scholarly journals Establishment and Verification of a Constitutive Model of Ice Material Considering the Effect of Temperature

2020 ◽  
Vol 8 (3) ◽  
pp. 193
Author(s):  
Tongqiang Yu ◽  
Kun Liu ◽  
Jiaxia Wang ◽  
Zili Wang
Keyword(s):  
Numerical Simulation ◽  
Constitutive Model ◽  
Arctic Region ◽  
Structure Design ◽  
Structural Deformation ◽  
The Arctic ◽  
Effect Of Temperature ◽  
Load Prediction ◽  
Finite Element Software ◽  
Ice Load

The increase in global warming has secured the arctic region as a research hotspot, and the existence of ice floes and massive icebergs poses a great challenge to the navigational safety of polar ships. For the finite simulation of ship–ice collisions, a reasonable description of the ice constitutive model is the most important factor for the accuracy of ice load prediction and structural deformation assessment. Due to the complex physical properties of natural sea ice materials, there are still many difficulties in achieving a widely accepted ice material model. In this paper, a constitutive model of ice material considering the influence of temperature is established and embedded into finite element software LS-DYNA, and the material property parameters are validated and analyzed. Then, the drop test in a published paper is recapitulated by the numerical simulation with the proposed method, and the results are compared. Good agreement is attained between the numerical simulation and published results. The influences of temperature and drop height are discussed, and the results show that both of them have an important effect on structural deformation. The research results can be used for ice load prediction and polar ship structure design.

Iceberg Shape Sensitivity in Ship Impact Assessment in View of Existing Material Models

2012 ◽  
Author(s):  
Martin Storheim ◽  
Ekaterina Kim ◽  
Jørgen Amdahl ◽  
Sören Ehlers
Keyword(s):  
Numerical Models ◽  
Significant Risk ◽  
Arctic Region ◽  
Material Model ◽  
High Energy ◽  
Structural Deformation ◽  
The Arctic ◽  
Physical Parameters ◽  
Material Models ◽  
The Arctic Region

Large natural resources in the Arctic region will in the coming years require significant shipping activity within and through the Arctic region. When operating in Arctic open water, there is a significant risk of high-energy encounters with smaller ice masses like bergy bits and growlers. Consequently, there is a need to assess the structural response to high energy encounters in ice-infested waters. Experimental data of high energy ice impact are scarce, and numerical models could be used as a tool to provide insight into the possible physical processes and to their structural implications. This paper focuses on impact with small icebergs and bergy bits. In order to rely on the numerical results, it is necessary to have a good understanding of the physical parameters describing the iceberg interaction. Icebergs are in general inhomogeneous with properties dependent among other on temperature, grain size, strain rate, shape and imperfections. Ice crushing is a complicated process involving fracture, melting, high confinement and high pressures. This necessitates significant simplifications in the material modeling. For engineering purposes a representative load model is applied rather than a physically correct ice material model. The local shape dependency of iceberg interaction is investigated by existing representative load material models. For blunt objects and moderate deformations the models agree well, and show a similar range of energy vs. hull deformation. For sharper objects the material models disagree quite strongly. The material model from Liu et.al (2011) crush the ice easily, whereas the models from Gagnon (2007) and Gagnon (2011) both penetrate the hull. From a physical perspective, a sharp ice edge should crush initially until sufficient force is mobilized to deform the vessel hull. Which ice features that will crush or penetrate is important to know in order to efficiently design against iceberg impact. Further work is needed to assess the energy dissipation in ice during crushing, especially for sharp features. This will enable the material models to be calibrated towards an energy criterion, and yield more coherent results. At the moment it is difficult to conclude if any of the ice models behave in a physically acceptable manner based on the structural deformation. Consequently, it is premature to conclude in a design situation as to which local ice shapes are important to design against.

scholarly journals Numerical Simulation of the Ice Breaking Process for Hovercraft

2021 ◽  
Vol 9 (9) ◽  
pp. 928
Author(s):  
Jiangjie Jin ◽  
Li Zhou ◽  
Shifeng Ding ◽  
Yingjie Gu
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Open Water ◽  
Structural Safety ◽  
Preliminary Design ◽  
Load Prediction ◽  
Ice Load ◽  
Hull Structure ◽  
Air Cushion ◽  
Ice Force

A hovercraft can adapt to an ice area, open water, land and other environments, owing to its unique hull structure. It also plays an important role in transporting supplies, rescuing people, breaking ice and conducting other tasks. Ice load prediction is very important for structural safety and navigation of a polar ship, especially in design of air cushion icebreakers or ice breaking platforms. In this paper, based on a simplified circumferential icebreaking pattern, the icebreaking force of the hovercraft operating on the ice sheet at low speed is simulated in a numerical way. Numerical analysis of the icebreaking process with different ice thicknesses and bending strengths are performed. The numerical results are compared with model test data in a time domain for three operating cases. By analyzing the average ice force, the errors between numerical simulation results and model test measurements are less than 30%. The present study is significant for the preliminary design of new icebreaking hovercraft and it assists the operation possibility for existing hovercraft.

Tension Based Heading Control Strategy of the Arctic FPSO With DP Assisted Mooring System

2019 ◽  
Author(s):  
Jaeyong Lee ◽  
Sol-Mi Choi ◽  
Seung Jae Lee ◽  
Kwang Hyo Jung
Keyword(s):  
Control Strategy ◽  
Computation Time ◽  
Arctic Region ◽  
Rate Of Change ◽  
The Arctic ◽  
Design Stage ◽  
Mooring System ◽  
Ice Load ◽  
Heading Control ◽  
Motion Characteristics

Abstract For offshore plants operating in the Arctic region, it is important to reflect the motion characteristics of the ice in the design stage. When the ice load is applied, the platform should rotate in the direction to reduce the tension acting on the mooring system using the DP system. However, it is very difficult to conduct the simulation by predicting the size and direction of the ice. This paper presents a heading control strategy to reduce the ice load acting on the arctic production platforms equipped with DP (Dynamic Positioning) Assisted Mooring System. In order to save computation time, grids are created in the operating area and the size of the tension acting on each grid is calculated considering the current position, the current tension, and the rate of change of tension. Based on the tension information, target heading angle is assigned and the platform is rotated with DP module. Developed process is validated through the simulation.

Numerical Prediction of Ship-Ice Interaction: A Project Presentation

2017 ◽  
Author(s):  
Malte Hahn ◽  
Hendrik Dankowski ◽  
Sören Ehlers ◽  
Sandro Erceg ◽  
Thomas Rung ◽  
...  
Keyword(s):  
Research Collaboration ◽  
Global Climate ◽  
Arctic Region ◽  
The Arctic ◽  
Current Status ◽  
Simulation Approach ◽  
Resource Exploitation ◽  
Load Prediction ◽  
Sea Ice Extent ◽  
Extreme Load

It is inevitable that commercial shipping and oil and gas resource exploitation activities in the Arctic will increase due to decreasing sea ice extent caused by global climate changes. Significantly more demanding and at the same time less well known environmental conditions create a need for reliable methods to assess icebreaking performance guaranteeing safe performance of the ships operating in this area subjected to various ice conditions. The classic approach of assessing ice-going performance, which combines class rules, experience and model tests, may not be applicable for the Arctic region in full. Furthermore, ship yards experience difficulties due to decreasing time frames and financial restrictions. Therefore this paper seeks to introduce a new development for a realistic and validated direct simulation approach for prediction of the hull load and icebreaking resistance that covers all aspects of the industrial design process and allows a more comprehensive analysis. The breaking model will provide a variable breaking pattern and is able to mimic the influence of the vessel speed and the environment on the ice loading and the predicted breaking length. In order to predict the extreme representative conditions to be simulated, a reverse extreme load prediction methodology is incorporated. An efficient, time dependent dynamic coupling between broken ice fragments, ice features, the 3D flow field and the ship’s hull provides resistance values for performance calculations. The computational model will be validated against full-scale data and class rules using deterministic and probabilistic measures. This simulation approach is developed within international research collaboration between Pella Sietas, Rolls Royce Marine, TUHH and NTNU. An overview of the project together with the current status of the ongoing work including first results is presented.

Numerical Simulation Analysis of the Typical Reinforced-Concrete Wall-Beam Joint

2012 ◽  
Vol 594-597 ◽  
pp. 973-976
Author(s):  
Ji Tong Jiang ◽  
Yang Liu ◽  
Wen Hui Wu ◽  
Song Yang ◽  
De Run Du
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Simulation Analysis ◽  
Complex Stress ◽  
Structure Design ◽  
Structural Deformation ◽  
Wall Structure ◽  
Concrete Wall ◽  
Element Analysis ◽  
Bond Slip

Based on the existing research results, this paper has primarily researched on numerical simulation analysis of a wall-beam joint in complex stress situation in a shear wall structure, in terms of structural deformation, crack of concrete, stress-strain condition of reinforced concrete, bond-slip state of concrete of the joint. The mature finite element analysis software ANSYS is selected as a platform and the parametric design language APDL is used as the foundation. Analyze the deformation of the joint; the cracks and the development status; the strain and stress of the joint and the bond-slip condition between steel bars and concrete. Some problems existing in the results at such joint calculated by commonly-used structure design software PKPM were found to need extra attention and then the paper put forward some feasible solutions.

Structure Design and Antiknock Performance Analysis of New Mine Refuge Chamber

2014 ◽  
Vol 945-949 ◽  
pp. 1227-1231
Author(s):  
Xiao Yan Gong ◽  
Xin Gao ◽  
Jun Guo ◽  
Jun Xu ◽  
Chao Ming Chen
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Performance Analysis ◽  
Coal Mine ◽  
Structure Design ◽  
Structure Model ◽  
Safety Problem ◽  
Impact Performance ◽  
Finite Element Software ◽  
Potential Safety

In order to solve the potential safety problem due to the explosion of coal mine caused the severe deformation of the front door not being opened normally and the emergency escape hatch was designed unreasonably, three types of structure model with emergency escape hatch being set in transition compartment as entrance and different locations of life supporting compartment as exit, which can avoid the potential safety problem above mentioned. Numerical simulation of antiknock impact performance of the three refuge cabins were calculated and analyzed by using the finite element software of LS-DYNA.The results indicated that the antiknock performance of structures could reach specifications, which could provide a new idea for the development of mine refuge chamber cabin.

Fully Coupled Numerical Simulation of Electromagnetic Forming

2012 ◽  
Vol 504-506 ◽  
pp. 1201-1206 ◽  
Author(s):  
Jyoti Kumar Doley ◽  
Sachin D. Kore
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Simulation Method ◽  
Electromagnetic Forming ◽  
Structural Deformation ◽  
Forming Process ◽  
Finite Element Software ◽  
Metal Forming Process ◽  
High Speed Forming ◽  
Fully Coupled

Electromagnetic forming (EMF) is a typical high speed forming process using the energy density of a pulsed magnetic field to form work pieces made of metals with high electrical conductivity like aluminum. In view of new lightweight constructions, special forming processes like EMF gain importance for the associated materials. In this paper modeling of electromagnetic sheet metal forming process is carried out by using commercial finite element software LS-DYNA®. A fully coupled numerical simulation method has been incorporated to study the interaction of the electromagnetic field and the structural deformation via transient analysis. Studies on the effect of first current pulse in electromagnetic forming are reported in the paper.

STORM ICE OIL WIND WAVE WATCH SYSTEM (SIOWS): WEB GIS APPLICATION FOR MONITORING THE ARCTIC

2017 ◽  
Author(s):  
Alexander Myasoedov ◽  
Alexander Myasoedov ◽  
Sergey Azarov ◽  
Sergey Azarov ◽  
Ekaterina Balashova ◽  
...  
Keyword(s):  
Satellite Data ◽  
Wind Wave ◽  
Arctic Region ◽  
Web Gis ◽  
The Arctic ◽  
Flexible Tool ◽  
In Situ Data ◽  
Current State ◽  
Watch System

Working with satellite data, has long been an issue for users which has often prevented from a wider use of these data because of Volume, Access, Format and Data Combination. The purpose of the Storm Ice Oil Wind Wave Watch System (SIOWS) developed at Satellite Oceanography Laboratory (SOLab) is to solve the main issues encountered with satellite data and to provide users with a fast and flexible tool to select and extract data within massive archives that match exactly its needs or interest improving the efficiency of the monitoring system of geophysical conditions in the Arctic. SIOWS - is a Web GIS, designed to display various satellite, model and in situ data, it uses developed at SOLab storing, processing and visualization technologies for operational and archived data. It allows synergistic analysis of both historical data and monitoring of the current state and dynamics of the "ocean-atmosphere-cryosphere" system in the Arctic region, as well as Arctic system forecasting based on thermodynamic models with satellite data assimilation.

Prévoir les variations saisonnières de la glace de mer arctique et leurs impacts sur le climat

2020 ◽  
pp. 024
Author(s):  
Rym Msadek ◽  
Gilles Garric ◽  
Sara Fleury ◽  
Florent Garnier ◽  
Lauriane Batté ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Region ◽  
Arctic Sea Ice ◽  
Climate Impacts ◽  
The Arctic ◽  
Recent Effort ◽  
Sea Ice Thickness ◽  
Arctic Sea ◽  
Ice Conditions ◽  
Upper Level

L'Arctique est la région du globe qui s'est réchauffée le plus vite au cours des trente dernières années, avec une augmentation de la température de surface environ deux fois plus rapide que pour la moyenne globale. Le déclin de la banquise arctique observé depuis le début de l'ère satellitaire et attribué principalement à l'augmentation de la concentration des gaz à effet de serre aurait joué un rôle important dans cette amplification des températures au pôle. Cette fonte importante des glaces arctiques, qui devrait s'accélérer dans les décennies à venir, pourrait modifier les vents en haute altitude et potentiellement avoir un impact sur le climat des moyennes latitudes. L'étendue de la banquise arctique varie considérablement d'une saison à l'autre, d'une année à l'autre, d'une décennie à l'autre. Améliorer notre capacité à prévoir ces variations nécessite de comprendre, observer et modéliser les interactions entre la banquise et les autres composantes du système Terre, telles que l'océan, l'atmosphère ou la biosphère, à différentes échelles de temps. La réalisation de prévisions saisonnières de la banquise arctique est très récente comparée aux prévisions du temps ou aux prévisions saisonnières de paramètres météorologiques (température, précipitation). Les résultats ayant émergé au cours des dix dernières années mettent en évidence l'importance des observations de l'épaisseur de la glace de mer pour prévoir l'évolution de la banquise estivale plusieurs mois à l'avance. Surface temperatures over the Arctic region have been increasing twice as fast as global mean temperatures, a phenomenon known as arctic amplification. One main contributor to this polar warming is the large decline of Arctic sea ice observed since the beginning of satellite observations, which has been attributed to the increase of greenhouse gases. The acceleration of Arctic sea ice loss that is projected for the coming decades could modify the upper level atmospheric circulation yielding climate impacts up to the mid-latitudes. There is considerable variability in the spatial extent of ice cover on seasonal, interannual and decadal time scales. Better understanding, observing and modelling the interactions between sea ice and the other components of the climate system is key for improved predictions of Arctic sea ice in the future. Running operational-like seasonal predictions of Arctic sea ice is a quite recent effort compared to weather predictions or seasonal predictions of atmospheric fields like temperature or precipitation. Recent results stress the importance of sea ice thickness observations to improve seasonal predictions of Arctic sea ice conditions during summer.

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