{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T16:11:56Z","timestamp":1788538316358,"version":"build-2803163510"},"reference-count":43,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T00:00:00Z","timestamp":1788480000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["12572159"],"award-info":[{"award-number":["12572159"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["12202311"],"award-info":[{"award-number":["12202311"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["12572159"],"award-info":[{"award-number":["12572159"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"award":["12202311"],"award-info":[{"award-number":["12202311"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100006606","name":"Tianjin Municipal Natural Science Foundation","doi-asserted-by":"publisher","award":["24JCQNJC00020"],"award-info":[{"award-number":["24JCQNJC00020"]}],"id":[{"id":"10.13039\/501100006606","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomimetics"],"abstract":"<jats:p>The inherent trade-off between strength and toughness in structural materials remains a critical challenge. Inspired by the hierarchical architecture of fish scales, this study proposes a novel overlapping helical composite structure. Multi-material three dimensional (3D) printing technology was employed to fabricate single-edge notched bending specimens. Quasi-static three-point bending experiment was conducted to investigate the mechanical performance of a fish scale-inspired structure. The results show that compared to the stiff bulk structure, the bio-inspired design exhibits a 60.4% enhancement in apparent fracture toughness and a 157.5% increase in energy absorption despite a reduction in flexural modulus and strength. The significant improvement may be attributed to the synergistic effects of crack deflection, which transform the fracture mode from catastrophic brittle failure to progressive damage with a stable post-peak deformation stage. Furthermore, parametric studies reveal that both the linear helical angle and its nonlinear gradient distribution critically govern the toughening efficiency. An optimal linear angle of 19\u00b0 provides the best overall performance, while a nonlinear gradient (e = 1.75) further shifts energy dissipation towards the post-peak deformation stage, achieving a higher toughening efficiency. This work establishes a fundamental understanding of an overlapping helical coupling toughening strategy and provides a promising design route for high-damage-tolerance composite structures.<\/jats:p>","DOI":"10.3390\/biomimetics11090633","type":"journal-article","created":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T15:10:53Z","timestamp":1788534653000},"page":"633","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Toughening Behavior Investigation of Fish Scale-Inspired Composite Structure with Overlapping Helical Architecture"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1941-3660","authenticated-orcid":false,"given":"Zhiquan","family":"Wei","sequence":"first","affiliation":[{"name":"School of Aeronautics and Astronautics, Tiangong University, Tianjin 300387, China"},{"name":"Tianjin Area Major Laboratory of Advanced Mechatronics Equipment Technology, Tianjin 300387, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinlan","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Aeronautics and Astronautics, Tiangong University, Tianjin 300387, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinran","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Tiangong University, Tianjin 300387, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yaozhe","family":"Yu","sequence":"additional","affiliation":[{"name":"School of Aeronautics and Astronautics, Tiangong University, Tianjin 300387, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"13416","DOI":"10.1002\/pc.29939","article-title":"Strength and toughness: Multi-particle synergism imparts rigid-toughness balance to poly(ether-ether-ketone) composites","volume":"46","author":"Zhang","year":"2025","journal-title":"Polym. 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