Studies on mixed mode interlaminar fracture toughness of m55j/m18 carbon/epoxy laminates

Experimental studies are carried out to determine the interlaminar fracture toughness of unidirectional laminates made of M55J/M18 carbon/epoxy material under different mixed mode ratios (GI /GII ). A mixed mode delamination fracture criterion using mixed mode bending specimens is developed. It is observed that when loading in mode I is predominant, GII has a considerable value but the opposite is not true when mode II is predominant.