有限元三维实体单元与壳单元的组合建模问题研究

Research on the Modeling by Solid Element and Thin-shell Element

板单元与实体单元之间的连接由于本身自由度的不同使转动自由度不连续 ,这个问题是有限元计算中比较难以解决的问题。本文采用复合单元来实现板单元与实体单元之间的过渡 ,复合单元可以看成是板单元与实体单元的组合 ,其刚度矩阵可以看成是板单元刚度矩阵与实体单元刚度矩阵的叠加 ,即复合单元具有三个方向的位移自由度和三个方向的转动自由度。通过对全实体有限元模型和具有复合单元的有限元模型的计算证明 ,采用复合单元来实现板单元与实体单元之间的过渡 ,其计算结果与全实体有限元模型的计算结果偏差较小 。

Solid element and thin shell element can′t be connected because of the discontinuousness of rotation DOF between them. This is a hard question in FEM calculation. In this paper the compound element is applied to solve the DOFs discontinuousness between solid element and thin shell element. The compound element can be seen as the combination of solid element and thin shell element, so it has six DOFs which are three displacement DOFs and three rotation DOFs. By the calculation of the solid FEM model and FEM model which connects solid element and thin shell element with the compound element, the result of this kind of model is almost equal to the solid model, the result is true and reliable.