含球关节间隙的RSSR机构动力学建模与仿真

Dynamics modeling and simulation of RSSR spatial mechanism with spherical clearance joint

为研究含球关节间隙对空间连杆机构动态性能的影响,建立含间隙的球关节运动学模型,基于拉格朗日乘子法,建立含球关节间隙的RSSR空间机构动力学模型,仿真分析了关节接触力模型、曲柄输入转速、间隙尺寸等因素对机构的动态性能的影响.仿真结果表明:不同的关节接触力模型,对仿真结果影响较大;球头与球窝的碰撞接触点主要分布在间隙球的两个局部区域;间隙尺寸对机构摇杆输出角加速度波动以及球关节接触力影响最大,间隙尺寸的大小与摇杆角加速度、关节接触力大小的变化呈现非线性正相关的趋势.

To explore the influence of spherical joint with clearances on the dynamic performance of spatial linkage mechanism, a kinematic model of the spherical joint with clearance is established based on the Cartesian coordinates,a spatial four-bar mechanism RSSR is used as an illustrative example and some numerical results are presented. The dynamics model of the RSSR mechanism with spherical joint clearance is also established based on the Lagrange-multiplier method. The dynamic properties of the RSSR mechanism with joint clearance are analyzed,which considered the effect of the size of joint clearance,crank driving speed and joint material. The results show that the difference contact force model of the joint will influence significantly the output result,the contact points of the ball and socket spread mostly in two regions on the clearance sphere,the clearance size of spherical joint affects the dynamic response of the mechanism dramatically. The influence of clearance size on the angel acceleration of the rocker and the contact force of the spherical joint with clearance is non-linearly and positively relation.