Abstract
A detailed experimental study is performed to investigate the mode-I dynamic fracture initiation toughness of through-thickness Nylon fibers reinforced glass/epoxy composites using a wet electrostatic flocking method. Composites of a double cantilever beam specimen configuration of two different deniers 1.5D and 3D of 0.75 mm long Nylon fibers with two different fiber densities 150 and 300 fiber/mm(2) and composites without Nylon fibers (control) are fabricated. The dynamic fracture initiation toughness is investigated by using a modified split Hopkinson pressure bar setup with a novel fixture in conjunction with a high-speed video camera. In addition, rate sensitivity on dynamic fracture initiation toughness is also investigated for control and composites of 1.5D with fiber density of 300 fibers/mm(2) as a function of three different rates of dynamic fracture toughness (G = 1500, 2010, and 2,150 kJ/m(2)/s). Results show that for the composite of 3D-0.75 mm Nylon fiber, G(IC) values reach 0.78 kJ/m(2) (110% increase) and 1.3 kJ/m(2) (250% increase) at flock densities of 150 and 300 fibers/mm(2) compared to the control sample with the lowest G(IC) value at 0.37 kJ/m(2). The same pattern is observed for a 1.5D-0.75 mm configuration at the flock fiber density of 150 fiber/mm(2) where G(IC) value demonstrates a 75% increase compared to control conditions. The dynamic fracture initiation toughness of flocked composites demonstrates significant rate sensitivity.