Research for surface semielliptical crack stress intensity factor numerical simulation in power station heat exchange tube

This paper introduces through the Ansys parametric design language (APDL) to establish finite element model containing surface semielliptical crack expansion of power station heat exchange tube. The type of finite element is used in this program is isoparametric degradation singular element,whice simulates crack stress singularities.And the crack front is token discrete. Based on this kind of finite element model the stress intensity factor value of the different shapes of crack at different depths has been calculated,the stress intensity factor value of distribution has been analysed and researched at the progress of different initial shape crack front expanding.And it provides important data for the prediction of the tube fatigue damage and using life. The results of this study show that: with the crack´s growth,the shape of crack which has different initial shape will tend to be in a shape ratio range.