PSI - Issue 77

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ScienceDirect Structural Integrity Procedia 00 (2026) 000–000 Structural Integrity Procedia 00 (2026) 000–000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 77 (2026) 135–142

International Conference on Structural Integrity Effects of Angular Corners on Short Fiber Orientation and Mechanical Integrity in Extrusion 3D Printing Jiongyi Yan a , Minghua Cao a , Yutai Su b , Andrew Gleadall a * International Conference on Structural Integrity Effects of Angular Corners on Short Fiber Orientation and Mechanical Integrity in Extrusion 3D Printing Jiongyi Yan a , Minghua Cao a , Yutai Su b , Andrew Gleadall a *

a Loughborough University, Epinal Way, Loughborough LE11 3TU, UK b Northwestern Polytechnical University, 127 West Youyi Road, Xi’An 710072, China a Loughborough University, Epinal Way, Loughborough LE11 3TU, UK b Northwestern Polytechnical University, 127 West Youyi Road, Xi’An 710072, China

© 2026 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 ICSI organizers Abstract Angular paths and corners are common in toolpaths in material extrusion additive manufacturing and could affect shear and material flow. This study focuses on 3D printed corners by using short fibre reinforced materials regarding the fibre orientation and mechanics. 3D fibre orientation tensor at different turn angles (30°-150°) was measured, and main-axis alignment was low when it turned orthogonally, while out-of-plane alignment increased with the angles. The fibre orientation closely links to mechanical properties. Tensile tests showed decreasing response force with increasing turn angles, and failure was attributed to fibre pull-out, fibre displacement, and matrix plastic deformation. We built 2D finite-element models of the 150° corner with the composite Hashin damage criterion and energy-based damage evolution law, in order to simulate large deformation failure model. The mechanical simulation successfully captured important features of specimen fracture due to crack initiation and propagation, which agreed with the experiment. Finally, cyclic tensile of displacement-controlled modes showed fast mechanical degradation of the sharp corners (greater turn angles) and compliance of smaller turn angles. This study highlights the variation of fibre orientation and mechanical weakness at corners, especially for sharp corners. It may enlighten design strategies (e.g. lattices with angular corners) to control fibre orientation and avoid mechanical weakness. © 2026 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 ICSI organizers Keywords: 3D printing; fibre orientation; corners; tensile properties; fatigue. 1. Introduction Material extrusion additive manufacturing (MEAM), where melted or semisolid materials are extruded through a nozzle, is transitioning from rapid prototyping to structural, biomedical, and energy applications (Placone & Engler, 2018). The mechanical properties of MEAM parts are not only defined by the materials used but also dependent on Abstract Angular paths and corners are common in toolpaths in material extrusion additive manufacturing and could affect shear and material flow. This study focuses on 3D printed corners by using short fibre reinforced materials regarding the fibre orientation and mechanics. 3D fibre orientation tensor at different turn angles (30°-150°) was measured, and main-axis alignment was low when it turned orthogonally, while out-of-plane alignment increased with the angles. The fibre orientation closely links to mechanical properties. Tensile tests showed decreasing response force with increasing turn angles, and failure was attributed to fibre pull-out, fibre displacement, and matrix plastic deformation. We built 2D finite-element models of the 150° corner with the composite Hashin damage criterion and energy-based damage evolution law, in order to simulate large deformation failure model. The mechanical simulation successfully captured important features of specimen fracture due to crack initiation and propagation, which agreed with the experiment. Finally, cyclic tensile of displacement-controlled modes showed fast mechanical degradation of the sharp corners (greater turn angles) and compliance of smaller turn angles. This study highlights the variation of fibre orientation and mechanical weakness at corners, especially for sharp corners. It may enlighten design strategies (e.g. lattices with angular corners) to control fibre orientation and avoid mechanical weakness. © 2026 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 ICSI organizers Keywords: 3D printing; fibre orientation; corners; tensile properties; fatigue. 1. Introduction Material extrusion additive manufacturing (MEAM), where melted or semisolid materials are extruded through a nozzle, is transitioning from rapid prototyping to structural, biomedical, and energy applications (Placone & Engler, 2018). The mechanical properties of MEAM parts are not only defined by the materials used but also dependent on

* Corresponding author. Tel.: +447841 699210. E-mail address: a.gleadall@lboro.ac.uk * Corresponding author. Tel.: +447841 699210. E-mail address: a.gleadall@lboro.ac.uk

2452-3216 © 2026 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 ICSI organizers 2452-3216 © 2026 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 ICSI organizers

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