Finite thermoelastic fracture criterion with application to laminate cracking analysis

A stress energy criterion for the development of a new finite size crack surface under temperature and load input, in the presence of thermal residual stresses, is established on the basis of an energy release formulation. It is shown that if a fixed specific crack opening surface energy gamma exists, an upper bound on the critical energy release can be established on the basis of the thermoelastic principle of minimum complementary energy. On the basis of a variational formulation of thermoelastic laminate analysis a relation is established which permits construction of thermoelastic solutions for cracked laminates by a simple replacement in the corresponding isothermal solution. The results described above are applied to establish relations between crack density and standard deviation of crack interdistances of crack distribution in a cross-ply laminate layer, and load/temperature inputs of the laminate. It is shown that for certain ranges of crack densities, one small to medium and one large, the standard deviation is not needed. The physical and experimental significance of the results obtained is discussed. Copyright (C) 1996 Elsevier Science Ltd