The mechanics of interface fracture in layered composite materials: (7) adhesion toughness of multilayer graphene membranes - nanoscale interface fractures

Adhesion toughness between graphene membranes and substrate is mode mixity dependent. Various experimental and analytical methods are discussed on the calculation of the adhesion toughness. The presence of sliding in multilayer graphene membranes increases the fracture mode mixity G_I/G_II, leading to a decrease in adhesion toughness measurements when using the circular blister test under either pressure load or point load. Once the mode I and II adhesion toughness are known, the adhesion toughness under general service loading conditions can be determined by using mixed mode partitions based on 2D elasticity and a linear failure criterion. The adhesion energy defined in literatures is generally different from the adhesion toughness unless the mode I adhesion toughness is equal to mode II adhesion toughness.