Brake Squeal - Modeling and Experimental Investigation Using a Work Criterion

Abstract

Squealing automotive brakes are usually not accepted by customers. However, squealing is an omnipresent phenomenon in disc brakes at least in certain operation states. During the development process of new brakes, engineers succeed more or less in covering this phenomenon with tools like using shims, modifying the structure or varying the mounted pads. In 2002 Popp et al. [1] described the pre-conditions for positive work of the friction forces (i.e. excitation of squeal) based on a very simple model. The essential point in this model is a phase shift between the inplane movement of the pad and the friction force. In [2] it was shown that it is possible to suppress actively brake squeal using this approach. Active pads with integrated piezoceramics were used as actuators. The authors of the present paper use multi body brake models for the investigation of the origin of the excitation mechanism by observing the work per period of the friction forces and comparing the results with the classic stability analysis. A measurement technique based on these theoretical investigations is developed for detecting parameter regions (e.g. for the brake pressure and corresponding squealing frequencies) which are suspicious for squeal. Considering two models of the brake, phase shifts between signals and measuring the work of the nonconservative forces are considered with respect to the question of detecting the tendency to squeal. Based on these theoretical results measurement procedures are developed and tested at test rigs at TU Berlin and TU Darmstadt. The results of this procedure coincide with results of state of the art experimental investigations but can be performed much faster. This new procedure yields even more significant results than the ones described in [2].

Steps towards Predictive Simulation and Faster Experimental Investigation of Automotive Brake Systems with Respect to Squeal

“…with piezo actors integrated in the pad as described in [14] and [15]) and measure averaged transfer-functions. The result of such an approach is shown in Figure 11 (the normalized work of the friction force per period versus the frequency with respect to the brake pressure).…”

“…Based on previous investigations [14] an experimental method is developed to identify squeal suspicious operating states of brake systems. The key-idea is to measure the work of the friction force with respect to the pad.…”

“…The third part of the paper deals with the rapid experimental identification of squeal states [14,15]. After the introduction of the theoretical background, the experimental set-up the processing of data and the results are presented.…”

nema

“…Експерименталне студије су акумулирале велику количину информација о природи шкрипе, модовима вибрација у њему, хабању кочних компонената, и фрикционој интеракцији у кочницама. Кроз најновија експериментална истраживања се осим верификације нумеричких модела остварује и провера метода елиминације шкрипе кочница[118,119,120]. Аналитичке студије су обезбедили корисне увиде у то како фрикциони закони, геометрија, и динамика кочних компоненти могу довести до шкрипе или нестабилности у једноставним моделима диск кочница.…”