As we have seen in Chapter 7, first ply failure (FPF) is the load at which the first crack appears in a lamina, and last ply failure (LPF) is an approximation to the load for which the laminate is no longer able to sustain any load. In Chapter 7, predictions of FPF and LPF are done with strength failure criteria (Sections 7.1, 7.2, and 7.3). Strength failure criteria have at least three limitations, as follows: