Modeling advanced composite materials can quickly become overwhelming when one starts to consider detailed phenomenological behavior of multilayered off-axis laminates with microstructural damage development resulting from aggressive thermal and mechanical cyclic loading. As such, an attempt is underway to develop a comprehensive solution algorithm, formulated from first-principle (simplified) criteria, which provides reasonable estimates of laminate behavior. The objective is to develop a detailed model based upon a series of modules each of which is derived from simplified theories. The formulation of the model in this manner is intended to reduce the complexities associated with modifying detailed micromechanical (or other) models to account for a myriad of laminate geometries, damage mechanisms and loading conditions.
This paper is an extension of previous works presented by the authors which outline the development of a simplified micromechanics model as described above. In particular, this paper examines required modifications to classical shear-lag models for considering fiber failure and other associated mechanisms such as fiber pull-out and laminate failure. The approach adopted herein assumes the development of an “effective applied stress” to undamaged fibers neighboring fibers which have fractured and/or have slipped (pull-out). Both modifications to the equilibrium relationship, as well as the net effect on the laminate strain due to these damage mechanisms are explored under specific laminate and loading conditions.