ABSTRACT
This apparatus is a computerized turn-key device capable of non-destructive testing of aircraft brake disks at eight locations simultaneously. The automatic non-destructive tester uses a step heating method to measure the thermal diffusivity (and hence thermal conductivity) of carbon-carbon brake disks. The test requires about five minutes. The basic idea is that one flat surface of the disk is subjected to a reasonably constant uniform heat flux and the resulting temperature response of the opposite face is monitored. Thermal diffusivity values are calculated from the temperature rise curves. The method used to calculate diffusivity values from the data generated with the non-destructive tester involves parameter estimation techniques.
Several apparatuses have been built, tested and supplied to users. Reproducibility of averaged diffusivity results is routinely within 3% on regular disks. The average diffusivity values agree within several percent with those obtained on small samples using our standard laser flash apparatus.
