Laminated materials with plastic interfaces: modeling and calculation

Abstract

In this paper, a model of laminated plates called M4-5N and validated in a previous paper is modified in order to take into account interlaminar plasticity by means of displacement discontinuities at the interfaces. These discontinuities are calculated by adapting a 3D plasticity model. In order to compute the model, a Newton–Raphson-like method is employed. In this method, two sub-problems are considered: one is linear and the other is non-linear. In the linear problem the non-linear equations of the model are linearized and the calculations are performed by making use of a finite element software. By iterating the resolution of each sub-problem, one obtains after convergence the solution of the global problem. The model is then applied to the problem of a double lap, adhesively bonded joint subjected to a tensile load. The adhesive layer is modeled by an elastic–plastic interface. The results of the M4-5N model are compared with those of a commercial finite element software. A good agreement between the two computation techniques is obtained and validates the non-linear calculations proposed in this paper. Finally, the numerical tool and a delamination criterion are applied to predict delamination onset in composite laminates.

Enhanced layerwise model for laminates with imperfect interfaces – Part 2: Experimental validation and failure prediction

“…It is clear that the evaluation of the accuracy of the model in the present paper uses more complex results than those used by Aquino de los Rios et al in [33]. Moreover, in the present paper, the interface properties are obtained from bulk material tests instead of an identification based on fitting the sliding measurements.…”

“…In [33], a comparison of the model results with the interlaminar sliding observed by Diaz and Caron [31] at the free edge of cross-ply carbon-epoxy laminates subjected to a tension load was proposed to identify the model parameters and test the accuracy of the model. In these laminates the "interface layer" was a thin matrix layer and its properties appearing in the model were those of an elastic, perfectly plastic material: the Young's modulus, the Poisson's ratio and the yield stress.…”

“…Few layerwise models take into account imperfect interfaces and their non-linear constitutive equations. In Part 1 of this work, the layerwise model called M4-5N for the analysis of laminates with imperfect interfaces developed by Aquino de los Rios et al [33] was enhanced to accurately predict stresses, strains and displacement discontinuities across interfaces.…”

Enhanced layerwise model for laminates with imperfect interfaces – Part 1: Equations and theoretical validation

“…In [28] and not the approximation of 3D strains and displacements. Actually, the original elastic model developed in [18,19] does not make any approximation of 3D strains and displacements.…”

“…Actually, the original elastic model developed in [18,19] does not make any approximation of 3D strains and displacements. Recently, the layerwise model proposed by Aquino de los Rios et al was adopted by Duong et al in [29] to develop a layerwise finite element for laminates with imperfect interfaces in a general 3D case (not only the plane strain state assumed in [28] for the numerical resolution of the equations).…”