Luleå University of Technology Publications
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Failure mechanism of aluminium – carbon fibre reinforced polymer interlocking joints through punching
No full textSingle-Step Punch Interlocking (SSPI) is a recently developed joining methodology between aluminium and Carbon Fibre Reinforced Polymer (CFRP) aiming to contribute to multi-material design of structural parts. This hybrid joint technology combines adhesive bonding with mechanical interlocking. Elucidating the failure mechanism of the developed joint is relevant to provide insights for future enhancements in performance, increase its lifespan and prevent premature failure. Therefore, the different subcritical failure events were identified through interrupted Single-Lap Shear (SLS) tests and subsequent non-destructive ultrasonic inspection, and the global failure mechanism was described. Results indicate that the addition of the SSPI joint delayed the onset and propagation of adhesive failure between both substrates, providing residual strength and increasing the ultimate load in a 65 % and the absorbed energy of the joint in a 156 %.Validerad;2025;Nivå 1;2025-08-06 (u5);Full text license: CC BY-NC-ND 4.0;Funder: Catalan Government</p
Innovative strategies for addressing fatigue challenges in laser powder bed fusion of AlSi10Mg specimens and topologically optimised components
No full textSurface roughness and process-induced defects, such as gas pores and lack of fusions, make additive manufacturing parts vulnerable to fatigue failure. As the conventional fatigue testing methods are time-consuming and require many specimens, several novel rapid fatigue test methods have emerged in recent years, including the stiffness method. In this work, the applicability of this method for AlSi10Mg parts printed by the laser powder bed fusion process is investigated. It is demonstrated that the stiffness method can obtain the fatigue limit of AlSi10Mg specimens with a small number of tests and has a minimal (1%) difference from conventional fatigue test method results. Furthermore, this methodology was applied to a fatigue demonstrator component obtained through a topology optimisation process. The fatigue limit of the demonstrator had less than a 10% difference compared to the conventionally tested ones and highlights the benefit of the stiffness method. In addition, these results led to the development of a framework which combines rapid fatigue testing and finite element modelling and can accurately predict the component fatigue life based on the results at the specimen scale, with a reported difference below 3%. This framework opens up a new avenue for faster qualification and certification of additively manufactured industrial components. Validerad;2025;Nivå 1;2025-11-05 (u8);Full text license: CC BY</p
In-situ monitoring and metallographic observations of mass transfer and defect formation during AlSi10Mg additive manufacturing using powder sheets
No full textMetal additive manufacturing using powder sheets (MAPS) melts powder attached in a sheet with a polymer binder, avoiding risks of loose powders in material waste, safety and health during laser additive manufacturing among other for e-mobility applications. However, this concept remains challenging for aluminum alloys due to occurring defects. To address this challenge, the mass transfer and defect formation mechanism during MAPS-AlSi10Mg were investigated using high-speed imaging and metallographic observations. The results showed that the mass transfer is realized via droplets formed first from the powder sheet in front of the melt pool and their incorporations into the melt pool. However, a much laser defocusing significantly inhibits the droplets’ incorporation into the melt pool and promotes the balling. Polymer coatings or it wrapped into the AlSi10Mg droplets, generates the inclusions once the droplets were incorporated into the melt pool. Furthermore, under the laser beam in focus, the large particle-size powder sheet, powder side up or low scanning speed easily induce pores via shielding gas/polymer vapor inclusion. The laser defocusing of +15 mm, average laser intensity of W/cm2, and binder side up induce defect-free tracks, owing to the complete removal of polymers by their sufficient evaporation and powder agglomeration spatters. This work unveils that the droplets’ incorporation into melt pool leads to the mass transfer of MAPS-AlSi10Mg while the droplets containing polymers and gas/vapor inclusion generate inclusions and pores. Meanwhile, the defect-free production strategy of suitable defocusing and high laser intensity is proposed.Validerad;2025;Nivå 2;2025-08-05 (u5);Full text license: CC BY 4.0;Funder: EIT RawMaterials (22021);</p
Search for dark matter produced in association with a Higgs boson decaying to a τ lepton pair in proton-proton collisions at √s = 13 TeV
No full textA search for dark matter particles produced in association with a Higgs boson decaying into a pair of τ leptons is performed using data collected in proton-proton collisions at a center-of-mass energy of 13 TeV with the CMS detector. The analysis is based on a data set corresponding to an integrated luminosity of 101 fb−1 collected in 2017–2018. No significant excess over the expected standard model background is observed. This result is interpreted within the frameworks of the 2HDM+a and baryonic Z′ benchmark simplified models. The 2HDM+a model is a type-II two-Higgs-doublet model featuring a heavy pseudoscalar with an additional light pseudoscalar. Upper limits at 95% confidence level are set on the product of the production cross section and the branching fraction for each of these two simplified models. Heavy pseudoscalar boson masses between 400 and 700 GeV are excluded for a light pseudoscalar mass of 100 GeV. For the baryonic Z′ model, a statistical combination is made with an earlier search based on a data set of 36 fb−1 collected in 2016. In this model, Z′ boson masses up to 1050 GeV are excluded for a dark matter particle mass of 1 GeV.Godkänd;2025;Nivå 0;2025-11-28 (u2);For funding information, see: https://doi.org/10.1007/JHEP10(2025)170Full text: CC BY license;</p
Modular RTIC: Lightweight Real Time for Customized Architectures
No full textLow-latency, hard real time (RT) architectures require well-coordinated hardware and software implementations. The RT interrupt-driven concurrency (RTIC) framework fuses hardware-accelerated stack resource policy (SRP)-based scheduling with the memory safety of the Rust programming language, offering the state of the art in terms of overhead for Rust-based, memory-safer, multitasking RT systems. RTIC uses a thin, monolithic DSL layer to map together the Rust-language user program, the SRP programming model, and the specific hardware target implementation. However, the monolithic design of the DSL limits its scalability, leading to a similarly monolithic codebase that hinders external contributions and complicates the integration of hardware- and use-case-specific extensions. In this article, we propose an extensible implementation of RTIC for customized architectures, introducing RTIC distributions to decouple high-level functionality from platform-specific details. In addition, we present a novel technique—compilation passes—that enables syntax extension through multipass procedural macro expansions, inspired by multistage processing as implemented by contemporary compilers. We validate this approach by adding support for two new targets: the Hippomenes softcore and the Atalanta softcore, along with two custom compilation passes: one that translates deadlines into static priorities based on task set analysis and one that leverages a hardware feature to selectively accelerate critical interrupts. Our evaluation demonstrates the ways in which the proposed architecture addresses existing limitations, enhances maintainability, and provides an outset for supporting customized hardware architectures in a scalable way.Validerad;2025;Nivå 2;2025-11-04 (u8);Full text license: CC BY</p
Temporal control of human DNA replication licensing by CDK4/6-RB signalling and chemical genetics
No full textCyclin-dependent kinases (CDKs) coordinate DNA replication and cell division, and play key roles in tissue homeostasis, genome stability and cancer development. The first step in replication is origin licensing, when minichromosome maintenance (MCM) helicases are loaded onto DNA by CDC6, CDT1 and the origin recognition complex (ORC). In yeast, origin licensing starts when CDK activity plummets in G1 phase, reinforcing the view that CDKs inhibit licensing. Here we show that, in human cells, CDK4/6 activity promotes origin licensing. By combining rapid protein degradation and time-resolved EdU-sequencing, we find that CDK4/6 activity acts epistatically to CDC6 and CDT1 in G1 phase and counteracts RB pocket proteins to promote origin licensing. Therapeutic CDK4/6 inhibitors block MCM and ORC6 loading, which we exploit to trigger mitosis with unreplicated DNA in p53-deficient cells. The CDK4/6-RB axis thus links replication licensing to proliferation, which has implications for human cell fate control and cancer therapy design.Validerad;2025;Nivå 2;2025-10-01 (u5);Full text license: CC BY 4.0;Funder: European Commission; Swiss National Science Foundation (182487,186230); Mark Foundation for Cancer Research</p
Unsupervised Segmentation and Classification of Waveform-Distortion Data Using Non-Active Current
No full textNon-active current in the time domain is considered for application to the diagnostics and classification of loads in power grids based on waveform-distortion characteristics, taking as a working example several recordings of the pantograph current in an AC railway system. Data are processed with a deep autoencoder for feature extraction and then clustered via k-means to allow identification of patterns in the latent space. Clustering enables the evaluation of the relationship between the physical meaning and operation of the system and the distortion phenomena emerging in the waveforms during operation. Euclidean distance (ED) is used to measure the diversity and pertinence of observations within pattern groups and to identify anomalies (abnormal distortion, transients, …). This approach allows the classification of new data by assigning data to clusters based on proximity to centroids. This unsupervised method exploiting non-active current is novel and has proven useful for providing data with labels for later supervised learning performed with the 1D-CNN, which achieved a balanced accuracy of 96.46% under normal conditions. ED and 1D-CNN methods were tested on an additional unlabeled dataset and achieved 89.56% agreement in identifying normal states. Additionally, Grad-CAM, when applied to the 1D-CNN, quantitatively identifies the waveform parts that influence the model predictions, significantly enhancing the interpretability of the classification results. This is particularly useful for obtaining a better understanding of load operation, including anomalies that affect grid stability and energy efficiency. Finally, the method has been also successfully further validated for general applicability with data from a different scenario (charging of electric vehicles). The method can be applied to load identification and classification for non-intrusive load monitoring, with the aim of implementing automatic and unsupervised assessment of load behavior, including transient detection, power-quality issues and improvement in energy efficiency.Validerad;2025;Nivå 2;2025-08-05 (u5);Full text license: CC BY 4.0;Funder: European Partnership on Metrology;This article has previously appeared as a manuscript in a thesis.</p
Multi-Factor Analysis of Cutting Parameters for Bamboo Milling
No full textIn industrial bamboo machining, the suboptimal selection of cutting parameters leads to elevated cutting power and increased surface roughness. To enhance the machinability of bamboo, a multi-objective optimization of cutting parameters was conducted using orthogonal experimental methods, with special focus on the influences of fiber direction, feed per tooth, and cutting speed on cutting power and surface roughness. The main findings of this study are summarized as follows: feed per tooth exhibited the greatest effect on cutting power, followed by cutting speed and fiber direction. In contrast, fiber direction exerted the most substantial influence on surface roughness, with feed per tooth and cutting speed ranking second and third, respectively. Furthermore, the optimal milling parameters for minimizing both cutting power and surface roughness were identified as a fiber direction of 0°, a feed per tooth of 0.2 mm/z, and a cutting speed of 400 m/min. Therefore, the obtained optimal parameters are recommended for industrial bamboo machining to achieve reduced cutting power and improved surface quality.Validerad;2025;Nivå 2;2025-10-06 (u2);Full text: CC BY License;Funder: International Cooperation Joint Laboratory for Production, Education, Research and Application of Ecological Health Care on Home Furnishing;</p
Health Web 1.0, a web-based occupational therapy group intervention for older adults: A study protocol for a feasibility study
No full textBackground: Health promotion interventions supporting the development of strategies for social participation when ageing is an important concern within occupational therapy. Therefore, a new intervention has been developed. Aim: To present a protocol for a feasibility study evaluating the feasibility of Health Web 1.0, a web-based occupational therapy group intervention supporting older adults’ social participation and meaningful activities in daily life. Material and methods: This feasibility study follows the framework for developing and evaluating complex interventions. This study will be conducted using a pre-test and posttest design without a control group to evaluate feasibility and potential results. Qualitative and quantitative data will be collected concurrently in a mixed-method design. The Health Web 1.0 will be conducted in municipal primary healthcare settings. The intervention is provided through a digital communication platform, delivered by occupational therapists. Results: Not applicable (N/A). Conclusions and significance: The intervention will have significance for occupational therapists to adapt to a more proactive role in supporting a meaningful everyday life when ageing. Additionally, the group format and digital delivery of the intervention will provide possibilities to use resources more effectively.Validerad;2025;Nivå 2;2025-12-04 (u8);Full text license: CC BY 4.0;</p
Hajar du?
No full textEn lekfull interaktiv pjäs där också publiken får vara med att föra historien frammåt. Pjäsen handlar om två hajkompisar som kommer bort från varandra och där den ena fångas av en fiskare och får sin fena bortkapad. I vidare mening tar den den upp hajarnas utrotningshot, vad som händer om de helt skulle försvinna, vad vi som människor kan göra åt det både för hajarnas och havens skull men också för vår egen och hela naturens skull. Validerad;2025;Nivå 1;2025-12-16 (U3)</p