Development of Ice Class Arc4 MK III™ Type LNG Carrier

2008 ◽  
Author(s):  
Yongsuk Suh ◽  
Kibok Jang ◽  
Hisashi Ito ◽  
Seungmun Park ◽  
Sungyong Han ◽  
...  
Keyword(s):  
High Reliability ◽  
Direct Calculation ◽  
Arctic Region ◽  
Structural Safety ◽  
Wave Loads ◽  
Extreme Wave ◽  
Ice Load ◽  
Containment System ◽  
Hull Structure ◽  
Ice Loads

It is a very challenging work to design 208K Arctic LNG carrier, since LNG carrier requires high reliability for the structural safety and the environment of Arctic region is known to be very severe. Therefore, special attention should be paid for the verifying the structural safety of LNG carrier particularly with regard to LNG leakage. In this paper, the safety of the hull structure and cargo containment system of 208K MK III™ type LNG carriers with Arc4 is investigated based on the direct calculation of ice loads as well as wave loads. Several scenarios like design ice load, accidental ice load, ramming, entrapment and extreme wave are considered. From the whole investigation, it is clear that the developed vessel — 208K MK III™ type LNG carrier with RMRS Ice class Arc4 — has enough strength and is safe to be operated in Arctic region.

Station Keeping Trials in Ice: Ice Load Monitoring System

2018 ◽  
Author(s):  
Håvard Nyseth ◽  
Anders Hansson ◽  
Johan Johansson Iseskär
Keyword(s):  
Data Sets ◽  
Station Keeping ◽  
Ice Load ◽  
Hull Structure ◽  
Load Monitoring ◽  
Ice Loads ◽  
Recorded Data ◽  
Measurement Concept ◽  
Ice Impacts ◽  
Basic Philosophy

In connection with the Statoil SKT project, DNV GL have developed a method for estimating ice loads on the ship hull structure and mooring tension of the anchor handling tug supply (AHTS) vessel Magne Viking by full scale measurements. In March 2017, the vessel was equipped with an extensive measurement system as a preparation for the dedicated station-keeping trial in drifting ice in the Bay of Bothnia. Data of the ice impacts acting on the hull were collected over the days of testing together with several other parameters from the ship propulsion system. Whilst moored, the tension in the mooring chain was monitored via a load cell and logged simultaneously to the other parameters. This paper presents the processes involved in developing the measurement concept, including the actual installation and execution phases. The basic philosophy behind the system is described, including the methods used to design an effective measurement arrangement, and develop procedures for estimation of ice loads based on strain measurements. The actual installation and the process of obtaining the recorded data sets are also discussed.

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.

Dimensioning of Rudder Systems for Ice Class Ships

2020 ◽  
Author(s):  
Rob Hindley ◽  
Jillian Adams ◽  
Ville Valtonen ◽  
Chi-Hyun Sung
Keyword(s):  
Critical Element ◽  
Element Analysis ◽  
Safety Critical ◽  
System Protection ◽  
Ice Load ◽  
Hull Structure ◽  
Protection Mechanisms ◽  
Ice Loads ◽  
Control Surfaces ◽  
Scale Data

Abstract Rudder systems (rudder control surfaces and steering gear) are a safety critical element of ships operating in ice-covered waters. Icebreaking ships equipped with single rudders are particularly vulnerable considering the remote and often isolated locations in which they operate. The IACS Polar Class Rules were developed as a set of harmonized requirements for ships operating in polar waters. First published in 2006 the rules contain requirements for dimensioning the hull structure and propulsion machinery to resist ice loads. There are however no specific requirements for rudders — the rules simply require appendages to be dimensioned using the hull ice load. This paper presents a series of studies aimed at providing guidance on dimensioning rudders and steering gear systems for operation in ice. Using existing ship reference cases and rudder ice loading scenarios found in previous rules and guidelines a simplified set of design approaches are presented. These approaches are evaluated with Finite Element Analysis and compared with selected measured full-scale data and damage incidents. Guidance is provided on system protection mechanisms for the steering gear under these design and over-load cases. In addition, a comparison is made between the results and those derived from using the hull area design pressures in the current IACS rules.

The effect of spatial correlation of sea states on extreme wave loads of ships

2021 ◽  
pp. 1-11
Author(s):  
Antonio Mikulić ◽  
Marko Katalinić ◽  
Maro Ćorak ◽  
Joško Parunov
Keyword(s):  
Spatial Correlation ◽  
Wave Loads ◽  
Extreme Wave

Structural Safety Assessment of a 1100 TEU Container Ship, Based on a Enhanced Long Term Fatigue Analysis

2014 ◽  
Vol 1036 ◽  
pp. 935-940
Author(s):  
Leonard Domnisoru ◽  
Ionica Rubanenco ◽  
Mihaela Amoraritei
Keyword(s):  
Safety Assessment ◽  
Safety Evaluation ◽  
Irregular Waves ◽  
Structural Safety ◽  
Random Wave ◽  
Wave Loads ◽  
Strength Assessment ◽  
Integrated Method ◽  
Hydroelastic Response

This paper is focused on an enhanced integrated method for structural safety assessment of maritime ships under extreme random wave loads. In this study is considered an 1100 TEU container test ship, with speed range 0 to 18 knots. The most comprehensive criteria for ships structural safety evaluation over the whole exploitation life is based on the long term ship structures analysis, that includes: stress hot-spots evaluation by 3D/1D-FEM hull models, computation of short term ship dynamic response induced by irregular waves, long term fatigue structure assessment. The analysis is enhanced by taking into account the ships speed influence on hydroelastic response. The study includes a comparative analysis on two scenarios for the correlation between the ships speed and waves intensity. The standard constant ship speed scenario and CENTEC scenario, with total speed loss at extreme waves condition, are considered. Instead of 20 years ship exploitation life estimated by classification societies rules from the long term structural safety criteria, the enhanced method has predicted more restrictive values of 14.4-15.7 years. The numerical analyses are based on own software and user subroutines. The study made possible to have a more realistic approach of ships structural strength assessment, for elastic and faster ships as container carriers, in compare to the standard one based only on naval rules, delivering a method with higher confidence in the designed structural safety.

Extreme wave loads on submerged water intakes in shallow water

2015 ◽  
Vol 27 (1) ◽  
pp. 38-51 ◽  
Author(s):  
Andrew Cornett ◽  
Mark Hecimovich ◽  
Ioan Nistor
Keyword(s):  
Shallow Water ◽  
Wave Loads ◽  
Extreme Wave

Extreme Wave Loads on Semi-Submersible Platform Columns, A Case Study

2015 ◽  
Author(s):  
B Ommani ◽  
◽  
H Lie ◽  
V O Aksnes ◽  
N Fonseca ◽  
...  
Keyword(s):  
Wave Loads ◽  
Extreme Wave

Hull Deformation Effect on Membrane-Type LNG Containment Systems

2016 ◽  
Author(s):  
Bo Wang ◽  
Yung-Sup Shin ◽  
Eric Norris
Keyword(s):  
Structural Integrity ◽  
Water Pressure ◽  
Local Deformation ◽  
Fatigue Tests ◽  
Wave Loads ◽  
Insulation System ◽  
Structural Fatigue ◽  
Hull Structure ◽  
Membrane Type ◽  
Global Deformation

The objective of this study is to investigate the relationship between the maximum allowable hull deformation, which includes global elongation and local deflection, and the capacity of the CCS in membrane-type LNG vessels. The LNG CCS mainly consists of the primary barrier (e.g. a corrugated membrane for GTT MK III system and an invar membrane for GTT NO 96 system) and the insulation panel which is attached to the inner hull through mastics or couplers. The excessive hull elongation due to dynamic wave loads may cause fatigue damage of the primary barrier. Thus, the maximum allowable hull elongation (global deformation) can be determined based on the fatigue strength of the primary barrier. On the other hand, the excessive hull deflection due to cargo or ballast water pressure may cause failure of the insulation panel and the mastic. Therefore, the maximum allowable hull deflection (local deformation) in the hull design can be determined based on the strength of the insulation panel and the mastic. In the present paper, the determination of fatigue life vs. strain curves of materials has been summarized for the primary barrier. Fatigue curves based on either structural fatigue tests or standard specimen tests can be applied in fatigue assessment of a primary barrier. As an example, the finite element (FE) analysis has been conducted on the MK III CCS with the hull structure under pressure loads. Two different load cases including full load and ballast load conditions have been considered to evaluate the structural integrity of the insulation system in numerical simulations. FE results show that the mechanical behavior of the insulation system and the mastic under the maximum allowable hull deflection has been examined based on the yielding strength of each individual component. Finally, the complete procedure to determine the maximum allowable hull elongation and the maximum allowable hull deflection has been developed for meeting the requirements of containment system design for membrane-type LNG carriers.

Springing Responses Analysis and Segmented Model Testing on a 550,000 DWT Ore Carrier

2016 ◽  
Author(s):  
Hui Li ◽  
Di Wang ◽  
Cheng Ming Zhou ◽  
Kaihong Zhang ◽  
Huilong Ren
Keyword(s):  
Natural Frequency ◽  
Design Stage ◽  
Resonant Vibration ◽  
Bending Moments ◽  
Wave Loads ◽  
Regular Waves ◽  
Segmented Model ◽  
Ship Model ◽  
Hull Structure ◽  
Stiffness Distribution

For ultra large ore carriers, springing response should be analyzed in the design stage since springing is the steady-state resonant vibration and has an important effect on the fatigue strength of hull structure. The springing response of a 550,000 DWT ultra large ore carrier has been studied by using experimental and numerical methods. A flexible ship model composed of nine segments was used in the experiment. The model segments were connected by a backbone with varying section, which can satisfy the request of natural frequency and stiffness distribution. The experiments in regular waves were performed and the motions and wave loads of the ship were measured. The experimental results showed that springing could be excited when the wave encounter frequency coincides with half or one-third the flexural natural frequency of the ship. In this paper, the analysis of the hydroelastic responses of the ultra large ore carrier was also carried out using a 3-D hydroelastic method. Comparisons between experimental and numerical results showed that the 3-D hydroelastic method could predict the motions and the vertical bending moments quite well. Based on this numerical method, the fatigue damage was estimated and the contribution of springing was analyzed.

Interaction of Ice Floes With Columns of a Semi-Submersible Platform

1983 ◽  
Vol 105 (4) ◽  
pp. 460-463
Author(s):  
P. G. Noble ◽  
D. Singh
Keyword(s):  
Maximum Load ◽  
Test Results ◽  
Ice Load ◽  
Physical Model Tests ◽  
Ice Concentration ◽  
Drilling Unit ◽  
Ice Loads ◽  
Ice Field ◽  
Preliminary Research ◽  
Ice Floes

A preliminary research project has been carried out to determine the effect of small ice floes on a semi-submersible drilling unit. Physical model tests have been conducted with two main objectives: first, to determine the ability of the columns to prevent ice from passing between them (arching) and thus minimizing the chance of riser damage, and second, to determine the total ice load on the semi-submersible during interaction with ice field concentrations. Three models were used, representing one half of a four, six or eight-legged semi-submersible platform. The dimensions and spacing of the columns were such that the heave and pitch responses were kept constant. The tests were conducted at a model scale of 1:30 using synthetic ice. Test results showed the maximum load measured on a four-legged semi-submersible model, at 100 percent ice floe concentration, was on the order of half of that measured on six or eight-legged semi-submersible models. Also the ice loads on a four-legged semi-submersible model at lower ice floe concentration were substantially less than those for six or eight-legged semi-submersible models. The total ice load on semi-submersible models is found to be a function of ice floe concentration. Up to about 75 percent ice concentration, ice loads varied linearly. Beyond that, the loads increased exponentially for all semi-submersible models.

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