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Offshore-Windenergieanlagen erfordern Gründungskonzepte aus unterpulver-(UP-)geschweißten Dickblechen (bspw. der Güte S420ML). Während der Schweißfertigung kann eine zeitverzögerte wasserstoffunterstützte Kaltrissbildung auftreten, deren Bewertung aufgrund der Bauteilgröße von Offshore-Strukturen sehr komplex ist. Deswegen wurde eine bauteilähnliche Geometrie (Mock-Up) entwickelt, um reale Steifigkeitsverhältnisse auf den Labormaßstab zu übertragen. Zusätzliche Versteifungen simulieren die Wirkung einer Einspannung bzw. Schrumpfbehinderung der Schweißnaht. Über die Verwendung von Schweißpulvern mit definierter Feuchte wurden zudem ein Extremszenario der Wasserstoffaufnahme simuliert. Entsprechend der vorgegebenen Mindestwartezeit für die ZfP von bis zu 48 h wurde die Schweißnaht zerstörungsfrei mit Phased-Array-Ultraschall-Prüfung (PAUT) geprüft und die Eigenspannungen über Röntgendiffraktometrie (XRD) bestimmt. Zusätzlich wurde die Wasserstoffverteilung in der Schweißverbindung numerisch simuliert. Außer zulässigen Defekten (wie Poren), wurde keine verzögerte Kaltrissbildung in den Mock-Ups festgestellt, was auf hohe Rissbeständigkeit hindeutet.
Hollow axle inspection can be performed without demounting the axles and without dismantling the wheels and the brake discs by using the drilling for the scan. To increase inspection reliability and inspection speed, the application of phased array systems instead of conventional probes is a good choice. For solid shaft inspection phased array setups became standard in the recent years. Nevertheless, for hollow axle inspection typically a number of conventional probes rotating through the axles drilling are applied.
The new approach uses an electronically steered rotating sound field from a phased array for the circumferential scan. This is realized by a cone shaped phased array which operates in immersion technique. That allows a significant increase in inspection speed and a reduction of the mechanical effort of the inspection system. The inspection can be carried out by a linear movement of the probe setup along the axles drilling. Applying additional focal laws allows exact inclination and focusing of the sound beam in the plane vertical to the specimen axis to concentrate the sound in the zones close to the external surface. An additional focus in the plane of incidence increases overall resolution and sensitivity.
The cone type phased array probe has been optimized to detect transversal flaws in and close to the outer surface of the hollow axle with orientation in the radial-radial plane. The prototype probe system, sound field simulations and measurement results are presented.
The inspection of the sealing weld is an important phase for the evaluation of the acceptability of final disposal canister, but the weld is only a part of the 3D shielding of copper shell. The main tasks for reliable NDT evaluation requires an extensive evaluation of the parameters which contains typical inspection related items like repeatability, S/N ratio, POD, setting up the equipment for inspection, and all practices for inspections. The other parameters are material parameters, their variation must be taken into account in the evaluation of NDT reliability. Further parameters include human factors, i. e. human inspectors and their interaction with technical systems; their effects were studied on an example of the evaluation of eddy current data. Final parameters are related to evaluation of detected defects, which means sizing and base for acceptance and this can be done in different ways. Some examples are given and results are compared with different methods for instance between radiographic testing and ultrasonic testing by raw data analysis and PA-SAFT results. Also, preliminary curves for the evaluation of metallographic results of 55 defects will be shown by EB weld measurements. Some practical items concerning copper inspections will be also discussed related to acceptability.
Die Gefährdung durch Pipelines ist in der Öffentlichkeit wegen zahlreicher Berichte über Unfälle weitgehend präsent. Warum? Weil jeder Unfall die Gefahr von massiven Umweltschäden mit sich bringt und bei Leitungen, die durch besiedeltes Gebiet führen, sogar mit menschlichen Opfern verbunden sein kann. Thema dieses Beitrags ist ein neuartiges Ultraschall-Verfahren, das eine schnellere, sichere und kostengünstigere Prüfung derartiger Rohrleitungssysteme erlaubt.
Defect sizing is required for a quantitative assessment of the quality and reliability of safety relevant components and materials using ultrasonic non-destructive testing. The SAFT (Synthetic Aperture Focussing Technique) and the TOFD technique (Time Of Flight Diffraction) are such promising sizing candidates, extracting more information from the raw ultrasound echo data and the corresponding crack tip response. In this work the phased array technique is used to inspect a clad mock-up model of a pressure vessel section. The full scale model contains artificial test reflectors which are located in the weld and in the cladding region as well. The defects—representing typical flaws at a very early stage—are analysed with different frequencies, beam angles and directions of incidence.
For the reconstruction of reflector indications a SAFT algorithm is applied to the phased array measurement results. Additionally the reflectors are analysed by means of the TOFD technique, using different beam angles at the same time. Both analysis methods are performed using different directions of incidence considering the complex cladding structure underneath the inner surface of the mock-up model. A direct comparison of the SAFT and TOFD techniques shows that, besides the clarity of the results, the detection and sizing capabilities of SAFT are far better.
NDT is a multidisciplinary research area fusing the disciplines of natural Science and engineering. Particularly in the early development stages of a new testing method, feasibility investigations focus on the fundamental physical interaction between the sensing mechanism and specimen. Research activities during subsequent phases of modular prototype development, technical System Integration and Validation primarily attempt to solve the practical engineering and real-life aspects of a testing method. We show several examples of new methods in different stages of development and highlight the potential for further industrial use. The first section deals with Steel surfaces of lightweight components which are
inspected with pm-sized magneto resistive sensor arrays. This quantitative magnetic stray field approach combines high spatial resolution and very high sensitivity, enabling the user to detect even very small micro-defects. Tuming to CFRP components we also show new developments in airbome ultrasonic testing. Here we use ferroelectret foils to reduce the acoustical mismatch between transducer and air, which enhances the signal-to-noise ratio. A further example illuminates the use of metallic nano layers as a broadband thermo acoustical emitter. Their use provides both high sound pressures and very broadband Signal characteristics. When it comes to CFRP components and other anisotropic and highly Scattering materials, ultrasonic matrix arrays in conjunction with many angles of incidences per transducer position can help to enhance the statistics of a testing problem. In the field of conventional water-coupled UT testing we also show the use of matrix array transducers
providing a tomographic-like 3D-image of impact damage in CFRP samples.
A time domain spectrometer in the range of 0.5–2 THz was used for time of flight (ToF) measurements of THz pulses for imperfection detection in non metallic materials. The measurements were performed in comparison to the established ultra sound pulse echo (PE) and time of flight diffraction (ToFD) technique. No coupling agent and no contact to the surface is required for THz ToFD measurements. Plastic test specimen with notches, voids and drilled side holes were used to study reflected and diffracted response signals. No major differences were observed between the UT and THz ToFD records for the first surface of the notches, voids and holes. Additionally to the UT records also signals were obtained from its back side and a second raw of holes. The THz measurement is fast and has the potential to substitute UT applications in some industrial areas. Within the German project 'Handheld' the potential for miniaturization of the time domain equipment is explored for efficient application.