不同自由度单元之间连接刚度问题的研究与应用

针对有限元分析中,板壳单元与实体单元之间由于自由度的不匹配,使转动自由度在板壳单元与实体单元交界处产生不连续的问题,提出了采用约束方程进行联合建模的思路。根据有限元理论进行公式推导,得到了约束方程在板壳单元与实体单元连接处的刚度协调方程;用有限元实例进行计算比较验证;将该建模方法运用于某地铁车的仿真当中。理论分析及仿真结果表明,非协调性单元之间自由度的协调统一对仿真结果有较大的影响,采用约束方程在板壳单元与实体单元之间形成过渡能有效消除自由度不协调的问题,从而得到更切合实际的仿真结果。

Research and Application about Connection Stiffness between Elements with Different DOFs

Because of the discontinuousness of rotation DOF between solid element and shell element,they can not be connected well at the connection points.Based on the finite element analysis（FEA）,the method of constraint equation co-modeling was proposed and used during the modeling.Firstly,according to the theory of FE,the stiffness compatibility equitation between the connection points of shell element and solid element was derived,then the FE examples were calculated and the results were compared,finally the method of this modeling was used in a metro car simulation.Theory analysis and simulation results show that the compatibility of DOF between the elements makes a greatly impact on results during the simulation.Using the constraint equation to make transitions between shell element and solid element can effectively eliminate the problem of compatibility of DOF,and thus get more realistic simulation results.