The Study Of Effects Performa Of Rolling Strengthening On Material Fatigue Performance Based On Micro Defects

The initiation of metal material fatigue crack is easy to be produced in the pore defects which are on or near the surface area. Surface rolling strengthening technology is used to increase the material surface state, and is one of the effective methods to improve the fatigue life of materials. Rolling reinforcement can affect the surface residual stress around the micro holes and change their shapes, which have effect on the fatigue performance of the material. Based on the two perspectives, the cast aluminum alloy is researched in this article by using finite element simulation technology, and the stress distributions around the holes are analyzed under different rolling parameters. The key rolling parameters that influence the fatigue life of material are finally to be found.A two-dimensional elastic-plastic finite element analysis model of rolling is established. And then by analyzing the relative distortion of rolling tool and the work piece, the type of the three dimensional finite element model of rolling analysis is determined. A three dimensional rolling rigid-plastic finite element analysis model is constructed on this basis. By setting the rolling parameters, the distributions of residual stress around the surface of different relative positions micro pores are analyzed and the influence of rolling reinforcement on material surface residual stress is obtained. By studying residual stress distributions around the hole under different rolling parameters, the key rolling parameters that have great influence on the distribution of residual stress are determined.Elastic finite element analysis model for the work piece after surface rolling strengthening is established. The stress distributions around the shape-changed micro pores in different relative positions that have same rolling parameters are researched by applying smaller nominal load. Then through the analysis of stress distributions around the shape-changed holes in the same relative position that have different rolling parameters, the key rolling parameters that have influence on shape-changed holes are to be found. Finally according to the results of the stress distribution around micro pore under different rolling parameters, the distributions of maximum stress around the holes are researched, and by comparing the maximum stress with the value of no-rolling micro pores, the rolling reinforcement effect on the stress concentration around the pores are to be determined and the key rolling parameters and their relative optimal value are to be found.