Predictions of thermo-mechanical behavior of a Nicalon-CAS 0°-90° ceramic matrix composite from constituent materials properties

A physics-based model, developed previously by the authors, for the thermo-mechanical behavior of ceramic matrix composite tows is used to study the performance of a Nicalon-CAS 0°/90° laminate. For this material, the room temperature uni-axial stress—strain curve and the transverse thermal conductivity—strain curves are available from a previous experimental investigation; these curves have been used as benchmarks to assess the fidelity of the model. For the stress—strain behavior, a dynamic fiber failure model is utilized which assumes that the local transverse stressing arising from the 0°/90° composite lay-up instantaneously deactivates fiber pullout and initiates dynamic fiber failure; and hence, triggers catastrophic failure of the axially stressed regions of the tow. The model is shown to accurately predict the experimentally measured stress—strain-failure behavior of the 0°/90° laminate. For the transverse thermal conductivity behavior, the predictions show good agreement with experimental results. Furthermore, it has been confirmed that the effect of the degradation of transverse thermal conductivity is due to strain driven growth of wakedebonded cracks.