| 1. |
- Babu, Ramesh, et al.
(författare)
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Additive manufactured marine component - Ni Al bronze propeller
- 2021
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Ingår i: Procedia Structural Integrity. - : Elsevier. - 2452-3216. ; , s. 20-25
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Konferensbidrag (refereegranskat)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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| 2. |
- Kroon, Martin, Professor, 1974-, et al.
(författare)
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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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Ingår i: Acta Mechanica. - : Springer. - 0001-5970 .- 1619-6937. ; 232, s. 189-218
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Kroon, Martin, Professor, 1974-, et al.
(författare)
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Prediction of welding residual stresses using an Eulerian plasticity model
- 2022
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Ingår i: 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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Konferensbidrag (refereegranskat)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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| 4. |
- Osterroos, Anna, et al.
(författare)
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Associations between capillary glucose during pregnancy and childhood growth to the age of five : a cohort study
- 2022
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to evaluate the relationship between random capillary glucose levels in healthy pregnant women and infant size at birth and childhood growth to the age of five years. This population-based cohort study comprised 10,937 healthy mother-child dyads. Data on highest maternal random capillary glucose level during pregnancy and sequential anthropometric data on their children during the first five years of life were gathered from the Uppsala County Mother and Child Cohort. Statistical analyses were performed with linear regression and linear mixed effect regression models. We found that higher glucose level during pregnancy was associated with higher weight z-score (beta 0.10, 95% confidence interval (CI) 0.08-0.11), length z-score (beta 0.05, 95% CI 0.03-0.07) and BMI z-score (beta 0.09, 95% CI 0.07-0.12) at birth, adjusted for maternal BMI and country of birth, smoking during pregnancy and parity. The association did not remain at 11/2, 3, 4 and 5 years of age. There was a positive relationship between higher glucose level during pregnancy and a decrease in weight z-score, height z-score and BMI z-score from birth to 5 years of age. In conclusion, higher random capillary glucose levels in pregnant healthy women were associated with greater infant size at birth, as well as decreased growth velocity in early childhood.
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