Blar i NTNU Open på forfatter "Ås, Sigmund Kyrre"
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A comparison of physical and numerical modeling of homogenous isotropic propeller blades
Savio, Luca; Sileo, Lucia; Ås, Sigmund Kyrre (Journal article; Peer reviewed, 2020)Results of the fluid-structure co-simulations that were carried out as part of the FleksProp project are presented. The FleksProp project aims to establish better design procedures that take into account the hydroelastic ... -
A gradient-based multiaxial criterion for fatigue crack initiation prediction in components with surface roughness
Skallerud, Bjørn Helge; Ås, Sigmund Kyrre; Ottosen, Niels S. (Journal article, 2018)The current study presents methods to predict the governing crack initiation site and fatigue crack initiation life of components with surface roughness. The surface topography is measured with white light interferometry ... -
Assessment of Pipeline Integrity after Trawling Impact by Investigating Dent with Gouge
Eliassen, Agnes Karin (Master thesis, 2016)Mechanical damage from trawling gear interference amongst others cause a significant amount of damage to pipelines. The present study has done a review of current standards and recommended practise for assessment methods ... -
Crystal plasticity modeling of microstructure influence on fatigue crack initiation in extruded Al6082-T6 with surface irregularities
Hallberg, Håkan; Ås, Sigmund Kyrre; Skallerud, Bjørn Helge (Journal article, 2018)The influence of surface roughness and microstructure heterogeneities in the vicinity of macroscopic stress concentrations are investigated by crystal plasticity simulations. It is shown that in the extruded Al6082-T6 alloy ... -
Digital image correlation for continuous mapping of fatigue crack initiation sites on corroded surface from offshore mooring chain
Qvale, Paul; P. Zarandi, Ershad; Ås, Sigmund Kyrre; Skallerud, Bjørn Helge (Peer reviewed; Journal article, 2021)The full-field digital image correlation (DIC) technique was used to identify crack initiation and early crack growth on irregular, corroded surfaces from offshore mooring chain. Finite element analysis was paired with the ... -
Effect of cyclic softening and mean stress relaxation on fatigue crack initiation in a hemispherical notch
Qvale, Paul; zarandi, ershad; Arredondo, Alberto; Ås, Sigmund Kyrre; Skallerud, Bjørn Helge (Journal article; Peer reviewed, 2022) -
Effect of long periods of corrosion on the fatigue lifetime of offshore mooring chain steel
Qvale, Paul; Nordhagen, Håkon Ottar; Ås, Sigmund Kyrre; Skallerud, Bjørn Helge (Peer reviewed; Journal article, 2022)R4-grade mooring chain steel specimens were subjected to alternating phases of saltwater corrosion and air fatigue to replicate seasonal load variations on chains in service. No significant difference in fatigue lifetimes ... -
Evaluation of the Hot-Spot Method for a Bracket Geometry
Mosbron, Erlend Rysstad (Master thesis, 2022)Et viktig del ved mekanisk design er å vurdere utmattingslevetid hos en komponent. En slik metode er hot-spot spenningsmetoden, som innebærer å beregne hot-spot spenningen ved sveisetåen. Ved å bruke denne metoden kan ... -
Examination of the Hot Spot Method and the Notch Stress Method for a Bracket Geometry
Sørli, Herborg (Master thesis, 2023)Denne masteroppgaven fokuserer på utmatting- og bruddanalyse av en brakettgeometri levert av Aker Solutions. I vurderingen av utmatting i sveisede strukturer benytter man vanligvis tre forskjellige tilnærminger: Den nominelle ... -
Experimental and numerical investigation of residual stresses in proximity girth welds
Bhardwaj, Sachin; Ås, Sigmund Kyrre; RATNAYAKE MUDIYANSELAGE, Chandima (Peer reviewed; Journal article, 2023)International fabrication codes and standards provide minimum distance criteria for proximity welds, although rigorous justification is lacking. These distances are either based on practical experience or mutual agreement ... -
Fatigue crack growth in mooring chain steel at different mean load levels
Hellum, Vidar; Gabrielsen, Øystein; Ås, Sigmund Kyrre (Peer reviewed; Journal article, 2023)The fatigue crack growth rates of R4 mooring chain steel at different R-ratios are investigated. Crack growth experiments are performed at three different R-ratios, 0.1, 0.3 and 0.7, utilizing compact tension specimens in ... -
Fatigue Monitoring of Crane Foundations
Ødegård, Randi Kyllo (Master thesis, 2023)Denne avhandlingen fokuserer på evaluering av utmattingsskader på sveisede flenser på kranfundamenter på servicefartøy som brukes i operasjoner i oppdrettsnæringen langs norskekysten. Målet med studien er å undersøke ... -
Isogeometric Phase-Field Methods for Modeling Fracture in Shell Structures
Proserpio, Davide (Doctoral theses at NTNU;2021:87, Doctoral thesis, 2021)The simulation of the fracture of engineering structures is a challenging topic that requires accurate and efficient numerical models. This thesis focuses on the modeling of brittle and ductile fracture in thin shell structures ... -
Material Parameter Identification Using Artificial Neural Networks and Genetic Algorithm
Midtgarden, Olav (Master thesis, 2018)Finite element method (FEM) simulations are widely used to perform structural analysis. To ensure that the results obtained from the simulations are realistic it is crucial to have a material model that is as close to ... -
Monitoring of Fatigue Damage for Offshore Wind Turbine Foundations - Investigating Operation Strain Estimation Techniques
Norbruis, Joris Obbe (Master thesis, 2017)A global focus on the shift to renewable energy has introduced international targets for sustainable energy production, which have strongly increased the interest in offshore wind turbines (OWT s). In order to make offshore ... -
Non-linear Irregular Wave Impact on Monopile Structures
Schöpfer, Philipp (Master thesis, 2016)This Master Thesis deals with non-linear wave impacts on monopile structures by introducing a potential flow solver named OceanWave3D (OCW3D) for simulating free surface waves and their kinematics under engineering ... -
Out of Plane Bending of Mooring Chains - Finite Element Analysis of a 7-link Model
Berthelsen, Katarina (Master thesis, 2017)This master's thesis is an investigation of out of plane bending (OPB) as a failure mode connected to the upper chain section of offshore mooring lines. A comprehensive literature study was done to present the OPB mechanism, ... -
Pipeline damage assessment after trawling impact
Ellingsen, Sondre Lydvo (Master thesis, 2018)Bulking av subsea-rørledning på grunn av kollisjon med trålere kan ha en betydelig effekt på den gjenverende utmattings-levetiden til røret. Kriterie som benyttes til å avgjøre om et rør et sikkert etter bulking har innebyg ... -
Pipeline Integrity Assessment of Dent with Gouge after Trawling Impact
Aadal, Adrian Haugsand (Master thesis, 2017)Damage to pipelines from interaction with trawler-gear affects the long-term integrity of the pipeline, and interference from trawling-equipment on subsea pipelines is a relatively common occurrence. This thesis looks on ... -
Towards Remaining Life Assessment by use of Conditional Adversarial Networks
Pettersen, Håkon Kvalvåg (Master thesis, 2021)Statistikk viser at fler-tallige tap av forankringsliner har skjedd tidlig i den designede levetiden. Forankringsliner av kjetting var ansvarlige for opptil 50 % av alle tap, hvor utmatting var en av hoved°arsakene for ...