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- Aktive Thermografie (4)
- Active thermography (2)
- Blitzanregung (2)
- Risse (2)
- Thermografie (2)
- Blitzthermografie (1)
- Bonding problems (1)
- Building façade (1)
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Eingeladener Vortrag
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For assessing building façades using active thermography, in case of direct solar exposure the sun itself can be used as heat source. It is shown that active thermography can be applied to large areas successfully, if a shadow cast occurs. After performing a sequence reconstruction in order to correct the temporal behaviour of shadow movement, the data could be analysed by pulse phase thermography (PPT). Compared to raw thermograms, the obtained phase images display an improved image quality with a lot of details. The frequency of the phase images is related to the probing depth. The presented case study describes the thermographic investigation of an historical building façade, where an area of 17 m x 13 m has been investigated.
Zum „Transfer von FuE-Ergebnissen durch Normung und Standardisierung“ fördert das Bundesministerium für Wirtschaft und Technologie (BMWi) Vorhaben mit dem Ziel, neueste Erkenntnisse der Forschung über die Normung in die Wirtschaft zu integrieren (http://www.ebn.din.de).
Aktuell begleitet das DIN NMP mehrere Projekte in diesem Programm, eines davon ist das Projekt „Entwicklung von Normen und Standards für die aktive Thermografie mit Blitzlichtanregung“, das von der BAM in Zusammenarbeit mit dem DIN und der DGZfP bearbeitet und von der Siemens AG unterstützt wird. Projektträger ist das Deutsche Institut für Luft und Raumfahrt (DLR), Ansprechpartner im DIN NMP ist Martin Sengebusch. Beginn war im März 2011, im Februar 2013 wird das Projekt beendet.
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 LevenbergMarquardt 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.