基于多尺度分析的EMAA自修复缝线复合材料层间增韧作用研究

Study on interlaminar fracture toughness of self-healing composites based on multi-scale analysis

为研究热塑性EMAA纤维缝线网络对碳纤维复合材料层合板的层间断裂韧性和加热修复后韧性的双重增韧作用,本文采用试验和数值多尺度建模分析相结合的方法,对含有EMAA缝线网络的碳纤维复合材料层合板在热修复前后的Ⅰ型层间断裂韧性进行了分析。根据碳纤维束微观模型预测碳纤维束等效力学参数,通过对缝线处单层板细观结构进行测量,建立细观尺度单胞模型,预测细观单胞的等效力学参数。完成DCB试件宏观模型构建,在宏观模型中添加黏性层模拟EMAA修复剂,来进行Ⅰ型层间断裂韧性分析,采用三维Hashin失效判定准则和渐进退化模型对纤维束及基体进行损伤分析,利用双线性本构模型对黏性层失效进行判定。通过将试验结果与仿真结果进行对比分析,验证了该多尺度模型的有效性;仿真和试验结果表明,EMAA缝线网络能有效提高层间断裂韧性,减缓裂纹扩展;三维缝合网络能够将自愈合EMAA送入损伤区域,继而实现分层裂纹层间断裂韧性的高恢复(修复率为175%)。

In order to study the dual toughening effect of the thermoplastic EMAA fiber suture on the interlayer fracture toughness of carbon fiber composite laminates and the toughness after heat repair,experimental and numerical multi-scale modeling methods were used,the typeⅠinterlaminar fracture toughness of carbon fiber composite laminates with EMAA suture network before and after thermal repair was analyzed.The equivalent mechanical parameters of carbon fiber bundles were predicted by the microscopic model of carbon fiber bundles,by measuring the meso-structure of the monolayer at the suture line,a meso-scale unit cell model was established to predict the equivalent mechanical parameters of the unit cell.The macro model of DCB specimen was constructed,and a viscous layer was added to the macro model to simulate EMAA repair agent to conduct typeⅠinterlaminar fracture toughness analysis.Three-dimensional Hashin failure criterion and progressive degradation model were used to conduct damage analysis on fiber bundle and matrix,and bilinear constitutive model was used to determine the failure of viscous layer.The effectiveness of the multi-scale model is verified by comparing the experimental results with the simulation results.The simulation and experimental results show that the EMAA suture network can effectively improve the fracture toughness between layers and slow down crack propagation.Moreover,the three-dimensional suture network can send self-healing EMAA into the injury area,and then achieve high recovery of fracture toughness between layered cracks(repair rate of 175%).