Evaluation of Delamination Induced by Low-Velocity Impact by Scanning Acoustic Microscope and Influence of Water Absorption on Delamination and Compression after Impact of CFRP.

Abstract

An investigation of water absorption on delamination by low-velocity impact loading, and compression strength and delamination growth behavior after impact by fatigue loading was carried out on quasi-isotropic laminated ([0°/±45°/90°]2s) carbon fiber reinforced epoxy matrix composite. Ply-to-ply delamination was evaluated by using a scanning acoustic microscope. Interlaminar strength was lowered by water absorption, and the impact-load-induced delamination area was increased by water absorption. Compressive strength after impact was evaluated as the sum of delaminated areas of respective ply-to-ply delamination ; when the delaminated area was large, compressive strength after impact was solely determined by the delaminated area, and no influence of water absorption was observed ; however, when the delaminated area was small, compressive strength after impact of the water absorbed specimen decreased. The fracture surface, in particular, topographic features of hackle patterns, was closely examined by a scanning electron microscope, and the fracture mechanism of compressive and fatigue failure mechanism were discussed