Abstract
The propagation behavior of mode I, mode II and mixed-mode I+II interlaminar cracks at 0°/0°, +30°/-30°, +45°/-45° and +60°/-60° interfaces in graphite/toughened epoxy laminates, IM600/#133,was studied under static loadings. The mixed-mode bending (MMB) method was used for mixed-mode I+II tests. The interlaminar fracture toughness increased with crack extension due to significant fiber bridging and transverse cracking but remained constant for 0°/0° interlaminar cracks subjected to mode I dominated loading. The effects of the mixed-mode ratio and fiber orientation on interlaminar fracture toughness at crack initiation were discussed.
