Multiscale enhancements in Z-pin reinforcement performance through curing parameters

Z-pinning is employed by composite laminates to enhance interlaminar performances. Z-pinned composites are then cured to obtain a vastly enhanced interlaminar fracture toughness. However, rare research has focused on the curing effects on the mechanical performances of Z-pinned laminates. This paper presents a multiscale experimental and simulation investigation of the curing effects on the individual Z-pin bridging behaviors and the mode Ⅰ interlaminar fracture of multi-pinned laminates by changing holding temperatures and times of cure. The results reveal that a low holding temperature for a long time decreases the cure-induced Z-pin/composite interfacial cracks, thus generating larger Z-pin energy dissipation and a better specimen's load-carrying capacity. Compared with 403 K for 150 min, the Z-pin energy dissipation and interlaminar fracture toughness increased by 32.22 % and 38.82 % by holding at 383 K for 200 min. Mesoscale and macroscale models were developed to predict the cure-induced Z-pin interfacial conditions, Z-pin bridging behaviors, and reinforcement efficiency. Combining the experiments and numerical illustration, this paper presents the possibility of optimizing the Z-pinning performances through the curing profiles.