Impact Damage Assessment of Composites

Abstract

The influence of impact damage on the structural performance of composite laminates was investigated by a joint effort and included nondestructive evaluation (NDE), mechanical testing and analysis. The impacted NASA Industry Standard Compression After Impact test specimen was chosen. Damage characterization incorporated ultrasonic and radiographic methods. Computerized and manual ultrasonic testing from both sides of the test panels provided accurate information on the damaged area. The findings were confirmed by a destructive X-ray microfocus technique combined with an opaque penetrant for damage enhancement. From the NDE data, a simplified damage model was constructed and analyzed for strength and stability. Failure loads and modes were predicted and compared to compression after impact test results. Preliminary tests showed very good agreement.

Partial volume correction for approximating crack opening displacements in CFRP material obtained from micro-focus X-ray CT scans

“…Common operating voxel resolutions of the order of 5 microns have been used in previous studies on impacted composites [2][3][4][5][6][7]; the significant limiting factor affecting resolution is the X-ray focal spot size and specimen size [8]. Whilst this resolution is useful for identifying the components of composite damage, quantification of key features, such as crack opening displacements (CODs) within impacted carbon fibre materials requires a higher fidelity.…”