Characterisation and optimization of in-process eddy current sensor arrays using computed tomography

Due to increasing demands towards serial production of carbon fibre reinforced plastics (CFRP) the method development for process integrated quality control has become inevitable. The preforming step of Resin Transfer Moulding (RTM) offers the possibility for process integration of eddy current sensor arrays, enabling 100% inspection of produced components. However, the application of this concept needs to take into account that optimal designs of applied sensors may vary depending on tool shape and inspected material. Therefore it is necessary to design and create a set of CFRP material standards with varying characteristics considering geometry and material. The created material standards are inspected via industrial computer tomography by using methods of image processing in order to acquire quantitative information about the structure of inspected material. Afterwards eddy current measurement is conducted with varying sensor properties in order to determine the optimal structure of an eddy current array that can be integrated in preforming tools. The presented paper includes detailed description of the approach focusing on the definition of reference geometries, measurement via computer tomography and eddy current testing.