Experimental study on effect of loading rate on mode I delamination of z-pin reinforced laminates

This paper presents an experimental investigation on mode I delamination of z-pinned double-cantilever-beams (DCB) and associate z-pin bridging mechanisms. Tests were performed with three types of samples: big-pin with an areal density of 2%, small-pin with an areal density of 2% and small-pin with an areal density of 0.5%. The loading rates for each type of samples were set at 1 mm/min and 100 mm/min. Comparison of fracture load under different loading rates shows the rate effects on delamination crack opening and delamination growth. Optical micrographs of z-pins after pullout were also presented to identify the bridging mechanisms of z-pins under different loading rates.