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- Active thermography (3)
- CFRP (3)
- GFRP (3)
- Aktive Thermografie (2)
- CFK (2)
- GFK (2)
- Active and passive thermography (1)
- Artificial and natural defects (1)
- Delaminations (1)
- Emissivity (1)
Organisationseinheit der BAM
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.
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.
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. In this contribution, results concerning the characterisation of CFRP and GFRP during and after quasi-static tensile loading are presented. It includes the measurement of optical properties in the infrared spectral range, tensile loading tests with the observation of the temperature distribution at one or both sides of the specimens using an infrared camera for the preparation and monitoring of intended natural defects, and active thermography inspections after tensile loading. It is shown that the defect preparation was successful. Thermographic monitoring during and active thermography testing after tensile loading enable the detection of the lateral extend of the generated defects. Differences between CFRP and GFRP materials are discussed.
In diesem Beitrag werden zerstörungsfreie Untersuchungen mittels aktiver Thermografie an Probekörpern aus CFK und GFK mit unterschiedlichen künstlichen Fehlstellen vorgestellt. Dabei wird die zeitliche und örtliche Temperaturverteilung nach Erwärmung mit Blitzlampen oder mit einem Infrarot-Strahler mit einer Infrarot-Kamera erfasst. Zur Rekonstruktion der Messdaten wurde ein numerisches Modell entwickelt. Dazu war die Bestimmung der thermischen und optischen Materialeigenschaften erforderlich.
Im EMRP-Projekt VITCEA werden komplementäre ZFP-Verfahren zur Prüfung von Faserverbundwerkstoffen weiterentwickelt und validiert. In diesem Beitrag werden Ergebnisse verschiedener Techniken der aktiven Thermografie und des Ultraschalls vorgestellt. Die Nachweisempfindlichkeiten bezüglich künstlicher und natürlicher Fehler mit unterschiedlichen lateralen Ausdehnungen und in verschiedenen Tiefen werden miteinander verglichen.
In diesem Beitrag werden zerstörungsfreie Untersuchungen mittels aktiver Thermografie an Probekörpern aus CFK und GFK mit unterschiedlichen künstlichen Fehlstellen vorgestellt. Dabei wird die zeitliche und örtliche Temperaturverteilung nach der Erwärmung mit Blitzlampen oder mit einem Infrarot-Strahler mit einer Infrarot-Kamera erfasst. Zur späteren Rekonstruktion der Messdaten wurde ein numerisches Modell entwickelt. Dazu war die Bestimmung der thermophysikalischen und optischen Materialeigenschaften erforderlich, was in diesem Beitrag ebenfalls beschrieben wird. Die Ergebnisse der numerischen Modellierung werden mit den experimentellen Untersuchungen der aktiven Thermografie verglichen. Weiterhin werden die experimentellen Untersuchungen hinsichtlich der beiden Materialsysteme CFK und GFK und unter Berücksichtigung der Teiltransparenz des GFK-Materials sowie der unterschiedlichen Anregungsquellen bewertet.
In order to test their suitability different non-destructive methods were performed to inspect a GFRP plate with artificial defects. These defects were manufactured by means of thin PTFE sheets inserted between two plies in three different depth. The inspection methods were microwave reflection, flash thermography and phased array ultrasonics, all applied to the same specimen. Selected results are shown for all methods demonstrating opportunities and limits of the particular inspection methods. The achieved detection limits and further application aspects are compared directly to provide a useful information for the planning of inspection tasks.
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 European Project VITCEA complementary methods (shearography, microwave, ultrasonics and thermography) have been further developed and validated. Together with partners from the industry, test specimens have been 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) have been considered. In this contribution, the validation of flash and lock-in thermography to these testing problems is presented. Data analysis is based on thermal contrasts and phase evaluation techniques. Experimental data are compared to analytical and numerical models. Among others, the influence of two different types of artificial defects (flat bottom holes and delaminations) with varying diameters and depths and of two different materials (CFRP and GFRP) with unidirectional and quasi-isotropic fiber alignment is discussed.