Abstract
In the present work, static and fatigue residual bending strengths of carbon fiber reinforced plastic (CFRP) laminates having impact damage are evaluated with four-and three-point bending tests. A steel ball was launched from an air gun and impacted upon CFRP laminates to generate impact damage. The delamination growth during fatigue tests and the fracture surface are observed with a scanning acoustic microscope and scanning electron microscope, respectively. The residual strengths determined by the four-point bending test are reduced, particularly when the impacted side is compressed. The degree of reduction is influenced by the propagation of surface cracks near the impact impression. The residual strengths determined by the three-point bending test are almost the same whether the impacted side is the top or the bottom. It is determined that the degree of reduction of strength is governed by the slide of the transverse cracks due to the shear force.
