Thermo-mechanical damage modeling for a glass-fiber phenolic-resin composite material

The objective of this research is the development of a thermo-mechanical damage model for composite materials subject to high temperature thermal and radiative environments that are representative of large scale fires. The damage to the structure is expressed as two regions of non-charred and charred material. In the char region, the pyrolysis process of resin is complete and there are only fiber, char and gas. Homogenization methods are imposed to treat the damaged material in terms of the volume fractions associated with composite fiber, resin and char. A transport equation for the phase averaged temperature is presented using a Darcy law to account for the gas transport in the structure. Mechanical response in the composite is taken into account by solving a homogenized form of the linear elasticity equations. Required transport properties for temperature and displacement equations are based on mixture weighted properties of the fiber, gas, resin and char and are dependent on the local volume fraction of each. Numerical simulations of a two-dimensional composite clamped beam subject to radiation heat loading are presented. Overall, good agreement is obtained between the numerical predictions and experimental data for temperature and gas pressure with comparisons to the thermal experimental data of Henderson and Florio [8,9]. Results show that during early stages of heating, the decomposition of the resin results in local stress concentrations due to the increase in temperature and pressure.