{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T09:03:55Z","timestamp":1789376635212,"version":"build-2803163510"},"reference-count":39,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,12]],"date-time":"2026-09-12T00:00:00Z","timestamp":1789171200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Hubei Provincial Natural Science Foundation Huanggang Joint Fund Key Project","award":["2025AFD322"],"award-info":[{"award-number":["2025AFD322"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Node fillet radius has a pronounced effect on the compressive performance of fused deposition modeling (FDM)-printed polymer honeycombs, yet quantitative design guidelines for PETG auxetic structures remain scarce. The effects of gradient node fillet radii (R0\u2013R7 mm) on the load-bearing capacity, deformation mechanisms and energy absorption of PETG auxetic honeycombs were investigated by quasi-static compression tests. Results reveal a dual competing mechanism: stress homogenization improves crushing stability, whereas nodal cross-section weakening reduces structural stiffness. Among the six configurations, R5 (35.7% radius-to-cell ratio) achieved the best balanced performance, with a peak strength of 0.35 MPa and specific energy absorption of 335.25 J\/kg, and crushed progressively without catastrophic load drops. At R3 mm, nodal weakening raised the working stress and caused premature brittle fracture; at R7 mm, excessive filleting lowered peak strength to 0.30 MPa, slightly below the unfilleted control. Although unfilleted R0 showed the highest total energy absorption, specific energy absorption (342.62 J\/kg) and efficiency (46.97%), its right-angle nodes induced disordered brittle collapse that compromises service safety. The resulting Pareto trade-off shows that moderate filleting best balances strength and energy absorption, providing parameter guidance for the topology optimization of 3D-printed polymer lightweight protective components.<\/jats:p>","DOI":"10.3390\/polym18182226","type":"journal-article","created":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T08:10:23Z","timestamp":1789373423000},"page":"2226","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effects of Node Fillet Radius on Compressive Properties and Energy Absorption of FDM-Fabricated PETG Auxetic Honeycombs"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-4975-0730","authenticated-orcid":false,"given":"Xin","family":"Kuang","sequence":"first","affiliation":[{"name":"School of Electromechanical and Intelligent Manufacturing, Huanggang Normal University, Huanggang 438000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhangyong","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Electromechanical and Intelligent Manufacturing, Huanggang Normal University, Huanggang 438000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruiyong","family":"Duan","sequence":"additional","affiliation":[{"name":"School of Electromechanical and Intelligent Manufacturing, Huanggang Normal University, Huanggang 438000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guangchao","family":"Zhan","sequence":"additional","affiliation":[{"name":"School of Electromechanical and Intelligent Manufacturing, Huanggang Normal University, Huanggang 438000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"112348","DOI":"10.1016\/j.tws.2024.112348","article-title":"A Review on Energy Absorption Performance of Auxetic Composites with Fillings","volume":"205","author":"Hu","year":"2024","journal-title":"Thin-Walled Struct."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"119838","DOI":"10.1016\/j.engstruct.2025.119838","article-title":"Mechanical Metamaterials with Negative Poisson\u2019s Ratio: A Review","volume":"329","author":"Zhang","year":"2025","journal-title":"Eng. 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