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2024-T4铝合金FSW接头疲劳裂纹扩展行为及寿命预测

Fatigue crack propagation behavior and life prediction of 2024-T4 aluminum alloy FSW joints

  • 摘要: 基于ABAQUS与FRANC 3D联合仿真的方法,对2024-T4铝合金搅拌摩擦焊接头预制裂纹于不同部位的紧凑拉伸试样进行裂纹扩展分析以及寿命预测,并深入分析不同部位裂纹扩展行为存在差异性的原因. 结果表明,随着裂纹长度的不断延长,裂纹尖端应力强度因子随之增大,且裂纹向前扩展路径基本沿直线扩展,ABAQUS与FRANC 3D联合仿真方法分析不同部位的裂纹尖端应力强度因子和裂纹扩展路径的理论计算和试验结果基本吻合,验证了分区域进行联合仿真的模型精度满足要求.不同部位裂纹扩展试样寿命预测结果与试验结果的相对误差均在5%左右,对焊接接头分区域联合仿真进行寿命预测是准确可行的. 裂纹位于不同部位的扩展试样断口处的疲劳辉纹间距不同导致预制裂纹于3个部位的疲劳寿命由低到高为:热影响区、垂直于焊缝方向、焊核区.

     

    Abstract: Based on the method of ABAQUS and FRANC 3D co-simulation, the crack growth analysis and life prediction were carried out on the compact tensile specimens with precracks in different zones of 2024-T4 aluminum alloy friction stir welding (FSW) joints, and the causes of the differences in crack propagation behavior in different zones were analyzed. The results showed that the crack tip stress intensity factor increased with the growth in crack length, and the crack forward expansion path basically expanded along the straight line. ABAQUS and FRANC 3D joint simulation method analysis of different areas of crack tip stress intensity factor and crack propagation path basically consistent with the theoretical calculation and test results, verifying that the model accuracy of the joint simulation by subregion is satisfactory. The relative errors of the life prediction results in different zones and the test results are about 5%, so it is accurate and feasible to predict the life of the joint by regional co-simulation. The fatigue striation spacing at the crack propagation fracture in different zones is different, resulting in the fatigue life of the prefabricated crack in three zones from low to high: the heat affected zone, perpendicular to the weld direction, and the weld core zone.

     

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