Influence of Dynamic Stiffness in Contact Region on Disk Brake Squeal

Abstract

The squeal generation mechanism in disk brakes is clarified by measuring the stiffness between the disk and pad in the contact region (contact stiffness) and performing an analysis using the surface contact analysis model. The results of a squeal test using a squeal testing machine with a simple structure show that the squeal frequency becomes higher as the thrust pressure for braking becomes larger. Since we thought that the contact stiffness depends on the thrust pressure and influences the squeal frequency because the vibration characteristics of the disk do not change with thrust pressure, we measured the contact stiffness under squeal generating conditions. The pad was given constant pressure and excitation force generated by random noise with the squeal bandwidth. Measurement results show that the contact stiffness depends on the thrust pressure and is different for each pad. To clarify the influence of contact stiffness on squeal, the disk-pad-caliper system was analyzed by using the surface contact analysis model, which connects the disk with the pad via distributed springs (contact stiffness). The analytical results show that squeal is easily generated and its frequency easily changes when the dependence of contact stiffness on thrust pressure is large.