{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,1]],"date-time":"2026-03-01T01:21:20Z","timestamp":1772328080143,"version":"3.50.1"},"reference-count":7,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2017,12,31]],"date-time":"2017-12-31T00:00:00Z","timestamp":1514678400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The increasing use of composite materials has led to a greater demand for efficient curing cycles to reduce costs and speed up production cycles in manufacturing. One method to achieve this goal is in-line cure monitoring to determine the exact curing time. This article proposes a novel method through which to monitor the curing process inside closed tools by employing ultrasonic spectroscopy. A simple experiment is used to demonstrate the change in the ultrasonic spectrum during the cure cycle of an epoxy. The results clearly reveal a direct correlation between the amplitude and state of cure. The glass transition point is indicated by a global minimum of the reflected amplitude.<\/jats:p>","DOI":"10.3390\/s18010096","type":"journal-article","created":{"date-parts":[[2018,1,3]],"date-time":"2018-01-03T12:00:06Z","timestamp":1514980806000},"page":"96","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["A Novel Approach to Monitoring the Curing of Epoxy in Closed Tools by Use of Ultrasonic Spectroscopy"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6312-6397","authenticated-orcid":false,"given":"Christian","family":"Pommer","sequence":"first","affiliation":[{"name":"Institut for Adaptronics and Function Integration, Technische Universit\u00e4t Braunschweig, Langer Kamp 6, 38106 Braunschweig, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1873-9140","authenticated-orcid":false,"given":"Michael","family":"Sinapius","sequence":"additional","affiliation":[{"name":"Institut for Adaptronics and Function Integration, Technische Universit\u00e4t Braunschweig, Langer Kamp 6, 38106 Braunschweig, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,12,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1243\/09544100JAERO158","article-title":"Dielectric non-destructive testing approach to cure monitoring of adhesives and composites","volume":"221","author":"Garden","year":"2007","journal-title":"Proc. Inst. Mech. Eng. Part G"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1016\/0266-3538(95)00007-0","article-title":"Dielectric monitoring of cure in a commercial carbon-fibre composite","volume":"53","author":"Maistros","year":"1995","journal-title":"Compos. Sci. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1860","DOI":"10.1177\/002199839903302001","article-title":"Fiber-Optic and Ultrasonic Measurements for In-Situ Cure Monitoring of Graphite\/Epoxy Composites","volume":"33","author":"Chen","year":"1999","journal-title":"J. Compos. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"S60","DOI":"10.1088\/1464-4258\/9\/6\/S09","article-title":"Optical fibre grating refractometers for resin cure monitoring","volume":"9","author":"Buggy","year":"2007","journal-title":"J. Opt. A"},{"key":"ref_5","unstructured":"Liebers, N., Raddatz, F., and Schadow, F. (2012, January 10\u201312). Effective and flexible ultrasound sensors for cure monitoring for industrial composite production. Proceedings of the Deutscher Luft- und Raumfahrtkongress 2012, Berlin, Germany."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1016\/0041-624X(95)00123-K","article-title":"Cure monitoring of carbon epoxy composites: An application of resonant ultrasound spectroscopy","volume":"34","author":"Whitney","year":"1996","journal-title":"Ultrasonics"},{"key":"ref_7","unstructured":"Karkanas, P. (1998). Cure Modelling and Monitoring of Epoxy\/Amine Resin Systems. [Ph.D. Thesis, Cranfield University]."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/1\/96\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:56:09Z","timestamp":1760208969000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/1\/96"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,12,31]]},"references-count":7,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2018,1]]}},"alternative-id":["s18010096"],"URL":"https:\/\/doi.org\/10.3390\/s18010096","relation":{"has-preprint":[{"id-type":"doi","id":"10.20944\/preprints201710.0089.v1","asserted-by":"object"}]},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,12,31]]}}}