Creep Groan: Fundamental Analysis of Different Pad-Disc Friction Curves


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Presentation Video


The simulation of brake noises and the validation of the simulation models are still one of the most challenging tasks in current brake development. Nonlinearities, like the friction characteristics between the brake disc and the pad material can lead to limit cycle amplitudes in different forms. Amongst others, the limit cycle can be the so-called “stick-slip” and the emerging noise in the car is typically described as creep groan. How the curve of the friction coefficient in the low velocity regime is influencing the creep groan behaviour is analysed in this contribution.

It is crucial to have a correct characterization of the friction curve to assess numerically the correct oscillation behaviour. The next step is to evaluate sensitivities and deviations of the friction characteristics on the limit cycle behaviour by exploiting a validated model, which correlates to vehicle measurements. Here the focus lies on the low velocity regime of the friction coefficient, e.g. different decaying characteristics.

Furthermore, this contribution introduces parameters that allow a more detailed description of the friction behaviour in the low velocity regime. It examines the influence of those parameters by utilizing finite element method and multibody simulation in particular, and compares the obtained results. The advantages and disadvantages of the utilized simulation approaches are also discussed. The aim of the analysis of those parameters is to give more insights into avoiding low frequency brake noise.

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