art multi body dynamics predictions use linear frequency response functions or non-linear polynomial approximations to describe the behavior of non-linear suspension components such as shock absorbers or bushings.
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