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Item type:Publication, Access status: with files , Enhancing fatigue performance by tuning of residual stresses in welded joints through nanometallic multilayerWelded joints suffer from reduced fatigue life due to geometric stress concentrations and metallurgical changes in the heat-affected zone that promote crack initiation under cyclic loading. This study investigates a novel postweld treatment, utilizing a Cu/Ni nanometallic multilayer thin film deposited onto the welded butt joint. Deposition current densities and individual Cu/Ni layer thicknesses are systematically varied to optimize fatigue performance. A multiscale residual stress (RS) analysis characterizes stress states within individual multilayers and in the steel substrate, indicating all substrate RS are compressive in nature after thin film deposition. Results demonstrate a direct correlation between compressive RS magnitude and fatigue strength improvement. Tested at ΔσR = 0.75 × fy, a more than a 300% increase in cycles to failure is seen compared to the as-welded condition. This postweld treatment offers a promising approach for extending the operational life of welded structures across industrial applications.Publicationtype: Journal Article36 10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Material mechanisms of the nanostructured metallic multilayer post-weld treatment for fatigue strength increase(Elsevier, 2025-12-10); ; ; ; While traditional post weld treatments intend to reduce the fatigue failure potential by changing the weld seam geometry, introduction of compressive residual stresses and shielding off environmental impacts, the novel nanostructured metallic multilayer (NMM) post-weld treatment covers all three mechanisms simultaneously. NMM offer combined high strength and ductility and a significantly enhanced fatigue resistance. In a recent study a strong enhancement in fatigue resistance was detected. Utilizing energy-dispersive X-Ray diffraction techniques at the P61A-beamline at the German Synchrotron (DESY), it was found that residual stresses generated during the deposition process play a crucial role in this enhancement. Specifically, tensile stresses within the nanolaminate induce beneficial compressive stresses in the underlying substrate, effectively inhibiting fatigue crack initiation and resulting in an unprecedented increase in fatigue strength. NMM treatment of the double-V weld increases the fatigue strength from FAT class 80 to 225. This paper investigates which process parameters optimize the compressive stress profile in the steel base material, paving the way for the NMM post-weld treatment to reliably and economically contribute to longevity of cyclically loaded metal infrastructure.Publicationtype: Journal Article20 12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A procedure for accurate dose measurement in radiotherapy research at millimetre-sized synchrotron beams(IOP Publishing, 2025-11-12); ; ; ; Objective.Synchrotron-based spatially fractionated radiotherapy and ultra-high dose rate (UHDR) radiotherapy have been shown to better spare healthy tissue function in comparison to conventional radiotherapy, while controlling the tumour with the same efficacy. In recent years, an increasing amount of research has been carried out in these fields with promising results. However, further experiments remain essential, since the underlying mechanisms of healthy tissue preservation are not yet fully understood. The characterisation of synchrotron beamlines at the Deutsches Elektronen-Synchrotron in Hamburg represents an opportunity to increase the number of sites where pre-clinical studies could be conducted in the future. However, the beams available at this synchrotron are only a few millimetres in size and measuring absorbed dose with established detectors and dosimetry protocols represents a challenge.Approach.We show a procedure to accurately determine the beam dose rate under such conditions by first characterising a monochromatic beamline. After validation, and with the support of Monte Carlo simulations, the procedure is adapted to investigate a white-beam beamline, at which photon flux and mean energy can be varied with Cu absorbers.Main results.With the developed procedure, it is possible to measure absorbed dose at these beamlines with relative uncertainties below 10%. In particular, at the white-beam beamline, the dose rate varies between about 20 Gy s-1and about 1800 Gy s-1, thus offering the opportunity to carry out much-needed systematic studies. Moreover, pilot experiments with a mouse phantom demonstrate that it is possible to treat small animals with such small-sized beams by using dose-painting techniques, with an agreement between prescribed and delivered dose within ±15%.Significance. This work represents a first step towards the implementation of reproducible pre-clinical studies at the PETRA III synchrotron, further contributing to a transition of spatially-fractionated and UHDR radiotherapy techniques into clinical practice.Publicationtype: Journal Article37 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , The Microbeam insert at the white beam beamline P61A at the synchrotron PETRA III/DESY : a new tool for high dose rate irradiation research(Multidisciplinary Digital Publishing Institute (MDPI), 2022-10-20); ; ; ; High dose rate radiotherapies such as FLASH and microbeam radiotherapy (MRT) both have developed to the stage of first veterinary studies within the last decade. With the development of a new research tool for high dose rate radiotherapy at the end station P61A of the synchrotron beamline P61 on the DESY campus in Hamburg, we increased the research capacity in this field to speed up the translation of the radiotherapy techniques which are still experimental, from bench to bedside. At P61, dose rates of several hundred Gy/s can be delivered. Compared to dedicated biomedical beamlines, the beam width available for MRT experiments is a very restrictive factor. We developed two model systems specifically to suit these specific technical parameters and tested them in a first set of experiments.Publicationtype: Journal ArticleScopus© Citations 1 92 167