Effect of Displacement Rate on Delamination Growth Rate in Unidirectional Glass Fiber Composites in Both Bridging and Non-Bridging Scenarios

Abstract

Experimentally, the mode I delamination behavior of unidirectional glass/epoxy composites at quasi-static displacement rates of 1, 3, and 5 is explored. When comparing the variation between fracture toughness GIC values at 1 mm/min and GIC at 3 mm/min, the average variation is 30% increasing. However, the average variance in GIC between 3 mm/min and 5 mm/min is increasing by 11%. As a result, the crack propagation velocity has a noticeable effect on the value of GIC at lower speeds and a limited effect at higher speeds. The same comparison is made with bridging specimens for 1 and 3 mm/min displacement rates; the average variation is a 37% reduction, which contradicts the non-bridging case. Fiber bridging causes the measured fracture toughness to be overestimated while concealing the displacement rate effect, according to our findings. It is apparent that the bridging phenomenon reflected the variation value in the bridging case. The specimens with a 5 mm/min displacement rate, on the other hand, did not produce the expected bridging and instead operated as non-bridging specimens. The viscoelastic nature of composites can be associated with these findings.