剪叉式提升机构受力特性分析

Force analysis of scissor lift mechanisms

为了对三级剪叉式提升机构的受力特性进行分析研究,首先将其简化为二级剪叉式机构,并利用虚位移原理和力学分析方法对简化后机构的轴力、弯矩和应力等进行了推导与分析,得到了机构受力与起升荷载、起升角度的关系式。然后结合对三级剪叉式机构受力特性的有限元仿真,得到了简化前后2种机构的受力特性曲线。最后对比分析发现:虽然简化后机构各点的受力特性会发生改变,但是机构中剪叉臂的轴向应力和剪切应力的最大值变化不大,剪叉臂所受的最大弯曲应力近似为简化前的2.3倍,并且这些应力的最大值均随着起升角度的增加而非线性地减小。因此,可以通过计算二级剪叉机构中的相关应力来估算三级剪叉机构中的应力。

To analyze firstly simplified as chanical analysis me the characteristics of the forces of the scissor lift mechanism with three levels, it was a two-level one, and the principles of virtual displacements together with some methods were applied to deducing and analyzing the axis force, the bending moment and the stress of the mechanism, thus obtaining the relationships between the forces and the lifting load and angle. Then,by means of finite element analysis and the simulation of the scissor lift mechanism with three levels, the curves regarding the stress characteristics of these two kinds of mechanisms were gained. Finally, the results show that the mechanical characteristics change after the simplifying. However, the maxima of the axial stresses and the shear stresses suffered by the connectors are roughly unchanged. Compared to the original values, the maxima of the bending stresses in scissor mechanism arms is increased by 1.3 times approximately. Besides, the maximum stresses in both mechanisms decrease nonlinearly with the increase of the lift angle. Hence, it is reasonable to calculate the maximum stresses in twolevel scissor mechanisms in order to estimate the counterparts in three-level ones.