Improving the quality of thermoplastic composite corners using laser-assisted tape placement

Over the past 25 years, interest in using thermoplastic composites in commercial and military aircraft has steadily increased. Combining winding and laser-assisted tape placement is a promising method to manufacture thermoplastic structures out-of-autoclave, as has been recently shown by manufacturing a variable stiffness, unitized, integrated-stiffener thermoplastic wingbox at the University of Limerick. The corner regions are one of the critical points of the structure and need to be characterized in more detail, for example by unfolding L-shaped samples in a 4-point bend test. In this work, samples with both 10mm and 3mm radii have been manufactured and tested. Two manufacturing parameters are varied: the speed and acceleration around the corners. The tests show that decreasing the radius has a positive influence on the corner strength. In addition, the highest speed and acceleration investigated lead to the highest corner strength for the same radius.