중형 버스의 브레이크 저더 현상 개선에 대한 해석적 고찰

Brake judder, one of low ftequency vibrations in brake system, is determined by the excitation of Brake Torque Variation (BTV). The largest contributor to BTV is disc thickness variation. In this study, the static loads of brake torque at Suspension Mounting Points (SMP) are obtained by the quasi-static analysis using DADS. The dynamic loads with frequency of BTV at SMP are derived from correlation between forced vibration analysis with static loads and brake test results. And the accelerations at steering wheel were analyzed by forced vibration analysis with dynamic loads using commercial finite element program MSC/NASTRAN so that vibration characteristics of vehicle due to brake judder were investigated. Reliability of analysis results was verified through comparing the brake test results. Also, a parametric study with natural frequencies of frame, such as the lst torsional mode and 1st bending mode, was conducted to reduce vibration amplitudes. As a result, we could detect frame natural frequency conditions to improve vibration characteristics and obtained the frame model to reduce vibration amplitude.