Model of multilayered materials for interface stresses estimation and validation by finite element calculations

The mechanical problem discussed in this paper focuses on the stress state estimation in a composite laminate in the vicinity of a free edge or microcracks. To calculate these stresses, we use two models called multiparticle models of multilayered materials (M4). The first one can be considered as a stacking sequence of Reissner-Mindlin plates (five kinematic fields per layer), while the second is a membranar superposition (two fields per layer plus a global one). These simplified models are able to provide finite values of interfacial stresses, even on the free edges of a structure. The current paper consists of validating the M4 by a finite element analysis through describing the stress fields in both a (0,90)_s laminate in tension (free-edge problem) and a transversally microcracked (0,90)_s laminate. A comparison of the various energy contributions helps yield a mechanical perspective: it appears possible to define an interply energy as well as a layer energy, these energies expressing the FE 3D reality.