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SAE International Journal of Passenger Cars Mechanical Systems
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Mode Coupling Instabilities Induced by a Periodic Coefficient of Friction

SAE International Journal of Passenger Cars - Mechanical Systems

Institute of Dynamics and Vibration-Matthias Graf
Technical Univ. of Braunschweig-Georg P. Ostermeyer
  • Journal Article
  • 2010-01-1687
Published 2010-10-10 by SAE International in United States
To predict and minimize squeal propensity in brake systems, numerous models, which perform friction induced vibration, are available. However, today there is no model that can explain satisfactorily the dynamic behavior of brake systems. We argue that this is - among other effects - because existing models are based on decaying or constant coefficient of friction, although many investigations indicate rich dynamics of the coefficient of friction. Stability analysis of linear differential equations with periodic coefficients shows that instability regions change with rising amplitude of the periodic coefficients. If the periodic coefficient corresponds to the coefficient of friction, its periodicity can lower the stability of a minimal model.
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Development of a Control Method to Reduce Acceleration Shock in Motorcycles

SAE International Journal of Passenger Cars - Mechanical Systems

Kawasaki Heavy Industries, Ltd.-Hirohide Matsushima
  • Journal Article
  • 2010-32-0106
Published 2010-09-28 by SAE International in United States
The purpose of this paper is to propose a control method to reduce acceleration shock in motorcycles. Reducing the acceleration shock is very important in improving driveability of motorcycles. Motorcycles equipped with manual transmission have some backlashes in the transmission, with large backlash especially in dog clutch portions. We have figured out that one of the main causes of the acceleration shock is the collision of the dogs at high relative angular velocity during acceleration. Also, our data analysis has revealed that there is a correlation between a peak value of the longitudinal body acceleration and the relative angular velocity at the moment of the dog collision. A simulation was undertaken to verify this phenomenon, and its results have made it clear that we need to decrease the relative angular velocity at the moment of the dog collision so as to reduce the acceleration shock. Therefore, we have developed a control method that estimates a relative angle of the dogs and implements ignition timing retard control just before the dog collision to decrease relative angular…
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A Procedure for Efficient Trimmed Body FE Simulations, Based on a Transfer Admittance Model of the Sound Package

SAE International Journal of Passenger Cars - Mechanical Systems

Dr. Ing. h.c. F. Porsche AG-Juergen Ochs
Rieter Automotive Management AG-Theophane Courtois, Claudio Bertolini
  • Journal Article
  • 2010-01-1405
Published 2010-06-09 by SAE International in United States
Porous materials are extensively used in the construction of automotive NVH parts. The sound package design during vehicle development requires simulation methods at vehicle level that can take into consideration the dynamical behavior of porous materials. This need has led to different numerical technologies based on Biot's equations. In particular, direct FE implementations of Biot's equations have been included into some commercial FE software programs. Such implementations, while giving good results, are time consuming and difficult to apply within the time constraints given by the timeline of vehicle development programs.This paper presents an alternative methodology, thanks to which it is possible to build the coupled vibro-acoustic model of a trimmed vehicle without modeling physically the trim components. The trim is represented by means of transfer admittance matrices whose evaluation is based on an analytical space-domain procedure relying on a modified version of the classical transfer matrix method. A tool was developed to calculate these transfer matrices, starting from the construction and materials of the trim part. These matrices are stored and suitably included into the…
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Effect of Regenerative Braking on Foundation Brake Performance

SAE International Journal of Passenger Cars - Mechanical Systems

General Motors-David B. Antanaitis
  • Journal Article
  • 2010-01-1681
Published 2010-10-10 by SAE International in United States
Regenerative braking is one of the key enablers of improved energy efficiency and extension of driving range in parallel and series hybrid, and electric-only vehicles. It is still used in conjunction with friction brakes, due to the enormous amount of energy dissipated in maximum effort stops (and the lack of a competitive alternate technology to accommodate this power level), and to provide braking when on-board energy storage/dissipation devices cannot store enough energy to support braking. Although vehicles equipped with regenerative braking are becoming more and more commonly available, there is little published research on what the dramatic reduction in friction brake usage means to the function of the friction brakes themselves. This paper discusses -with supporting data from analysis and physical tests - some of the considerations for friction brakes related to usage on vehicles with regenerative braking, including corrosion, off-brake wear, and friction levels. It also proposes how a brake system configuration for a regenerative braking-equipped vehicle may be balanced differently than a system for a vehicle with conventional braking.
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