Rapid prototyping with fiber composites - Manufacturing of an amphibious UAV

Abstract: Rapid prototyping has in the last few years gained an ever increasing central role in projects thanks to its agile benefits. Because of that, boundaries regarding what can be accomplished can be pushed and new techniques for achieving goals can be explored at a reasonable cost. A challenge that remains though, is to be able to prototype rapidly with advanced materials such as fibre composites, in a cost effective and reliable manner. The Maritime Robotics Laboratory at KTH Royal Institute of Technology is developing an unmanned fixed-wing aerial vehicle that is also submersible and takes off from the water surface. The design for the craft is completely novel in order to meet the necessary requirements.  The goal of this master's thesis is to assist with the design of the craft in order to ensure its manufacturability. When the design was finished, a structural analysis of said design was performed, utilizing finite element software. This ensured that the correct amount of material was used, where it was needed. Lastly, and the main scope of this thesis, is the manufacture of the components which make up the craft. Several options were considered during the manufacturing process, like vacuum infusion and prepreg due to the varying size and complexity of all the components which are to be manufactured.  More conventional materials (such as medium density fibreboard) was decided upon when manufacturing the molds for the main airframe of the craft due to its sheer size. The method which was decided upon for building all auxiliary components was to use inexpensive 3D-printed polylactic acid molds, coated with glass fibre reinforce adhesive polytetrafluoroethylene film, in conjunction with a low-temperature prepreg. The trials eventually turned out successful and the components which were built using this technique came out according to their specified dimensions that were provided and in accordance to the structural analysis which was conducted. This is promising for rapid prototyping in where only entry-level composites manufacturing equipment is accessible.