Numerical analysis of three-dimensional I/II mixed-mode elastic-plastic fracture of aeronautical structural aluminum alloy
Received:March 13, 2009  Revised:December 17, 2009
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KeyWord:three-dimensional I/II mixed-mode elastic-plastic fracture  crack initial angle  the maximum tangential stress criterion  three-dimensional out-of-plane constraint factor
王芳丽 南京航空航天大学 高新技术研究院, 江苏 南京
佘崇民 南京航空航天大学 高新技术研究院, 江苏 南京
郭万林 南京航空航天大学 高新技术研究院, 江苏 南京
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      Based on three-dimensional I/II mixed-mode fracture experiments of the LC4CS aluminum alloy, three-dimensional I/II mixed-mode elastic-plastic finite element models were established. The coupled effects of mixed loading and thickness on the elastic-plastic field near the crack front and the initial angle of crack were analyzed systematically. It is shown that the angle of the maximum tangential stress is the same with the angle of the minimum three-dimensional out-of-plane constraint factor under various mixed loadings and thicknesses. Next, when the mode I loading is dominant(βeq>65.45°), the crack initiation angle of finite element calculation based on the maximum tangential stress criterion is closer to the experimental data than the value predicted by two-dimensional the maximum tangential stress criterion. Finally, The experimental measure crack initiation angle of 8 mm thickness is much smaller than the value calculated by two-dimensional fracture criterion. It is necessary to develop a new universal three-dimensional mixed mode fracture criterion that is nearer the truth.