TY - JOUR A1 - Müller, Jan P. A1 - Götschel, S. A1 - Maierhofer, Christiane A1 - Weiser, M. T1 - Determining the Material Parameters for the Reconstruction of Defects in Carbon Fiber Reinforced Polymers from Data Measured by Flash Thermography JF - AIP Conference Proceedings N2 - Flash thermography is a fast and reliable non-destructive testing method for the investigation of defects in carbon fiber reinforced polymer (CFRP) materials. In this paper numerical simulations of transient thermography data are presented, calculated for a quasi-isotropic flat bottom hole sample. They are compared to experimental data. These simulations are one important step towards the quantitative reconstruction of a flaw by assessing thermographic data. The applied numerical model is based on the finite-element method, extended by a semi-analytical treatment of the boundary of the sample, which is heated by the flash light. A crucial part for a reliable numerical model is the prior determination of the material parameters of the specimen as well as of the experimental parameters of the set-up. The material parameters in plane and in depth diffusivity are measured using laser line excitation. In addition, the absorption and heat transfer process of the first layers is investigated using an IR microscopic lens. The performance of the two distinct components of CFRP during heating – epoxy resin and carbon fibers – is examined. Finally, the material parameters are optimized by variation and comparison of the simulation results to the experimental data. The optimized parameters are compared to the measured ones and further methods to ensure precise material parameter measurements are discussed. T2 - 43rd Review of Progress in Quantitative Nondestructive Evaluation CY - Atlanta, GA, USA DA - 17.07.2016 KW - Aktive Thermografie KW - Thermische Diffusivität KW - Zerstörungsfreie Prüfung KW - Kohlenstofffaserverstärkter Kunststoff KW - CFK KW - Active thermography KW - Thermal diffusivity KW - Non-Destructive testing KW - Carbon fiber reinforced polymer KW - CFRP PY - 2017 SN - 978-0-7354-1474-7 DO - https://doi.org/10.1063/1.4974671 SN - 0094-243X VL - 1806 IS - 1 SP - UNSP 100006-1 EP - 11 PB - AIP Publishing CY - Melville, NY, USA AN - OPUS4-39332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Jan P. A1 - Götschel, S. A1 - Maierhofer, Christiane A1 - Weiser, M. T1 - Thermografie mit optimierter Anregung für die quantitative Untersuchung von Delaminationen in kohlenstofffaserverstärkten Kunststoffen N2 - Da kohlenstofffaserverstärkte Kunststoffe (CFK) in anspruchsvollen sicherheitsrelevanten Einsatzgebieten wie im Automobilbau und in der Luftfahrt eingesetzt werden, besteht ein zunehmender Bedarf an zerstörungsfreien Prüfmethoden. Ziel ist die Gewährleistung der Sicherheit und Zuverlässigkeit der eingesetzten Bauteile. Aktive Thermografieverfahren ermöglichen die effiziente Prüfung großer Flächen mit hoher Auflösung in wenigen Arbeitsschritten. Ein wichtiges Teilgebiet der Prüfungen ist die Ortung und Charakterisierung von Delaminationen, die sowohl bereits in der Fertigung als auch während der Nutzung eines Bauteils auftreten können, und dessen strukturelle Integrität schwächen. In diesem Beitrag werden CFK-Strukturen mit künstlichen und natürlichen Delaminationen mit Hilfe unterschiedlich zeitlich modulierter Strahlungsquellen experimentell untersucht. Verwendet werden dabei Anregungen mit Blitzlampen und mit frequenzmodulierten Halogenlampen. Mittels Filterfunktionen im Zeit- und Frequenzbereich wird das Kontrast-zu-Rausch-Verhältnis (CNR) der detektierten Fehlstellen optimiert. Verglichen werden anschließend die Nachweisempfindlichkeit, das CNR und die Ortsauflösung der zu charakterisierenden Delaminationen für die unterschiedlichen Anregungs- und Auswertungstechniken. Ergänzt werden die Experimente durch numerische Simulationen des dreidimensionalen Wärmetransportes. T2 - DGZfP Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - CFRP KW - CFK KW - Lock-In Thermografie KW - Blitz-Thermografie KW - Konstrast-Rausch-Verhältnis PY - 2017 AN - OPUS4-40566 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Gower, M. A1 - Lodeiro, L. A1 - Baker, G. A1 - Aktas, A. A1 - Shaw, R. T1 - Introduction into the EMRP-Project VITCEA N2 - Defects in FRP structures may be introduced during the processing and fabrication of composite components and can initiate or grow in-service. In the context of this JRP, the term ‚defect‘ refers to imperfections introduced during manufacture/processing and/or secondary machining operations, as well as damage sustained during a component‘s service life. One of the challenges facing accurate and repeatable defect detection in FRP composites is the multitude of defect types that exist, each with characteristics that present different challenges to the NDE practitioner. In order for a particular NDE technique to achieve broad acceptance by industry, it is desirable for the technique to be able to detect a range of defect types with a high level of confidence. Project VITCEA (Validated Inspection Techniques for Composites in Energy Applications) is developing and validating traceable procedures for novel NDE techniques with contrasting detection capabilities, which will underpin the increased use of FRP composites for improved efficiency and reliability in energy related applications e.g. wind and marine turbine blades, nacelles, oil and gas flexible risers. T2 - Training Course Ultrasonics and Active Thermography CY - Berlin, Germany DA - 28.03.2017 KW - CFRP KW - GFRP KW - Active thermography KW - Ultrasonics KW - Microwaves KW - Shearography PY - 2017 AN - OPUS4-41091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Myrach, Philipp A1 - Unnikrishnakurup, Sreedhar T1 - Theory and data anaylsis of pulse and lock-in thermography N2 - CFRP and GFRP test specimens have been investigated with pulse and lock-in thermography. Both methods are compared quantitatively. T2 - Training Course Ultrasonics and Active Thermography CY - Berlin, Germany DA - 28.03.2017 KW - CFRP KW - GFRP KW - Active thermography KW - Flash excitation KW - Lock-in excitation PY - 2017 AN - OPUS4-41092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Röllig, Lodeiro A1 - Krankenhagen, Rainer A1 - Unnikrishnakurup, Sreedhar A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. T1 - Evaluation of different techniques of active thermography for quantification of artificial and natural defects in fiber reinforced composites N2 - For assuring the safety and reliability of components and constructions in energy applications made of fiber reinforced polymers (e. g. blades of wind turbines and tidal power plants, engine chassis, flexible oil and gas pipelines) innovative non-destructive testing methods are required. Within the EMRP project VITCEA complementary methods (shearography, microwave, ultrasonics and thermography) are further developed and validated. Together with partners from the industry, test specimens were constructed and selected on-site containing different artificial and natural defect artefacts. As base materials, carbon and glass fibers in different orientations and layering embedded in different matrix materials (epoxy, polyamide) were considered. In this contribution, the validation of different techniques of active thermography like flash, step heating and lock-in thermography to these testing problems is presented. Experimental data are compared to analytical and numerical models. Among others shows that although flash and lock-in thermography have the same detectability of flat bottom holes in the phase images, the detectability of delaminations is different. In another example, it is demonstrated that for GFRP, the transmissivity of the material has to be considered for the quantitative data analysis. T2 - 19th International Conference on Photoacoustic and Photothermal Phenomena - ICPPP 2017 CY - Bilbao, Spain DA - 16.07.2017 KW - CFRP KW - GFRP KW - Active thermography KW - Flash excitation KW - Lock-in excitation PY - 2017 AN - OPUS4-41103 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ziegler, Mathias A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias T1 - Characterization of defects in fibre reinforced composites (FRC) using passive and active thermography N2 - Impact damages and delaminations in fibre-reinforced composites (FRC) might not be visible at the surface, but could have an influence on the resistance and on the long-term behaviour of the component. Therefore, and especially for safety relevant structures, non-destructive methods are required for the assessment of such damages. Active thermography methods are suitable to characterize damages after loading using different kind of excitation techniques and various configurations of infrared (IR) camera and heating sources. Here, flash lamps, impulse excitation with infrared radiator and lock-in technique with halogen lamps or widened laser beams are suited. In addition, non-optical sources like sonotrodes (requiring direct contact to the structure) or induction generators (only suited for carbon fibre reinforced polymer (CFRP) structures) could be applied as well. For the investigation of the evolution of the damage during the impact, passive thermography can be applied in-situ. Elastic and plastic deformations alter the temperature of the structure and thus the temperature on the surface. In this contribution, at first the general principles of quantitative defect characterisation in FRC using active thermography with flash, impulse and lock-in excitation are described. Optical and thermal properties of the FRC material and its anisotropy are considered. Results of phase differences obtained at flat bottom holes with flash and lock-in thermography are compared for qualifying both methods for quantitative defect characterization. Secondly, the damage evolution of CFRP and GFRP structures under impact load and static tensile loading is described. The spatial and temporal evolution of the surface temperature enables us to distinguish matrix cracks or fibre-matrix separation from delaminations between the layers. Afterwards, all results for loading defects, obtained by passive and active thermography, are compared with each other. Fig. 1 and 2 show the difference of passive and flash thermography obtained at impact and tensile loaded CFRP plates, respectively. As one purpose of these investigations is the development of standards within national (DIN) and European (CEN) standardisation bodies, new draft and final standards are presented and further needs are discussed at the end of the presentation. T2 - INTERNATIONAL SCHOOL OF QUANTUM ELECTRONICS, 62nd Course, Progress in Photoacoustic & Photothermal Phenomena CY - Erice, Italy DA - 06.09.2018 KW - Thermography KW - Flash thermography KW - Lock-in thermography KW - CFRP KW - GFRP PY - 2018 AN - OPUS4-46283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Rehmer, Birgit A1 - Gower, M. A1 - Baker, G. A1 - Lodeiro, M. A1 - Aktas, A. A1 - Knaszovicka, L. A1 - Blahut, A. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. T1 - Characterisation of artificial defects in CFRP and GFRP sheets designed for energy applications using active thermography T2 - Proceedings of Conference QIRT 2016 N2 - The increased use of fibre-reinforced plastic (FRP) composites for improved efficiency and reliability in energy related applications e.g. wind and marine turbine blades, nacelles, oil and gas flexible risers, also increases the demand for innovative non-destructive testing technologies. Thus, in order to achieve increased acceptance of suited and optimized non-destructive testing (NDT) methods in industry, the European Metrology Research Programme (EMRP) project ENG57 Validated Inspection Techniques for Composites in Energy Applications (VITCEA) deals with the development and validation of innovative NDT technologies. In this contribution, results concerning thermographic investigations at test specimens during tensile loading and active thermography testing after tensile loading are presented. Additionally, the determination of the optical properties (relative transmittance and directional spectral emissivity) of CFRP and GFRP test specimens is described. T2 - Conference QIRT 2016 CY - Gdansk, Poland DA - 04.07.2016 KW - Active thermography KW - CFRP KW - GFRP KW - Validation of methods PY - 2016 UR - http://qirt.gel.ulaval.ca/archives/qirt2016/papers/076.pdf DO - https://doi.org/10.21611/qirt.2016.076 SN - 2371-4085 SP - Paper 076, 527 EP - 536 CY - Quebec, Canada AN - OPUS4-37512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Rehmer, Birgit A1 - Riemer, Sven A1 - Gower, M. A1 - Baker, G. A1 - Lodeiro, M. A1 - Knazovicka, L. A1 - Blahut, A. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. T1 - Characterisation of artificial and natural defects in fibre reinforced plastics designed for energy applications using active thermography - EMRP VITCEA N2 - Amongst various other NDT methods, within the EMRP-project ‘VITCEA’ active thermography is validated for testing of CFRP and GFRP structures constructed for energy application. In this contribution, the optical and thermal properties of CFRP and GFRP reference defect artefact (RDA) and natural defects artefact (NDA) test specimens are characterized. Different excitation techniques and techniques for data analysis are compared for optimizing the number of detected defects. T2 - 19th World Conference on Non-destructive Testing (WCNDT) CY - Munich, Germany DA - 13.06.2016 KW - Active thermography KW - CFRP KW - GFRP KW - Artificial and natural defects KW - Emissivity PY - 2016 AN - OPUS4-36700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Rehmer, Birgit A1 - Gower, M. A1 - Baker, G. A1 - Lodeiro, M. A1 - Aktas, A. A1 - Knaszovicka, L. A1 - Blahut, A. A1 - Monte, C. A1 - Adibekyan, A. A1 - Gutschwager, B. T1 - Characterisation of artificial defects in CFRP and GFRP sheets designed for energy applications using active thermography N2 - The increased use of fibre-reinforced plastic (FRP) composites for improved efficiency and reliability in energy related applications e.g. wind and marine turbine blades, nacelles, oil and gas flexible risers, also increases the demand for innovative non-destructive testing technologies. Thus, in order to achieve increased acceptance of suited and optimized non-destructive testing (NDT) methods in industry, the European Metrology Research Programme (EMRP) project ENG57 Validated Inspection Techniques for Composites in Energy Applications (VITCEA) deals with the development and validation of innovative NDT technologies. In this contribution, results concerning thermographic investigations at test specimens during tensile loading and active thermography testing after tensile loading are presented. Additionally, the determination of the optical properties (relative transmittance and directional spectral emissivity) of CFRP and GFRP test specimens is described. T2 - Conference QIRT 2016 CY - Gdansk, Poland DA - 04.06.2016 KW - Active themrography KW - GFRP KW - CFRP KW - Validation of methods PY - 2016 AN - OPUS4-37513 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Casperson, Ralf A1 - Pohl, Rainer A1 - Lohde, Sebastian A1 - Aydoğdu, M. T1 - Non-Destructive Testing of Composite Pressure Vessels using Conventional and High-Frequency Eddy Current Technique N2 - Composite-Druckgefäße für den Gefahrguttransport sowie für Wasserstoff- und Erdgasfahrzeuge bestehen aus einem lasttragenden Composite und einer gasdichten, metallischen oder polymeren Barriereschicht (Liner). Zur Untersuchung des Alterungsverhaltens solcher Composite-Druckgefäße wurde in der BAM das interdisziplinäre Themenfeldprojekt COD-AGE durchgeführt. Ziel des Projektes war die Entwicklung von Methoden und Modellen zur Beschreibung und Bestimmung des Alterungsverhaltens von Carbonfaser-Compositen am Beispiel von Druckgefäßen, um eine bessere Vorhersage der Alterung und der sicheren Gebrauchsdauer zu ermöglichen. Ein Schwerpunkt in diesem Projekt war die Bereitstellung geeigneter ZfP-Methoden. Dabei ging es sowohl um versuchsbegleitende Prüfungen, als auch um die mögliche Entwicklung von Prüfeinrichtungen für den späteren praktischen Gebrauch. In dem Vortrag werden Prüfergebnisse der alterungsbegleitenden Wirbelstromprüfung an Composite-Druckgefäßen vorgestellt. In Alterungsversuchen wurden Druckgefäße aus einem ca. 4 mm dicken Aluminiumliner und ca. 8 mm dicker CFK-Ummantelung untersucht. Typisches Einsatzgebiet solcher Druckgefäße sind Atemschutzgeräte der Feuerwehr. Die Druckgefäße wurden sowohl mit konventioneller Wirbelstromtechnik von außen und von innen als auch mit hochfrequenter Wirbelstromtechnik von außen geprüft. Es konnten sowohl Beschädigungen des metallischen Liners, als auch Strukturen des CFK-Geflechts nachgewiesen werden. Eine besondere mechanische Herausforderung bestand in der Prüfung der Innenseite der Liner, da hier eine zylindrische Fläche mit einem Innendurchmesser von 150 mm durch einen Zugang von nur 15 mm Durchmesser geprüft werden muss. N2 - Composite pressure vessels for transporting dangerous goods and for hydrogen and natural gas vehicles consist of a load-bearing composite and a gas-tight, metallic or polymeric barrier layer (liner). To investigate the aging behavior of such composite pressure vessels, BAM carried out the interdisciplinary project COD-AGE. The aim of the project was the development of methods and models for the description and determination of the aging behavior of carbon fiber composites using the example of pressure vessels in order to better predict aging and safe working life. One focus of this project was the provision of suitable NDT methods. These included both test-related tests and the possible development of test equipment for later practical use. In the lecture, test results of the age-related eddy current test on composite pressure vessels are presented. In aging tests, pressure vessels made of an approximately 4 mm thick aluminum liner and approx. 8 mm thick CFRP layer were examined. Typical application of such pressure vessels are respiratory protective devices of the fire department. The pressure vessels were tested using conventional eddy current technology from the outer and inner side as well as with high-frequency eddy current technology. Both damage to the metallic liner and structures of the CFRP could be detected. A particular mechanical challenge was the inspection of the inside of the liners, since a cylindrical surface with an inside diameter of 150 mm has to be tested with an access of only 15 mm diameter. T2 - TAHYA-Workshop CY - Berlin, Germany DA - 27.11.2019 KW - NDT KW - Composite pressure vessel KW - CFRP KW - Eddy current testing PY - 2019 AN - OPUS4-49829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -