移动式架车机伸缩托头-托架接触的有限元分析

Finite element analysis of telescopic head-bracket contact of mobile car machine

采用基于接触对的非线性接触分析处理接触问题时,其分析结果更接近工程应用实际,但计算成本比较高且存在不收敛的情况。而自由度节点耦合分析不但能降低计算成本,而且能够保证一定精度。为了探究在一定误差范围内选用自由度节点耦合分析来替代基于接触对的非线性接触分析的可行性,以举升重量为15t的移动式架车机为研究对象,在ANSYS软件中建立伸缩托头-托架的接触模型与节点耦合模型,在举升高度最大且伸缩托头完全伸出的工况下进行有限元分析,考虑接触刚度系数与摩擦因数对有限元分析结果的影响,分析了2种模型各接触区域等效应力的区别。通过比较2种模型的有限元分析结果可知,2种模型各接触区域的等效应力值存在一定的相对误差,且接触区域内2个接触面的相对滑动程度决定了接触分析的精度。对于精度要求不高的机械结构,可以考虑用自由度节点耦合分析来替代基于接触对的非线性接触分析。

Using the nonlinear contact analysis based on contact pairs to deal with the contact problem,the calculation cost is higher and there exists case of no-convergence although the finite element analysis result is closer to the engineering application.The degree of freedom(DOF)node coupling analysis not only has a relatively low computational cost,but also guarantees a certain precision.In order to explore the feasibility of using DOF node coupling analysis to replace nonlinear contact analysis based on contact pairs in a certain error range,the mobile car machine with a lifting weight of 15 t was taken as the research object.The contact model and node coupling model of the telescopic head-bracket were established in ANSYS software,and the finite element analysis was carried out under the condition of maximum lifting height and full extension of the head.The effects of contact stiffness coefficient and friction factor on the results of finite element analysis were considered.The difference of equivalent stress in each contact area of the two models was analyzed.By comparing the results of the finite element analysis of the two models,there was a certain relative error between the equivalent stress values of the contact area of the two models,and it was showed that the relative sliding degree of the two contact surfaces in the contact area determined the accuracy of the contact analysis.For mechanical structures with less precise requirements,a DOF node coupling analysis can be considered instead of nonlinear contact analysis based on contact pairs.