Numerical simulation of the Z-pin inserting effect on mechanical properties of 2D woven composite laminate

The Z-pinned woven composite unit cell models of lamina and laminate were developed based on the plain woven composite micro-structure with carbon fiber reinforced after Z-pin inserted. The influence of Z-pin diameter and distribution interval on the in-plane longitudinal tensile mechanical properties was predicted. The stress concentration around Z-pin in the Z-pinned woven composite unit cell model was recognized. The strength would be reduced after unit cell been failed due to the stress concentration. The process of Z-pin pulled out from laminated plates was simulated. The pull-out force versus displacement curves with different Z-pin diameters and thicknesses of separate sub layer were obtained. The double cantilever beam (DCB) with nonlinear spring element and virtual crack closure technique (VCCT) was developed. The mode I crack propagation of Z-pinned laminate was simulated. It was concluded that equivalent mode I energy release rate G _IC of the laminate and its waviness amplitude were larger caused by larger Z-pin diameter. Moreover, the denser the Z-pin distribution was, the larger G_ICwas and the smaller its wavelength was.