A STUDY ON RESIDUAL FATIGUE BENDING STRENGTH AND DAMAGE BEHAVIOR OF CFRP COMPOSITES SUBJECTED TO IMPACT LOADINGS

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 exp eriment are CF/EPOXY and CF/PEEK orthotropy laminated plates with two- interfaces [theta degrees(4)/90 degrees(4)](S). A Steel ball launched by an air gun collides against the CFRP laminates to generate impact d amages. The damage growth during a bending fatigue test is observed by a scanning acoustic microscope (SAM). When the impacted side is compr essed, 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 th e transverse crack generated near the impact point. In the case of imp acted-side tension, however, the fracture ee develops toward the impac t point from the edge of interface-B delamination.