摩擦片材料和结构对制动器热弹性失稳影响

Effect of Material Properties and Structure of Frictional Pad on Thermoelastic Instability of Disc Brake

摘要:

建立了二维摩擦制动器热弹性失稳(TEI)数学模型.基于反对称热点分布模式，采用扰动分析法研究了临界速度、扰动增长系数以及扰动迁移速度的变化规律，讨论和比较了摩擦片厚度、热物理特性参数和有限周向接触弧长对系统稳定性的影响.结果表明：临界速度随扰动频率呈先减小后增大的变化规律；扰动迁移速度在摩擦片和金属盘内随扰动频率呈相反的变化趋势，且扰动在具有较高导热系数的金属盘内的速度几乎为零；增加摩擦片厚度、导热系数、比定压热容和减小弹性模量均可提高滑动摩擦系统的热弹性稳定性.

关键词:制动器; 热弹性失稳(TEI); 扰动增长系数; 临界速度; 扰动频率

Abstract:

A mathematical model on thermoelastic instability (TEI) of two dimensional disc brake was built. Change rules of critical speed, growth rate of perturbation and its migration velocity in metal disk and frictional pad were respectively resolved by utilizing perturbation method with the assumption that hot spots were antisymmetrically distributed on frictional surfaces. Then, the effects of frictional pad’s thickness, material properties and finite contact length on critical speed were analyzed and compared. The results show that, critical speed will decrease firstly and then grow again with wave number and there is an opposite trend of migration velocity in brake disk and frictional pad. Meanwhile, it is almost zero in metal disk with higher thermal conductivity. The stability of sliding frictional system can be enhanced by increasing the thickness, thermal conductivity and specific heat of the frictional pad.

Key words:disc brake; thermoelastic instability(TEI); growth rate of perturbation; critical speed; wave number