无轨伸缩式门式起重机接触部位的有限元分析

非线性接触分析在处理接触问题时可以更加接近工程实际，但在实际应用中，接触参数设置复杂、计算效率低以及计算收敛性难以保证等因素制约了它的实用性。节点耦合分析是不存在收敛问题的线性分析，计算成本比接触分析低。为了探讨2种模型在应用中的差异，研究节点耦合线性分析代替非线性接触分析的可行性，以起重量为12 t的无轨伸缩式门式起重机为例，在有限元分析软件ANSYS中分别构建其接触模型和节点耦合模型，考虑接触刚度和摩擦系数对计算结果的影响，在伸缩支腿全伸的工况下比较2种模型下无轨伸缩式门式起重机各接触部位等效应力值的差异。通过对比计算结果发现：2种模型中，最大等效应力均出现在车架施加起升载荷处，计算值相差1.3%，结果差异不大。由于节点耦合分析忽略了摩擦系数，所以2种模型中各接触部位等效应力值存在差异，根据接触部位的相对滑动，在接触模型中选择合适的摩擦系数可减小此差异。研究结果表明：考虑接触区域相对滑动对计算结果的影响，节点耦合分析能较好地模拟接触分析，对于精度要求不高或接触区域基本无相对滑动的模型，可采用节点耦合分析这种简化方式来代替接触分析，以提高计算效率。

Research on contact problem of trackless telescopic gantry crane

Nonlinear contact analysis can be closer to reality when dealing with contact problems, however, the complicated contact parameter setup, low computation efficiency and the computation convergence with no guarantee, which make contact analysis difficult to be applied to engineering practice. Node coupling analysis is a linear analysis without convergence problem, so the node coupling analysis is superior to the contact analysis because of its lower computational expense. In order to explore the differences in the application between the two models and study the feasibility of using the node coupling linear analysis instead of the nonlinear contact analysis, the trackless telescopic gantry crane with 12 ton lifting capacity was taken as the example, and the finite element analysis software ANSYS was used to establish a contact model and a node coupling model. The influences of contact stiffness and friction coefficient on the calculation results was considered, and the equivalent stress differences of each contact part between two models were compared under the condition of telescopic leg extending. By comparing the computation results, it was found that the maximum equivalent stress of two models appeared at the crane frame where the lifting load was applied. Besides, there was no significant difference with the relative error was 1.3%. Furthermore, the equivalent stress value of each contact part had some differences since the node coupling analysis neglected the friction coefficient, therefore, the relative error can be reduced by selecting the appropriate friction coefficient in the contact model according to the relative sliding of the contact part. According to the results, considering the influence of relative sliding on the calculation results, node coupling analysis can simulate contact analysis favorably, for models with no high precision or no relative slip of the contact area, a simplified approach based on node coupling analysis can be used to replace contact analysis to improve computational efficiency.