X-Ray Radiography Study of Delamination Growth in Notched Carbon/Epoxy Laminates

摘要

Nondestructive investigation of damage growth in a notched carbon/epoxy composite laminate subjected to compression fatigue loading is described. Coupon specimens were fatigue loaded in compression at different constant load amplitudes in an ambient laboratory environment. Damage was determined at certain intervals of load cycles using tetrabromoethane enhanced X-ray radiography. Under continued cyclic loading the major damage growth is growth of delaminations as stable cracks. In order to quantify the extent of delamination growth during cyclic loading the delaminated area was determined by a measuring microscope. Results show that delamination initiates at stress levels as low as half the static compression strength. A large amount of scatter is inherent in all fatigue data, probably related to the surface roughness of the drilled hole. It is therefore important to control the quality of holes or cut-outs in structures subjected to compression fatigue.