Comfort is one of the most important criteria in current automobile development. Characteristics such as ride comfort, vibration, acoustics and the fine-tuning (between components, systems and the whole vehicle) have become high priority. One of the most important comfort requirements for vehicles is a vibration-free steering wheel during braking events. Those problems are referred to as 'brake judder' or roughness. Brake judder induces oscillations of the steering wheel, and in some cases even the whole front of the vehicle. Those vibrations often cause painful driving which may result in customer complaints. The source of brake judder resides in brake disk thickness variation (DTV). Such variation can be generated for example by corrosion when the vehicle was not used during a longer period or by uneven wear of the brake disk. Even small amounts of DTV may lead to noticeable steering wheel vibration in case of high vehicle sensitivity. During a braking event with a rotor with thickness variation, alternating forces and moments are generated in the suspension. These dynamic forces are superimposed onto the regular static loads the suspension is subjected to because of braking. These alternating forces and torques cause alternating motions. The suspension construction and design parameters determine at which DTV level a comfort problem appears. Along the transfer path from tire footprint to steering wheel oscillation, the vibration can get amplified due to subsystems resonances. It is thus essential to investigate and quantify the dynamics effects of local (subsystems) and global (system) resonances in the vibration path. In this paper the authors describe an investigation undertaken by Continental NVH Engineering to assess vehicle sensitivity to brake torque variation and to identify interaction between the brake-system with the suspension and steering systems. It could be shown that steering wheel vibration caused by judder is a function of DTV as well as of several attributes in the suspension contribute to the transmission/amplification of such vibration.


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    Title :

    Suspension sensitivity investigation: Steering wheel oscillations induced by brake judder


    Additional title:

    Lenkraddrehschwingungen durch Bremsenrubbeln: Untersuchung der Fahrzeugempfindlichkeit


    Contributors:
    Pankau, J. (author) / Boulahbal, D. (author) / Gauterin, F. (author) / Schille, K. (author)


    Publication date :

    2003


    Size :

    16 Seiten, 20 Bilder, 11 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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