碳/碳编织复合材料连接结构的拉脱性能分析

Pull-through Performance of Carbon/Carbon Braided Composite Joints

对碳/碳(C/C)编织复合材料沉头螺栓与凸头螺栓连接结构在面外载荷下的拉脱强度进行试验和数值研究。测试不同螺栓形式及沉头角度的C/C编织复合材料螺栓连接结构在面外载荷下的失效模式和拉脱性能。结果显示,螺栓形式对结构的拉脱性能有显著的影响,凸头螺栓的载荷位移曲线有明显的线性阶段,接近于脆性失效,沉头螺栓的载荷位移曲线为非线性,表现为双峰值,其更接近于塑性失效。采用ABAQUS建立了基于Hashin失效准则的连接结构非线性接触模型,有效预报了C/C编织复合材料连接结构的失效模式及载荷-位移曲线。得到C/C编织复合材料连接结构渐近损伤过程及失效机理,给出连接参数(螺栓形式、沉头角度和约束面积)对拉脱失效的影响机制。随着沉头螺栓角度的增加,结构的拉脱失效载荷先增加,后降低,在110°附近达到极值,约束区域尺寸变化导致凸头螺栓的失效模式由剪切失效转变为弯曲失效。

Pull-through performance of the C/C composite joints are studied through experiments and numerical simulations.Failure process,mode,and pull-through strength are investigated experimentally for bolt forms and countersunk head angles.The results show that the bolt form has a significant effect on the pull-thought performance of the structure.The load-displacement curve of protruding head bolts has an obvious linear stage.The failure mode is close to brittle failure.The load-displacement curve of countersunk head bolts is nonlinear.A non-linear contact model,based on the Hashin failure criterion,is established using ABAQUS.The model is validated by comparing failure modes and load-displacement curve to experimental results.The progressive damage and failure mechanism of the joints are obtained,and the influence mechanism of parameters(bolt form,countersunk head angle and constraint area)on pull-thought failure is given.The results show that the pullout failure load of the structure increases first and then decreases as the increase of the countersunk angle,and the failure load reaches the peak near 110°.Failure mode changes from shear failure to bending failure due to increase of constraint area.