The employment of 0/90 unsymmetric samples for the characterisation of the thermo-oxidation behaviour of composite materials at high temperatures

The present paper explores the possibility to employ 0/90 unsymmetric plates as a tool for characterising the thermo-oxidation behaviour and the environmental ageing of composite materials at high temperature. The continuous monitoring of the out of plane displacements and the curvatures of such samples can be used for the identification of the thermo-oxidation induced irreversible chemical strain/stress build up and material property changes. A model has been developed to take into account the effects of thermo-oxidation on the time-dependent plate curvatures. Simulations show that 0/90 unsymmetric plates are very sensitive to thermo-oxidation induced changes, thus effective for capturing the searched thermo-oxidation effects. The predictions of the present model may serve for parametric studies and design of tests.