Evaluating the potential for in-process eddy-current testing of composite structures

The experimental practicality and sensitivity of eddy-current testing (ECT) techniques was explored for the in-line monitoring of carbon fibre reinforced polymer (CFRP) composite materials. The project sought to determine whether; a) eddy-current testing was capable of monitoring critical properties of uncured composite materials i.e. fibre orientation and fibre density, and b) if certain manufacturing conditions, including applied pressure, scanning height, applied temperature and scanning speed, affected the ability to evaluate component quality. Experimental studies were conducted evaluate ECT under these conditions and a lab-bench test platform was developed for further studies.
Although a full suite of studies into all the conditions highlighted above was not possible during the period of the FS, key experimental results were obtained confirming the potential for ECT monitoring of fibre alignment and fibre density (pressure) in uncured composites up to a standoff of 8mm from the surface. However, the FS also demonstrated that ECT measurements struggle to penetrate deeper than one or 2 ply layers in uncured composites, most likely due to the lack of cross-linking between fibres in adjacent ply layers. Important lab capabilities, academic and industrial collaborations were also developed to support continued research through PhDs and other funding opportunities.