{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T10:00:38Z","timestamp":1775037638188,"version":"3.50.1"},"reference-count":16,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2017,10,3]],"date-time":"2017-10-03T00:00:00Z","timestamp":1506988800000},"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>Composite material structures are commonly used in many industrial sectors (aerospace, automotive, transportation), and can operate in harsh environments where impacts with other parts or debris may cause critical safety and functionality issues. This work presents a method for improving the accuracy of impact position determination using acoustic source triangulation schemes based on the data collected by piezoelectric sensors attached to the structure. A novel approach is used to estimate the Differential Time-of-Arrival (DToA) between the impact response signals collected by a triplet of sensors, overcoming the limitations of classical methods that rely on amplitude thresholds calibrated for a specific sensor type. An experimental evaluation of the proposed technique was performed with specially made circular piezopolymer (PVDF) sensors designed for Structural Health Monitoring (SHM) applications, and compared with commercial piezoelectric SHM sensors of similar dimensions. Test impacts at low energies from 35 mJ to 600 mJ were generated in a laboratory by free-falling metal spheres on a 500 mm \u00d7 500 mm \u00d7 1.25 mm quasi-isotropic Carbon Fiber Reinforced Polymer (CFRP) laminate plate. From the analysis of many impact signals, the resulting localization error was improved for all types of sensors and, in particular, for the circular PVDF sensor an average error of 20.3 mm and a standard deviation of 8.9 mm was obtained.<\/jats:p>","DOI":"10.3390\/s17102270","type":"journal-article","created":{"date-parts":[[2017,10,3]],"date-time":"2017-10-03T11:33:30Z","timestamp":1507030410000},"page":"2270","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["A Novel Differential Time-of-Arrival Estimation Technique for Impact Localization on Carbon Fiber Laminate Sheets"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1875-1964","authenticated-orcid":false,"given":"Eugenio Marino","family":"Merlo","sequence":"first","affiliation":[{"name":"Department of Information Engineering, University of Florence, Via S. Marta 3, 50139 Firenze, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4180-7284","authenticated-orcid":false,"given":"Andrea","family":"Bulletti","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Florence, Via S. Marta 3, 50139 Firenze, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1243-8504","authenticated-orcid":false,"given":"Pietro","family":"Giannelli","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Florence, Via S. Marta 3, 50139 Firenze, Italy"}]},{"given":"Marco","family":"Calzolai","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Florence, Via S. Marta 3, 50139 Firenze, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4432-3197","authenticated-orcid":false,"given":"Lorenzo","family":"Capineri","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Florence, Via S. Marta 3, 50139 Firenze, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2017,10,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.ultras.2013.06.009","article-title":"Acoustic source localization","volume":"54","author":"Kundu","year":"2014","journal-title":"Ultrasonics"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1016\/j.ijpvp.2004.03.009","article-title":"Application of wavelet transform on modal acoustic emission source location in thin plates with one sensor","volume":"81","author":"Jiao","year":"2004","journal-title":"Int. J. Press. Vessels Pip."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1777","DOI":"10.1016\/j.compositesa.2010.08.013","article-title":"A new algorithm for acoustic emission localization and flexural group velocity determination in anisotropic structures","volume":"41","author":"Ciampa","year":"2010","journal-title":"Compos. Part Appl. Sci. Manuf."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"643","DOI":"10.1177\/1475921712451951","article-title":"Impact localization in composite structures of arbitrary cross section","volume":"11","author":"Ciampa","year":"2012","journal-title":"Struct. Health Monit."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Garofalo, A., Testoni, N., Marzani, A., and Marchi, L.D. (2016, January 18\u201321). Wavelet-based Lamb waves direction of arrival estimation in passive monitoring techniques. Proceedings of the IEEE International Ultrasonics Symposium (IUS), Tours, France.","DOI":"10.1109\/ULTSYM.2016.7728808"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1776","DOI":"10.1016\/j.ultras.2014.03.001","article-title":"Improving accuracy of acoustic source localization in anisotropic plates","volume":"54","author":"Nakatani","year":"2014","journal-title":"Ultrasonics"},{"key":"ref_7","unstructured":"Mueller, I., Larrosa, C., Roy, S., Mittal, A., Lonkar, K., and Chang, F.-K. (October, January 27). An integrated health management and prognostic technology for composite airframe structures. Proceedings of the Annual Conference on Prognostics and Health Management, San Diego, CA, USA."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"864","DOI":"10.1109\/TUFFC.2016.2545716","article-title":"An Integrated Acousto\/Ultrasonic Structural Health Monitoring System for Composite Pressure Vessels","volume":"63","author":"Bulletti","year":"2016","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1016\/j.sna.2005.05.013","article-title":"A new design and manufacturing process for embedded Lamb waves interdigital transducers based on piezopolymer film","volume":"123","author":"Bellan","year":"2005","journal-title":"Sens. Actuators A Phys."},{"key":"ref_10","unstructured":"Galeazzi, R. (2016, April 11). Studio Sperimentale Finalizzato al Monitoraggio di Difettosit\u00e0 interne in Laminati CFRP per Utilizzo Aeronautico, Mediante Approccio Ultrasonoro con Onde di Lamb. Available online: https:\/\/www.politesi.polimi.it\/handle\/10589\/83381."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1266","DOI":"10.1016\/j.proeng.2014.11.416","article-title":"Arrays of conformable ultrasonic Lamb wave transducers for structural health monitoring with real-time electronics","volume":"87","author":"Capineri","year":"2014","journal-title":"Procedia Eng."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1243","DOI":"10.1016\/j.proeng.2014.11.408","article-title":"A real-time electronic system for automated impact detection on aircraft structures using piezoelectric transducers","volume":"87","author":"Capineri","year":"2014","journal-title":"Procedia Eng."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4583","DOI":"10.1109\/JSEN.2017.2710425","article-title":"Multifunctional Piezopolymer Film Transducer for Structural Health Monitoring Applications","volume":"17","author":"Giannelli","year":"2017","journal-title":"IEEE Sens. J."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1370","DOI":"10.1016\/j.compscitech.2006.09.023","article-title":"Group velocity and characteristic wave curves of Lamb waves in composites: Modeling and experiments","volume":"67","author":"Wang","year":"2007","journal-title":"Compos. Sci. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Adams, D. (2007). Health Monitoring of Structural Materials and Components: Methods with Applications, John Wiley & Sons Ltd.","DOI":"10.1002\/9780470511589"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2669","DOI":"10.1121\/1.426883","article-title":"Time-frequency analysis of the dispersion of Lamb modes","volume":"105","author":"Prosser","year":"1999","journal-title":"J. Acoust. Soc. Am."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/10\/2270\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:46:31Z","timestamp":1760208391000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/10\/2270"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,10,3]]},"references-count":16,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2017,10]]}},"alternative-id":["s17102270"],"URL":"https:\/\/doi.org\/10.3390\/s17102270","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,10,3]]}}}