Compression Failure of Carbon Fiber-Epoxy Laminates in Fire

Abstract

This paper investigates the compression failure of carbon fiber-epoxy laminates when exposed to fire. The investigation gives insights into the softening and failure of carbon-epoxy laminates supporting compression loads in the event of aircraft fire. A thermomechanical model is presented for calculating the compression properties and failure of polymer matrix laminates under combined loading and one-sided heating by fire. The accuracy of the model to predict the failure time of carbon-epoxy laminates at different compression load levels and fire temperatures is determined with structural fire tests performed on woven carbon-epoxy panels. The model predicts a gradual increase in the failure time of the laminate with decreasing compression stress (down to 10% of the room temperature buckling load) and decreasing heat flux (or temperature) of the fire. This was confirmed by the fire tests, which showed good agreement between the calculated and measured failure times. Compression failure of the laminate usually occurred within relatively short times (less than a few minutes) by viscous softening of the polymer matrix. For long failure times, matrix decomposition was shown to influence the failure process. Parametric analysis using the model reveals that raising the glass transition temperature of the polymer matrix increases the compression failure time of laminates in fire. However, only small improvements to the failure time are achieved by raising the glass transition temperature of laminates exposed to high-temperature fires typical of postcrash aircraft accidents. = an empirical exponent of the remaining resin content fitted to experimental data to best describe the order of the relationship between polymer mass loss and residual strength Q p = decomposition energy of polymer matrix R rc T = remaining resin content T = temperature T g = chemical glass transition temperature T k = mechanical glass transition temperature t = heating time w f = final remaining mass fraction of polymer resin x = through-thickness coordinate = heating rate of laminate = laminate density c 0 = room temperature compression strength c R = residual compression strength c T = compression strength as a function of temperature x k = strength at position x k in the through-thickness direction of the laminate = rate of strength decay

A study of material removal and surface characteristics in micro‐electrical discharge machining of carbon fiber‐reinforced plastics

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Fire structural resistance of basalt fibre composite

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