{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:22:14Z","timestamp":1760239334300,"version":"build-2065373602"},"reference-count":39,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2020,11,4]],"date-time":"2020-11-04T00:00:00Z","timestamp":1604448000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["VO 1487\/11-1","VO 1487\/11-2"],"award-info":[{"award-number":["VO 1487\/11-1","VO 1487\/11-2"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Current testing methods are capable of measuring strain near the surface on structural parts, for example by using strain gauges. However, stress peaks often occur within the material and can only be approximated. An alternative strain measurement incorporates fibre-optical strain sensors (Fiber Bragg Gratings, FBG) which are able to determine strains within the material. The principle has already been verified by using embedded FBGs in tensile specimens. The transition area between fibre and aluminium, however, is not yet properly investigated. Therefore, strains in tensile specimens containing FBGs were measured by neutron diffraction in gauge volumes of two different sizes around the Bragg grating. As a result, it is possible to identify and decouple elastic and plastic strains affecting the FBGs and to transfer the findings into a fully descriptive FE-model of the strain transition area.We thus accomplished closing the gap between the external load and internal straining obtained from cast-in FBG and generating valuable information about the mechanisms within the strain transition area.It was found that the porosity within the casting has a significant impact on the stiffness of the tensile specimen, the generation of excess microscopic tensions and thus the formation of permanent plastic strains, which are well recognized by the FBG. The knowledge that FBG as internal strain sensors function just as well as common external strain sensors will now allow for the application of FBG in actual structural parts and measurements under real load conditions. In the future, applications for long-term monitoring of cast parts will also be enabled and are currently under development.<\/jats:p>","DOI":"10.3390\/s20216276","type":"journal-article","created":{"date-parts":[[2020,11,4]],"date-time":"2020-11-04T10:32:36Z","timestamp":1604485956000},"page":"6276","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Evaluation of Strain Transition Properties between Cast-In Fibre Bragg Gratings and Cast Aluminium during Uniaxial Straining"],"prefix":"10.3390","volume":"20","author":[{"given":"Florian","family":"Heilmeier","sequence":"first","affiliation":[{"name":"Chair of Metal Forming and Casting, Technical University of Munich (TUM), 85748 Garching, Germany"}]},{"given":"Robert","family":"Koos","sequence":"additional","affiliation":[{"name":"Research Neutron Source Heinz Maier-Leibnitz, TUM, 85748 Garching, Germany"}]},{"given":"Michael","family":"Singer","sequence":"additional","affiliation":[{"name":"Chair of Metal Forming and Casting, Technical University of Munich (TUM), 85748 Garching, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0871-4425","authenticated-orcid":false,"given":"Constantin","family":"Bauer","sequence":"additional","affiliation":[{"name":"Chair of Metal Forming and Casting, Technical University of Munich (TUM), 85748 Garching, Germany"}]},{"given":"Peter","family":"Hornberger","sequence":"additional","affiliation":[{"name":"Application Center for CT in Metrology, Fraunhofer Institute for Integrated Circuits, IIS, 94469 Deggendorf, Germany"}]},{"given":"Jochen","family":"Hiller","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering and Mechatronics, Deggendorf Institute of Technology, 94469 Deggendorf, Germany"}]},{"given":"Wolfram","family":"Volk","sequence":"additional","affiliation":[{"name":"Chair of Metal Forming and Casting, Technical University of Munich (TUM), 85748 Garching, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,4]]},"reference":[{"key":"ref_1","unstructured":"Warnke, E. (2008). Mit Eigenspannungen leben: Entstehung, Auswirkungen, Messung, Berechnung und Vermeidung von Eigenspannungen, Ausblick. Konstruieren und Giessen, Bundesverband der Deutschen Gie\u00dferei-Industrie."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Weraneck, K., Heilmeier, F., Lindner, M., Graf, M., Jakobi, M., Volk, W., Roths, J., and Koch, A.W. (2016). Strain Measurement in Aluminium Alloy during the Solidification Process Using Embedded Fibre Bragg Gratings. Sensors, 16.","DOI":"10.3390\/s16111853"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"384","DOI":"10.3390\/s110100384","article-title":"Strain measurements of composite laminates with embedded fibre bragg gratings: Criticism and opportunities for research","volume":"11","author":"Luyckx","year":"2011","journal-title":"Sensors"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1016\/j.compstruct.2019.01.079","article-title":"Smart cure cycles for fiber metal laminates using embedded fiber Bragg grating sensors","volume":"213","author":"Prussak","year":"2019","journal-title":"Compos. Struct."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1016\/j.compstruct.2019.02.085","article-title":"Internal strain assessment using FBGs in a thermoplastic composite subjected to quasi-static indentation and low-velocity impact","volume":"215","author":"Mulle","year":"2019","journal-title":"Compos. Struct."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.sna.2018.01.027","article-title":"Sensing performance assessment of twisted CFRP with embedded fiber Bragg grating sensors subjected to monotonic and fatigue loading","volume":"271","author":"Li","year":"2018","journal-title":"Sens. Actuators A Phys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"04019065","DOI":"10.1061\/(ASCE)AS.1943-5525.0001057","article-title":"Bridge Retrofitting Using FRP-Wrapped Balsa Wood Deck: Experimental Study and Field Evaluation","volume":"32","author":"Nair","year":"2019","journal-title":"J. Aerosp. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/j.conbuildmat.2019.05.017","article-title":"Strain monitoring of low carbon steel in a corrosive environment using fiber Bragg technology","volume":"217","author":"Cinitha","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1016\/j.optlaseng.2019.04.028","article-title":"Fiber-optic Fabry\u2014Perot pressure sensor for down-hole application","volume":"121","author":"Zhou","year":"2019","journal-title":"Opt. Lasers Eng."},{"key":"ref_10","first-page":"271","article-title":"In-situ strain measurements in the plastic deformation regime inside casted parts using fibre-optical strain sensors","volume":"618","author":"Heilmeier","year":"2019","journal-title":"Prod. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"094007","DOI":"10.1088\/0957-0233\/24\/9\/094007","article-title":"Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres","volume":"24","author":"Aulbach","year":"2013","journal-title":"Meas. Sci. Technol."},{"key":"ref_12","unstructured":"Deutsches Institut f\u00fcr Normung e.V (2019). Aluminium und Aluminiumlegierungen\u2014Chemische Zusammensetzung und Mechanische Eigenschaften, Beuth Verlag GmbH."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"107939","DOI":"10.1016\/j.measurement.2020.107939","article-title":"Calibration of cast-in fibre Bragg gratings for internal strain measurements in cast aluminium by using neutron diffraction","volume":"163","author":"Heilmeier","year":"2020","journal-title":"Measurement"},{"key":"ref_14","unstructured":"Weraneck, K. (2018). Struktur\u00fcberwachung Mittels Eingebetteter Faser-Bragg-Gitter, Universit\u00e4tsbibliothek der TU M\u00fcnchen."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1277","DOI":"10.1109\/50.618322","article-title":"Fiber grating spectra","volume":"15","author":"Erdogan","year":"1997","journal-title":"J. Light. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1088\/0957-0233\/8\/4\/002","article-title":"In-fibre Bragg grating sensors","volume":"8","author":"Rao","year":"1997","journal-title":"Meas. Sci. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Wagreich, R.B., and Sirkis, J.S. (1997, January 28\u201331). Distinguishing Fiber Bragg Grating Strain Effects. Proceedings of the 12th International Conference on Optical Fiber Sensors, Williamsburg, VA, USA.","DOI":"10.1364\/OFS.1997.OTuB2"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Cuadrado-Laborde, C. (2013). A Guide to Fiber Bragg Grating Sensors. Current Trends in Short- and Long-Period Fiber Gratings, IntechOpen.","DOI":"10.5772\/3320"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.1016\/S1003-6326(11)61276-4","article-title":"Effect of Al\u2014TiB master alloy addition on microstructure, wear and compressive deformation behaviour of aluminum alloys","volume":"22","author":"Mondal","year":"2012","journal-title":"Trans. Nonferrous Met. Soc. China"},{"key":"ref_20","unstructured":"Randau, C. (2012). Entwicklungen am Neutronendiffraktometer STRESS-SPEC f\u00fcr Schnelle und Lokale Polfigurmessungen zur Bestimmung Ortsaufgel\u00f6ster Texturen: Dissertation. [Ph.D. Thesis, Technische Universit\u00e4t Clausthal]."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1417","DOI":"10.1016\/j.nucengdes.2010.02.011","article-title":"Core model of new German neutron source FRM II","volume":"240","year":"2010","journal-title":"Nucl. Eng. Des."},{"key":"ref_22","unstructured":"Gabrys, B.J. (2014). Applications of Neutron Scattering to Soft Condensed Matter, Chapman and Hall\/CRC."},{"key":"ref_23","unstructured":"Meier, L. (2017). In-Situ-Messung der Phasenumwandlungskinetik von Ausferritischem Guasseisen, Shaker Verlag. utg-Forschungsberichte."},{"key":"ref_24","first-page":"428","article-title":"The Reflection of X-rays by Crystals","volume":"88","author":"Bragg","year":"1913","journal-title":"Proc. R. Soc. A Math. Phys. Eng. Sci."},{"key":"ref_25","unstructured":"ISO International Organization for Standardization (2005). Non-Destructive Testing: Standard Test Method for Determining Residual Stresses by Neutron Diffraction, ISO."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Hanke, R., Fuchs, T., Salamon, M., and Zabler, S. (2016). X-ray microtomography for materials characterization. Materials Characterization Using Nondestructive Evaluation (NDE) Methods, Woodhead Publishingr.","DOI":"10.1016\/B978-0-08-100040-3.00003-1"},{"key":"ref_27","unstructured":"Buzug, T. (2008). Computed Tomography: From Photon Statistics to Modern Cone-Beam CT, Springer."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1972","DOI":"10.1118\/1.1759828","article-title":"The cone-beam algorithm of Feldkamp, Davis, and Kress preserves oblique line integrals","volume":"31","author":"Rodet","year":"2004","journal-title":"Med. Phys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"612","DOI":"10.1364\/JOSAA.1.000612","article-title":"Practical cone-beam algorithm","volume":"1","author":"Feldkamp","year":"1984","journal-title":"J. Opt. Soc. Am. A"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Lange, K., and P\u00f6hlandt, K. (1984). Vergleichende Betrachtung der Verfahren zur Pr\u00fcfung der Plastischen Eigenschaften Metallischer Werkstoffe, Springer.","DOI":"10.1007\/978-3-662-10772-0"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Papula, L. (2011). Mathematik f\u00fcr Ingenieure und Naturwissenschaftler, Vieweg+Teubner Verlag.","DOI":"10.1007\/978-3-8348-8133-5"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1035","DOI":"10.1016\/j.physb.2006.05.331","article-title":"The new materials science diffractometer STRESS-SPEC at FRM-II","volume":"385\u2013386","author":"Hofmann","year":"2006","journal-title":"Phys. B Condens. Matter"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/j.nima.2013.01.049","article-title":"Rotatable multifunctional load frames for neutron diffractometers at FRM II\u2014Design, specifications and applications","volume":"711","author":"Hoelzel","year":"2013","journal-title":"Nucl. Instrum. Methods Phys. Res. Sect. A Accel. Spectrometers Detect. Assoc. Equip."},{"key":"ref_34","unstructured":"Reihle, M.M. (2016). Entstehung und Auspr\u00e4gung von Eigenspannungen in Verbundgussteilen. [Ph.D. Thesis, Technische Universit\u00e4t M\u00fcnchen]."},{"key":"ref_35","unstructured":"Firsching, M., Salamon, M., Ke\u00dfling, P.M., Nachtrab, F., Krumm, M., Uhlmann, N., and Hanke, R. (2010). Micro Structural Analysis of AlSi6Cu4 Using Quantitative Computed Tomography Methods, Fraunhofer IIS."},{"key":"ref_36","unstructured":"Reinhart, C. (2018). VGStudio MAX Referenzhandbuch, Volume Graphics GmbH."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/j.actamat.2014.07.052","article-title":"Microstresses and crack formation in AlSi7MgCu and AlSi17Cu4 alloys for engine components","volume":"81","author":"Baumgartner","year":"2014","journal-title":"Acta Mater."},{"key":"ref_38","unstructured":"Deutsches Institut f\u00fcr Normung e.V (2019). Metallische Werkstoffe\u2014Zugversuch: Teil 1: Pr\u00fcfverfahren bei Raumtemperatur, Beuth-Verlag GmbH."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/j.compositesa.2013.05.005","article-title":"Residual strain monitoring of out-of-autoclave cured parts by use of polarization dependent loss measurements in embedded optical fiber Bragg gratings","volume":"52","author":"Lammens","year":"2013","journal-title":"Compos. Part A Appl. Sci. Manuf."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/21\/6276\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:29:12Z","timestamp":1760178552000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/21\/6276"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,11,4]]},"references-count":39,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["s20216276"],"URL":"https:\/\/doi.org\/10.3390\/s20216276","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2020,11,4]]}}}