聚四氟乙烯网格状人工缺陷对复合材料胶结结构力学性能的影响OA北大核心CSTPCD

Five kinds of composite bonding joints with different grid contents(P)were designed by embedding polytetrafluoroethylene(PTFE)grids into the bonding interface as artificial defects.The computed tomography(CT)and ultrasonic C-scan are the nondestructive testing(NDT)methods used to examine the embedding grids.The mechanical performance was characterized by single-lap joints(SLJ)test and double cantilever beam(DCB)test.Comparing to C-scan,the embedded PTFE grids with different P contents could be detected clearly by CT.The SLJ result showed that the shear strength of the joints increased from 13.85 MPa to 15.15 MPa,when the P content was less than 10%.When the P content was higher than 10%,the shear strength decreased with increasing P values.The damage morphology of SLJ adhesive joints had a transition from cohesive failure to a mixed failure,and final an interfacial failure mode with the increase of P.With the increase of P,on the one hand,the GIC value increased initially,followed by a decrease.On the other hand,the crack propagation changed from a stable and continuous condition to an unstable and"stick-slip"state.