Analysis On Aircraft Brake Squeal Problem Based On Finite Element Method

As the demand of comfort keeps rising these years, and research on NVH(noise vibration harshness) problems makes considerable progress in the field of civil transport, the aircraft disc brake’s noise problem gradually accumulates a lot of researchers’ conscientious attention. This type of brake-induced noise issue is believed to possess a fair amount of nonlinearity, which brings about serious difficulty in dealing with relevant issues. Until now, there has never been a completely accurate and reliable theory to solve the brake-induced noise problem.This thesis focuses on a specific type of aircraft disc brake. Previous theoretical results and experimental phenomena have been summarized, and the relationship between brake part vibration and brake-induced noise. FEM method has been applied, comparisons between complex mode analysis and transient dynamics has been conducted. Reasons for brake squeal problem have been carefully studied. Different parameters affecting brake squeal phenomenon have been addressed and validated. Damping vibration attenuation has been applied to deal with the brake squeal problem.First of all, according to the space relationship and assembly situation among different parts, aircraft disc brake system simulation model has been constructed. Simulation using complex mode analysis has been performed, and unstable vibration modes have been extracted. Their vibration properties have been thoroughly researched. Next, explicit dynamic method has been introduced to the transient dynamics procedure. System responses in both time domain and frequency domain have been recorded and analyzed. These two different research approaches have been compared and judged according to their respective features. Taken simulation accuracy and effectiveness into consideration, complex mode analysis has been decided to be used for upcoming parameter study.Research on parameter affecting brake squeal phenomenon has been conducted. Change of disc friction coefficient and disc stiffness have been simulated and ruled out based on the feasibility assessment of these two strategies. Damping vibration attenuation has been asserted, as a result, damping material can be added to the vibration system in order to soften the vibration generated by modal coupling. The correctness of this method has been verified by complex mode analysis.