UQ eSpace

Abstract

A local podiatry company has recently purchased a state-of-the-art 3D printer for manufacturing orthotic insoles. The HP Jet Fusion will replace the existing manufacturing techniques which are time consuming and labour intensive. However, due to the innovative printing process, the long-term durability of the material produced by the device is currently unknown. Fatigue is a significant concern in the design of orthotics due to the constant cyclic loading experienced during walking or running. As such, this thesis set out to determine the suitability of the Jet Fusion printer for producing orthotics from a fatigue perspective. Following an extensive literature review, flexural fatigue testing was conducted using the ASTM D7774 standard. The tests compared the Jet Fusion samples to the performance of specimens produced through fused deposition modelling (FDM). The results indicated that the Jet Fusion and FDM samples had fatigue limits of 22.4 MPa and 7.7 MPa respectively. The number of cycles to failure and flexural stress levels were found to be logarithmically correlated for both materials. With the maximum stress experienced by orthotic insoles being in the order of 1 MPa, it was found that both materials had sufficient properties to avoid failure due to fatigue. As such, it has been concluded that from a fatigue perspective, the HP Jet Fusion Printer is suitable for use in manufacturing orthotic insoles. ii ACKNOWLEDGEMENTS I would firstly like to thank my supervisor Dr Gui Wang for taking me on at such short notice. His expertise and guidance throughout this project have been of tremendous help and I am sincerely thankful for his assistance. I would also like to acknowledge: Daniel Graham for his assistance with setting up the testing machines; the UQ Workshop for producing the mounting rig; and iOrthotics for the inspiration for the topic and provision of testing samples. Finally, my heartfelt thanks go to my wonderful family and friends for their endless support and encouragement.