Definition of a Suitable Parameter for Characterizing Creep-Groan Propensity in Brake Pads

The present paper addresses an investigation about the definition of a parameter for quantifying the creep-groan propensity in brake pads. Creep-groan is a self-excited vibration caused by stick-slip phenomenon [1, 2, 3]. For the definition of the creep-groan propensity parameter, extensive experimental work was performed on a laboratory-scale tribometer. The experiments are divided in two main parts: (i) study of correlation between accelerometer signal with physical and operating parameters. (ii) validation of the chosen parameter, which was based on stick-slip tests performed with three different materials, one low-metallic (low-met) and two non-asbestos organic (NAO 1 and 2). From the first study, it was found that both the slip power and mean torque multiplied by torque variation showed a slightly higher correlation with the acceleration signal. However, results from the second study (validation) revealed that slip power is the most suitable parameter to quantify the creep-groan propensity. In the end, based on the slip power parameter, a ranking among the selected materials is established. The ranking in descending order of creep-groan propensity was: low-met > NAO 1 > NAO 2.