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.