The Actual Stress Method Based On Damage Mechanics To Predict Life On ANSYS Platform

For the damage calculation of the 3-D stress status, this article for elements in numerical simulation for components is based on the finite element method about damage mechanics of the interaction of creep and fatigue. Writing program with using the APDL of ANSYS unifies components ' life forecast technique based on damage mechanics and the ANSYS structure analysis and has achieved component's damage computation and the life forecast. Using the actual stress method solves component's stress strain and avoids the stiffness matrix revision repeatedly.Because of the elements under the 3-D stress status, we should obtain the damage equivalent stress to compute element damage according to the element stress condition and introduce the concept of the damage equivalent stress in damage evolution equation. The method of superimposition is most commonly used by mechanical damage of the interaction of creep and fatigue. In the cumulative damage computation, the damage increase about the interaction of creep and fatigue is linear iteration about two kinds of damage increase. In order to calculate the life under the 3-D complex status, taking the damage mechanics and the finite element method as foundations, using the actual stress law after primary load determines the damage equivalent stress and introduces revision of damage equivalent stress when taking the close-effect into accout. Material parameters in damage evolution equation are determined by consulting the correlation data. Firstly, three principal stresses and the equivalent stress determined by the first primary damage are used to calculate the damage equivalent stress. Then, the application in the damage evolution equation can calculate the extent and field of about element damage by applying the finite element method about the actual stress method and the APDL to write program. This method may solve the fatigue life under 3-D complex status. The result indicated that the data obtained from the compilation procedure is consistent with the experimental result basically. This method carries on view of the element, and can be applied widely and used in the computation under the complex status and the complex loading environment.