MICROSCOPIC FATIGUE DAMAGE PROGRESS IN CFRP CROSS-PLY LAMINATES

Damage progress in toughened-type carbon fibre-reinforced plastic (CFR P) cross-ply laminates under tensile fatigue loading was measured usin g the replica technique. The laminate configuration was [0/90(m)/0], w here m = 4, 8 and 12. The damage parameters, transverse crack density and delamination ratio, were determined. A power-law model was propose d, relating the cyclic strain range and the number of cycles at transv erse crack initiation. Based on experimental data, a simple shear-lag analysis combined with the modified Paris law was conducted to model t he transverse crack multiplication. An extension of the shear-lag anal ysis for laminates containing delaminations initiating from the tips o f the transverse cracks was used to conduct a modified Paris law analy sis for delamination growth.