压力容器有限元计算中的整体建模方法研究

Ensemble Modeling Method in Finite Element Analysis for Pressure Vessels

在压力容器有限元计算中,通常仅针对所关心局部区域进行建模;但局部建模将带来边界条件难以确定的问题。针对一受内压作用的过热器强度计算问题,提出一种实体单元/壳单元混合建模的整体建模方法。对较厚区域,关注的局部区域及结构不连续区域采用实体单元建模;其余薄壁结构用壳单元建模。通过改变实体单元/壳单元连接位置,建立不同的计算模型。计算结果和实测结果比较表明:通过合理选择壳单元和实体单元连接位置,该整体建模方法所得计算应力能与实测应力较好吻合。既避免了局部建模边界条件难以确定的问题,又达到了减小整体模型计算规模,同时保证局部计算精度的目的,为类似的工程问题提供了参考。

In finite element analysis for pressure vessels,a partial model is generally built,which brings in the problem that boundary conditions are not defined properly.A hybrid modeling method with solid / shell elements coupling is proposed to solve the strength problem for a super-heater.Relatively thick regions,important regions or discontinuous regions are modeled by solid elements;other regions are modeled by shell elements.Different FEA models of the super-heater are built in order to find out the reasonable position of the connection between solid and shell elements,FEA results are compared with experimental results.The comparison shows that the computational results are in good agreement with the experiment results if the connection position is chosen properly.The purpose of both limiting the size of the computing model and ensuring local accuracy is achieved,and the method could be reference for similar engineering problem.