{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T17:50:30Z","timestamp":1770745830091,"version":"3.49.0"},"reference-count":57,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,4,1]],"date-time":"2025-04-01T00:00:00Z","timestamp":1743465600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Portuguese FCT (Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia)","award":["UIDB\/50022\/2020"],"award-info":[{"award-number":["UIDB\/50022\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Composite materials are increasingly being implemented in various solutions, ranging from conventional applications, like furniture, to more advanced ones, such as aerospace, based on their excellent properties, such as high mechanical strength and low weight. There are applications in which these materials are coupled to other parts. To achieve this connection, drilling processes are commonly used. Drilling causes irreversible damage to the material, which influences the mechanical strength of the plates. This study was conducted on 48 carbon\/epoxy plates, each with two drilled holes, based on DOE (design of experiments) and the Taguchi method to design the experimental plan and to validate the results. Three control factors were considered for drilling: drill bit type, cutting speed, and feed rate, as it is expected that a low feed rate and a high cutting speed is the drilling configuration that inflicts the least damage. Subsequently, these specimens were subjected to enhanced radiography and an image analysis processing tool based on MatLab\u00ae to assess the data collected and compute damage results. At the end, in analyzing the results of the Taguchi method, it is possible to validate the assumptions on the influence of the drilling process in delamination extension.<\/jats:p>","DOI":"10.3390\/ma18071595","type":"journal-article","created":{"date-parts":[[2025,4,1]],"date-time":"2025-04-01T08:21:41Z","timestamp":1743495701000},"page":"1595","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Statistical Study on the Influence of Drilling Process in Delamination Observed in Composite Plates"],"prefix":"10.3390","volume":"18","author":[{"given":"Hugo R. C.","family":"Cerqueira","sequence":"first","affiliation":[{"name":"ISEP, Polytechnic of Porto, rua Dr. Ant\u00f3nio Bernardino de Almeida, 4249-015 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5126-188X","authenticated-orcid":false,"given":"Jo\u00e3o E.","family":"Matos","sequence":"additional","affiliation":[{"name":"ISEP, Polytechnic of Porto, rua Dr. Ant\u00f3nio Bernardino de Almeida, 4249-015 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9936-9083","authenticated-orcid":false,"given":"Jos\u00e9 L.","family":"Esteves","sequence":"additional","affiliation":[{"name":"INEGI Instituto de Ci\u00eancia e Inova\u00e7\u00e3o em Engenharia Mec\u00e2nica e Engenharia Industrial, 4200-465 Porto, Portugal"},{"name":"FEUP Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8076-9914","authenticated-orcid":false,"given":"Susana C. F.","family":"Fernandes","sequence":"additional","affiliation":[{"name":"ISEP, Polytechnic of Porto, rua Dr. Ant\u00f3nio Bernardino de Almeida, 4249-015 Porto, Portugal"},{"name":"INEGI Instituto de Ci\u00eancia e Inova\u00e7\u00e3o em Engenharia Mec\u00e2nica e Engenharia Industrial, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0002-5836","authenticated-orcid":false,"given":"Luis M. P.","family":"Dur\u00e3o","sequence":"additional","affiliation":[{"name":"ISEP, Polytechnic of Porto, rua Dr. Ant\u00f3nio Bernardino de Almeida, 4249-015 Porto, Portugal"},{"name":"INEGI Instituto de Ci\u00eancia e Inova\u00e7\u00e3o em Engenharia Mec\u00e2nica e Engenharia Industrial, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"032011","DOI":"10.1088\/1757-899X\/971\/3\/032011","article-title":"A review of carbon fiber materials in automotive industry","volume":"971","author":"Ahmad","year":"2020","journal-title":"IOP Conf. Ser. Mater. Sci. Eng."},{"key":"ref_2","unstructured":"Continental Reifen Deutschland GmbH (2019). Off-The-Road Tires\u2014Technical Data Book, Continental Reifen Deutschland GmbH."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1016\/S0263-8223(00)00175-6","article-title":"Review of advanced composite structures for naval ships and submarines","volume":"53","author":"Mouritz","year":"2001","journal-title":"Compos. Struct."},{"key":"ref_4","unstructured":"(2024, October 24). Enercom\u2014Production & Sourcing. Available online: https:\/\/www.enercon.de\/en\/company\/production-sourcing."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Sreejith, M., and Rajeev, R.S. (2021). Fiber reinforced composites for aerospace and sports applications. Fiber Reinforced Composites: Constituents, Compatibility, Perspectives and Applications, Woodhead Publishing.","DOI":"10.1016\/B978-0-12-821090-1.00023-5"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"101277","DOI":"10.1016\/j.rineng.2023.101277","article-title":"Challenges for recycling medium-density fiberboard (MDF)","volume":"19","author":"Zimmer","year":"2023","journal-title":"Results Eng."},{"key":"ref_7","unstructured":"Composite Panel (2024, October 21). Association\u2014Medium Density Fiberboard. Available online: https:\/\/www.compositepanel.org\/products\/medium-density-fiberboard\/."},{"key":"ref_8","first-page":"173","article-title":"Optimization of Drilling Parameters in Composite Sandwich Structures (PVC Core)","volume":"2","author":"Ghabezi","year":"2014","journal-title":"Indian J. Sci. Res."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"454","DOI":"10.1177\/1056789519860573","article-title":"Defect evaluation of the honeycomb structures formed during the drilling process","volume":"29","author":"Ghabezi","year":"2020","journal-title":"Int. J. Damage Mech."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"01013","DOI":"10.1051\/matecconf\/201711201013","article-title":"Investigation on hole quality of cutting conditions in drilling of CFRP composite","volume":"112","author":"Yasar","year":"2017","journal-title":"MATEC Web Conf."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"507","DOI":"10.1108\/PRT-10-2016-0097","article-title":"Experimental investigation and analysis of factors influencing delamination and thrust force during drilling of carbon-fibre reinforced polymer composites","volume":"46","author":"Rajkumar","year":"2017","journal-title":"Pigment. Resin Technol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1256","DOI":"10.1016\/j.jmrt.2022.09.100","article-title":"Experimental study of drilling behaviors and damage issues for woven GFRP composites using special drills","volume":"21","author":"Xu","year":"2022","journal-title":"J. Mater. Res. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Martins, A., Carvalho, A., Bragan\u00e7a, I.M.F., Barbosa, I.C.J., Barbosa, J.I., and Loja, M.A.R. (2024). A Statistical Assessment of Drilling Effects on Glass Fiber-Reinforced Polymeric Composites. Materials, 17.","DOI":"10.3390\/ma17225631"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1016\/j.compstruct.2019.02.099","article-title":"Delamination formation, evaluation and suppression during drilling of composite laminates: A review","volume":"216","author":"Geng","year":"2019","journal-title":"Compos. Struct."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"100312","DOI":"10.1016\/j.jcomc.2022.100312","article-title":"A review of recent advancements in drilling of fiber-reinforced polymer composites","volume":"9","author":"Kumar","year":"2022","journal-title":"Compos. Part C Open Access"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"9677","DOI":"10.1016\/j.jmrt.2023.05.023","article-title":"A review on CFRP drilling: Fundamental mechanisms, damage issues, and approaches toward high-quality drilling","volume":"24","author":"Xu","year":"2023","journal-title":"J. Mater. Res. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1016\/j.procir.2012.04.084","article-title":"Influence of Point Angle on Drill Hole Quality and Machining Forces when Drilling CFRP","volume":"1","author":"Heisel","year":"2012","journal-title":"CFRP Procedia Cirp"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4258","DOI":"10.3390\/ma7064258","article-title":"Experimental Analysis of the Influence of Drill Point Angle and Wear on the Drilling of Woven CFRPs","volume":"7","author":"Feito","year":"2014","journal-title":"Materials"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1278","DOI":"10.1016\/j.matpr.2020.01.118","article-title":"Effect of Point Angle in Twist Drill Bit on Delamination in CFRP","volume":"21","author":"Tejas","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1007\/s00170-021-06733-z","article-title":"The impact of tool point angle and interlayer gap width on interface borehole quality in drilling CFRP\/titanium stacks","volume":"114","author":"Pardo","year":"2021","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3802","DOI":"10.3390\/ma7053802","article-title":"Drilling Damage in Composite Material","volume":"7","author":"Tavares","year":"2014","journal-title":"Materials"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1177\/0021998318787855","article-title":"Analysis of damage outcome in the strength of polymer composite materials","volume":"53","author":"Silva","year":"2019","journal-title":"J. Compos. Mater."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1219","DOI":"10.1016\/j.compositesa.2012.03.004","article-title":"A finite fracture mechanics model for the prediction of the open-hole strength of composite laminates","volume":"43","author":"Camanho","year":"2012","journal-title":"Compos. Part A"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.compstruct.2016.05.017","article-title":"Progressive failure analysis on scaled open-hole tensile composite laminates","volume":"150","author":"Bao","year":"2016","journal-title":"Compos. Struct."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"107914","DOI":"10.1016\/j.engfailanal.2023.107914","article-title":"Composite pipelines: Analyzing defects and advancements in non-destructive testing techniques","volume":"157","author":"Waqar","year":"2024","journal-title":"Eng. Fail. Anal."},{"key":"ref_26","unstructured":"Kapadia, A. (2024, November 12). Best Practice Guide Non Destructive Testing of Composite Materials. Available online: https:\/\/avaloncsl.com\/wp-content\/uploads\/2013\/01\/ncn-best-practice-ndt.pdf."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1016\/j.prostr.2016.02.008","article-title":"A review of non-destructive testing methods of composite materials","volume":"1","author":"Gholizadeh","year":"2016","journal-title":"Procedia Struct. Integr."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1016\/j.compscitech.2017.10.023","article-title":"X-ray computed tomography of polymer composites","volume":"156","author":"Garcea","year":"2018","journal-title":"Compos. Sci. Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"110494","DOI":"10.1016\/j.compscitech.2024.110494","article-title":"Trans-scale analysis of 3D braided composites with voids based on micro-CT imaging and unsupervised machine learning","volume":"249","author":"Song","year":"2024","journal-title":"Compos. Sci. Technol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1282","DOI":"10.1016\/j.ijmachtools.2005.01.009","article-title":"Computerized tomography and C-Scan for measuring delamination in the drilling of composite materials using various drills","volume":"45","author":"Tsao","year":"2005","journal-title":"Int. J. Mach. Tools Manuf."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"917","DOI":"10.1016\/j.compstruct.2016.10.124","article-title":"X-ray computed tomography study of kink bands in unidirectional composites","volume":"160","author":"Wang","year":"2017","journal-title":"Compos. Struct."},{"key":"ref_32","unstructured":"Coelho, B. (2024, November 22). Dete\u00e7\u00e3o de defeitos em materiais comp\u00f3sitos usando tecnologia de ultrassons. (In Portuguese)."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"112145","DOI":"10.1016\/j.compstruct.2020.112145","article-title":"An improved method of Eddy current pulsed thermography to detect subsurface defects in glass fiber reinforced polymer composites","volume":"242","author":"Xu","year":"2020","journal-title":"Compos. Struct."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Versaci, M., Lagan\u00e0, F., Morabito, F.C., Palumbo, A., and Angiulli, G. (2024). Adaptation of an Eddy Current Model for Characterizing Subsurface Defects in CFRP Plates Using FEM Analysis Based on Energy Functional. Mathematics, 12.","DOI":"10.3390\/math12182854"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"116588","DOI":"10.1016\/j.compstruct.2022.116588","article-title":"Non-destructive inspection of military-designated composite materials with the use of Terahertz imaging","volume":"306","year":"2023","journal-title":"Compos. Struct."},{"key":"ref_36","unstructured":"Besson, A., and Minasyan, A. (2017, January 13\u201317). Terahertz Imaging for Composite Non Destructive Testing. Proceedings of the 15th Asia Pacific Conference for Non-Destructive Testing, Singapore. Available online: https:\/\/www.ndt.net\/?id=22114."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"576","DOI":"10.1016\/j.compstruct.2012.08.003","article-title":"Damage evaluation of drilled carbon\/epoxy laminates based on area assessment methods","volume":"96","author":"Tavares","year":"2013","journal-title":"Compos. Struct."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1919","DOI":"10.1007\/s00170-014-5616-y","article-title":"Methodology analysis for evaluation of drilling-induced damage composites","volume":"71","author":"Silva","year":"2014","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_39","first-page":"1139","article-title":"Evaluation of Delamination Damage on Composite Plates using an Artificial Neural Network for the Radiographic Image Analysis","volume":"44","author":"Tavares","year":"2009","journal-title":"J. Compos. Mater."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Caggiano, A., Mattera, G., and Nele, L. (2023). Smart Tool Wear Monitoring of CFRP\/CFRP Stack Drilling Using Autoencoders and Memory-Based Neural Networks. Appl. Sci., 13.","DOI":"10.3390\/app13053307"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1097","DOI":"10.1016\/S0890-6955(96)00095-8","article-title":"Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates","volume":"37","author":"Chen","year":"1997","journal-title":"Int. J. Mach. Tools Manuf."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/j.proeng.2016.06.632","article-title":"Damage quantification for machining of CFRP: An introduction about characteristic values considering shape and orientation of drilling-induced delamination","volume":"149","author":"Lissek","year":"2016","journal-title":"Procedia Eng."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1939","DOI":"10.1016\/j.compscitech.2006.10.009","article-title":"A novel approach based on digital image analysis to evaluate the delamination factor after drilling composite laminates","volume":"67","author":"Davim","year":"2007","journal-title":"Compos. Sci. Technol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"617","DOI":"10.1007\/s00170-011-3532-y","article-title":"Evaluation of a novel approach to a delamination factor after drilling composite laminates using a core-saw drill","volume":"59","author":"Tsao","year":"2012","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1076","DOI":"10.1016\/j.compstruct.2018.06.051","article-title":"Study of drilling-induced defects for CFRP composites using new criteria","volume":"201","author":"Xu","year":"2018","journal-title":"Compos. Struct."},{"key":"ref_46","first-page":"1649","article-title":"Comparative analysis of drills for composite laminates","volume":"46","author":"Tavares","year":"2011","journal-title":"J. Compos. Mater."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1465","DOI":"10.1177\/0021998317726366","article-title":"Comparisons of the use of twist, pilot-hole and step-drill on influence of carbon fiber-reinforced polymer drilling hole quality","volume":"52","author":"Wang","year":"2018","journal-title":"J. Compos. Mater."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1403","DOI":"10.1016\/j.ijmachtools.2005.10.004","article-title":"Effects of special drill bits on drilling-induced delamination of composite materials","volume":"46","author":"Hocheng","year":"2006","journal-title":"Int. J. Mach. Tools Manuf."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1653","DOI":"10.1016\/j.ijmachtools.2005.08.015","article-title":"The effect of pilot hole on delamination when core drilling composite materials","volume":"46","author":"Tsao","year":"2006","journal-title":"Int. J. Mach. Tools Manuf."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Dur\u00e3o, L.M.P., Matos, J.E., Loureiro, N.C., Esteves, J.L., and Fernandes, S.C.F. (2023). Damage Propagation by Cyclic Loading in Drilled Carbon\/Epoxy Plates. Materials, 16.","DOI":"10.3390\/ma16072688"},{"key":"ref_51","unstructured":"Roy, R.K. (2024, December 13). A Primer on the Taguchi Method\u2014Google Books. Available online: https:\/\/books.google.pt\/books?id=OUI54mrYdqIC&printsec=frontcover&hl=pt-PT#v=onepage&q&f=false."},{"key":"ref_52","unstructured":"(2024, December 16). Taguchi Robust Design and Loss Function. Available online: https:\/\/sixsigmastudyguide.com\/taguchi-robust-design\/."},{"key":"ref_53","unstructured":"(2019). Plastics\u2014Determination of tensile properties. Part 1: General principles (Standard No. ISO 527-1)."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"236","DOI":"10.1115\/1.2899580","article-title":"Delamination during drilling in composite laminates","volume":"112","author":"Hocheng","year":"1990","journal-title":"J. Eng. Ind."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"103565","DOI":"10.1016\/j.ijmachtools.2020.103565","article-title":"A thermo-mechanical model of drill margin-borehole surface interface contact conditions in dry drilling of thick CFRP laminates","volume":"154","author":"Karpat","year":"2020","journal-title":"Int. J. Mach. Tools Manuf."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Wysmulski, P. (2023). Failure Mechanism of Tensile CFRP Composite Plates with Variable Hole Diameter. Materials, 16.","DOI":"10.3390\/ma16134714"},{"key":"ref_57","unstructured":"(2017). Standard Test Method for Bearing Response of Polymer Matrix Composite Laminates (Standard No. ASTM D5961)."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/7\/1595\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:07:57Z","timestamp":1760029677000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/7\/1595"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,4,1]]},"references-count":57,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2025,4]]}},"alternative-id":["ma18071595"],"URL":"https:\/\/doi.org\/10.3390\/ma18071595","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,4,1]]}}}