Measurement of interfacial temperatures during testing of a subscale aircraft brake

Interfacial temperatures have been measured using fibre optic inserts in the stationary brake ring during ring-on-ring, subscale dynamometer aircraft brake testing. The brake materials are carbon fibre-reinforced, carbon-matrix (carbon - carbon) composites. The temperature distribution varies with dynamometer test conditions and demonstrates the non-uniformity of contact pressure within the interface. A two-dimensional, axis-symmetric finite element model (FEM) is presented that is used to estimate temperature profiles during braking using either a constant pressure or constant energy flux assumption. The model incorporates the measured temperature-dependence of the thermal diffusivity and specific heat capacity for the composite materials. The surface temperatures obtained from the FEM are compared with the measured surface temperatures. Substantial differences between the two results are observed and discussed.