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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 10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Significant improvement of the fatigue performance of ER70S-6 WAAM un-milled structures: a Cu/Ni multilayer nanotechnology approach(Elsevier, 2025-12-10); ; ; ; In recent years, the adoption of Wire Arc Additive Manufacturing (WAAM), now defined as Directed Energy Deposition based on Gas Metal Arc Welding (DED-Arc), in steel construction has increased significantly. However, the sequential layer deposition inevitably creates surface notches that cause high stress concentrations, leading to fatigue crack initiation. The current industrial standard for post-processing, CNC milling, is time-consuming and resource-intensive. A novel research approach focuses on directly controlling critical residual stresses of as-built specimens by introducing near-surface compressive residual stresses using a Cu/Ni nanostructured metallic multilayer (NMM). This study investigates the effect of NMM on DED-Arc structures and extends its application to metallic 3D-printed components. Optical microscopy provides detailed surface morphology and reliable roughness measurements, while X-ray diffraction (XRD) confirms the presence of residual tensile stresses in the NMM and the resulting residual compressive stresses in the steel substrate. Preliminary tension-tension fatigue testing provides insights into the fatigue strength increase due to NMM treatment of DED-Arc dogbone specimen.Publicationtype: Journal Article38 19 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Enhancing the lifespan of steel structures through a 3D-printed coating device for the application of a nanometallic multilayer on weld seams(Elsevier, 2025-12-10); ; ; ; Given the substantial environmental and economic consequences associated with deteriorating infrastructure, prolonging the service life of steel bridges is essential for advancing sustainability and economic viability. A critical factor in achieving this goal is enhancing the integrity of welded joints, which play a pivotal role in the bridge’s performance under dynamic loading conditions. Research indicates that the fatigue strength of welds can be increased by up to sixfold through the application of a nanometallic multilayer (NMM) composed of nickel and copper. To date, investigations into the fatigue enhancement of welded joints using NMM have predominantly been conducted on a laboratory scale. To enable practical application on existing infrastructure, a coating device is being developed to apply the NMM treatment directly onto surfaces without the need for full immersion in an electrolyte bath, thus supporting its implementation as a post-treatment process for steel bridges.Publicationtype: Journal Article10 27 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Merging nano and macro structure design: opportunities for the structural integrity of steel infrastructure(Elsevier, 2025-12-10); ; ; ; Merging the macro-level design with the nano-level design in structural engineering, hence, using the superior properties of nanostructured metallic multilayers for protecting fatigue-critical joints of the macrostructure and ensuring the structural integrity of the steel infrastructure are the objectves of a research effort at TU Hamburg. Nanostructured metallic multilayers (NMM) have significantly higher strength, fatigue resistance and ductility than monolithic homogeneous metal cross sections. The superior structural properties of these nanostructured cross sections are known, and so it is surprising why no attempt has been made to date to use nanostructured cross sections in macro cross sections in structural engineering to improve the cross section properties. This paper links the advantages of nanostructured multilayers with the needs of homogeneous metallic macro-cross sections and examines the question to which extent the high-performance material nanolaminate can compensate for the structural weak parts of metallic infrastructure. The welded joint subjected to fatigue is addressed as vulnerable part of metallic infrastructure. The article provides insights on how nanostructured multilayer can potentially contribute to the future of steel construction, further, how nanostructured multilayer can potentially affect fatigue design. The design as well as the maintenance of cyclically loaded metallic infrastructures, such as bridges and offshore wind turbines, are discussed herein and it is shown how sustainability, resource conservation, reduction of CO2 footprint, readiness, security of supply and economic viability of steel infrastructure can potentially be achieved.Publicationtype: Journal Article17 10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , HOOU an der TU Hamburg : Jahresbericht 2024(Technische Universität Hamburg, 2025); ; ; ; In diesem Bericht stellt die Hamburg Open Online University an der TU Hamburg (HOOU@TUHH) ihre Arbeit im Jahr 2024 vor.Publicationtype: Project Deliverable95 56