PSI - Issue 49

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000–000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 49 (2023) 37–42

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICMD3M 2023 organizers Abstract This paper focuses on characterisation of localised compliance in material extrusion additive manufacturing (MEAM) for use in single wall 3D-printed orthotics. Specifically designed 3D-printed specimens were developed as representative sections of an orthotic edge to include localised compliance created by custom tool paths. Toolpath designs were created with intricate control over the nozzle position and printing conditions, including the explicit design of start and end points for each layer to avoid defects being introduced by the process. A new testing method, using cantilever testing principles, was used to evaluate the specimens’ bending stiffness. Specimens with sinusoidal waveforms of varying wavelengths and fixed amplitude at three different extrusion thicknesses were tested along with straight specimens (i.e. wavelength approaching infinity). To allow direct comparison between specimens of different thicknesses, the bending stiffness results for all specimens were normalised to the reference specimen for each thickness. Increasing the frequency of the sine waves (reducing the wavelength) led to a reduced normalised stiffness for all extrusion thicknesses. © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICMD3M 2023 organizers Keywords: Additive Manufacturing; Orthotics; MEAM; Comfort Medical Devices: Materials, Mechanics and Manufacturing Design and Classification of Compliant Geometries in Orthotics Using Extrusion Additive Manufacturing Teiba Ahmed a , Matthew Nolan-Thomas b , Andrew Gleadall a * a Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, LE11 3TU, UK b The Spine Corporation Ltd, Millennium House, Peak Business Park, Foxwood Rd, Chesterfield, S41 9RF, UK

* Corresponding author. Tel.: +441509 227578 . E-mail address: A.Gleadall@lboro.ac.uk

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICMD3M 2023 organizers

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICMD3M 2023 organizers 10.1016/j.prostr.2023.10.007