Tensile properties of Z-pinned composite laminates with low damage insertion technique

In this paper, the effects of Z-pin diameter and Z-pin length on the tensile properties of carbon fiber reinforced laminates were studied. A new Z-pin insertion technique which causes less microdamage damage than the original method was developed. Experimental testing reveals that the in-plane tensile strength of Z-pin specimens is 96.98%-105.32% of the control group. The best performance of in-plane tensile properties is TF18 group which pinned by full-depth F0.18mm diameter. The tensile strength increases by 5.32%, and the Young's modulus increases by 4.71% relative to the control group. Compared with the group of large diameter Z-pin, the in-plane performance of the ultra-fine diameter group is better due to the less in-plane damage. In the half-depth group, delamination occurred between the middle Z-pin sublayer and the upper and lower layers, thus reducing the in-plane tensile property. The Poisson's ratio increases in both full depth and half depth after Z-pinned and it is only related to insertion depth.