循环加载下的热弹塑蠕变有限元分析

本文考虑在循环加载条件下, 采用混合强化模型, 导出相应的热弹塑性蠕变增量本构方程及有限元格式。研制出平面应力程序, 用牛顿迭代法求弹塑性权, 并提出精度高的屈服吸面校正方法, 程序经考核, 可供工程设计使用。 

ANALYSIS OF THERMOELASTOPLASTIC CREEP FINITE ELEMENT UNDER CYCLIC LOADING

The incremental constitutive equations of thermoelastoplastic creep analysis has been derived under the conditions of variable temperatures and loadings.The finite element basic formulation of the plane stress state has been deduced and the program MTEPCA of its thermoelastoplastic creep analysis under cyclic loading has been worked out.Two sophisticated problems in the programming have been tackled.One is how to improve computational accuracy under the influence of various thermoelastoplastic creep factors.For this purpose the subincremental method and the Newton iteration are applied to calculation of the stress and the elastoplastic weight coefficient respectively,besides a high accurate method is proposed for yield surface correction.The other is how to deal with Δα z and Δε z of plane stress problem becauase they are not equal to zero.The solution of this problem is also provided in the program.Several numerical examples are given to check the reliability of the MTEPCA program.The stress strain hysteresis loops of the point A (danger point) on the analogue sample under cyclic loading are analysed for the structural integrity research.