PSI - Issue 77

Jiongyi Yan et al. / Procedia Structural Integrity 77 (2026) 135–142 J. Yan/ Structural Integrity Procedia 00 (2026) 000–000

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tensile tests revealed higher stiffness and specific strength of small-angle corners compared to the sharp corners. All corner specimens were straightened and opened under tensile, and fractography evidenced fibre pull-out and fibre displacement, especially for sharp corners. The sharp 150° corner was modelled with homogeneous composite properties and the Hashin damage criteria, and the simulation results showed crack initiation and propagation, similar to the experiment results. Significant mechanical degradation was found in cyclic tensile tests, where the peak force and hysteresis energy decreased dramatically over cycles. This study critically linked microstructural features and their mechanical properties by identifying the mechanical weakness at 3D printed corners. 3D printed parts often have numerous corners in toolpaths (part corners, periphery, infill lattices), and these corners may act as mechanical weakness points when subject to bending, compression, stretching, all contributing to the corner opening and rupture. It is advisable that corners should avoid direct contact of loading which may result in large deformation. Acknowledgements The authors acknowledge European Union’s Horizon Europe Research and Innovation Programme under Grant Agreement (No. 101130241) and UKRI (Grants 10099133 and 10100435). The authors thank Loughborough Material Characterisation Centre LMCC and technical help from Sam Davis. References Ding, S., Zou, B., Zhang, P., Liu, Q., Zhuang, Y., Feng, Z., Wang, F., & Wang, X. (2024). Layer thickness and path width setting in 3D printing of pre-impregnated continuous carbon, glass fibers and their hybrid composites. Additive Manufacturing, 83(December 2023), 104054. Friedrich, L., & Begley, M. (2020). Corner accuracy in direct ink writing with support material. Bioprinting, 19(April), e00086. Gleadall, A. (2021). FullControl GCode Designer - open-source software for unconstrained design in additive manufacturing. Additive Manufacturing, 46(June), 102109. Liu, J., Kang, Y., Ma, C., & Wang, Y. (2022). Research on a Fiber Corner Compensation Algorithm in a 3D Printing Layer of Continuous Fiber Reinforced Composite Materials. Applied Sciences (Switzerland), 12(13). Liu, Z., Li, M., Tay, Y. W. D., Weng, Y., Wong, T. N., & Tan, M. J. (2020). Rotation nozzle and numerical simulation of mass distribution at corners in 3D cementitious material printing. Additive Manufacturing, 34(October 2019), 101190. Mollah, M. T., Moetazedian, A., Gleadall, A., Yan, J., Alphonso, W. E., Comminal, R., Seta, B., Lock, T., & Spangenberg, J. (2022). Investigation on corner precision at different corner angles in material extrusion additive manufacturing: An experimental and computational fluid dynamics analysis. Solid Freeform Fabrication 2022: Proceedings of the 26th Annual International Solid Freeform Fabrication Symposium, 872–881. Placone, J. K., & Engler, A. J. (2018). Recent Advances in Extrusion-Based 3D Printing for Biomedical Applications. Advanced Healthcare Materials, 7(8), 1–11. Qamar Tanveer, M., Mishra, G., Mishra, S., & Sharma, R. (2022). Effect of infill pattern and infill density on mechanical behaviour of FDM 3D printed Parts- a current review. Materials Today: Proceedings, 62, 100–108. Randy S., B., Charles L., T., Bay, R. S., & I, C. L. T. (1992). Stereological Measurement and Error Estimates for Three-Dimensional Fiber Orientation. Polymer Engineering and Science, 32(4), 240–253. Yan, J., Demirci, E., Ganesan, A., & Gleadall, A. (2022). Extrusion width critically affects fibre orientation in short fibre reinforced material extrusion additive manufacturing. Additive Manufacturing, 49(July 2021), 102496. Yan, J., Demirci, E., & Gleadall, A. (2023a). Are classical fibre composite models appropriate for material extrusion additiv e manufacturing ? A thorough evaluation of analytical models. Additive Manufacturing, 62(0), 1–14. Yan, J., Demirci, E., & Gleadall, A. (2023b). Single-filament-wide tensile-testing specimens reveal material-independent fibre-induced anisotropy for fibre-reinforced material extrusion additive manufacturing. Rapid Prototyping Journal, 29(7), 1453–1470. Yan, J., Demirci, E., & Gleadall, A. (2023c). 3D short fibre orientation for universal structures and geometries in material extrusion additive manufacturing. Additive Manufacturing, 69(March), 103535. Akhoundi, B., Nabipour, M., Kordi, O., & Hajami, F. (2023). Calculating printing speed in order to correctly print PLA/continuous glass fiber composites via fused filament fabrication 3D printer. Journal of Thermoplastic Composite Materials, 36(1), 162–181.