Using different commercial polymers and composite filaments to manufacture a small scale tidal turbine blade and performance evaluation

Abstract

This research aimed to utilize 3D printing technology, including fused deposition modelling (FDM) and Stereolithography (SLA), combined with several commercial 3D printing materials to manufacture tidal turbine blades for low-speed tidal energy. The project can be separated into blade model construction and printing, materials static and cyclic testing, and blade testing. The first section aimed to verify the feasibility of applying 3D printing technology to realize blade manufacturing. Then, the purpose of the second part was to find the materials and printing parameters which have the most superior mechanical properties, and the final part was to verify if the selected materials and printing structures could still maintain their advantages on the blade structure and prove whether the blade could meet the projected requirements in actual performance. The results proved the feasibility of manufacturing blades with various commercial materials through 3D printing technology. Most importantly, the process showed the advantages of the 3D printing process: less labour and time cost. For materials selection, nylon-based composites, including carbon nylon and glass nylon, have been proven to have the most superior mechanical properties over other materials. Despite this, their poor water resistance led to individual research on preventing water from penetrating the blade surface. As a result, two post-processing methods for the blade have been proposed and applied. After that, the projects showed that the impact of printing parameters on mechanical properties was significant, especially for infill densities and build directions. As for blade testing, the conclusion derived from static and cyclic bending tests agreed with standard mechanical testing. Besides, the optimised structure designed by Smart Slice in CURA proved to have the best bending resistance. The blade with an optimised structure has also been fabricated by 3D printing, and the bending test result validated the computing results obtained from Smart slice. On the other hand, results from the finite element analysis performed by ANSYS suggested that the blade fabricated by 3D printing still cannot achieve the same mechanical performance compared to a blade made by traditional methods. Besides, the comparison between experimental and simulation methods has also been studied with the assistance of ANSYS. The results between the two methods showed a significant similarity. However, some extra work is still required to be done in the future.