Year

2022

Degree Name

Master of Philosophy (Biofabrication)

Department

School of Chemistry and Molecular Bioscience

Abstract

Surfing is a highly competitive sport, to which additive manufacturing technology can be applied to develop new solutions to improve knowledge.

The main focus of this study was to design, prototype and test 3D printed surfboard fins with incorporated sensors interfaced with an instrumented surfboard prototype. Specific aim 1 (customisation of a 3D printer in order to 3D print with carbon fibre composites) was addressed by changing the nozzle, extruder, motherboard, stepper drivers, heat bed surface, and introduction of the dry box to the Creality CR-10S 3D printer. Introduced modifications resulted in successful 3D printing using abrasive and hygroscopic filament materials. Specific aim 2 (3D printing of model samples and instrumented fins) was achieved by using a customised 3D printer to fabricate 101 rectangular samples and six instrumented fins. The surfboard fin was designed in CAD and inspired by Futures T1 Twin HC (Futures Fins). Two sensors were incorporated into the fin. The first was 3D printed in-house out of conductive PLA, and TPU filaments while the second one was a commercially obtained 350 Ω full Wheatstone bridge. Specific aim 3 (design, and manufacturing of moulds and tools used for mechanical analysis and data collection unit) was addressed by the development of the so-called pandemic tool, a Shimadzu EZ-S mechanical analyser adapter, touch probe, fin mould, mould for rectangular samples (produced from high-density poly(ethylene) (HDPE) material), and router templates. The comparison between the so-called pandemic tool and the Shimadzu EZ-S laboratory tool showed an excellent accuracy of around 20 % in a range of 0 to around 5 GPa of calculated flexural modulus. The accuracy above 5 GPa was exponentially lower. Specific aim 4 (mechanical analysis of model samples and fins) was achieved using the pandemic tool during Covid-19 pandemic related lockdowns, and the Shimadzu EZ-S between lockdowns. Mechanical analysis of rectangular samples concluded that carbon fibre reinforced Nylon 6 (CF-PA6) with prepreg composite exhibited the highest flexural modulus value (12 ± 1 GPa). The final aim (laboratory and field-testing of instrumented fins) was addressed by laboratory testing of an instrumented fin using a universal mechanical analyser. The results of a tested prototype of an instrumented fin indicated that under tension the commercial Wheatstone bridge exhibited a linear response to applied stroke in a range of up to 7.7 ± 0.1 % of a fin flex. Field-testing was achieved in two trials. The first field test involved driving with a car that had the instrumented surfboard and fins mounted onto it. The second field test involved paddling and walking the instrumented surfboard and fins in a waveless part of the ocean (Gunnamatta Bay, NSW, Australia). The preliminary data results indicate the excellent GPS accuracy of the telemetry unit. Data from sensors installed in the surfboard and fins were saved on the µSD card, while it was simultaneously transferred in real-time between the surfboard’s electronics and the transceiver connected to the laptop with a 13 Hz sampling rate.

The main outcome of this project was the development of a working prototype of a surfboard with inbuilt electronics and a set of instrumented fins.

FoR codes (2008)

0912 MATERIALS ENGINEERING, 0913 MECHANICAL ENGINEERING, 0910 MANUFACTURING ENGINEERING

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.