增强假设变形梯度有限元方法稳定性计算

Stability of the enhanced assumed strain finite element method

讨论了非协调增强假设变形梯度有限元的基本理论、所采用的本构关系和有限元列式.为了克服原先由Simo建议的方法中所固有的缺陷,即在模拟压缩变形时容易出现奇异能量模式而导致计算失稳甚至崩溃,对原方法中有关内变量和应力更新算法进行了改进.计算结果表明,改进的方法在模拟压缩和拉伸模型时,具有较好的计算稳定性.

The basic theory of the Enhanced Assumed Strain Modes （EASM） and the corresponding constitutive relationship as well as finite element formulation were addressed. In order to overcome the deficiency of the original method proposed by Simo, i.e., the Hourglass modes appear in the case of compression, algorithms for updating stresses and interior variables were developed by using an optimal post-process technique. It were proved from numerical results that the improved EASM is of good stability especially in the case of large compressive situation being involved.