计及热效应的闭环柔性机械系统的动力学分析

Dynamic Analysis of a Closed-loop Flexible Mechanical System in Consideration of the Effect of Thermal Disturbance

基于柔性多体系统动力学理论对一个刚柔耦合的平面闭环机械系统的动力学特性进行分析。首先推导出不计热效应时的平面机械系统的第一类拉格朗日动力学方程,然后利用热应力理论得到柔性梁的应力-应变关系,进而对系统的动力学方程进行修正以得到计及热效应的系统动力学方程。数值仿真结果显示,当系统运行到奇异点位置附近时,各个动力学特性变量均出现明显的增大趋势;当温度发生变化时,各个构件的位移基本保持不变,但构件的速度、机械臂的轴向变形和轴向约束力则产生明显波动,从而揭示出热应力对系统动力学性态的影响。

Based on the theory of flexible muhibody system, the paper presents the dynamic analysis of a planar rigid-flexible coupling mechanical system. The influence of thermal stress on dynamic characteristics of the system is also studied. Firstly, the first Lagrange dynamic equations of the planar mechanical system without considering thermal disturbance are deduced. Then the stress-strain relationship of flexible beam is studied by using the theory of thermal stress. Finally the dynamic equations are modified to obtain those with consideration of the effect of thermal disturbance. Numerical simulations＇ results indicate that when the system moves and approaches the location of a singular configuration, all the dynamic variables of the system become evidently larger. With the effect of thermal disturbance considered, the displacement of every component of the system shows small change compared with those without considering the effect of thermal disturbance, but velocities of components, axial deformations and axial constraint forces of mechanical arms fluctuate with the change of temperature, revealing the effect of thermal disturbance.