粗糙接触面旋转铰间隙碰撞动力学建模与仿真

运动副间隙会导致机构关节间发生碰撞接触,粗糙的运动副接触面会对含有间隙的机械系统动态特性产生较大的影响;针对机构中常见的旋转较结构特点,建立了一种兼顾能量损失和粗糙接触面动力学特性的碰撞模型,并考虑了接触面形貌的影响。分析了碰撞速度、恢复系数以及粗糙度等因素对接触碰撞力的影响规律,以曲柄滑块机构为研究对象进行动力学建模,仿真结果发现,随着碰撞速度和恢复系数的增大,碰撞力和碰撞变形逐渐增大,碰撞持续时间缩短;随着微凸体粗糙度的增大,碰撞力和碰撞变形逐渐减小,碰撞持续时间缩短;曲柄滑块机构的间隙越小,滑块承受的碰撞力越小,运动副内碰撞发生的频率越高。研究结果表明所建立的模型能够完善碰撞力模型,为机构设计提供参考,有利于工程实际应用。

Impact dynamic modeling and simulation for a revolute joint with rough contact surfaces and a clearance

The clearance in a kinematic pair causes impact contact in joints of mechanisms. Rough contact surfaces of a kinematic pair can significantly affect dynamic characteristics of a machinery system with clearances. Aiming at structural features of a common revolute joint in mechanisms, an impact model considering energy loss, dynamic characteristics of rough contact surface and effects of contact surface morphology was established to analyze influence laws of impact velocity, restitution coefficient and roughness, etc. on the contact impact force. A crank-slider mechanism was taken as the study object to establish its dynamic model. The simulation results showed that with increase in impact velocity and restitution coefficient, impact force and impact deformation gradually increase, and impact duration shortens;with increase in microconvex roughness, impact force and impact deformation gradually decrease, and impact duration shortens;the smaller the clearance of the crank-slider mechanism, the less the impact force exerted on the slider, the higher the frequency of impact appearing in the kinematic pair;so the established model can be used to impove the impact force model, provide a reference for mechanism design and it is beneficial to engineering application.