A study on residual fatigue bending strength and damage behavior of CFRP composites subjected to impact loadings

Abstract

This paper evaluates the static and fatigue bending strengths of CFRP (carbon-fiber reinforced plastic) laminates having impact damages, e.g., foreign object damages (FOD). Composite laminates used in this experiment are CF/EPOXY and CF/PEEK orthotropy laminated plates with two-interfaces [0°4/90°4]s A steel ball launched by an air gun collides against the CFRP laminates to generate impact damages. The damage growth during a bending fatigue test is observed by a scanning acoustic microscope (SAM). When the impacted side is compressed, the residual fatigue bending strength of CF/PEEK specimen P is greater than that of CF/EPOXY specimen B. On the other hand, when the impacted side is in tension, the residual fatigue bending strength of CF/PEEK specimen P is smaller than that of CF/EPOXY specimen B. In the case of impacted-side compression, the fracture is propagated from the transverse crack generated near the impact point. In the case of impacted-side tension, however, the fracture develops toward the impact point from the edge of interface-B delamination.