Collision resistance and fatigue strength of new oiltanker with advanced double hull structure

The structure of the hull of the project 1288 trawler in a region of fore hold was improved to ensure fatigue strength of assemblies of the intersection of main frames with the second bottom. To this end, a study of the fatigue strength of these assemblies was carried out for the original side structure and two versions of its modernization. Values of internal forces at the points of appearance of fatigue cracks in the compartment have been determined for three design versions of the side. It was found that the greatest forces act in the middle of the fore half of the compartment. Calculations of parameters of the long-term distribution of magnitudes of ranges of total equivalent operating stresses according to the Weibull law in the points of occurrence of fatigue cracks for different design versions of the side grillage have been performed. These parameters were determined for the middle of the fore hold of the vessel and for the areas in which maximum values of bending moment ranges are in effect with and without corrosive wear. Values of total fatigue damage and durability of the studied assemblies were determined. Calculations were carried out by nominal stress method, hot spot stress method, and experimental and theoretical method. It was shown that in order to ensure fatigue strength of the assembly under consideration, it is necessary to extend the intermediate frames of the original version of the side structure to the level of the second bottom fixing them to the deck. It is also necessary to attach a cargo platform to the side thus reducing the frame span. As a result, the level of fatigue damage over 25 years of operation will decrease by about 3.5 times. As it was found, approximate consideration of the slamming effect does not significantly increase the amount of fatigue damage to the assembly. The results of the development of recommendations for modernization of the side structure can be implemented both on ships of the 1288 project and on other ships with a transverse side framing system.

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Measured Imperfections and Their Effects on Strength of Component Plates of a Prototype Double Hull Structure

Journal of Ship Production ◽

10.5957/jsp.1995.11.1.47 ◽

1995 ◽

Vol 11 (01) ◽

pp. 47-52

Author(s):

Alan AhKum Pang ◽

Robert Tiberi ◽

Le-Wu Lu ◽

James Ricles ◽

Robert Dexter

Keyword(s):

Residual Stresses ◽

High Strength ◽

The Finite Element Method ◽

Initial Imperfections ◽

Hsla Steels ◽

Hull Structure ◽

Surface Combatant ◽

Double Hull ◽

The U.S ◽

Compressive Tests

The U.S. Navy is currently studying the use of double hull designs in high strength low alloy (HSLA) steels for surface combatant ships. A full-scale prototype double hull module was fabricated, from which multicellular box column specimens were cut for compressive tests to failure. Initial imperfections, i.e., initial plate deflections and welding residual stresses, affect the stiffness and strength of welded members. This paper describes the measurement of these imperfections and the analysis of their effects on the component plates of the cellular box specimens. Initial deflections were measured in the laboratory, where the maximum values did not exceed the Navy's guidelines or proposed values of several researchers. Residual stresses in a box specimen were also measured in the laboratory under more controlled conditions. Using the measured imperfections, the plate arrangements were analyzed using the finite element method. The imperfections were found to reduce the stiffness and strength of the plates. The results show that for accurate prediction of the strength of welded plates, initial imperfections must be taken into account.

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A Method for Fatigue Evaluation of Trimaran Cross Structure With the Influence of Slamming

Volume 3A: Structures, Safety and Reliability ◽

10.1115/omae2017-62492 ◽

2017 ◽

Author(s):

Zhe Li ◽

Huilong Ren ◽

Kai Jin

Keyword(s):

Stress Response ◽

Fatigue Strength ◽

Fatigue Damage ◽

Linear Response ◽

Operating Conditions ◽

Wave Load ◽

Hull Structure ◽

Non Linear ◽

Slamming Load ◽

Cross Structure

Slamming is a highly non-linear phenomenon between hull structure and wave. Due to the special structure of trimaran, the slamming mode is extremely different from that of traditional vessel. Besides bow emergence and enter, the slamming phenomenon of the out shell at the cross structure is also obvious. In conventional hull structure fatigue strength evaluation, the slamming load is usually not considered. However, the slamming problem is unavoidable at danger load cases, and the stress concentration of the trimaran cross structure is serious. So it is dangerous to ignore the existence of slamming in serious load cases when evaluating the structural fatigue strength. Therefore, it is necessary to study the contribution of slamming load to fatigue damage. In this paper, a practical method for calculating and analyzing is presented to consider the effect of slamming on the fatigue strength of the trimaran cross structure to ensure that the fatigue life of the structure is closer to the true value. According to the linear theory, the relative motion and relative speed of the hull in wave and the stress response of the wave load on the structure are calculated firstly. Then, the stress response of the non-linear out shell slamming force is calculated. The linear response and non-linear response are combined. And the stress response time history under the combined action of slamming and wave load are obtained. Finally, the fatigue damage of the structure under dangerous operating conditions is calculated by the rain flow counting method. And the contribution value of the slamming load to the structural damage degree is calculated. The paper will put forward some reference suggestions for fatigue study calculation and evaluation of Trimaran cross structure with the influence of slamming.

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Influence of Acoustic Coating on the Underwater Sound Radiation of a Double Hull Cylindrical Shell Structure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.338.406 ◽

2011 ◽

Vol 338 ◽

pp. 406-410

Author(s):

Fu Zhen Pang ◽

Fu Bin Pang ◽

Xu Chao Yin ◽

Shuai Lv

Keyword(s):

Cylindrical Shell ◽

Noise Reduction ◽

Shell Structure ◽

Sound Radiation ◽

Radiation Characteristic ◽

Underwater Sound ◽

Surrounding Water ◽

Covering Density ◽

Hull Structure ◽

Double Hull

This paper studies the influence of acoustic coating to the underwater sound radiation characteristic of a double hull cylindrical shell by the Statistical Energy Analysis (SEA) method. Influence of covering density and laying location of acoustic coating to the underwater sound radiation characteristic of the double hull cylindrical shell structure are discussed. Study shows that low covering density of acoustic coating will cause “sound leaking” phenomena, sound will leak out from the uncovered area of the double hull cylindrical hull structure and radiate into the surrounding water, which harms the underwater noise reduction performance of the acoustic coating; however, the noise reduction capacity of the acoustic coating improves gradually as the covering density increases. Besides, laying location of acoustic coating also impact the underwater sound radiation performance of the double hull cylindrical shell structure; inner hull covered with acoustic coating is better than the outer hull covered from the noise treatment point of view

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Numerical Investigation on the Plastic Response of a Small-Scale Laterally Impacted Tanker Double Hull Structure

Volume 2: Structures, Safety and Reliability ◽

10.1115/omae2012-84016 ◽

2012 ◽

Author(s):

Richard Villavicencio ◽

Young-Hun Kim ◽

Sang-Rai Cho ◽

C. Guedes Soares

Keyword(s):

Dynamic Response ◽

Strain Rate ◽

Scaling Laws ◽

Full Scale ◽

Scale Model ◽

Small Scale ◽

Plastic Response ◽

Hull Structure ◽

Double Hull ◽

The Impact

Numerical simulations are presented, on the dynamic response of a one-tenth scaled tanker double hull structure struck laterally by a knife edge indenter. The small stiffeners of the full-scale prototype are smeared in the small-scale model by increasing the thicknesses of the corresponding plates. The dynamic response is evaluated at an impact velocity of 7.22 m/s and the impact point is chosen between two frames to assure damage to the outer shell plating and stringers. The simulations are performed by LS-DYNA finite element solver. They aim at evaluating the influence of strain hardening and strain rate hardening on the global impact response of the structure, following different models proposed in the literature. Moreover, the numerical model is scaled to its full-scale prototype, summarizing the governing scaling laws for collision analysis and evaluating the effect of the material strain rate on the plastic response of large scaled numerical models.

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Strength evaluation of intersection between stiffeners and primary supporting members in double hull structure

Marine Structures ◽

10.1016/j.marstruc.2020.102789 ◽

2020 ◽

Vol 74 ◽

pp. 102789

Author(s):

Liuting Gu ◽

Tetsuo Okada ◽

Lijuan Xia ◽

Yasumi Kawamura

Keyword(s):

Strength Evaluation ◽

Hull Structure ◽

Double Hull

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Comparative Study on Collision Resistance of Side Structure

Marine Technology and SNAME News ◽

10.5957/mt1.1997.34.4.293 ◽

1997 ◽

Vol 34 (04) ◽

pp. 293-308

Author(s):

Ou Kitamura

Keyword(s):

Numerical Study ◽

Fem Simulation ◽

Absorption Capacity ◽

Second Phase ◽

Practical Application ◽

Energy Absorption Capacity ◽

Collision Resistance ◽

Hull Design ◽

Design Options ◽

Double Hull

In the second phase of ASIS 's 7-year research project for improved tanker safety against collision and grounding supported by Ministry of Transport, a series of numerical simulations of side damage due to collision was carried out adopting ASIS's methodology based on the customized explicit FEM simulation system in order to demonstrate its potential power in the field of practical application Assuming the simplified rigid bow of a 150K DWT colliding ship, the energy absorption capacity of the various side double hull design options for a VLCC, such as increased number of side stringers, double side structure with top side tank in conjunction with hopper tank, and unidirectional girder stiffening system, was studied The contribution of each structural component, -side shell, inner hull, transverse web, side stringer, etc. -was also investigated in detail. Based on the results of both the numerical study and the 1/2-scale collision experiments, a new conceptual design of a VLCC side structure was developed Further study on crushable bow structure against collision and enhanced design of bottom structure against grounding is now in progress.

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The Fatigue Strength Assessment for Hull Structure of Steel Fishing Vessel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.189.334 ◽

2012 ◽

Vol 189 ◽

pp. 334-339

Author(s):

Gao Sheng Yang ◽

Yong He Xie

Keyword(s):

Fatigue Strength ◽

Fishing Vessel ◽

Strength Assessment ◽

Computing Platform ◽

Hull Structure ◽

Fatigue Strength Assessment ◽

Classification Society

According to the norms “the fatigue strength assessment for hull structures in 2007” issued by China Classification Society, the combined computing platform established is composed of mature hydrodynamic software SESAM from Det NorskeVeritas(DNV)and MSC.PATRAN/NASTRAN, the fatigue strength assessment for hull structure of a steel fishing vessel is studied.

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