TY - CONF A1 - Maierhofer, Christiane A1 - Myrach, Philipp A1 - Röllig, Mathias A1 - Steinfurth, Henrik T1 - Validation of active thermography techniques for the characterization of CFRP structures N2 - Lockin thermography as well as flash thermography are very well suited for non-destructive testing and characterisation of inhomogeneities and damage in CFRP structures. Both methods are applied more and more in research and industry, but until know it is not clear which are the advantages of one method against the other. In this paper, results of two research projects concerning the validation and standardisation of both methods are presented. Three different types of CFRP test specimens consisting of well-defined flat bottom holes, of artificial delaminations made of PTFE plates embedded in CFRP and of real impact damage have been investigated systematically with flash and lockin excitation. Here, the phase images of both methods are compared qualitatively as well as quantitatively. T2 - ECNDT 2014 - 11th European conference on non-destructive testing CY - Prague, Czech Republic DA - 06.10.2014 KW - Active thermography KW - Flash KW - Lockin KW - CFRP KW - Flat bottom holes KW - Delamination KW - Impact damage PY - 2014 UR - http://www.ndt.net/events/ECNDT2014/app/content/Paper/199_Maierhofer_Rev2.pdf SN - 978-80-214-5018-9 SP - Paper 199, 1 EP - 10 AN - OPUS4-31940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Ehrig, Karsten A1 - Meinel, Dietmar A1 - Céspedes-Gonzales, G. T1 - Validation of flash thermography using computed tomography for characterizing inhomogeneities and defects in CFRP structures N2 - Active thermography is an efficient non-destructive testing method for investigating the internal structure of larger carbon fiber reinforced plastic (CFRP) components as well as smaller CFRP components in mass customization. The method can be applied contactless and automated. This study contains systematic investigations of CFRP structures with typical defects and inhomogeneities occurring during production by means of flash thermography in reflection and transmission configuration and by computed tomography (CT). The latter one was used as a reference method, since also very small defects at larger depth can be visualized with high spatial resolution. The CFRP structures consist of plates which contain metallic and non-metallic inclusions, contaminations with glue or wax rests, areas with inhomogeneous re-injection of dry parts, fiber misalignments, and fiber damages. Further on, two specimens have been glued together with different artificial inhomogeneities of the four glue beads. The results of the applied methods are compared and the advantages and disadvantages of each configuration are discussed based on the detectability of the inhomogeneities. It is shown that although CT has led to best contrasts and spatial resolutions in displaying the inhomogeneities and inclusions, flash thermography is very well suited to detect most of these structures. Considering that flash thermography can be applied on-site and has a high potential for automation and for a fast and efficient testing, it can be highly recommended for quality assurance during and after production of CFRP structures. KW - A. Laminates KW - B. Defects KW - D. Radiography KW - D. Thermal analysis PY - 2014 DO - https://doi.org/10.1016/j.compositesb.2014.04.027 SN - 1359-8368 VL - 64 SP - 175 EP - 186 PB - Elsevier CY - Oxford [u.a.] AN - OPUS4-30771 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Worzewski, Tamara A1 - Krankenhagen, Rainer A1 - Doroshtnasir, Manoucher A1 - Röllig, Mathias A1 - Steinfurth, Henrik A1 - Maierhofer, Christiane T1 - IKARUS - Forschung zur thermografischen Zustandsinspektion von Offshore Rotorblättern N2 - Eine Arbeitsgruppe der BAM in der Abteilung für Zerstörungsfreie Prüfung forscht seit 2011 an verschiedenen technischen Fragestellungen, die sich aus dem thermografischen Lösungsansatz ergeben. Zum Beispiel werden spezielle Prüfkörper aus GFK im Labor unter dem Gesichtspunkt untersucht, inwieweit (materielle) innere Strukturen und äußerlich nicht sichtbare Schäden mit Thermografie offenbart werden können. Hierbei werden verschiedene Anregungs- und Auswertungstechniken auf ihre Eignung für diese Problemstellung untersucht. Der folgende Beitrag erläutert einige technische Schwierigkeiten bei der praktischen Anwendung der geplanten Inspektionsmethode und stellt einen erfolgversprechenden Lösungsansatz vor. KW - Zerstörungsfreie Prüfung KW - Rotorblatt KW - Windkraftanlage KW - Thermografie KW - IKARUS PY - 2014 SN - 0941-3898 VL - 34 IS - 1 SP - 20 EP - 22 PB - Verl. Natürl. Energie CY - Seevetal AN - OPUS4-30245 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Myrach, Philipp A1 - Steinfurth, Henrik A1 - Reischel, Mercedes A1 - Röllig, Mathias T1 - Development of standards for flash thermography and lock-in thermography N2 - Standards for the application of flash thermography as well as of lock-in thermography are urgently required. Both methods are applied more and more often in research and industry, but still extensive validation procedures are required for each individual application. In this paper, the results of two research projects concerning the validation and standardisation of both methods are presented. This includes results of a detailed study of the influence of measurements parameters on flash thermography, of the comparison of the lateral resolution obtained with flash and lock-in thermography and the description of a draft standard for flash thermography. T2 - QIRT 2014 - 12th International conference on quantitative infrared thermography CY - Bordeaux, France DA - 07.07.2014 KW - Active thermography KW - Flash KW - Lockin KW - CFRP KW - Metal KW - Standardization PY - 2014 UR - http://qirt.gel.ulaval.ca/archives/qirt2014/QIRT%202014%20Papers/QIRT-2014-032.pdf DO - https://doi.org/10.21611/qirt.2014.032 SP - 1 EP - 9 AN - OPUS4-31187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maierhofer, Christiane A1 - Myrach, Philipp A1 - Reischel, Mercedes A1 - Steinfurth, Henrik A1 - Röllig, Mathias A1 - Kunert, M. T1 - Characterizing damage in CFRP structures using flash thermography in reflection and transmission configurations N2 - Carbon fiber reinforced polymer (CFRP) specimens with artificial delaminations and with impact damage have been characterized using active thermography with flash excitation. Systematic investigations have been performed in four different experimental configurations of flash lamps and infrared (IR) camera in transmission as well as in reflection alignment. It is shown here that the diffusivities determined for the sound and for the damaged areas give a good measure for damage characterization. Although reflection measurements also give information about defect depth, reflection measurements from only one side are not sufficient for assessing the whole cross section of the specimens. Thus, depending on sample thickness the lateral size of damage could only be determined from reflections measurements from both sides or from transmission measurements. In this paper, measurement accuracy and limits of flash thermography for the investigation of CFRP specimens are presented in detail together with quantitative data concerning the defects. KW - D. Non-destructive testing KW - D. Thermal analysis KW - B. Thermal properties KW - B. Delamination KW - Flash thermography PY - 2014 DO - https://doi.org/10.1016/j.compositesb.2013.09.036 SN - 1359-8368 VL - 57 SP - 35 EP - 46 PB - Elsevier CY - Oxford [u.a.] AN - OPUS4-29582 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Worzewski, Tamara A1 - Krankenhagen, Rainer A1 - Doroshtnasir, Manoucher A1 - Steinfurth, Henrik A1 - Röllig, Mathias A1 - Maierhofer, Christiane T1 - Thermografie unter wechselnden Witterungsbedingungen zur Zustandsüberwachung eines Windkraftanlagen-Rotorblattes N2 - Weltweit errichtet man zunehmend Offshore-Windkraftanlagen (WKA). Diese auf hoher See errichteten WKA benötigen geeignete Wartungs- und Instandhaltungskonzepte. Bestehende Konzepte aus dem Landbereich geraten unter Offshore-Bedingungen an ihre Grenzen oder lassen sich überhaupt nicht anwenden, daher müssen neue Ansätze erprobt werden. Im Rahmen des BMBF geförderten Forschungsprojektes "IKARUS" ist das Potential der (berührungslosen) thermografischen Fernerkundung zur Zustandsüberwachung der Rotorblätter von WKA zu untersuchen. Veränderungen der Umgebungsbedingungen wie z.B. solare Einstrahlung oder der Tagestemperaturgang führen zu veränderlichen Energieeinträgen in ein Objekt, die beim Vorhandensein von Inhomogenitäten im Material oder Strukturmerkmalen thermische Signaturen hervorrufen können. Ebenso können Veränderungen der Witterungsbedingungen dazu führen, dass bereits vorhandene thermische Signaturen wieder ausgelöscht werden. Daher ist es unbedingt notwendig, systematische Langzeitmessungen bei verschiedenen Umgebungsbedingungen durchzuführen, um Fehlinterpretationen zu vermeiden. In diesem Beitrag wird anhand von Laborversuchen und Simulationen zunächst die grundsätzliche Eignung des thermografischen Ansatzes für glasfaserverstärkte Kunststoffe (GFK), aus denen die Außenhüllen der Rotorblätter gefertigt sind, demonstriert. Hierbei werden unterschiedliche Arten von Defekten an GFK vorgestellt, die zu thermischen Signaturen an Rotorblättern führen können. Anschließend werden Zwischenergebnisse aus einem laufenden Langzeitversuch zu einem demontierten Rotorblattsegment vorgestellt, welches unter verschiedenen Witterungsbedingungen und zu verschiedenen Tages- und Jahreszeiten thermografisch beobachtet wurde. T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 26.05.2014 PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-309000 SN - 978-3-940283-61-0 IS - DGZfP-BB 148 SP - Di.2.B.3, 1 EP - 10 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-30900 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -