PSI - Issue 68

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 68 (2025) 942–948

European Conference on Fracture 2024 Mechanical characterization and modeling of cyclic and time dependent behavior of a soft 3D printed photopolymer A. Avanzini a *, D. Battini a , S. Bonometti a , F. Libonati b a University of Brescia, Dept.of Mechanical and Industrial Engineering, Via Branze, 38, 25123, Brescia, Italy b University of Genoa, Dept. of Mechanical, Energy, Management and Transportation Engineering, via all’Opera Pia, 15/A, 16145 Genova, Italy Abstract TangoBlackPlus © (TB+) is a 3D printable photopolymer frequently employed in advanced materials, as additively manufactured biomimetic composites and metamaterials, or soft actuators based on shape memory effects. Thorough knowledge of its mechanical response is essential to identify constitutive laws for the modelling of innovative devices or fine tuning of simulations of the fracture process. In the present work we investigated the response of TB+ under different types of mechanical loading, including uniaxial tension at different strain rates, stepped stress relaxation and cyclic imposed loads. The experimental results were used to evaluate the predictive capabilities of visco-plasticity modelling approach. The Bergstrom-Boyce (BB) model showed remarkable accuracy, as also verified through FE implementation, allowing prediction of large deformation, time-dependent response and residual strain resulting from cyclic loading. © 2025 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 ECF24 organizers Keywords: Additive Manufacturing, Photopolymer, Biomimetic materials, Viscoplasticity 1. Introduction TangoBlackPlus © (TB+) is a flexible elastomer available to PolyJet © technology, an additive manufacturing (AM) process based on photopolymer jetting. This technology involves the deposition of droplets of photopolymer resins onto a print bed, followed by curing with ultraviolet (UV) lamps to form a polymerized layer. Then, similarly © 2025 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 ECF24 organizers

* Corresponding author. Tel.: +39 030 3715526 E-mail address: andrea.avanzini@unibs.it

2452-3216 © 2025 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 ECF24 organizers

2452-3216 © 2025 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 ECF24 organizers 10.1016/j.prostr.2025.06.154