{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,18]],"date-time":"2026-04-18T19:21:25Z","timestamp":1776540085433,"version":"3.51.2"},"reference-count":41,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"71","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sci. Robot."],"published-print":{"date-parts":[[2022,10,26]]},"abstract":"<jats:p>Aside from some living tissues, few materials can autonomously learn to exhibit desired behaviors as a consequence of prolonged exposure to unanticipated ambient loading scenarios. Still fewer materials can continue to exhibit previously learned behaviors in the midst of changing conditions (e.g., rising levels of internal damage, varying fixturing scenarios, and fluctuating external loads) while also acquiring new behaviors best suited for the situation at hand. Here, we describe a class of architected materials, called mechanical neural networks (MNNs), that achieve such learning capabilities by tuning the stiffness of their constituent beams similar to how artificial neural networks (ANNs) tune their weights. An example lattice was fabricated to demonstrate its ability to learn multiple mechanical behaviors simultaneously, and a study was conducted to determine the effect of lattice size, packing configuration, algorithm type, behavior number, and linear-versus-nonlinear stiffness tunability on MNN learning as proposed. Thus, this work lays the foundation for artificial-intelligent (AI) materials that can learn behaviors and properties.<\/jats:p>","DOI":"10.1126\/scirobotics.abq7278","type":"journal-article","created":{"date-parts":[[2022,10,19]],"date-time":"2022-10-19T17:58:07Z","timestamp":1666202287000},"source":"Crossref","is-referenced-by-count":90,"title":["Mechanical neural networks: Architected materials that learn behaviors"],"prefix":"10.1126","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2509-1677","authenticated-orcid":true,"given":"Ryan H.","family":"Lee","sequence":"first","affiliation":[{"name":"Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA."}]},{"given":"Erwin A. B.","family":"Mulder","sequence":"additional","affiliation":[{"name":"Mechanics of Solids, Surfaces, and Systems, University of Twente, Enschede, Netherlands."}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4752-746X","authenticated-orcid":true,"given":"Jonathan B.","family":"Hopkins","sequence":"additional","affiliation":[{"name":"Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA."}]}],"member":"221","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature14539"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-017-07754-z"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1109\/TII.2018.2822828"},{"key":"e_1_3_2_5_2","first-page":"115","article-title":"A logical calculus of the ideas immanent in nervous activity","volume":"5","author":"McCulloch W. S.","year":"1943","unstructured":"W. S. McCulloch, W. Pitts,A logical calculus of the ideas immanent in nervous activity. Bull. Math. Biol.5,115\u2013133 (1943).","journal-title":"Bull. Math. Biol."},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1037\/h0042519"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2019.2945545"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1016\/0893-6080(89)90020-8"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature14441"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.abj7943"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1109\/LED.2021.3125966"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1109\/TCSI.2018.2885574"},{"key":"e_1_3_2_13_2","doi-asserted-by":"crossref","unstructured":"S. Dillavou M. Stern A. J. Liu D. J. 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