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SAE International Journal of Passenger Cars Mechanical Systems
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Influence of Rubber Temperature on Transfer Functions of Bushings

SAE International Journal of Passenger Cars - Mechanical Systems

AUDI AG-Peter Knauer
Technische Universitaet Dresden-Peter Koch, Christian Angrick, Denise Beitelschmidt, Günther Prokop
  • Journal Article
  • 2015-01-9115
Published 2015-12-01 by SAE International in United States
In ride comfort as well as driving dynamics, the behavior of the vehicle is affected by several subsystems and their properties. When analyzing the suspension, especially the characteristics of the main spring and damper but also rubber bushings are of main importance. Still, the properties of the different components are dependent on the present operating conditions. Concerning rubber bushings, several effects have already been investigated, e.g. dependencies of the transfer function of frequency, amplitude or load history. In this context influences of changes in temperature are often neglected. However, in the following research, the focus specifically lies on determination and analysis of the temperature dependency of rubber bushings. For this purpose, initially the relationship between properties of pure rubber and rubber bushings is described, which serves as a basis for correlating respective temperature dependencies. Furthermore, bushings of the suspension and power train have been measured using a novel testing method for vehicle bushings incorporating a hydraulic test rig in combination with a heating chamber. Based on the conducted measurements, static as well as dynamic properties…
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Optimization of Lateral Vehicle Dynamics by Targeted Dimensioning of the Rim Width

SAE International Journal of Passenger Cars - Mechanical Systems

Audi AG-Andreas Wagner
Technische Universitat Dresden-Hendrik Abel, Sebastiaan van Putten, Günther Prokop
  • Journal Article
  • 2015-01-9114
Published 2015-12-01 by SAE International in United States
The aim of this investigation is the improvement of the lateral vehicle dynamics by optimizing the rim width. For that purpose, the rim width is considered as a development tool and configured with regard to specified targets. Using a specifically developed method of simulation, the influence of the rim width is analysed within different levels - starting at the component level “tyre” and going up to the level of the whole vehicle. With the help of substantial simulations using a nonlinear two-track model, the dimensioning of the rim width is brought to an optimum. Based on both, tyre and vehicle measurements, the theoretical studies can be proved in practice. As a result, the rim width has a strong influence on the behaviour of the tyre as well as on the overall vehicle performance, which emphasises its importance as a potential development tool within the development of a chassis.
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An Application of Shape Optimization to Brake Squeal Phenomena

SAE International Journal of Passenger Cars - Mechanical Systems

Gifu University-Kohei Furuya
Toyota Motor Corp.-Kohei Shintani, Satoshi Ito
  • Journal Article
  • 2015-01-2658
Published 2015-09-27 by SAE International in United States
The present paper describes an application of non-parametric shape optimization to disc brake squeal phenomena. A main problem is defined as complex eigenvalue problem in which the real part of the complex eigenvalue causing the brake squeal is chosen as an objective cost function. The Fre´chet derivative of the objective cost function with respect to the domain variation, named as the shape derivative of the objective cost function, is evaluated using the solution of the main problem and the adjoint problem. A selection criterion of the adoptive mode number in component mode synthesis (CMS), which is used in the main problem, is presented in order to reduce the computational error in complex eigenvalue pairs. A scheme to solve the shape optimization problem is presented using an iterative algorithm based on the H1 gradient method for reshaping. For an application of the optimization method, a numerical example of a practical disc brake model is presented. The numerical result illustrates that the real part of the target complex eigenvalue monotonously decreases until it reach zero.
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A Study on Trigger of Disc Brake Squeal Generation

SAE International Journal of Passenger Cars - Mechanical Systems

Teikyo University-Masaaki Nishiwaki
Toyota Motor Corp.-Ryutaro Misumi
  • Journal Article
  • 2015-01-2682
Published 2015-09-27 by SAE International in United States
It is well known that disc brake squeal is often caused by high friction coefficient pad materials. Disc brake squeal is caused by dynamic unstable system under small disturbance of friction force variation. Today, disc brake squeal comes to be simulated by FEA, but it is very difficult to put so many dynamic unstable solutions into stable solutions. Therefore it is very important to make it clear the influence of friction force variation.This paper describes a study on trigger of disc brake squeal generation. First, the development of experimental set-up for disc brake squeal basic research and experimental results are described. Second, the equation of motion in disc brake squeal is derived and the vibration induced by small disturbance are analyzed. Furthermore, kinetic energy increase per 1 cycle in minute vibration are calculated, which represents the influence of friction and wear between disc and pad with caliper. Based on this analysis, trigger of disc brake squeal generation is considered.
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Brake Squeal Simulation by Energy Flow Analysis

SAE International Journal of Passenger Cars - Mechanical Systems

Akebono Engineering Center-Keqin Xu, Li Lee, Gang Lou
  • Journal Article
  • 2015-01-2657
Published 2015-09-27 by SAE International in United States
This paper presents a new FEA approach for brake squeal simulation, the energy flow analysis. It demonstrates that under certain conditions, two system normal modes with equal or close frequencies may start injecting vibration energy into each other, from dynamic friction mechanism. The vibrations, therefore, can “self-grow” (limited cycle), resulting in system instability, such as brake squeal and brake moan. The theoretical conditions for such positive energy flows to occur are discussed. Test examples and application case studies are presented, along with comparison with, and linkage to, complex eigenvalue analysis.
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An Improvement of Brake Squeal CAE Model Considering Dynamic Contact Pressure Distribution

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai Motor Company-Ju Young Kim, Jeongkyu Kim, Young Min Kim
MOBIS-Wontae Jeong, Hojoon Cho
  • Journal Article
  • 2015-01-2691
Published 2015-09-27 by SAE International in United States
In the brake system, unevenly distributed disc-pad contact pressure not only leads to a falling-off in braking feeling due to uneven wear of brake pads, but also a main cause of system instability which leads to squeal noise. For this reason there have been several attempts to measure contact pressure distribution. However, only static pressure distribution has been measured in order to estimate the actual pressure distribution.In this study a new test method is designed to quantitatively measure dynamic contact pressure distribution between disc and pad in vehicle testing. The characteristics of dynamic contact pressure distribution are analyzed for various driving conditions and pad shape.Based on those results, CAE model was updated and found to be better in detecting propensity of brake squeal.
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The Development of Terrain Pre-filtering Technique Based on Constraint Mode Tire Model

SAE International Journal of Passenger Cars - Mechanical Systems

Northern Arizona University-Eric neisen
Purdue University-Cannon Cheng
  • Journal Article
  • 2015-01-9113
Published 2015-09-01 by SAE International in United States
The vertical force generated from terrain-tire interaction has long been of interest for vehicle dynamic simulations and chassis development. To improve simulation efficiency while still providing reliable load prediction, a terrain pre-filtering technique using a constraint mode tire model is developed. The wheel is assumed to convey one quarter of the vehicle load constantly. At each location along the tire's path, the wheel center height is adjusted until the spindle load reaches the pre-designated load. The resultant vertical trajectory of the wheel center can be used as an equivalent terrain profile input to a simplified tire model. During iterative simulations, the filtered terrain profile, coupled with a simple point follower tire model is used to predict the spindle force. The same vehicle dynamic simulation system coupled with constraint mode tire model is built to generate reference forces. This terrain pre-filtering technique proves to improve the computational efficiency by three orders of magnitude with no statistically significant change in resultant load prediction.
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A Parallel Hybrid Electric Drivetrain Layout with Torque-Fill Capability

SAE International Journal of Passenger Cars - Mechanical Systems

Oerlikon Graziano SpA-Carlo Cavallino
Univ. of Surrey-Arash Mehdizadeh Gavgani, Timothy Bingham, Aldo Sorniotti, John Doherty
  • Journal Article
  • 2015-01-9108
Published 2015-07-01 by SAE International in United States
This paper discusses the torque-fill capability of a novel hybrid electric drivetrain for a high-performance passenger car, originally equipped with a dual-clutch transmission system, driven by an internal combustion engine. The paper presents the simulation models of the two drivetrains, including examples of experimental validation during upshifts. An important functionality of the electric motor drive within the novel drivetrain is to provide torque-fill during gearshifts when the vehicle is engine-driven. A gearshift performance indicator is introduced in the paper, and the two drivetrain layouts are assessed in terms of gearshift quality performance for a range of maneuvers.
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On Optimum Choice of Forchheimer Equation Coefficients for Computational Fluid Dynamics Simulation of Heat Exchangers

SAE International Journal of Passenger Cars - Mechanical Systems

Cranfield Univ-Klementina Gerova, Anthony Savill
  • Journal Article
  • 2015-01-9110
Published 2015-07-01 by SAE International in United States
The simulation of heat exchanger air flow characteristics using Computational Fluid Dynamics requires knowledge of the experimental pressure drop across the element concerned. This is normally achieved through wind tunnel testing of either full scale heat exchangers or by using laminations of various porous materials and honeycombs to represent these. The current paper both continues and compliments prior work published by the lead author, which entailed a series of measurements of the pressure drop in both the near and far field, across screens with porosity (β) in the range 0.41 < β < 0.76. This experimental investigation established a relationship between the porosity and the pressure drop characteristics of a given material at various angles of inclination to the free-stream flow. In addition, the effect of screen depth was investigated using honeycombs. The present paper investigates the use of a weighted least squares regression model to correct the previously obtained Forchheimer Equation coefficients for residual errors associated with the data being a function of the underlying experimental measurements. Following a review of the available relations…
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Introducing Functional Data Analysis to Coast Down Modeling for Rolling Resistance Estimation

SAE International Journal of Passenger Cars - Mechanical Systems

Roskilde University Center-Lasse G. Andersen, Jesper K. Larsen
  • Journal Article
  • 2015-01-9111
Published 2015-07-01 by SAE International in United States
Coast-down modeling has been widely used to assess vehicle aerodynamic drag and rolling resistance by fitting a vehicle resistance model to speed measurements and thereby get an estimate on model parameters. Here a coast-down model is used for assessing how road surface characteristics influence rolling resistance. Parameter estimation as well as an extensive perturbation analysis of the parameter fit with respect to data noise has been performed. Functional Data Analysis (FDA) is introduced and discussed as a tool for this. It is concluded that FDA is a powerful tool for 1) approximating derivatives, 2) assessing the degree of smoothing of the data 3) handling noise sources in the perturbation analysis and 4) enabled numerical solutions of the coast-down Ordinary Differential Equation (ODE) model. Investigations showed that MPD was the most important parameter compared to IRI although MPD data required smoothing for optimal model fit. Furthermore, it is concluded that the model responds nicely to the statistical tests in the perturbation analysis. However, certain parameters associated with surface related rolling resistance were unstable in the sensitivity…
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