Characterisation of low energy impact damages in composites

A non-destructive examination technique using an electromagnetic testing method has been developed for the inspection of reinforced carbon fibre materials. Damage detection was performed on a total of 53 low energy impacts (from 0.5 to 10 Joules) which were induced in realistic samples supplied by the aerospace industry. The eddy-current technique employed was proven very accurate and inherently reproducible in the detection of low energy impact damages in carbon reinforced materials. These damages were below the detection threshold of other conventional NDT methods such as ultrasonic, infrared thermography and radiography. A statistical analysis, making use of probability of detection curves (POD) and receiver operating characteristic curves (ROC) has been performed in order to evaluate the performance of different inspection systems. Computer visualisation facilities were used to locate and quantify impacts on carbon materials. The technique was also proven very efficient to assess the structural integrity of CFRP and GFRP helicopter rotor blades. If correctly applied, eddy current inspection will certainly enhance the quality and efficiency of non-destructive examinations and improve the level of quality and safety required by the aerospace industry.