A numerical analysis of friction-induced noise in stick-slip friction

This Thesis presents the numerical investigation on Friction-induced noise with FEM-simulation. In recent decades, exploring the noise problems in mechanical properties increases widely. Especially, numerical studies are now very popular because of simulation and high prediction rate. This study is a validation of experimental test with a pin on disk method. Stick- slip friction is the main causes of unstable vibrations and noise. In this study, we try to simulate the stick-slip friction in a pin-on-disc system. FEM-simulation was performed with using COMSOL commercial program. A detailed three-dimensional model of the acoustic room was simulated. Input variables such as sound absorption, friction coefficient, materials characteristics, velocity and normal loads needed. The first step is to simulate a friction-induced vibration in stick-slip form and it developed by the Multibody dynamic method. The second step is to simulate acoustical condition of friction-induced vibration to get SPL inside the room. We cannot simulate the SPL of room and motor, which are outside of acoustic room; therefore, results are just for friction-induced noise by stick-slip vibration without any other sound sources. Complex Eigenvalue Analysis (CEA) results indicated that the friction system had a tendency to cause unstable vibration and squeal, and the vibration of the system. The vibration acceleration and contact pressure are responsible to induced noise. It concluded that the vibration amplitude induced by friction is always high near the moving pin. Increasing the normal load and disc linear velocity generally increases the induced vibration amplitude and it causes to increase noise (dB). The effect of normal load is different, in lower speed of rotating by increasing the normal load vibration acceleration increases, however, in higher velocities it increases and then decreases.