| The overall objective of this dissertation research is to develop a modeling and simulation approach for predicting the thermo-mechanical damage of composite materials subjected to fire environments. A three dimensional thermo-mechanical damage model is developed for glass-reinforced polymer composite materials subject to high temperature and radiative environments. The damaged composite is expressed as regions of non-charred and charred materials. Homogenization methods are used to formulate the damaged material in terms of the volume fractions associated with composite fiber, resin and char. Equations are derived that employ Darcy's law to account for the transport of the decomposed gas within the structure. The thermal damage model is implemented in Abaqus via an overlaid element approach and extended to a thermo-mechanical damage model. The solution of the mechanical response is based on the existing functions in Abaqus in order to model the nonlinear geometry using large-displacement analysis. The thermal response of chopped fiber and laminated composite materials are studied first. Overall, consistent agreement is obtained between the numerical predictions and experimental data for temperature and gas pressure. The extended thermo-mechanical damage model is then applied to small, intermediate, and large scale composite laminates and their sandwich structures subject to radiative heating and compressive loading. The predictions of temperature field match very well with experimental data. Reasonable agreement is achieved in predicting the deflection and the time-to-failure of the structure. |
