{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,22]],"date-time":"2025-10-22T22:24:50Z","timestamp":1761171890138,"version":"build-2065373602"},"reference-count":25,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,20]],"date-time":"2025-10-20T00:00:00Z","timestamp":1760918400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\/MCTES through national funds (PIDDAC) under the R&amp;D Unit C-MAST\/Center for Mechanical and Aerospace Science and Technologies","award":["UIDB\/00151\/2020"],"award-info":[{"award-number":["UIDB\/00151\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JMMP"],"abstract":"<jats:p>The introduction of functional elements is essential for many industrial components which rely on elements such as bolts, screws, nuts, or clips that are integrated into the workpieces. In the field of cold joining technologies, double-sided self-pierce riveting (DS-SPR) presents itself as a proper alternative to produce the mechanical connection of those elements into sheet panels. For the purpose of this investigation, a tubular rivet with a machined thread to replicate a hollow bolt was joined to a sheet panel. Since this application will be subjected to torsion loads when a nut or other elements are fastened, tubular rivets with different numbers of semi-longitudinal rectangular openings at their ends (0, 2, 4, and 8) were investigated to identify the optimal design that ensures proper performance during its service life. The results show that rivets with four openings achieved a torsional resistance of more than 40 N\u00b7m, which is over double that of the original rivet without openings, while maintaining comparable shear strength (~10 kN). A functional hollow bolt with an outer thread was successfully produced, achieving a torque capacity of 35 N\u00b7m, equivalent to an M8 solid bolt, but with reduced weight. These findings highlight DS-SPR as a viable technology for manufacturing functional riveted elements that combine the permanent joints between sheets and removable connections with secondary components, offering both structural performance and lightweight advantages.<\/jats:p>","DOI":"10.3390\/jmmp9100344","type":"journal-article","created":{"date-parts":[[2025,10,20]],"date-time":"2025-10-20T13:54:41Z","timestamp":1760968481000},"page":"344","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Introduction of Functional Elements with Double-Sided Self-Pierce Riveting"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1121-9473","authenticated-orcid":false,"given":"Rafael M.","family":"Afonso","sequence":"first","affiliation":[{"name":"Engineering Department, Atl\u00e2ntica University Institute, F\u00e1brica da P\u00f3lvora de Barcarena, 2730-036 Oeiras, Portugal"},{"name":"Centre for Mechanical and Aerospace Science and Technologies (C-MAST), University of Beira Interior, Rua Marqu\u00eas d\u2019\u00c1vila e Bolama, 6201-001 Covilh\u00e3, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7170-0333","authenticated-orcid":false,"given":"Lu\u00eds M.","family":"Alves","sequence":"additional","affiliation":[{"name":"IDMEC, Instituto Superior T\u00e9cnico, University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1541","DOI":"10.1007\/s00170-020-05503-7","article-title":"Double-sided self-pierce riveting","volume":"108","author":"Alves","year":"2020","journal-title":"J. Adv. Manuf. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1007\/s11740-022-01125-y","article-title":"Mechanical joining in versatile process chains","volume":"16","author":"Meschut","year":"2022","journal-title":"Prod. Eng."},{"key":"ref_3","unstructured":"(2023, August 04). Tox Pressotechnik. Available online: https:\/\/uk.tox-pressotechnik.com\/applications\/functional-element-insertion\/overview\/."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Hetzel, A., Schulte, R., Vogel, M., Lechner, M., Besserer, H.-B., Maier, H.J., Sauer, C., Schleich, B., Wartzack, S., and Merklein, M. (2021). 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