Dynamic bending behaviour of woven composites for sports products: experiments and damage analysis

© 2015 Elsevier Ltd. Carbon fabric-reinforced polymer (CFRP) laminates employed in sports products are usually subjected to large-deflection quasi-static and dynamic bending deformations during service. Such loading conditions induce damage within the material affecting its strength, stiffness and energy-absorbing capability. To study this, mechanical behaviour of woven CFRP composites in on- and off-axis orientations is first quantified by carrying out large-deflection quasi-static bending tests followed by dynamic ones employing an Izod type impact tester. CFRP laminates of various orientations were tested at loads increasing up to failure to determine their energy-absorbing capability. On-axis laminates demonstrated better strength and stiffness whereas off-axis laminates exhibited good energy-absorbing capability. However, for applications demanding strength, stiffness and energy absorption as in sports products, a combination of both types of plies, as in a quasi-isotropic layup, is an optimum choice. Micro-computed tomography (micro-CT) analysis of the tested specimens showed that matrix cracking, delamination and tow debonding were the dominant damage modes at the specimen's impact location, whereas fabric fracture occurred at the bending location. Further, a catastrophic brittle fracture was observed in the on-axis laminates whereas the off-axis laminates exhibited pseudo-ductile behaviour thanks to matrix cracking and fibre trellising before their failure at higher energies.