组合强化模型及其在弹塑性有限元分析中的应用

提出了一种组合形式的强化模型，编制了用于平面问题的弹塑性有限元法的等参元分析程序．实例计算表明，本文所提出的组合强化模型是合理和有效的，使用很方便。文中还推荐了一种关于迭代过程中的卸载问题的处理方法，它能有效地提高迭代收敛性，从而对于一般的等向强化有限程序设计也有一定的参考价值．

A Combined Hardening Model Applicable to Engineering Elastic-Plastic Finite Element Analysis of the Process of Fastener Hole Coldworking in China''s Aircraft Industry

The research results presented in this paper were closely connected with a prokct concerning thecoldworking of fastener holes in China's aircraft industry. Tlic author's method is believed to bemore convenient than previously known methods. The kinematic hardening model has been considered to be the proper model accounting for Bauschingcr's effect of materials in spite of the widelyused isotropic hardening model.Both models are unified in this paper so as to describe any intermediate work-hardening case. Formulas are derived in general incremental form in which the flexibilityof combination of the two models depends only on the selection of a constant parameter. Von Misesyield criterion and uniaxial stress-strain relation are adopted in the design of a 2-D elastic-plasticfinite clement method program. The calculation and analysis of resiudal stresses of fastener hole expansion show that the estimation of the combined model correlates well with the experiments. Amethod improving the convcrgcnce of iteration is recommended to dcal with the unloading in plasticregion during iteration process.