指数型摩擦因数对制动摩擦振动行为的影响

Study on the Influence of Exponential Friction Coefficient on Friction-induced Vibration Behavior of Brake System

为探索摩擦因数同制动器摩擦振动行为的内在联系,本研究建立起某盘式制动器有限元模型,编写VFRIC_COEF摩擦因数子程序并引入有限元模型中,从而探索指数型摩擦因数的相关参数对制动系统摩擦振动行为的影响。研究结果表明,指数型摩擦因数比定值摩擦因数,更易诱发制动系统产生高强度的摩擦振动现象。这说明在对制动系统进行动力学分析时,采用定值摩擦因数进行模拟具有一定的局限性。动摩擦因数μk对制动系统动力学行为影响显著,随着μk逐渐增大,活塞侧将出现粘—滑摩擦振动现象,且振动频率由多频振动逐渐变为单一频率的振动。而钳指侧的振动随μk的增大呈现出先增大后减小的趋势。另一方面,静摩擦因数μs也将影响制动系统的动力学行为,且对制动盘两侧摩擦面的影响行为差异显著。当μs逐渐增大时,活塞侧的粘—滑摩擦振动现象先出现后消失,且振动强度略微下降。钳指侧的摩擦振动则未见明显的粘—滑振动现象,同时该侧的振动强度随μs的增大而逐渐增强。综合以上,由于钳指侧和活塞侧的受力情况各不相同,因此两侧表现出的振动行为各不相同,两侧受到摩擦因数的影响状态也不同,因此在对制动系统进行动力学分析时,应该对制动器两侧的振动进行讨论,否者相关结果对认识制动器的运动行为具有一定的局限性。

In order to explore the relation between the friction coefficient and brake friction-induced vibration behavior,a finite element model of a disc brake system is established in this study,and the subroutine of VFRIC_COEF friction coefficient is written and introduced into the finite element model,so as to explore the influence of relevant parameters of exponential friction coefficient on brake friction-induced vibration behavior.Results show that the exponential friction coefficient makes it easier for the brake system to produce high intensity friction-induced vibration,compared to the case of constant friction coefficient.Thus,the results suggest that there are certain limitations in using constant friction coefficient to simulate the braking system dynamics.The dynamic friction coefficientμkhas a significant effect on the dynamic behavior of the braking system.With the increase ofμk,the stick-slip friction vibration will appear on the piston side,and the vibration frequency gradually changes from multi-frequency to a single frequency.While for the finger side,the vibration increases first and then decreases.On the other hand,the static friction coefficientμsalso affects the dynamic behavior of the brake system,and the influence behavior on both sides of the brake disc is significantly different.Whenμsincreases gradually,the stick-slip friction vibration on the piston side first appears and then disappears,and the vibration intensity decreases slightly.While the friction vibration of the finger side shows no visible stick-slip vibration,the vibration intensity of the finger side increases gradually with the increase ofμs.Since the force on the finger side and the piston side is different,thus the vibration behavior on bothsides is different as well.Therefore,the vibration on both sides of the brake should be discussed in the dynamic analysis,otherwise the relevant results have certain limitations for understanding the motion behavior of the brake.