Application of the Thermoelastic Effect to Typical Aerospace Composite Materials

This paper describes a series of laboratory tests undertaken to demonstrate the application of thermoelastic measurements for use on typical woven carbon epoxy composites used in the aerospace industry. The tests undertaken showed that the woven carbon epoxy produced linear thermoelastic output with increasing load. No significant changes in thermoelastic output were observed with changes in warp direction relative to load direction. A carbon aluminium honeycomb specimen was examined and clear differences in the stress distribution were seen between the two surfaces of the honeycomb. These are attributed to local geometry changes resulting from the manufacturing methods. The results demonstrate the suitability of the thermoelastic effect to assess non-homogeneous anisotropic materials. Considerable time and cost savings could be made by the application of thermoelastic techniques to existing composite fatigue and mechanical testing programmes.