Parametric analysis of enhancement of Z-pins on asymmetric delamination of Z-pinned laminated composites——ModeⅠdelamination toughness

The bridging forces provided by the fiber Z-pins were assumed to be proportional to their length embedded in the laminates. Based on the currently available Z-pin micro-model，a Z-pin element was developed and a beam element model was proposed in this paper to study the effect of Z-pins on modeⅠdelamination toughness of Z-pinned double cantilever beam (DCB) specimens. A contact element was also introduced to the proposed model to avoid the unrealistic penetration of the two substrate beams at the delamination crack tip. The numerical results show that the Z-pins can significantly improve the modeⅠdelamination toughness of the Z-pinned laminated DCB specimens. However，less enhancement on modeⅠdelamination toughness is obtained when the delamination is close to the surface of DCB.