Progressive crushing of a unidirectional CFRP plate with V-shaped trigger

The fundamentals of progressive crushing were studied using a unidirectionally laminated carbon fiber reinforced plastic (CFRP) plate. A special test fixture was used for the test and crushing behavior of the CFRP was observed from the side. During progressive crushing, the fractured part was separated into a pillar and fronds. Fibers fractured periodically in the pillar. In contrast, fronds were delaminated without fiber fracture. The pillar carried almost all the applied load; however, the progressive crushing stress was much lower than the static compressive strength. The intervals of the periodic fiber fracture in the pillar were 50–100 μm which coincided with kink-band width of the compressive failure. Since the interval of the periodic fiber fracture varied along the pillar thickness because of the bending deformation, compressive stress also varied along the pillar thickness. The crushing stress was, therefore, much lower than the static compressive strength.