基于道路试验的制动颤振非线性特性分析

为了探究制动器摩擦颤振内在非线性特性,设计平路D档起步和坡道空挡下坡两种试验工况,采集制动器振动信号并进行时域、时频域和相图分析。分析表明:平路D档起步工况下的摩擦颤振具有明显的短时、宽频带和冲击特征,振幅随制动压力变大而增大,持续时间随压降率减小而增长;坡道空挡下坡工况下既会发生短时、宽频带和冲击颤振,也会发生长时、多频率和周期型颤振。在不同的相对运动速度下,会因摩擦-速度非线性发生单周期、倍周期、多耦合周期乃至混沌振动。摩擦颤振存在3种不同的基础频率及其非线性耦合关系,表明颤振机理既有黏滑振动效应,也可能有底盘角系统的模态耦合效应。

Nonlinear Vibration Characteristic Analysis of Brake Groan Based on Road Tests

Order to probe into the original nonlinear characteristics of fictional brake groan, two test conditions are devised, which are starting on level road under D shift and coasting on gradient road under neutral gear. Under these conditions caliper 3D vibration signals are sampled and analyzed in time domain, time-frequency domain and phase diagram. The analysis results show that the brake groan during D shift starting on level road conditions is an obvious short-time impact with a wide frequency band. The vibration amplitudes increase with the augment of brake pressure, and the durations rise up with the increase of the pressure reduction rate. Brake groan during neutral gear coasting on gradient road conditions, can be a short-time impact with a wide frequency band, or a periodic stationary vibration with multi-frequencies. Under different relative velocities, periodic, period-doubling, multi coupled period vibrations, even chaotic vibration will occur due to the nonlinear friction-velocity characteristics. Three basic frequencies and their coupled relationships indicate that the frictional mechanism of brake groan is not only induced by the stick-slip effect, but also the nonlinear mode coupling effect in a chassis corner system.