Influence of Pads' Surface Texture on Disk Brake Squeal

Abstract

Preventing brake squeal is a significant task in brake development because brake squeal bothers users, thereby reducing a vehicle's commercial value. Many researchers have tried to find the mechanisms that cause brake squeal, so the number of complaint to brake squeal is declining. However, brake squeal sometimes appears after a vehicle has been in use for years even though it was not generated early in the vehicle's life. In order to enable people to use vehicles for a long time with a high satisfaction level, it is important to find the factor that causes brake squeal to arise gradually because of specific changes; so we focused on the stiffness of brake pads, which are always wearing during braking, because the pads' stiffness correlates with brake squeal. This study presents the influence of pads' surface texture on disk brake squeal. Pads with different surface texture were prepared by changing the braking time and machining. We measured the pads' stiffness, which we evaluated by exciting a pad at the frequency and vibration amplitude that cause brake squeal. The measurement results show that pads' stiffness increases as their surface becomes smoother, which means that the surface stiffness of pad influences the pads' stiffness. Finally, we used a numerical model to analyze the generation of squeal, which is caused by pads' surface texture.