Surface topography evolution of woven thermoplastic composites under deformation

The evolution of architectural distortion of woven composites can significantly influence the deformation behaviour but is challenging to measure experimentally. In this paper, two techniques are proposed to examine the out-of-plane topography of composites under deformation measured using stereo Digital Image Correlation (DIC). The primary method relies on fitting a surface to the data to compensate for global sample distortion and reveal local topography while the supplementary method uses local curvatures calculated for each data point on the surface. These methods have been applied to thermoplastic composites with different weave architectures, matrix and fibre materials. Topography results show good agreement in magnitude and form with mesoscale Finite Element Analysis (FEA). The methods improve existing experimental techniques to examine local effects with multiple applications regarding deformation, defect detection and failure analysis of composites.