Date of Graduation


Document Type



Failure in materials occurs as a result of damage accumulation. Damage in composite material can be studied applying the continuum approach or the micromechanical approach. The continuum approach treats the composite material as transversely isotropic medium. In this approach, there is no distinction between the fiber and the matrix. The micromechanical approach studies the different damage mechanisms such as, fiber damage, fiber/matrix debonding, and matrix cracking. The research in this dissertation is focused on applying the micromechanical approach. A micromechanical macrobrittle damage (damage under monotonic load) model is developed and compared with available experimental data. Then an anisotropic fatigue damage (damage under cyclic load) model is derived and integrated with the micromechanical macrobrittle damage model to develop a micromechanical fatigue damage model. Great effort was invested in developing a physically and mathematically consistent representation of damage evolution. The model was tested on [±45], [0/±30], and [0/90/±45] T300-5208 laminated composite.