Experimental set-up and the associated model for squeal analysis

Brake squeal is commonly defined at frequency upper than 1000 Hz and occurs if the system has a very high amplitude mechanical vibration with sound pressure level above 120 dB. Many studies are devoted to this problem and many of recent ones show that contact conditions and friction material behavior have a major influence on squeal occurrence. To investigate this aspect, an experimental set-up has been developed in this study. It is based on a simplified system in order to focus on the influence of the material in the one hand and surface conditions in the other hand. In this paper, the design of the pin-on-disc is described and an analytical model is also presented in order to understand the dynamic behavior of the system. Macroscopic aspects are investigated by varying the pin geometry. The results show clearly the influence of the variation of the contact length size on squeal occurrence. Comparison with the model shows good agreement and exhibit the necessity of considering an improved model of the friction material behavior. This study also gives information on the comprehension of squeal mechanisms.