• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.1
• /
• pp.10-19
• /
• 2023

Blast Hardened Bulkhead (BHB) is an important measure that can increase the ship's survivability as well as protect the lives of the crew by mitigating the damage extent caused by an internal explosion in the ship. In particular, both the pressure and the shock impulse should be considered when designing the BHB against reflected shock waves having a high pressure with a short duration. This study proposes a design method for BHB that considers both the pressure and the shock impulse generated during the internal explosion. In addition, analysis and design concepts for accident loads such as explosion, fire, and collision of NORSOK and DNVGL, one of the international design guidelines for the curtain plate type blast hardened bulkhead type applied by the Korean Navy, are utilized. If this method is applied, it is expected that it can be used as a design concept for the pressure as well as the shock impulse of the explosion load of the curtain plate.

• Journal of the Society of Naval Architects of Korea
• /
• v.46 no.5
• /
• pp.510-519
• /
• 2009

Ship structure is composed of the welded mixture members which are plate and stiffeners. Ship structure is also influenced by variable loadings such as wave and inertia load. There have been several fatigue damage problems on the connection between longitudinal and transverse web due to wide usage of high tensile steel and adoption of wide web space to improve shipbuilding productivity. It is impossible to estimate the fatigue lives for all connection details through refined fatigue analysis. It is necessary to use the simplified approach for the fatigue life estimation of the connection details. PLUS analysis, which is suggested by the classification society, is one of the simplified approaches and is widely adopted to get fatigue lives for the connection details along whole cargo hold area. However, ship building yards still have difficulties to get fatigue lives due to large amount of calculation and time even if this approach reduce the time and amount of calculation. This paper treats the computing system developed to reduce efforts of estimating the fatigue lives. The influence factors of mean shear stress and local dynamic pressure are easily calculated and fatigue lives for all hot spots can be estimated automatically by the developed computing system. It is possible to reduce computing time and efforts to get the fatigue lives for the connection details between longitudinals and transverse webs along the ship. This system was applied to get fatigue lives on the connection details of a VLCC and verified the availability.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.5
• /
• pp.380-387
• /
• 2014

Piper Alpha disaster drew attention to the damage likely to arise from explosions and fires on an offshore platform. And great concerns have been increased to prevent these hazards. Blast wall is one of the passive safety systems; it plays a key part of minimizing the consequences. However, a buckling due to explosion loads is a factor which can reduce the strength of blast wall. The buckling often occurs between web and flange at the center of blast wall. This study aims to find a solution for reinforcing its strength by installing a flat plate at the spot where the buckling occurs. First of all, ANSYS finite element method is adopted to numerically compute the structural resistance characteristic of blast wall by using a quasi-static approach. Sequentially, the impact response characteristics of blast wall are investigated the effect on thickness of flat plate by using ANSYS/LS-DYNA. Finally, pressure-impulse diagrams (P-I diagram) are presented to permit easy assessment of structural response characteristics of stiffened blast wall. In this study, effective use is made to increase structural intensity. of blast wall and acquired important insights have been documented.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.3
• /
• pp.421-425
• /
• 2018

The icebreaking research vessel ARAON performed ice field tests during her 2016 Arctic voyage. The ship is subjected to ice loads through ice-ship interaction processes. Local ice load acting on ARAON's bow section was measured by using stain gauges installed on the inner hull plates and transverse frames of bow section. In this paper the local ice loads at transverse frames estimated from shear strain data were compared to ice loads from hull plate pressures by using the influence coefficient method. In addition to the analysis of local ice loads, the characteristics of peak ice loads with the ship speed is also discussed. It is recommended that the local ice loads estimated by calculating shear forces acting on transverse frames may be useful in estimating local ice loads on the hull of ship.

• Journal of the Society of Naval Architects of Korea
• /
• v.59 no.6
• /
• pp.413-422
• /
• 2022

Blast Hardened Bulkheads (BHB) are used to suppress damage propagation by internal explosions to reduce ships'vulnerability. However, for this reason, the weight of the ship inevitably increased, and other functions such as the ships'mobility were bound to deteriorate. Therefore, it is essential in the initial design of the ship to optimize the dimensions of the bulkhead to minimize the weight while decreasing the vulnerability of the ship. Research on design optimization of BHB has been conducted, but it has not considered explosive load in various hit scenarios. This study proposed an optimal design method for the curtain plate type blast hardened bulkhead, which is currently frequently applied by the Korean Navy in consideration of various hit scenarios. Using genetic algorithms, multiobjective design optimizations that minimize weight increase as well as minimize damage to ships were obtained. By optimizing the dimensions of the BHB considering various hit scenarios, the ship's vulnerability was improved while maintaining its mobility due to weight reduction.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.11
• /
• pp.1437-1443
• /
• 2011

Thick plates produced by the rolling process are used as the basic elements of ship structures. In this paper, we present a setup model for controlling the asymmetric factors causing plate bending in the width direction during plate rolling. A series of three-dimensional finite element analyses is conducted to predict the relationship between various asymmetric factors and plate bending. The setup model is developed by performing regression on the relationship to produce linear equations with several nondimensional parameters. The setup model is verified with a pilot rolling test in which variations in thickness and temperature differences in the width direction exist. The results show that the bending curvatures predicted by the model are in fairly good agreement with the measured results for those asymmetric factors.

• Journal of Advanced Marine Engineering and Technology
• /
• v.26 no.1
• /
• pp.48-58
• /
• 2002

There is a purpose of this study for the proposal of the optimum technique utilized for the vibration design initial step. The stiffened plate structure for the ship hull is made for analysis model. To begin with, dynamic characteristics of stiffened plate structure is analysed using FEM. Main vibrational mode of the structure is decided in the analytical result of FEM. The simplified equation on the natural frequency of the main vibrational mode is induced. Next, sensitivity analysis is carried out using the simplified equation, and rate of change of dynamic characteristics is calculated. Then, amount of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of panel, cross section moment of stiffener and girder become a design variable. The validity of the optimization method using simplified equation is examined. It is shown that the result effective in the optimum modification for natural frequency of the stiffened plate structure.

• Journal of the Korean Institute of Navigation
• /
• v.25 no.1
• /
• pp.45-52
• /
• 2001

The purpose of this study is the optimum modification of dynamic characteristics of stiffened plate structure. In the method of the optimization, finite element method(FEM), sensitivity analysis and optimum structural modification method are used. To begin with, using FEM, the dynamic characteristics of stiffened plate structure is analyzed. Next, rate of change of dynamic characteristics by the change of design variable is calculated using the sensitivity analysis. Then, amount of change of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of plate and cross section moment become a design variable. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate structure.

• Journal of the Society of Naval Architects of Korea
• /
• v.53 no.1
• /
• pp.69-75
• /
• 2016

Fabrication of the hull plate demands a lot of man-hour and a high degree of technology. In recent years, commercial shipping orders have been fallen because of intensifying competition with low price of order and labor cost. In order to solve this problem, a countermeasure such as a cost reduction is required. In this study, we are dealing with the method of supplying the forming information of the hull to the production site. We reviewed studies of hull forming that have been proposed so far to develop a method for providing hull forming information. On the basis of given production plans from the production site of shipyard, we discuss how to convert shell plate to production plan. Then, we will discuss the efficiency of the distribution method through the network about the method of hull forming. Thus, we have modified the distribution method which was proposed before. Finally, we will introduce the enhanced method for providing fabrication information of the hull plate to the small and medium-sized shipyards.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.389-394
• /
• 2008

Nowadays Plate Heat Exchanger (PHE) is widely used in different industries such as chemical, food and pharmaceutical process and refrigeration due to the efficient heat transfer performance, extreme compact design and efficient use of the construction material. In present work, PHE is applied in the fresh water generator system. Fresh water generators or desalinators are installed in ship to convert seawater to fresh water using heat from engines. PHE is an important part of a condensing or evaporating system. Among many of factors which should be concentrated on, the heat transfer and pressure drop is most important parts during sizing and rating the performance of PHE. Flow maldistribution is common but it will significantly reduce the heat exchanger performance. In this paper provide a overview of PHE cover basic of theory and conduct a numerical approach for flow distribution in plate channel. An experimental study on the performance of fresh water generator system which developed by plate heat exchanger will presented in future research. Thus, extensive experiment and analysis is required to study the thermal and fluid flow characteristics of PHE.