Research of large scale mechanical structure crack growth method based on finite element parametric submodel

摘要

With the development of mechanical structure in large scale, the dimension difference between whole structure and part damage-crack can be widely further. In order to get a precise analytic result of crack structure the grid of crack structure finite element model should be meshed very dense so that the calculation scale is very large and calculation efficiency is lower even the calculation cannot be completed. To solve this mull scale problem of crack structure, presently the submodel method is used, but in the method crack growth trajectory need to be supposition and the crack model also need to be built by man-made, which is not satisfied with need of mix-mode crack growth especially for continuously reconstructing of crack model. In this paper the parametric submodel will be put forward. The method describes crack coarse model and submodel data by parameter way, including meshing, load, boundary condition etc. In the method dynamic relationship of analytical results between coarse model and submodel is built, so that crack stress intensity factor and growth angle can be automatically calculated for every crack tip. According to the dynamic modification of crack coarse model and submodel, the crack growth trajectory simulation can be calculated through iterative steps instead of the traditional supposition growth trajectory and crack propagation life calculation can also be finished. The method gets the accuracy crack growth trajectory and improves analytical efficiency. At last the case of the crack growth trajectory and life analysis in gantry crane verifies the validity of this method.