Understanding the Performance of 3D Printed Carbon Fibre Reinforced Polymer (CFRP) and Carbon Continuous Fibre Filament (CFF)

Finan, Michael (2018) Understanding the Performance of 3D Printed Carbon Fibre Reinforced Polymer (CFRP) and Carbon Continuous Fibre Filament (CFF). [USQ Project]


In the last decade, additive manufacturing techniques, such as fused deposition modelling (FDM), has gained popularity due to the ease of use, speed of printing, and low cost of machine and materials. Markforged has produced a material that is nylon polymer with short carbon fibre embedded in it, this strengthens the material greatly resulting in stronger prints. This material, called Carbon Fibre Reinforced Polymer (CFRP) can be combined with a technology called carbon Continuous Fibre Filament (CFF), which is where a polymer has a carbon fibre embedded in it, this can produce a material that is stronger than aluminium in tensile testing. This project looks to test the material in the real-world scenario of a bicycle crank arm. The chosen design was tested using FEA simulation to determine the weak points, which was then optimised. Both the original and optimised design were printed and tested to determine how the material and technology performed when applied to a specific scenario. This specific scenario of a bicycle crank arm tests how the part performs with an intricate spline drive, and how it performs as a moment arm. Testing was done with static loadings determine the specimen’s breaking point and the weakness in the design. The static loading applied a force to the end of the 175mm bar and the deflection at the end of the crank was recorded and the load was graphed against this deflection.

The materials tested were Steel, Nylon, CFRP and the CFRP+ CFF. The CFRP+ CFF part fractured at 712N with 21mm of deflection. The 3D printed test specimens with CFF performed the best, followed by CFRP, and finally the nylon performed the worst with 194N and 135mm of deflection with no failure. The steel crank arm broke the testing apparatus at 1.1KN but gave a good indication of the materials performance. From the testing it was clear that the carbon CFF had a significant impact on the material stiffness and strength. The parts containing carbon CFF performed in a linear manor allowing their deflection to be predicted and the failure was as expected. The geometry plays an important role in the part strength, and the optimised design performed better than the original part. The FEA results and the real-world testing results were different due to the 3D printed material having a much higher porosity due to the printing method.

The key outcomes for this project was to gain a further understanding of what the material is capable of and what it’s limitations are within the manufacturing industry. This was better understood through testing, at the peak load, a pair of cranks would be able to support an average weighed adult, however if any further load was applied, particularly a dynamic load, the part would fail. It is suggested that further testing be conducted, as well as more variables changed in the print settings to ensure the part is optimised for this particular application. And in general, this technology could be applied to any project that requires a small number of parts, and the parts can be optimise for strength, weight or cost. It is best suited for prototypes, complex geometry, or one off parts, due to the time taken to print, it’s limited strength and the ability to generate complex geometry is a relatively short time.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering (1 Jul 2013 - 31 Dec 2021)
Supervisors: Islam, Mainul
Qualification: Bachelor of Engineering (Honours) (Mechanical)
Date Deposited: 31 Aug 2022 04:35
Last Modified: 29 Jun 2023 01:31
Uncontrolled Keywords: Carbon Fibre Reinforced Polymer (CFRP); carbon Continuous Fibre Filament (CFF)
URI: https://sear.unisq.edu.au/id/eprint/40722

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