Reliability of composite laminates through a damage tolerance approach: Applications into carbon-epoxy and glass-epoxy composite shells

In the present paper, the damaged mechanical behaviour of carbon-epoxy and glass-epoxy composite shells has been characterised into quasi-static condi tions, under different uniaxial or biaxial loadings. The experimental data obtained through different tests upon [+/-55 degrees](3) glass-epoxy lamina tes and upon [+/-55 degrees](3), [+/-35 degrees](3), [+/-75 degrees](3) car bon-epoxy shells have been compared with the numerical results based on a d amage-elastoplastic theoretical model. This damage model has been developed by introducing damage and elastoplastic parameters into layer constitutive equations. In particular, a tensor quantity has been introduced, able to s imulate damage in the elastoplastic field and to describe the new stress di stribution into lavers. The resulting strongly non-linear set of equations requires numerical solution, since generally, the mechanical characteristic s of the layers result function of their position into laminate shell, and depending on damage through its characteristic tensor variable.