TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc T1 - Numerical method of active thermography for the reconstruction of back wall T2 - QIRT 2012 11th International Conference on Quantitative InfraRed Thermography CY - Naples, Italy DA - 2012-06-11 PY - 2012 AN - OPUS4-26214 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Götschel, S. A1 - Weiser, M. T1 - Data Enhancement for Active Thermography T2 - QIRT 2012 11th International Conference on Quantitative InfraRed Termography CY - Naples, Italy DA - 2012-06-11 PY - 2012 AN - OPUS4-26215 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc A1 - Schlilling, M. T1 - Numerical method of active thermography for the reconstruction of back wall geometry T2 - Vlth Inernational Workshop NDT in Progress CY - Prague, Czech Republic DA - 2011-10-10 PY - 2011 AN - OPUS4-24549 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc A1 - Schilling, M. T1 - Numerical method of active thermography for the reconstruction of back wall geometry N2 - The paper presents numerical methods to detect and classify defects and inhomogeneities by means of active thermography. The objective is to determine the wall thickness of structure elements with an inaccessible back wall, for example, of pipes or Containers. As test specimens we used approximately 2 cm thick PVC samples with spatial variations in the back wall geometry. Flash lamps provided the heating. To know the thickness of the wall, we used two inversion methods and compared the results achieved. One is an iterative echo defect shape method and already tested on Steel test specimens with good reconstruction results. The second one is the Levenberg-Marquardt method, applied here to thermographic data for non-destructive testing. Since data capturing using active thermography and the presented numerical methods can easily be automated, the combination of these two procedures is a promising approach providing a broad area of application. T2 - 6th Workshop 'NDT in progress' CY - Prague, Czech Republic DA - 10.10.2011 KW - Impulse-thermography KW - Inversion KW - Levenberg-Marquardt method KW - Echo defect shape KW - Defect shape reconstruction PY - 2011 SN - 978-80-214-4339-6 IS - Chapter 8 SP - 245 EP - 252 AN - OPUS4-25144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Kreutzbruck, Marc A1 - Maierhofer, Christiane T1 - Numerische Verfahren für die aktive Thermografie zur Untersuchung von Rückwandgeometrien N2 - In diesem Beitrag werden numerische Verfahren zur Erkennung und Charakterisierung von Fehlstellen, Schichtdicken, Wanddicken und Inhomogenitäten mittels aktiver Thermografie vorgestellt. Eine uantitative Beurteilung der nicht immer zugänglichen Rückwand eines Bauteils (Minderdicken) ist durch Inversion thermografischer Messdaten möglich. Diese quantitativen Informationen können durch iterative Methoden vom Gauß-Newton-Typ (Inversion) gewonnen werden. Als reale Prüfobjekte werden ca. 2 cm dicke PVC-Platten mit örtlich variierender Rückwandgeometrie untersucht. Die Erwärmung erfolgt mit Blitzlampen, welche die PVC-Platte kurzzeitig um mehrere K erwärmt. Ein wichtiger Teil der Inversion ist die Simulation des Experiments, welche mit Finite-Elemente-Methoden (FEM) in 2D realisiert wird. Da Inversion und active Thermografie automatisierbar sind, bietet die Kombination breite Anwendungsgebiete innerhalb der Industrie. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Deutschland DA - 30.05.2011 KW - Inversion KW - Aktive thermografie KW - Wanddicke KW - Rückwand KW - Minderdicken KW - Schichtdicken PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-252812 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (P45) SP - 1 EP - 6 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-25281 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Götschel, S. A1 - Weiser, M. T1 - Fast defect shape reconstruction based on travel time in pulse thermography T2 - Nondestructive Testing of Materials and Structures CY - Istanbul, Turkey DA - 2011-05-15 PY - 2011 AN - OPUS4-25302 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Götschel, S. A1 - Weiser, M. A1 - Maierhofer, Christiane A1 - Richter, Regina A1 - Röllig, Mathias ED - Büyüköztürk, O. ED - Tasdemir, M.A. ED - Günes, O. ED - Akkaya, Y. T1 - Fast defect shape reconstruction based on the travel time in pulse thermography N2 - Pulse thermography is a non-destructive testing method based on ­infrared imaging of transient thermal patterns. Heating the surface of the structure under test for a short period of time generates a non-stationary temperature distribution and thus a thermal contrast between the defect and the sound material. In modern NDT, a quantitative characterization of hidden imperfections in materials is desired. In particular, defect depth and shape are of interest. The reconstruction of the defect from thermography data is a nonlinear inverse problem, and ill-posed. We propose an algorithm for the identification of subsurface defects based on the travel time of the reflected thermal pulse. Our work extends results by Lugin and Netzelmann, taking lateral thermal flows directly into account while retrieving the defect depth. This requires significantly less computational work. Quantitative information about the defect shape and depth is obtained. Application of our method to both thermography data generated by a finite element simulation and experimental heating of PVC test specimens with different defects yields good reconstruction of the actual defects. KW - Defect shape reconstruction KW - Finite element simulation KW - Pulsed thermography KW - Quantitative characterization KW - Thermal contrast KW - Inversion KW - Aktive Thermografie KW - Wanddicke KW - Rückwand KW - Minderdicken KW - Schichtdicken KW - Thermische Welle PY - 2013 SN - 978-94-007-0722-1 DO - https://doi.org/10.1007/978-94-007-0723-8_11 SN - 2211-0844 N1 - Serientitel: RILEM bookseries – Series title: RILEM bookseries VL - 6 SP - 83 EP - 89 PB - Springer AN - OPUS4-27619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Kreutzbruck, Marc A1 - Maierhofer, Christiane T1 - Untersuchungen zur 2D- und 3D-Rekonstruktion von Rückwandgeometrien in der Impuls-Thermografie T2 - DACH-Jahrestagung 2012 CY - Graz, Austria DA - 2012-09-17 KW - Rekonstruktion KW - Inverse Probleme KW - Defekte PY - 2012 SN - 978-3-940283-44-3 IS - DGZfP-BB 136 SP - Poster 33, 1 EP - 8 AN - OPUS4-27694 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc T1 - Untersuchungen zur 2D- und 3D-Rekonstruktion von Rückwandgeometrien in der Impuls-Thermografie T2 - DGZfP-Jahrestagung CY - Graz, Austria DA - 2012-09-17 PY - 2012 AN - OPUS4-27023 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc ED - Cardone, G. T1 - Numerical method of active thermography for the reconstruction of back wall geometry T2 - QIRT 11 - 11th International conference on Quantitative InfraRed Thermography CY - Prague, Czech Repubilc DA - 11.06.2012 KW - Rekonstruktion KW - Inverse Probleme KW - Defekte PY - 2012 SP - 1 EP - 9 AN - OPUS4-26446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Götschel, S. A1 - Weiser, M. A1 - Maierhofer, Christiane A1 - Richter, Regina ED - Cardone, G. T1 - Data enhancement for active thermography T2 - QIRT 11 - 11th International conference on Quantitative InfraRed Thermography CY - Naples, Italy DA - 2012-06-11 KW - Datenglättung KW - Rekonstruktion PY - 2012 SP - 1 EP - 9(?) AN - OPUS4-26447 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc T1 - Numerical method of active thermography for the reconstruction of back wall geometry N2 - The paper presents a numerical method to detect and characterise defects and inhomogeneities by means of active thermography. The objective was to determine the wall thickness of structure elements with an inaccessible back wall, e.g., elements of pipes or containers. As test specimens we used PVC samples with the thickness of about 2 cm that had spatial variations in the back wall geometry. Flash lamps provided the heating. To measure the thickness of the wall, we employed the Levenberg–Marquardt method, which we applied here to experimental thermographic data for non-destructive testing. We started the inversion procedure by making a rough first estimation of the back wall geometry following the echo defect shape method, and then we calculated the thickness of the back wall. We found reasonable reconstruction results which differed from the real value significantly below 1 mm at the defect centre, whereas the error wais increased at the edge of the defect, depending on its shape and depth. KW - Pulse thermography KW - Wall thickness KW - Inverse problems KW - Reconstruction KW - Defects KW - Rekonstruktion KW - Inverse Probleme KW - Defekte PY - 2013 DO - https://doi.org/10.1016/j.ndteint.2012.10.010 SN - 0963-8695 VL - 54 SP - 189 EP - 197 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-28895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Regina A1 - Maierhofer, Christiane A1 - Kreutzbruck, Marc T1 - Numerische Verfahren für die aktive Thermografie zur Untersuchung der Rückwand T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 2011-05-30 PY - 2011 AN - OPUS4-24105 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -