Effect of PTFE Grid Artificial Defects on the Mechanical Behavior of Composite Joints
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.
国家科技期刊平台
NSTL
万方数据
维普
