ABSTRACT
In Section I, Chapters 5 and 6, we have reported some specific degradation processes of laminated composite parts. We return more broadly in this chapter to the damage and failure criteria. First of all, we focus on the overall problem of damage and degradation of composite parts. We then talk about the characteristics and the general shape of a fracture criterion, in particular in the case of an orthotropic material. Then, we concentrate on the general form of the quadratic failure criterion for the particular plane stress case with the Tsai-Wu criterion and the Tsai–Hill criterion. Finally, to allow an application in the next chapter to D-D laminates, we translate the Tsai-Wu stress criterion in the strain space and take into account the mechanical properties of the damaged ply.
