Delamination fractures in composite materials

Delamination, that is, crack growth between different plies, is a common failure mode in laminated composites. Analysis, testing, and designing against delamination crack growth is discussed in the present chapter. In comparison with crack growth in isotropic metals, delamination is complicated by elastic orthotropy, mixed-mode crack growth, and large-scale bridging (LSB).

This draws attention to the need for dedicated fracture mechanics to test both specimens and theory in order to characterize delamination in a proper manner. For instance, J-integral specimens are preferred for the determination of bridging laws (traction-separation laws) to describe LSB. Micromechanical models describing toughening due to crack bridging are also briefly reviewed..