Investigation of the dynamic response in a dry friction process using a rotating stick–slip tester

In this paper, the friction stability of brake materials is investigated by means of a rotating stick–slip tester. Experimental results are compared with a computational model implemented in Simulink. The main goal of this work is to find out how vibrations induced by friction are related to mechanical system parameters such as inertia (mass), stiffness, damping and sliding speed. At the same time, a computational model is developed in order to analyse the dynamic response of a dry friction process at different conditions. A friction sample with nominal contact area of 254 mm2 was subjected to sliding against a gray cast iron disk. The sliding speed was varied between 0.28 and 10 mm/s, while the normal load was kept constant (400 N, equivalent nominal pressure 1.57 MPa). Moreover, tests were carried out in three different damping values and two different stiffnesses. Experimental results show typical stick–slip behaviour for the lowest speeds while for the highest speeds stick–slip disappears and smooth sliding prevails. The computational model can be used to evaluate the dynamic response in dry friction process, as far as static/dynamic coefficient of friction of the mating materials are known as well as the mechanical characteristics of the system.