A novel image analysis procedure for measuring fibre misalignment in unidirectional fibre composites

A novel image analysis procedure named Fourier transform misalignment analysis (FTMA) for measuring fibre misalignment in unidirectional fibre composites is presented. Existing methods are briefly illustrated and evaluated. The FTMA-method is presented, describing the specimen preparation and elaborating how the image analysis algorithm uses Fourier transformation and a least squares method to compute single fibre orientations. On the basis of parameter investigations the robustness of the FTMA-method is investigated. Software generated micrographs with known fibre misalignment are used to determine the precision of the method. The precision is used, along with computation time and memory usage, to benchmark the FTMA-method against the existing multiple field image analysis (MFIA) method. It is found that the FTMA-method is at least as accurate as existing methods. Furthermore, the FTMA-method is much faster than the existing methods, completing a typical analysis in approximately 1 min. Overall, it is concluded that the FTMA-method is a robust, precise and time efficient tool for determining fibre misalignment in unidirectional fibre composites, offering a higher degree of detail than the existing MFIA-method.