Failure analysis of CF/epoxy hollow beam components using digital image correlation and acoustic emission analyses

Abstract

Testing of carbon fibre epoxy hollow beam components was undertaken using digital image correlation and acoustic emission techniques. Static and fatigue testing was used to characterise the damage mechanisms of the components under two separate compressive loading cases. Firstly, the load was transferred via simple contact of a rectangular pusher plate, whilst in the second case the plate was bolted to the top surface of the beam. Digital image correlation determined the full field deformation and strain on the beams’ side while strain gauges validated the accuracy of the measurements during testing. Acoustic emission analyses provided a more in-depth inspection of the failure location as the first damage event was not visible from an external visual inspection. Acoustic emission captured a precise map of damage events which indicated the failure location at a point under the loading plate edge and centred at the corner of the beam structure. While digital image correlation gives a full field view of strains on the component surface before and after failure, the acoustic emission analysis shows a higher sensitivity to the characterisation of damage, providing a more conservative and accurate estimate of the failure behaviour.