Delamination in Bio-inspired Laminates

Abstract

It was previously shown that stacking unidirectional carbon fiber composite helicoidally with small angles can result in improvements in terms of maximum load resistance against transverse load. Through simulations and experiments on 19 ply helicoidal and cross-ply configurations, it was concluded that one of the reasons 19 ply single helicoidal configurations outperform common cross-ply configuration is because the helicoidal laminate has a single large delamination at middle of the through thickness under transverse load, previous study has shown the merging of the fiber/matrix damage initiates at bottom of the plate and the large delamination layer causes load drops which decreases maximum load. helicoidal outperforms cross-ply because the fiber/matrix damage initiating from the bottom surface in helicoidal plate has to grow further to reach the delamination layer located at middle and will not cause load drop until final failure where multiple large delamination in cross-ply plate will cause multiple load drops. This allows a large increase in stiffness and maximum load bearing capability for helicoidal configuration. Following on from this finding, further experiments have been conducted to study the performance of helicoidal configurations. Experimental results show the location and numbers of delamination can be controlled through ply orientation, which further improves the performance of helicoidal laminates.