激光选区熔化成形铝合金板与CFRP复合材料层合板螺栓连接结构失效分析方法评估
Assessment of failure analysis method for the bolted structure between selective laser melting aluminum plate and CFRP composite laminate

对激光选区熔化成形（SLM）铝合金板与碳纤维增强树脂基（CFRP）复合材料层合板两列四排沉头螺栓单剪连接件在拉伸载荷作用下进行了数值分析和试验研究。基于渐进损伤法的三维有限元模型准确地预测了连接件材料损伤萌生和演变，对比试验和三维有限元所得钉载比例、极限载荷及失效模式，可以发现，通过拟合SLM铝合金板断裂应变和应力三轴度曲线，编写UMAT子程序引入韧性准则和Hashin失效准则的三维有限元模型预测的连接件失效载荷与试验值误差仅为1.9%，且失效模式均为净截面拉断，两者吻合，此方法可以满足工程精度要求。利用经过验证的数值模型，分别预测了SLM铝合金板和CFRP层合板损伤演变过程，并分析了SLM铝合金板刚度对连接结构失效模式的影响，当SLM铝合金板厚度增大到4 mm时，连接结构失效模式由SLM铝合金板净截面拉断转移到CFRP层合板上。 The multi-bolt countersunk single-lap joint of SLM aluminum plate and CFRP composite laminate under tensional load was analyzed via numerical simulation and experiment. Damage initiation and progression in the structure were present in 3D FEM based on the progressive damage analysis (PDA), and the bolt load distributions as well as the failure loads and modes were compared with the physical test. With the consideration of fracture stain to stress triaxiality curve approximated by the author, it is found that there is only 1.9% difference of the failure loads between FEM and test, when both Ductile damage and Hashin criteria are introduced through UMAT. Besides, the failure modes are both pulling out illustrated in FEA and experiment. Consequently, the method assessed in this study has enough accuracy to satisfy the application requirement for such an engineering problem. The progressive damage process of both SLM aluminum plate and CFRP laminate were investigated with the validated FEM and the effect on the failure mode of the joint was studied with different stiffness of SLM aluminum plates. When the thickness of SLM aluminum plate increases to 4 mm, the pulling-out failure mode of the joints transfers from SLM aluminum plate to the CFRP composite laminate.