Mechanical Behaviour of Photopolymer Cell-Size Graded Triply Periodic Minimal Surface Structures at Different Deformation Rates

Date

2024-05-01

Author

Yılmaz, Yunus Emre
Novak, Nejc
Al-Ketan, Oraib
Erten, Hacer Irem
Yaman, Ulaş
Mauko, Anja
Borovinsek, Matej
Ulbin, Miran
Vesenjak, Matej
Ren, Zoran

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This study investigates how varying cell size affects the mechanical behaviour of photopolymer Triply Periodic Minimal Surfaces (TPMS) under different deformation rates. Diamond, Gyroid, and Primitive TPMS structures with spatially graded cell sizes were tested. Quasi-static experiments measured boundary forces, representing material behaviour, inertia, and deformation mechanisms. Separate studies explored the base material’s behaviour and its response to strain rate, revealing a strength increase with rising strain rate. Ten compression tests identified a critical strain rate of 0.7 s−1 for “Grey Pro” material, indicating a shift in failure susceptibility. X-ray tomography, camera recording, and image correlation techniques observed cell connectivity and non-uniform deformation in TPMS structures. Regions exceeding the critical rate fractured earlier. In Primitive structures, stiffness differences caused collapse after densification of smaller cells at lower rates. The study found increasing collapse initiation stress, plateau stress, densification strain, and specific energy absorption with higher deformation rates below the critical rate for all TPMS structures. However, cell-size graded Primitive structures showed a significant reduction in plateau and specific energy absorption at a 500 mm/min rate.

Subject Keywords

cellular materials, computer simulations, experimental compressive testing, mechanical properties, photopolymer, strain rate, triply periodical minimal surface

URI

https://hdl.handle.net/11511/110020

Collections

Department of Mechanical Engineering, Article