Keywords: software, composites, laminates, failure envelope, interfacial stress, edge effect.

The authors propose herein a software application called MAC LAM: Mechanical Analysis of Composites and LAMinates. The software contains three modules for calculating the stresses, stiffness and strengths of fibrous composites and multi-layers. These calculations are based on classical homogeneization techniques and on a model of plates for evaluating the edge effects on the interfacial stresses in a laminate. The main features of MAC LAM, among others, are the possibility of solving problems with hygrothermal loads and complex loadings on the edges of a laminate, the versatility of the material and laminate libraries and the plot of the design failure envelopes of a laminate. MACLAM can be a worthy tool in composite structure design and a helpful software for teaching mechanics of composite materials.

The first module is called "Micromechanics" and is an application of classical formula for predicting the mechanical properties of fiber reinforced materials. The second module is called "Laminates"; it performs a mechanical analysis of multi-layers based on the classical laminates theory. The module is divided in three sub-modules: "Stiffness", "Stresses" and "Strengths". In these modules, the user must input the stacking sequence, the elastic and hygrothermal properties of the layers in the orthotropy directions. In "Stiffness", the apparent properties of the laminate such as the ABD matrix are calculated. In "Stresses", the stresses and strains in the layers for a given load are calculated by means of the classical laminate theory. In "Strength", the failure envelope of the laminate can be visualized.

The last module is a new version of a software application called DEILAM [1]. With DEILAM, one can evaluate the interfacial stresses in a symmetrical laminate by means of a model of elastic plates called M4-5N [2]. DEILAM makes a finite element resolution of the model equations. Calculations show that no singularities exist for the M4-5N model even at the edges and results converge quickly. Calculations are validated by comparing DEILAM results with finite element calculations and with Pagano's local model [3]. The originality of this new version of DEILAM is the possibility to consider different types of boundary conditions at the edges. In the module DEILAM, the user must first input the stacking sequence and the layer properties as in the previous module. Next, the loads and the meshing must be defined. The software calculates then the forces and the displacements of the model, especially the interfacial stresses. In Figure 1, an example of an adhesive joint is considered and by symmetry reasons only a half of the joint may be studied. In this figure, the interfacial stresses (normal and shear stresses) along the upper adhesive/steel interface are displayed. If delamination occurs in this adhesive joint, it is provoked mostly by the normal interfacial stress at the edges. For other multi-layers and for other mechanical or hygrothermal loads, DEILAM can calculate the interfacial stresses easily and quickly (even for a great number of layers). This module with a delamination criterion involving the maximum interfacial stresses can help predict delamination.

1

A. Diaz Diaz, J.F. Caron, R.P. Carreira, "Software application for evaluating interfacial stresses in inelastic symmetrical laminates with free edges", Journal of Composite Structures, 58, 195-208, 2002. doi:10.1016/S0263-8223(02)00123-X

2

R.P. Carreira, J.F. Caron, A. Diaz Diaz, "Model of multilayered materials for interface stresses estimation and validation by finite element calculations", Mechanics of Materials, 34, 217-230, 2002. doi:10.1016/S0167-6636(02)00102-3

3

N.J. Pagano, "Stress fields in composite laminates", International Journal of Solids and Structures, 14, 385-400, 1978. doi:10.1016/0020-7683(78)90020-3

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £135 +P&P)