一种可应用于板壳成形过程模拟的绝对-相对自由度壳单元

相对自由度壳单元是采用有限元法分析板壳成形过程的一种有效单元形式。它不仅可以解决采用实体单元模拟板壳成形过程所存在的问题 ,同时它与主从自由度壳单元相比还具有简单易用的特点。然而 ,目前尚未见到对该单元边界条件如何进行具体处理的方法的报道。作者的研究表明 ,该类单元应用于模拟薄壁件成形过程时尚不能直接采用置“1”法或置大数法处理其边界条件。为此 ,本文在该单元的基础上提出了一种绝对自由度和相对自由度相结合的壳单元。将该单元应用于薄壁管弯曲过程模拟的结果表明 ,它不仅继承了相对自由度壳单元的优势 ,而且可直接采用置“1”法或置大数法处理边界条件。

A Shell Element with Relative and Absolute Degrees of Freedom Suitable for the FEM Simulation of Shell Forming Processes

The shell element with relative degrees of freedom is an effective shell element for the FEM simulation of shell and plate forming processes, which can resolve the difficulties when the solid element is adopted in the FEM simulation, and it is much easier to be realized in the FEM program compared with the shell element based on the master-slave degrees of freedom at the same time. Nevertheless, large number or "1" substitution method cannot be directly used to deal with the boundary conditions if this element is employed in the FEM program. Moreover, the approach designed to solve the boundary conditions concerned with the element has not been found so far. Consequently, a new shell element is developed based on the element with relative degrees of freedom, which combined absolute degrees of freedom and relative degrees of freedom. The new element not only has the advantages of the shell element with relative degrees of freedom, but also deal with the boundary conditions in FEM codes by the large number or "1" substitution method.