Bio-inspired composite laminate design with improved out-of-plane strength and ductility

Low failure strain and catastrophic failure are the most critical challenges of carbon fiber reinforced polymer composite laminates. To tackle these challenges, inspired by core shells, we created discontinuities in the laminate microstructure to activate extra energy dissipation mechanisms that improves flexural response. In bio-inspired laminates, embedded defects and delaminations are imposed at different thickness positions of the laminate during lamination process. The flexural properties of the proposed bio-inspired laminates were characterized using three-point bending test. Different damage modes and their sequences in conventional and bio-inspired laminates were identified using microcomputed tomography. Experimental results showed that, the flexural properties of bio-inspired composites can be tailored by changing the through-the-thickness delamination position and size. It was demonstrated that, the strength, failure strain and energy absorption ability of the optimized bio-inspired laminates, with 10 mm delamination diameter at the nearest interface to the indenter, were improved by 11.9%, 208% and 288.1% compared to conventional laminate. Moreover, these bio-inspired composites showed a progressive damage mode with pseudo-ductility response, where a slight degradation of the strength occurred followed by increased strain and sustaining the same strength up to failure strain two times larger than the initiation strain. Therefore, the proposed bio-inspired laminates showed a metal-like failure that provides warning alert to the final failure, which makes them applicable in many industrial applications.