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- Atif, Yacine, 1967-, et al.
(author)
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Cyber-Threat Intelligence Architecture for Smart-Grid Critical Infrastructures Protection
- 2017
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Conference paper (peer-reviewed)abstract
- Critical infrastructures (CIs) are becoming increasingly sophisticated with embedded cyber-physical systems (CPSs) that provide managerial automation and autonomic controls. Yet these advances expose CI components to new cyber-threats, leading to a chain of dysfunctionalities with catastrophic socio-economical implications. We propose a comprehensive architectural model to support the development of incident management tools that provide situation-awareness and cyber-threats intelligence for CI protection, with a special focus on smart-grid CI. The goal is to unleash forensic data from CPS-based CIs to perform some predictive analytics. In doing so, we use some AI (Artificial Intelligence) paradigms for both data collection, threat detection, and cascade-effects prediction.
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- Babu, Ramesh, et al.
(author)
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Additive manufactured marine component - Ni Al bronze propeller
- 2021
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In: Procedia Structural Integrity. - : Elsevier. - 2452-3216. ; , s. 20-25
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Conference paper (peer-reviewed)abstract
- Seaworthiness, also known as Fitness For Service (FFS), assessment of marine structures and machinery components is performed in accordance with the actual ship classification society’s Rules and/or Standards. The maritime industry is for the time being taking an interest into Additive Manufacturing (AM) for the sake of design and manufacturing cost optimization. Components of particular interest appear to be valves, heat exchangers and propellers. For conventional manufactured materials, for example cast, forged, rolled, and extruded copper alloys there are well established marine classification rules and standards. Recently, Ship Classification Rules and Standards for AM materials has been published. The seaworthiness or FFS of a Ni Al bronze (NAB) marine propeller constructed by Wire Arc Additive Manufacturing (WAAM) has been scrutinized by a novel approach of combining conventional material qualification procedures with identification and data acquisition (DAQ) of essential WAAM process parameters. A 520 kg heavy marine propeller, with a diameter of 2 m, was manufactured by the South Korean company SY Metal under strict observation of DNV South Korea. In this report the authors are presenting essential WAAM process parameters and authentic mechanical properties of the Ni Al bronze WAAM marine propeller; benchmarked toward authentic NAB cast propeller data. © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)
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| 8. |
- Kroon, Martin, Professor, 1974-, et al.
(author)
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An Eulerian thermomechanical elastic-viscoplastic model with isotropic and directional hardening applied to computational welding mechanics
- 2021
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In: Acta Mechanica. - : Springer. - 0001-5970 .- 1619-6937. ; 232, s. 189-218
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Journal article (peer-reviewed)abstract
- An Eulerian thermomechanical elastic-viscoplastic model with isotropic and directional hardening is used to analyse the residual mechanical state resulting from the arc welding of a multi-pass weld. Details of the weld test plate, weld filler material, and numerical implementation of the model are provided, including integration algorithms and consistent tangent modulus. For the computational welding mechanics analyses, the austenitic ASME stainless steel grade 316L was considered so that no phase transformations of solid states needed to be considered. The maximum residual stresses were found to be about 500-600 MPa, which is of the order of the yield stress of the base material. Variations in the heat input and the resulting weld cooling time had a significant influence both on the residual stress state and on the resulting geometry of the weld. The predicted stress levels were compared to the experimental results. Overall, the proposed Eulerian framework seems to be a promising tool for analysing melting/solidification processes and residual mechanical states.
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| 9. |
- Kroon, Martin, Professor, 1974-, et al.
(author)
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Prediction of welding residual stresses using an Eulerian plasticity model
- 2022
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In: Proceedings M2D2022 - 9th International Conference on Mechanics and Materials in Design, Funchal/Portugal 26-30 June 2022. - 9789895475636 ; , s. 167-168
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Conference paper (peer-reviewed)abstract
- Solidification processes play an important role in several industrial processes, such as weldingand additive manufacturing, and the resulting residual stress state is often critical for thestructural integrity of the material. A thermomechanical model was developed for the analysisand prediction of such solidification processes. The approach is based on a model proposed byRubin (Int. J. Eng. Sci. 25, 1175-1191, 1987). This plasticity model was formulated for finitestrains using an Eulerian evolution equation for a unimodular elastic distortional deformationtensor. This evolution equation automatically ensures thermodynamic consistency andpreservation of isochoric inelastic deformations. A 2D problem in the form of a butt weld jointwas analyzed. The main outcome from the analyses were the residual stress distributions. Theresults are compared to experimental data from the literature.
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| 10. |
- Lindström, Per, 1967-, et al.
(author)
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2D, Axisymmetric and 3D Finite Element Analysis Assessment of the IIW RSDP Round Robin Initiative, Phase 1 and Phase 2
- 2012
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Reports (other academic/artistic)abstract
- A further assessment of the IIW numerical and experimental test RSDP Round Robin Initiative, Phase 1 and Phase 2 is presented. Focus is on the weld process specification, and the importance ofuse of as realistic as possible weld process parameters in the weld simulations. Considerable interpretation is often required of the weld designer and of the FE modeller when simulatinga weld process. The paper demonstrates, on the IIW RSDP round Robin benchmarks, that with interpretation and judgement, Computational Welding Mechanics using a variety of models and approaches is possible. Difficulties in interpretation could be substantially reduced through the use of industrial methods of specification, weld process specifications (WPS). For this reason, the authors recommend that all benchmarks follow the standards and definitions used in internationally recognised industrial standards. For the Phase 1 benchmark three-pass butt welded pipe case, which was a designed case for weld simulations, rotationally symmetric and fully 3D results are presented for temperatures, deformations and stresses. These results are compared with IIW benchmark results, and differences caused by weld process parameters and material modelling (for the mechanical analysis) are discussed.For the Phase 2 benchmark two pass butt welded coupon plate case, experimental results are available. The incomplete documentation from the weld experiment compared to realistic WPS is discussed. 3D thermal results coupled with generalised plane strain 2D results for temperatures, deformations and stresses using correct WPS and realistic material data are presented and compared with IIW benchmark results. SFor both Benchmarks the LS-Dyna FE software was used, with a major modification being a modified Goldak heat source model.
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