Robot-guided eddy current measurement of yarn orientation change during stepwise 3D draping

The production of high-performance carbon fiber-reinforced plastics (CFRP) involves the draping of the carbon fiber fabrics to a 3D shape, a process which changes the orientation of the load-bearing fibers in the fabric and therefore has a high impact on the strength of the final composite part. This paper investigates the change in yarn orientation during the 3D-draping process of biaxial carbon-fiber non-crimp fabrics to a hemispherical shape. The draping process is partitioned in several steps, after each of which the yarn orientation in the fabric is measured by a robot-guided eddy current scanning system. The results show that the greatest change in yarn orientation occurs in the final stages of the draping. Furthermore, the yarn orientation change is not linear - in some regions, later draping steps reverse the yarn orientation change from earlier steps. These results are of high importance for a better controlling of the textile draping process.