3D Printed Unidirectional Carbon Fibre Reinforced Polymers for aerospace applications

Abstract

In order to save weight and reduce the impact on the environment, the aerospace industry keeps searching for strong and lightweight materials to reduce fuel consumption. A relatively new manufacturing technique made it possible to print nylon, reinforced with continuous unidirectional carbon fibres on a layer-by-layer basis and praised itself for making materials as strong as Aluminium 6061-T6. In this study, several coupons were 3D printed and tested in tensile, compression and three point bending mode to determine the material properties. When loaded in the direction of the fibres, the material did not live up to the upper limit of the rule of mixtures for fibre reinforced composites, which is mainly due to the amount of voids in the material. These voids were discovered when studying the micro-structure of the material and were both in between the layers, as well as in the layers themselves.
The mechanical tests were performed to validate constructed finite element models, simulated in Abaqus/CAE. The simulation results showed some mismatches with the mechanical test results, which were caused by the assumptions made to simplify the models. Finally, an air plane chair bracket, which has as task to transfer loads from the back seat panel to the chair, was modelled, simulated and designed. Major issues in the designing process were the limitations of the printer, such as not being able to choose which exact areas to reinforce in a specific layer. The final design of the chair bracket was manufactured and was tested to see if it could withstand a load of 375 N. The part did not fracture under the load, but a high displacement of the back seat was observed, as well as damage occurring at other locations than the simulations indicated.

The study showed that this 3D printing technique is able to print structural aerospace parts, given that the part is not too complex and that it is loaded in a static nature. More freedom in the design software of the 3D printer could allow the user to successfully design more complex structural aerospace parts. Since the constructed parts were only tested under static loading, further research has to be conduction into dynamic loading of these parts before it is possible to actually implement these in air planes.