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To predict the damage variable of a 90° ply in an arbitrary lay-up laminate subjected to a certain loading, we formulated a damage progression law that represents the damage variable as a function of the damage-associated variable based on continuum damage mechanics (CDM). Utilizing the three-dimensional laminate theory and this CDM model, we predicted the damage progression of a 90° ply in cross-ply and quasi-isotropic laminates. In this analysis, the effective compliance of Lopes' model was adopted. Additionally, the failure pressure of a filament-wound (FW) cylindrical vessel was predicted by coupling the analytical solution with the present CDM model, and the predicted failure pressure was compared with the results obtained using Christensen's failure stress criteria. As a result, it was indicated that the prediction of the final fracture of FW vessel requires the CDM approach. [ABSTRACT FROM AUTHOR]

The present paper proposes a new analytical model for predicting the effective stiffness of composite laminates with fiber breaks and transverse cracks. The model is based on continuum damage mechanics and the classical laminate theory. We derived damage variables describing stiffness reduction due to fiber breaks and its maximum value during ultimate tensile failure from the global load-sharing model. Furthermore, a simplified analytical model is presented for obtaining two damage variables for a cracked ply subjected to transverse tensile loading or in-plane shear loading. This model was developed assuming that the displacement field of the longitudinal direction can be expressed in the form of a quadric function by loosening the boundary condition for the governing differential equation. For verifying the developed model, the elastic constants of damaged composite laminates were predicted for cross-ply and angle-ply laminates and compared with the finite element analysis results. As for the appropriate expression of the effective elastic stiffness matrix of the damaged ply, we verified four types of effective compliance/stiffness matrices including the Murakami, Yoshimura, Li, and Maimí models. We found the Maimí model to be the most appropriate among these four models. Moreover, we successfully simplified the expressions for damage variables in the complicated infinite series obtained in our previous study. We also proved that this could contribute toward improving the accuracy of our analysis. After verifying the present model, the stress–strain response and failure strength of carbon- or glass-fiber-reinforced plastic cross-ply laminates were predicted using Maimí's compliance model and the simplified damage variables. [ABSTRACT FROM AUTHOR]

This study predicted transverse cracking progression in laminates including 90° plies. The refined stress field (RSF) model, which takes into account thermal residual strain for plies including transverse cracks is formulated, and the energy release rate associated with transverse cracking is calculated using this model. For comparison, the energy release rate based on the continuum damage mechanics (CDM) model is formulated. Next, transverse cracking progression in CFRP cross-ply laminates including 90° plies is predicted based on both stress and energy criteria using the Monte Carlo method. The results indicated that the RSF model and the CDM model proposed in this study can predict the experiment results for the relationship between transverse crack density and ply strain in 90° ply. The models presented in this paper can be applied to an arbitrary laminate including 90° plies. [ABSTRACT FROM PUBLISHER]