An investigation of matrix cracking damage evolution in composite laminates – Development of an advanced numerical tool

In this study, progressive matrix cracking damage analyses are performed for general symmetric laminate with any number of plies under in-plane tensile/shear loading condition. To predict initiation and evolution of matrix cracking in each layer of such laminate, an advanced numerical tool is developed here. The tool consists of, (i) a micromechanic-based damage model to find stiffness reduction of the laminate and damage parameters due to the presence of matrix cracking, (ii) an energy-based evolution law to predict initiation and progression of the damage and (iii) a finite element (FE) basement to implement the constitutive damage law analyzing laminates under complex boundary conditions. The stress transfer method is used to find the displacement and stress fields in a unit cell confined between two consecutive matrix cracks. Then, the degradation of elastic constants and damage parameters are calculated for each damaged layer of the laminate. New formulation is also developed to implement the evolution law at integration points to eliminate the length dependency of the energy-based damage criterion. The crack density is used as the only state variable which controls the damage state. An eight node element is developed using the full layerwise plate theory and the damage constitutive law is implemented in the formulation of a user defined element routine in Abaqus commercial software. The developed procedure is validated favorably with published experimental and numerical results for matrix cracking damage mechanism in general symmetric laminates. Concurrent progressive damage analyses in different plies of various laminates are also investigated and some results which are rarely available in the literature are presented in this paper.