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SAE International Journal of Passenger Cars Mechanical Systems
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Fast Characterization of Brake Squeal Behavior

SAE International Journal of Passenger Cars - Mechanical Systems

Technische Universität Berlin-Stefan Schlagner, Utz von Wagner
  • Journal Article
  • 2009-01-3006
Published 2009-10-11 by SAE International in United States
The last decades have shown extensive efforts on the investigation of automotive disk brake squeal. The origin of brake squeal is seen in self-excited vibrations, caused by the friction forces transferring energy from the rotating disk into the brake system. Based on a very simple model, Popp et al. described in 2002 the conditions for positive work of the friction forces (i.e. excitation of squeal), which depends on the phase shift between the in-plane motion (with respect to the disk) of the brake pad and the friction forces. Experiments on active manipulation of this phase shift using pads with integrated piezoceramic actuators, performed by von Wagner et al. in 2004, resulted in successful suppression of disk brake squeal.The authors of the present paper used a variety of models for the investigation of the origin of the excitation mechanism by observing phase relations between the friction forces and the vibrations of the pads. Several measurement techniques based on these theoretical investigations are developed in order to detect parameter regions (e.g. brake pressure, temperature, rotation speed) which…
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Systematic Brake Development Process and Optimized Robust Design of Front Axle Kinematics in Order to Reduce Oscillation Sensitivity

SAE International Journal of Passenger Cars - Mechanical Systems

Audi AG-Jan Muenchhoff
Technische Universitaet Muenchen-Albert Schlecht, Bernd Heissing
  • Journal Article
  • 2009-01-3038
Published 2009-10-11 by SAE International in United States
Brake judder is about oscillations excited by brake application, which are generated in the contact area between brake pad and brake disc and are transmitted by the elements of the suspension to body and steering system. The driver perceives these perturbations as brake pedal pulsations, steering wheel rotational and body vibrations. The evaluation of a suspension concerning brake judder often takes place for the first time in road tests, since established simulation processes with a high significance concerning ride comfort are missing. At such a late moment necessary modifications in the development process are only hardly possible and very expensive. For avoiding brake judder a systematic development process is needed for brake and suspension. Each one can separately be improved in measurably borders so that their assembly is free of cold brake judder. The present paper shows appropriate test and simulation methods to achieve this.
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The Influence of Vibration on Friction

SAE International Journal of Passenger Cars - Mechanical Systems

University of South Florida-Daniel P. Hess
  • Journal Article
  • 2009-01-3015
Published 2009-10-11 by SAE International in United States
This paper summarizes results from the author's work on friction in dry sliding contacts in the presence of vibration. A number of idealized models of smooth and rough contacts are examined. It is shown that vibration can cause up to a 10% reduction in average friction even with continuous contact. A larger reduction in friction occurs when there is intermittent contact loss. This is found to be true for both elastic and plastic contacts, and for adhesive and plowing mechanisms of friction. The results of this work are compared and validated with measurements from experiments. The results presented are fundamental, but applicable to machine components with contacts including brake systems.
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Main Design Factors and Unified Software Structure for Cable Puller and Caliper Integrated Type Electric Parking Brakes

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai MOBIS-J. S. Cheon, J. W. Jeon, H. M. Jung, I. U. Park, C. H. Park, T.-J. Yeo
  • Journal Article
  • 2009-01-3022
Published 2009-10-11 by SAE International in United States
The main classification of Electric Parking Brakes (EPB) can be made into cable puller and caliper integrated types. In this paper, the main design considerations that need to be made for each type of system will be examined. In terms of mechanical design, actuator design factors including target capacity, system size, and vehicle mounting will be briefly discussed. In terms of software, a unified software structure that can incorporate both types of EPBs will be introduced. This unified approach, made up of fixed and variable modules, allows for more efficient software development for both types of EPB systems. The fixed modules are related to the identical target functions regardless of EPB type, while the variable modules are made up of the different considerations that need to be made depending on the EPB type in order to meet such targets. Finally, some test results of target functions for both types of EPB systems will be given.
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Stability Analysis of a Disc Brake with Piezoelectric Self-Sensing Technique

SAE International Journal of Passenger Cars - Mechanical Systems

Institut für Dynamik und Schwingungen-Marcus Neubauer, Andreas Renner, Jens Twiefel
  • Journal Article
  • 2009-01-3034
Published 2009-10-11 by SAE International in United States
Piezoelectric self-sensing allows to measure frequency response functions of dynamical systems with one single piezoelectric element. This piezoceramics is used as actuator and sensor simultaneously. In this study, a model-based piezoelectric self-sensing technique is presented to obtain potential squealing frequencies of an automotive disc brake.The frequency-response function of the brake system is obtained during operation by measuring the current flowing through the piezoelectric element while the piezoelectric element is driven by a harmonic voltage signal with constant amplitude. The current flow is composed of the part which is required to drive the piezoelectric element as an actuator and a second part which is the sensor signal that is proportional to the vibration amplitude of the attached mechanical system. Typically the first part is dominant and the influence of the mechanical system is marginal.With an idealized mathematical model of the piezoelectric element, the admittance can be calculated and the actuator current eliminated from the measured signal. This software-based solution does not require any additional electrical circuits or precise tuning during the measurements.Potential squealing frequencies which agree…
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Current and New Approaches for Brake Noise Evaluation and Rating

SAE International Journal of Passenger Cars - Mechanical Systems

Harald Abendroth, Michael Haverkamp, Wolfgang Hoffrichter, Boris Wernitz
HEAD acoustics GmbH-Peter Blaschke, Günter Mauer
  • Journal Article
  • 2009-01-3037
Published 2009-10-11 by SAE International in United States
Predominant brake noise evaluation and rating was developed many years ago and no longer fulfills the need of modern development work.An extended description of a noisy brake event (European expert group guideline EKB 3006) and a standardized test data exchange format, allowing the comparison of different source test results (EKB 3008) are presented.Today's noise rating systems are described and compared by selected examples.The paper proposes an open 4 level noise rating system (EKB 3007). It starts with simple occurrence statistics, noise rating based on sound levels, situational noise rating including duration and finally based on the human perception, described by psychoacoustics.
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