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机构转动副中的间隙当其零件间的接触消失时会给系统带来破坏性的冲击。为了建立保持接触的条件,或为了预测接触消失的条件,就需要对运动的机构进行动力学分析。这种分析需要考虑转动副的间隙。本文分析了在一个转动副中含有间隙的四连杆机构,以求得转动副零件间的接触条件。一个尺寸相当小的间隙可模拟为一个具有有限长度的无质量构件。这样的模型具有增加机构一个自由度的效应。为了求解运动方程式,需要已知两个构件在某一特定时间的角位置和角速度。曲柄给定的运动,提供了其中的两个初始条件。由于间隙构件是无质量的,所以它的方向和运动是与间隙构件矢量力的方向和方向变化率是一致的。系统的动力学分析可以建立一组非线性的无法直接求解的微分方程式。本文试图根据零间隙轴承矢量力的方向和方向变化率来建立合理的初始条件,并试图确定机构对任选初始条件的运动响应的灵敏度。总的来说,机构构件的运动不受无质量间隙构件的影响。然而,间隙轴承矢量力是取决于间隙构件的角速度和角加速度,而且这些运动对初始条件是敏感的。在确定实际的轴承矢量力时,无质量间隙构件的振荡运动尤为重要,在转动副零件间的接触消失的条件下也是如此。可以参考实验数据,以证明预测的转动副力的振荡。
Clearances in the swivel of the mechanism can cause damaging impact on the system when the contact between the parts disappears. In order to establish the conditions for keeping contact or to predict the disappearance of contact, kinematic analysis of the moving body is required. This analysis requires consideration of the clearance of the turning pair. This paper analyzes the four-bar mechanism with a gap in a rotating pair to find the contact conditions between the rotating parts. A fairly small gap can be modeled as a massless member with a finite length. Such a model has the effect of adding one degree of freedom to the mechanism. In order to solve the equations of motion, it is necessary to know the angular position and angular velocity of two components at a specific time. The given motion of the crank provides two of these initial conditions. Since the gap member is massless, its direction and motion are consistent with the direction and rate of change of the vector force of the gap member. The system dynamics analysis can establish a set of nonlinear differential equations that can not be solved directly. This paper attempts to establish a reasonable initial condition according to the direction and rate of change of the zero-gap bearing vector force and try to determine the sensitivity of the mechanism to the motion response of an optional initial condition. In general, the movement of the structural member is unaffected by the massless gap member. However, the clearance bearing vector force is dependent on the angular velocity and angular acceleration of the clearance member, and these movements are sensitive to the initial conditions. In determining the actual bearing vector force, the oscillation of the mass-gap member is of particular importance, even with the contact between the rotating pair of parts disappearing. You can refer to the experimental data to prove the predicted oscillation of the secondary force of rotation.