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Numerical 2D model to quantify defects in semitransparent materials by pulsed thermography

  • Pulsed thermography is a well-known non-destructive testing technique and has proven to be a valuable tool for evaluation of material defects. Material defects are often simulated by flat-bottom holes (FBH) or grooves. Typically, analytical 1D models are used to determine the defect depth of FBHs, grooves or delaminations. However, these models cannot take into account lateral heat flows, or only to a limited extent (semi-empirical model). Their applicability is therefore limited by the FBHs aspect ratio (diameter to remaining wall thickness), to ensure that the heat flow above the defect can still be described one-dimensionally. Additionally, the surfaces of semi-transparent materials have to be blackened to absorb the radiation energy on the surface of the material. Without surface coatings, these models cannot be used for semi-transparent materials. Available 1D analytical models for determination of sample or layer thicknesses also do not take into account lateral heatPulsed thermography is a well-known non-destructive testing technique and has proven to be a valuable tool for evaluation of material defects. Material defects are often simulated by flat-bottom holes (FBH) or grooves. Typically, analytical 1D models are used to determine the defect depth of FBHs, grooves or delaminations. However, these models cannot take into account lateral heat flows, or only to a limited extent (semi-empirical model). Their applicability is therefore limited by the FBHs aspect ratio (diameter to remaining wall thickness), to ensure that the heat flow above the defect can still be described one-dimensionally. Additionally, the surfaces of semi-transparent materials have to be blackened to absorb the radiation energy on the surface of the material. Without surface coatings, these models cannot be used for semi-transparent materials. Available 1D analytical models for determination of sample or layer thicknesses also do not take into account lateral heat flows. Here, we present an approach for quantitative determination of the geometry of FBHs or grooves in semi-transparent materials by considering lateral heat flow. For this purpose, the results of a numerical 2D model are fitted to experimental data, e.g., to determine simultaneously the defect depth of a FBH or groove and its diameter or width, respectively. The model considers semi-transparency of the sample within the wavelength range of the excitation source as well as of the IR camera and thermal losses at its surfaces. Heat transport by radiation within the sample is neglected. It supports the use of an arbitrary temporal shape of the heating pulse to properly describe the measurement conditions for different heat sources.zeige mehrzeige weniger

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Metadaten
Autor*innen:Raphael Bernegger
Koautor*innen:Simon Altenburg, Christiane Maierhofer
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Deutsch
Jahr der Erstveröffentlichung:2018
Organisationseinheit der BAM:8 Zerstörungsfreie Prüfung
8 Zerstörungsfreie Prüfung / 8.0 Abteilungsleitung und andere
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:2D model; Data reconstruction; Flat bottom holes; Notches; Numerical modelling; Pulse thermography; Semitrasnparent materials
Themenfelder/Aktivitätsfelder der BAM:Chemie und Prozesstechnik
Veranstaltung:Progress in Photoacoustic & Photothermal Phenomena
Veranstaltungsort:Erice, Italy
Beginndatum der Veranstaltung:06.09.2018
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:01.10.2018
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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