Development & assessment of equipment and procedure for continuous ultrasonic welding of thermoplastic composites

Ultrasonic welding (USW) is a technique used to bond materials together by heating the bonding surfaces with ultrasound. Its main advantage is the high processing speed, which is in the order of seconds. However, application of this technique with thermoplastic composite (TPC) materials is still limited. One of the areas in which almost no research has been done is continuous ultrasonic welding of TPCs. This MSc thesis therefore explores some possibilities on a continuous variant of the ultrasonic welding process, applicable to TPCs. To do this, a machine was designed and developed which has a single, horizontally moving axis. This machine is able to weld in a straight line, complying to any thickness changes in the material. The design has been tested by comparing welds made with it with welds made on a conventional machine. The machine works correctly, but the frame has to be made stiffer, for which recommendations are made. Research was conducted into multiple-pass welding as well, as it is a potential solution for some of the problems sequential ultrasonic welding is facing. This research consisted of welding lap shear specimens in two separate passes, and comparing the produced weld with a reference (single-pass) weld. It is shown that the welding processes and welds are very similar, which makes current knowledge on ultrasonic welding applicable to multiple-pass welding.Structural Integrity & CompositesAerospace Structures and MaterialsAerospace Engineerin