Modeling laminated composite structures as assemblage of sublaminates
A mixed variational principle is presented for stress analyses of laminated composite structures with or without delaminations and discontinuities. Of particular interest is the use of a functional involving interlaminar stresses and in-plane strains, instead of strain or complementary energy. A laminate is then treated as an assemblage of sublaminates with assumed variations of displacements and interlaminar stresses through the thickness of each sublaminate. Application of the variational principle, at this stage, reduces the problemn to a set of differential equations and constitutive relations for each sublaminate similar to those encountered in higher order plate theories, as well as continuity conditions of displacements and equilibrium of surface tractions at perfectly bonded interfaces. It is demonstrated with an example of a disbonded laminate modeled as an assemblage of two sublaminates that the mixed boundary conditions at a partly bonded interface yield concentrated forces at the disbond tips. This is the exact form of stress singularity in this model. Finite element analyses are utilized for obtaining solutions with more sublaminates. Stress fields and energy release rates at delamination tips are compared with elasticity and standard finite element solutions in another illustrative example.
scientific article; zbMATH DE number 4037359