{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T18:31:07Z","timestamp":1774377067378,"version":"3.50.1"},"reference-count":39,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2021,8,24]],"date-time":"2021-08-24T00:00:00Z","timestamp":1629763200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Horizon 2020","award":["769288"],"award-info":[{"award-number":["769288"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The development of health indicators (HI) of diagnostic and prognostic potential from generally uninformative raw sensor data is both a challenge and an essential feature for data-driven diagnostics and prognostics of composite structures. In this study, new damage-sensitive features, developed from strains acquired with Fiber Bragg Grating (FBG) and acoustic emission (AE) data, were investigated for their suitability as HIs. Two original fatigue test campaigns (constant and variable amplitude) were conducted on single-stringer composite panels using appropriate sensors. After an initial damage introduction in the form of either impact damage or artificial disbond, the panels were subjected to constant and variable amplitude compression\u2013compression fatigue tests. Strain sensing using FBGs and AE was employed to monitor the damage growth, which was further verified by phased array ultrasound. Several FBGs were incorporated in special SMARTapesTM, which were bonded along the stiffener\u2019s feet to measure the strain field, whereas the AE sensors were strategically placed on the panels\u2019 skin to record the acoustic emission activity. HIs were developed from FBG and AE raw data with promising behaviors for health monitoring of composite structures during service. A correlation with actual damage was attempted by leveraging the measurements from a phased array camera at several time instances throughout the experiments. The developed HIs displayed highly monotonic behaviors while damage accumulated on the composite panel, with moderate prognosability.<\/jats:p>","DOI":"10.3390\/s21175701","type":"journal-article","created":{"date-parts":[[2021,8,24]],"date-time":"2021-08-24T22:09:39Z","timestamp":1629842979000},"page":"5701","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":31,"title":["Health Monitoring of Aerospace Structures Utilizing Novel Health Indicators Extracted from Complex Strain and Acoustic Emission Data"],"prefix":"10.3390","volume":"21","author":[{"given":"Georgios","family":"Galanopoulos","sequence":"first","affiliation":[{"name":"Applied Mechanics Laboratory, Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Rio, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dimitrios","family":"Milanoski","sequence":"additional","affiliation":[{"name":"Applied Mechanics Laboratory, Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Rio, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9392-483X","authenticated-orcid":false,"given":"Agnes","family":"Broer","sequence":"additional","affiliation":[{"name":"Structural Integrity and Composites Group, Faculty of Aerospace Engineering, Delft University of Technology, 2629 Delft, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dimitrios","family":"Zarouchas","sequence":"additional","affiliation":[{"name":"Structural Integrity and Composites Group, Faculty of Aerospace Engineering, Delft University of Technology, 2629 Delft, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Theodoros","family":"Loutas","sequence":"additional","affiliation":[{"name":"Applied Mechanics Laboratory, Department of Mechanical Engineering and Aeronautics, University of Patras, 26504 Rio, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Kassapoglou, C. (2013). Design and Analysis of Composite Structures: With Applications to Aerospace Structures, John Wiley & Sons.","DOI":"10.1002\/9781118536933"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"260","DOI":"10.1016\/j.matpr.2020.03.081","article-title":"Fatigue testing and damage evaluation using smart CFRP composites with embedded PZT transducers","volume":"34","author":"Andreades","year":"2021","journal-title":"Mater. Today Proc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1016\/j.compstruct.2018.10.047","article-title":"Remaining useful life prediction of laminated composite materials using thermoelastic stress analysis","volume":"210","author":"Marques","year":"2019","journal-title":"Compos. Struct."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"522","DOI":"10.1016\/j.compstruct.2016.10.109","article-title":"A data-driven probabilistic framework towards the in-situ prognostics of fatigue life of composites based on acoustic emission data","volume":"161","author":"Loutas","year":"2017","journal-title":"Compos. Struct."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"473","DOI":"10.1177\/1475921716646579","article-title":"Fatigue damage diagnostics and prognostics of composites utilizing structural health monitoring data and stochastic processes","volume":"15","author":"Eleftheroglou","year":"2016","journal-title":"Struct. Health Monit. Int. J."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Grassia, L., Iannone, M., Califano, A., and D\u2019Amore, A. (2019). Strain based method for monitoring the health state of composite structures. Compos. Part B Eng., 176.","DOI":"10.1016\/j.compositesb.2019.107253"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1177\/1045389X20924822","article-title":"Strain-based health indicators for the structural health monitoring of stiffened composite panels","volume":"32","author":"Milanoski","year":"2021","journal-title":"J. Intell. Mater. Syst. Struct."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2410","DOI":"10.1016\/j.compscitech.2007.09.020","article-title":"Disbond growth detection in composite\u2013composite single-lap joints using chirped FBG sensors","volume":"68","author":"Palaniappan","year":"2008","journal-title":"Compos. Sci. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1007\/s13320-012-0065-4","article-title":"Use of FBG Sensors for SHM in Aerospace Structures","volume":"2","author":"Kahandawa","year":"2012","journal-title":"Photonic Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"813","DOI":"10.1016\/j.compstruct.2011.02.020","article-title":"Damage monitoring of CFRP stiffened panels under compressive load using FBG sensors","volume":"94","author":"Takeda","year":"2012","journal-title":"Compos. Struct."},{"key":"ref_11","unstructured":"Sbarufatti, C., Corbetta, M., San Millan, J., Frovel, M., Stefaniuk, M., and Giglio, M. (2016, January 5\u20138). Model-Assisted Performance Qualification of a Distributed SHM System for Fatigue Crack Detection on a Helicopter Tail Boom. Proceedings of the 8th European Workshop on Structural Health Monitoring, Bilbao, Spain."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"667","DOI":"10.1016\/j.ymssp.2013.06.003","article-title":"Performance optimization of a diagnostic system based upon a simulated strain field for fatigue damage characterization","volume":"40","author":"Sbarufatti","year":"2013","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Guemes, A., Sierra, J., Rodellar, J., and Mujica, L. (2013). A robust procedure for Damage detection from strain measurements based on Principal Component Analysis. Key Engineering Materials, Trans Tech Publications Ltd.","DOI":"10.4028\/www.scientific.net\/KEM.558.128"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"G\u00fcemes, A., Fern\u00e1ndez-L\u00f3pez, A., D\u00edaz-Maroto, P.F., Lozano, A., and Sierra-Perez, J. (2018). Structural Health Monitoring in Composite Structures by Fiber-Optic Sensors. Sensors, 18.","DOI":"10.3390\/s18041094"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Saeedifar, M., and Zarouchas, D. (2020). Damage characterization of laminated composites using acoustic emission: A review. Compos. Part B Eng., 195.","DOI":"10.1016\/j.compositesb.2020.108039"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1177\/0309324716645244","article-title":"Acoustic emission response and micro-deformation behavior for compressive buckling failure of multi-delaminated composites","volume":"51","author":"Zhou","year":"2016","journal-title":"J. Strain Anal. Eng. Des."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Carmi, R., Wisner, B., Vanniamparambil, P.A., Cuadra, J.A., Bussiba, A., and Kontsos, A. (2019). Progressive Failure Monitoring of Fiber-Reinforced Metal Laminate Composites Using a Nondestructive Approach. J. Nondestruct. Eval. Diagn. Progn. Eng. Syst., 2.","DOI":"10.1115\/1.4043713"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Liu, Y., Mohanty, S., and Chattopadhyay, A. (2009, January 11\u201312). A Gaussian process based prognostics framework for composite structures. Proceedings of the Modeling, Signal Processing, and Control for Smart Structures 2009, San Diego, CA, USA.","DOI":"10.1117\/12.815889"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/j.compscitech.2016.09.017","article-title":"A novel method of identifying damage types in carbon fiber-reinforced plastic cross-ply laminates based on acoustic emission detection using a fiber-optic sensor","volume":"135","author":"Yu","year":"2016","journal-title":"Compos. Sci. Technol."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Perez, I.M., Cui, H., and Udd, E. (2001, January 5\u20136). Acoustic emission detection using fiber Bragg gratings. Proceedings of the Smart Structures and Materials 2001: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials, Newport Beach, CA, USA.","DOI":"10.1117\/12.435542"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2942","DOI":"10.1364\/OL.34.002942","article-title":"Acoustic emission measurement using a strain-insensitive fiber Bragg grating sensor under varying load conditions","volume":"34","author":"Tsuda","year":"2009","journal-title":"Opt. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Broer, A., Galanopoulos, G., Benedictus, R., Loutas, T., and Zarouchas, D. (2021). Fusion-based damage diagnostics for stiffened composite panels. Struct. Health Monit., in press.","DOI":"10.1177\/14759217211007127"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Broer, A.A.R., Galanopoulos, G., Zarouchas, D., Loutas, T., and Benedictus, R. (2020, January 6\u20139). Damage Diagnostics of a Composite Single-Stiffener Panel Under Fatigue Loading Utilizing SHM Data Fusion. Proceedings of the European Workshop on Structural Health Monitoring, Palermo, Italy.","DOI":"10.1007\/978-3-030-64594-6_60"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"5022","DOI":"10.1109\/TIE.2019.2926048","article-title":"Valve Failure Prognostics in Reciprocating Compressors Utilizing Temperature Measurements, PCA-Based Data Fusion, and Probabilistic Algorithms","volume":"67","author":"Loutas","year":"2020","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.ress.2018.04.031","article-title":"Structural health monitoring data fusion for in-situ life prognosis of composite structures","volume":"178","author":"Eleftheroglou","year":"2018","journal-title":"Reliab. Eng. Syst. Saf."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Hu, C., Youn, B.D., Wang, P., and Yoon, J.T. (2012, January 12\u201315). An ensemble approach for robust data-driven prognostics. Proceedings of the International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Chicago, IL, USA.","DOI":"10.1115\/DETC2012-70529"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Wen, P., Zhao, S., Chen, S., and Li, Y. (2021). A generalized remaining useful life prediction method for complex systems based on composite health indicator. Reliab. Eng. Syst. Saf., 205.","DOI":"10.1016\/j.ress.2020.107241"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Eleftheroglou, N., Zarouchas, D., Loutas, T., Alderliesten, R.C., and Benedictus, R. (2016). Online remaining fatigue life prognosis for composite materials based on strain data and stochastic modeling. Key Engineering Materials, Trans Tech Publications Ltd.","DOI":"10.12783\/shm2017\/14012"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Milanoski, D., Galanopoulos, G., Broer, A., Zarouchas, D., and Loutas, T. (2020, January 6\u20139). A Strain-Based Health Indicator for the SHM of Skin-to-Stringer Disbond Growth of Composite Stiffened Panels in Fatigue. Proceedings of the European Workshop on Structural Health Monitoring, Palermo, Italy.","DOI":"10.1007\/978-3-030-64594-6_61"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.apacoust.2017.12.003","article-title":"Reciprocating compressor prognostics of an instantaneous failure mode utilising temperature only measurements","volume":"147","author":"Loukopoulos","year":"2019","journal-title":"Appl. Acoust."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"763","DOI":"10.1007\/s00170-013-4797-0","article-title":"Intelligent fault diagnosis and prognosis approach for rotating machinery integrating wavelet transform, principal component analysis, and artificial neural networks","volume":"68","author":"Zhang","year":"2013","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Shahid, N., and Ghosh, A. (2019). TrajecNets: Online Failure Evolution Analysis in 2D Space, United Technologies Research Center, Penrose Wharf Business Center.","DOI":"10.36001\/ijphm.2019.v10i4.2614"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Inaudi, D., and Glisic, B. (2005, January 23\u201327). Development of distributed strain and temperature sensing cables. Proceedings of the 17th International Conference on Optical Fibre Sensors, Bruges, Belgium.","DOI":"10.1117\/12.623802"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1346","DOI":"10.1177\/1045389X14541493","article-title":"Damage detection in composite materials structures under variable loads conditions by using fiber Bragg gratings and principal component analysis, involving new unfolding and scaling methods","volume":"26","author":"Mujica","year":"2015","journal-title":"J. Intell. Mater. Syst. Struct."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Ahmed, M., Gu, F., and Ball, A. (2012, January 27\u201331). Fault detection of reciprocating compressors using a model from principles component analysis of vibrations. Proceedings of the Journal of Physics: Conference Series, Varenna, Italy.","DOI":"10.1088\/1742-6596\/364\/1\/012133"},{"key":"ref_36","unstructured":"Milanoski, D.P., and Loutas, T.H. (2019, January 8\u201311). Strain-based damage assessment of stiffened composite panels for structural health monitoring purposes. Proceedings of the 9th Thematic Conference on Smart Structures and Materials, Paris, France."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"647","DOI":"10.1109\/TIE.2014.2327917","article-title":"Enabling health monitoring approach based on vibration data for accurate prognostics","volume":"62","author":"Javed","year":"2014","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_38","first-page":"36","article-title":"Image processing with ImageJ","volume":"11","author":"Ram","year":"2004","journal-title":"Biophotonics Int."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Holmes, C., Godfrey, M., Bull, D.J., and Dulieu-Barton, J. (2020). Real-time through-thickness and in-plane strain measurement in carbon fibre reinforced polymer composites using planar optical Bragg gratings. Opt. Lasers Eng., 133.","DOI":"10.1016\/j.optlaseng.2020.106111"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/17\/5701\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:50:47Z","timestamp":1760165447000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/17\/5701"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,8,24]]},"references-count":39,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2021,9]]}},"alternative-id":["s21175701"],"URL":"https:\/\/doi.org\/10.3390\/s21175701","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,8,24]]}}}