纤维金属层板接缝局部起裂准则研究

RESEARCHES ON FRACTURE CRITERIONS FOR THE SPLICES OF A FIBER METAL LAMINATE

从金属层接缝界面端应力场分析出发,确定热-机耦合载荷作用下纤维金属层板接缝局部起裂控制参数,并据此建立界面端起裂准则。基于有限元特征分析法获得界面端奇异性应力场特征解,同时采用界面连续条件和自由边应力条件获得常数应力项,最后采用有限元方法结合最小二乘曲线拟合法获得热-机载荷下的应力强度系数。通过与实验结果对比发现:热-机耦合载荷作用下的应力强度系数可以作为接缝起裂控制参数;通过机械载荷作用下的应力强度系数,可以预测纤维金属层板接缝局部起裂载荷;应力强度系数准则具有很好的通用性,可以预测不同接缝宽度和纤维层厚度情况下的临界起裂载荷。

Based on stress analyses near an interface edge of dissimilar materials, fi＇acture control parameters for metal splices in fiber metal laminates under thermo-mechanical coupling load are solved to establish local fracture criterion. In order to solve stress fields near an interface edge of dissimilar materials, a finite element eigen-analysis method fur obtaining stress singularities is introduced to obtain the numerical eigen-solutions of singular stress fields, meanwhile numerical solutions of regular stress terms are solved by continuous conditions across interfaces and traction free boundary conditions across free edges, and finally a conventional finite element method together with the least square method are used to obtain the stress intensity parameters. All computational results and experiment results shows that, the total stress intensity parameters for thermo- mechanical eoupling load can be used for judgement of the local fracture load, the stress intensity parameter for mechanical load can he used to predict critical fracture load, and the stress intensity parameter based fracture criterion is suitable fro＂ structures with various splice wide and fiber layer thickness.