Research On Thermal Weight Function Method And Program For Mixed-Mode Crack Based On MARC

Safety analysis of structure with cracks under thermal shock is concerned by researchers. The variation of the temperature field is usually rapid and the gradient of the temperature field is high, so for the structure with cracks under strong thermal shock, the analysis of variation of transient stress intensity factors (SIFs) for the crack tip under thermal shock is often an important problem for engineering areas. A lot of work needs to do when some currently used methods are used to solve this kind of problem. Thus, make a research on how to solve this complicated problem has a very practical meaning.Thermal weight function (TWF) method was used to effectively calculate the variation of SIFs of mixed-mode crack under thermal shock. TWF is independent of time during thermal shock, so the whole variation of transient SIFs can be directly calculated through integration of products of TWF and transient temperatures and temperature gradients. The main work and achievements as below:1. Theories about TWF method were studied, TWF method and finite element (FE) method were combined, and the FE implementation of the TWF method for mixed-mode crack in plane stress and plane strain problems was presented in this paper.2. FE analysis software MSC.MARC and its user subroutine interfaces were studied. User subroutine interfaces of MSC.MARC were used to realize the computation of TWF and the heat transfer analysis function of MSC.MARC was used to fulfill the analysis of temperature field.3. The program using TWF method to calculate the variation of transient SIFs was established.4. Some examples were studied and discussed. The results showed that the scheme shown in this paper was of very high efficiency and of good accuracy. In the meanwhile, it had about the same level of accuracy as that using the direct thermoelasticity method was achieved.5. Fast assessment method for the safety of mixed-mode cracked bodies under thermal shock was studied in this paper. In the future, we can study on three-dimensional mixed-mode crack problem with TWF method, and can also study on cracked bodies under thermal chock and other press.