Strength Analysis of the Hull Structure for a Submersible Drone

Many modern ships, particularly large containerships, are characterized by extreme bow flare, large stern overhang, and low torsional rigidity due to an open deck structural configuration. Software package GL ShipLoad was developed as an aid to assess the structural integrity of such ships. This software tool became the standard method to generate rule based loads for a global strength finite element analysis of sea going displacement ships. It efficiently generates loads based on first principles. A graphical user interface facilitates the convenient application of ship and cargo masses to the finite element model and aids in the selection of relevant design wave situations. User defined selection criteria, such as maximum values of rule based bending moments, shear forces, or torsional moments, specify which waves have to be chosen for the global strength analysis. This approach yields a reduced number of balanced load cases that are sufficient to dimension the hull structure. To adequately simulate roll motion, additional roll angles are analyzed that simulate realistic distributions of torsional moments over the ship length. A strength analysis of a typical post-panamax containership demonstrated the load generation procedure. First, efficiently modeled mass items were grouped into reusable assembled masses for the ship at hydrostatic equilibrium. Second, regular design wave scenarios were estimated, and hydrodynamic pressures for a large number of regular waves were computed. Third, a reduced number of relevant wave situations were automatically selected, and balanced hydrostatic, hydrodynamic, and inertia loads were applied to the finite element model. Enforced roll angles were found to contribute significantly to the initial torsional moment in the fore holds. Finally, based on a locally refined FE submodel of the hatch corners in way of the ship’s fore hold, a fatigue analysis was performed to assess effects of critical loading under enforced roll angles.

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The Study on Hull Structure Strength Analysis and Opening Calculation of CJ46 Jack-Up Drilling Unit

Volume 7: Ocean Engineering ◽

10.1115/omae2015-41209 ◽

2015 ◽

Author(s):

Zeng Ji ◽

Chen Gang ◽

Mo Jian ◽

Wang Yuhan ◽

Zhang Wei

Keyword(s):

Yield Strength ◽

Element Model ◽

Strength Analysis ◽

Ocean Engineering ◽

Engineering Structures ◽

Hull Structure ◽

Key Issues ◽

Drilling Unit ◽

Main Support ◽

Jack Up

The structural strength of jack-up units is the key issues in the design of ship and ocean engineering structures. Based on ABS MODU, the yield strength of CJ46 self-elevating drilling platform main hull structure is checked. Firstly, the environmental loads (wind, wave and flow) in three loading conditions which are required by specification are calculated by using GeniE (DNV). Then the 3D finite element model of main hull structure is established. The yield strength is checked and the results shown the large stress areas are leg well, jackcase which is connected with the leg and bulkhead which is main support structure under the cantilever sliding device, while the results meet the requirements of ABS MODU. Finally, the influence of the openings located in main longitudinal bulkheads are evaluated, meanwhile the main longitudinal bulkheads under skidding box need particular concern.

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Numerical Methods for Hull Structure Strength Analysis and Ships Service Life Evaluation, for a LPG Carrier

Volume 2: Structures, Safety and Reliability ◽

10.1115/omae2008-57602 ◽

2008 ◽

Author(s):

Leonard Domnisoru ◽

Dumitru Dragomir ◽

Alexandru Ioan

Keyword(s):

Service Life ◽

Dynamic Response ◽

Ship Hull ◽

Design Stage ◽

Head Wave ◽

Strength Analysis ◽

Response Analysis ◽

Wave Loads ◽

Life Evaluation ◽

Hull Structure

In this paper the authors focus on the ship hull structure strengths and fatigue analyses, in order to estimate the ship service life period at the initial design stage. The topic of the paper is divided in three-interlinked parts. The first part includes the method for the hull strength analysis, based on 3D/1D-FEM models, under equivalent quasi-static head wave loads. The second part presents the method for the ship hull dynamic response analysis, based on non-linear hydroelasticity theory with second order wave spectrum. The last part includes the fatigue analysis method for the initial ship hull structure, based on the long-term prediction ship dynamic response, the cumulative damage ratio and the design S-N material curves. The numerical analyses are carried out for a LPG carrier with independent cargo-tanks type A. Two significant load cases are considered: full and ballast. The numerical results outline the extreme wave loads and the ships initial service life evaluation.

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Structural Strength Analysis of Main Crane Pedestal of the Jack-Up Wind Turbine Installation Vessel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.351-352.7 ◽

2013 ◽

Vol 351-352 ◽

pp. 7-12

Author(s):

Xiang Zhu ◽

Yong Sheng Tang ◽

Fei Xiang Li ◽

Yao Zhao

Keyword(s):

Wind Turbine ◽

Structural Strength ◽

Limit State ◽

Offshore Wind ◽

Strength Analysis ◽

Ultimate Limit State ◽

Fe Model ◽

Hull Structure ◽

Jack Up ◽

Turbine Installation

The jack-up wind turbine installation vessel is a special kind of vessel for building the offshore wind power farm. The main crane pedestal, which is the supporting structure of the crane on the main deck of the vessel, is always under high level loads when the ship is in operation condition. In this paper, the structural strength analysis of main crane pedestal of the jack-up wind turbine installation vessel was presented. The direct calculated method was used to evaluate the strength of the main crane pedestal. The FE model of main crane pedestal was established with refined mesh, and the adjoining hull structure was also modeled to provide accurate boundary condition. Considering the permanent loads, variable loads (crane loads) and wind loads on the pedestal, the load combinations were defined for the ultimate limit state for every 45 degree. The deformation and stress of the pedestal and the hull structures were calculated and checked. The results showed that all stress results were within the maximum allowable stresses. The critical areas are often located at the link region of hull and pedestal.

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Silicon Tetrachloride Synthesis from Rice Hulls: Transmission and Scanning Electron Microscope Study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100094437 ◽

1972 ◽

Vol 30 ◽

pp. 236-237 ◽

Cited By ~ 1

Author(s):

Richard S. Thomas ◽

Prabir K. Basu ◽

Francis T. Jones

Keyword(s):

Silicon Tetrachloride ◽

Silica Sand ◽

Mineral Matter ◽

Chemical Heterogeneity ◽

Scanning Electron Microscope Study ◽

Rice Hulls ◽

Hull Structure ◽

Lower Temperature ◽

Image Position ◽

Disposal Problem

Silicon tetrachloride, used in industry for the production of highest purity silicon and silica, is customarily manufactured from silica-sand and charcoal.SiCl4 can also be made from rice hulls, which contain up to 20 percent silica and only traces of other mineral matter. Hulls, after carbonization, actually prove superior as a starting material since they react at lower temperature. This use of rice hulls may offer a new, profitable solution for a rice mill byproduct disposal problem.In studies of the reaction kinetics with carbonized hulls, conversion of SiO2 to SiCl4 was found to proceed within a few minutes to a constant, limited yield which depended reproducibly on the ambient temperature of the reactor. See Fig. 1. This suggested that physical or chemical heterogeneity of the silica in the hull structure might be involved.

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