X-ray backscatter sensing of defects in carbon fibre composite materials

X-ray backscatter (XBS) provides a novel approach to the field of non-destructive evaluation (NDE) in the aerospace industry. XBS is conducted by collecting the radiation which is scattered from a sample illuminated by a well-defined Xray beam, and the technique enables objects to be scanned at a sub-surface level using single-sided access, and without the requirement for coupling with the sample. Single-sided access is of particular importance when the objects of interest are very large, such as aircraft components. Carbon fibre composite materials are being increasingly used as a structural material in aircraft, and there is an increasing demand for techniques which are sensitive to the delaminations which occur in these composites as a result of both large impacts and barely visible impact damage (BVID). The XBS signal is greatly enhanced for plastics and lightweight materials, making it an ideal candidate for probing sub-surface damage and defects in carbon fibre composites. Here we present both computer modelling and experimental data which demonstrate the capability of the XBS technique for identifying hidden defects in carbon fibre.