PSI - Issue 72

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ScienceDirect

Procedia Structural Integrity 72 (2025) 491–498

12th Annual Conference of Society for Structural Integrity and Life (DIVK12) Aging Effects on the Bending Performance of DLP and FDM Printed PLA Božica Bojović a , Zorana Golubović a, * Aleksa Milovanović b

a Faculty of Mechanical Engineering, University of Belgrade, 11120 Belgrade, Serbia b Innovation Center of Faculty of Mechanical Engineering, 11120 Belgrade, Serbia

Abstract This research explores how 3D-printed PLA parts change over time, both mechanically and structurally. Two common 3D printing methods: Fused Deposition Modeling (FDM), which uses PLA filament, and Digital Light Processing (DLP-LCD), which uses a PLA-like resin are compared. Test specimens were examined right after printing, then again after one and two months of aging under everyday indoor conditions that included regular cleaning to simulate real-world use. To observe changes, three-point bending tests were used to assess flexural strength, stiffness, and strain, and microscopy helped reveal structural changes inside the materials. Specimens made with FDM printing showed minimal changes over time. Their stiffness (flexural modulus) remained mostly unchanged, strength dropped slightly (by up to 9%), and flexibility (strain at failure) increased moderately (up to 17%). This suggests the material stayed strong and elastic, with a slight shift toward being more ductile. In contrast, the PLA-like resin specimens printed with DLP-LCD technology showed a clear decline in performance. Their stiffness and strength dropped significantly - down to about 45% and 43% of their original values — and their flexibility increased similarly. These results point to a shift in the material’s behavior: it became softer and more flexible, but at the cost of structural integrity. In summary, FDM-printed PLA held up well over time, making it a reliable choice for parts that need to retain their shape and strength. On the other hand, the resin-based parts showed signs of weakening, highlighting how important it is to match the right material and printing method to the demands of the final application. © 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 Aleksandar Sedmak, Branislav Djordjevic, Simon Sedmak Dr. Simon Sedmak, ssedmak@mas.bg.ac.rs, Innovation Center of Faculty of Mechanical Engineering, Belgrade, Serbia

* Corresponding author. E-mail address: zzgolubovic@mas.bg.ac.rs

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 Aleksandar Sedmak, Branislav Djordjevic, Simon Sedmak Dr. Simon Sedmak, ssedmak@mas.bg.ac.rs, Innovation Center of Faculty of Mechanical Engineering, Belgrade, Serbia 10.1016/j.prostr.2025.08.131