• Title/Summary/Keyword: Hull girder load

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Estimation about Local Strength using FE-Analysis for Steel Yacht (유한요소해석을 이용한 강선요트의 국부강도 평가)

  • Park Joo-Shin;Ko Jae-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.11 no.2 s.23
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    • pp.77-82
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    • 2005
  • Previously sailing yachts or leisure yachts were mainly made from FRP(Fiber glass reinforced plastic) in the small shipbuilding, but recently there is a trend to replace it for steel or aluminum to substitute FRP for environmental friendly materials. Although It have to need a many checked item in case of hull girder strength and transverse strength normally evaluate base on calculation of class guideline so called direct calculation method. Otherwise. this method of initial structural design considered enough for safety margin on the structure. But, case of small craft must consider for evaluating local strength through rational method. In this paper, check the bow structure members for satisfying results base on allowable stress criterion of damaged bow structure by dynamic load due to slamming and bottom impact load due to pitching motion through finite element analysis. and investigate engine bed structure considering engine weight load and transverse wave load.

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Effect of Stiffener's Web Height against Axial Compression Ultimate Strength Considering Lateral Pressure Load (횡하중을 고려한 압축최종강도에 대한 보강재 치수의 영향)

  • Oh, Young-Cheol;Ko, Jae-Yong;Oh, Dong-Ki
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.14 no.1
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    • pp.89-93
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    • 2008
  • Stiffened panels are basic strength members which have been used widely in a vessel or an offshore. They have been used often a deck, a side and a bottom structure of ship and have a number of one sided stiffener in either one or both directions called grillage. Their buckling and plastic collapse become damaged reason of the hull girder so it needs to investigate accurately buckling and ultimate strength of stiffened panels. In the present paper, using the ANSYS, a commercial finite element analysis code, we conducted the evaluation regarding buckling and post-buckling behaviour of stiffened panels, and analyzed stiffener's web height change, considering the effect of lateral pressure load against compression ultimate strength.

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A Study on the Structural Analysis of Curved Portions of Pipe Loops Used in Ships (선박용 파이프 루프 곡선부의 구조해석에 관한 연구)

  • Park, Chi-Mo;Bae, Byoung-Il
    • Journal of Ocean Engineering and Technology
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    • v.24 no.5
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    • pp.88-93
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    • 2010
  • Many pipes that are arranged longitudinally in ships have loops at intervals to prevent the failure of the pipes as they absorb large portions of the axial load caused by the bending of the hull girder and/or thermal loads when the pipes are carrying very hot fluids. Since the loops are curved at corners, an efficient method for conducting the structural analyses of these curved portions is required. In this paper, a pipe loop was analyzed by an analytical method and by the finite-element method in four different ways, i.e., based on straight-beam elements, curved-beam elements, 2-D shell elements, and 3-D solid elements. The results of the five analyses were compared to check the validity of the current curved-beam theory. The paper includes some suggestions on how to analyze the pipe loops efficiently.

On the New Design of Liquid Dome Chair in Membrane Type LNG Carrier (멤브레인형 LNG선박의 리퀴드 돔 체어 구조개발)

  • Kim, Jeong-Hwan;Kim, Yooil
    • Journal of the Society of Naval Architects of Korea
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    • v.54 no.5
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    • pp.361-367
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    • 2017
  • A membrane type LNG cargo tank is equipped with a pump tower and a liquid dome for loading and unloading of LNG. However, the membrane running continuously on the tank wall to prevent leakage of LNG is interrupted by the liquid dome, hence care should be taken in the design of liquid dome and its substructures. In case of GTT NO96 membrane type cargo containment system, chair structure is arranged along the periphery of the liquid dome targeting to support the membrane which is exposed to the both hull girder and thermal load. This paper proposes a new and simple chair structure, which outperforms traditional design from productivity point of view maintaining same level of structural safety. Strength assessment on the new design was performed to guarantee the structural safety of the new design, which includes strength, fatigue and crack propagation analysis.

Assessment of the Effect of Probabilistic Modeling of Sea-States in Fatigue Damage Calculations

  • FolsØ, Rasmus;Dogliani, Mario
    • Journal of Ship and Ocean Technology
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    • v.3 no.3
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    • pp.1-12
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    • 1999
  • Spectral fatigue damage calculations has been performed on four ships in order to assess the effect that the probabilistic modeling of sea states has on the estimated fatigue life. The damage estimation method is based on the Miner- Palmgren fatigue damage formulation and a spectral approach is used to determine the necessary variances of the stress processes. Both the horizontal and vertical hull girder bending induced stress process together with the local water pressure induced stress process is taken into account. The wave scatter diagrams are applied in the calculations and their fatigue severity is assessed by analyzing the results obtained with the ten scatter diagrams and the four ships. All four ships are analyzed both in full load and ballast conditions and while traveling at both full and reduced speed. It is found that the fatigue severity of a wave scatter diagram is dependent on several parameters, some of these being the extreme wave hight extrapolated from the scatter diagram and the mean zero up-crossing period in conjunction with the ship length . Based on these three parameters and expression is derived in order to calculate one single number describing the fatigue severity of a scatter diagram with respect to a certain ship.

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Ultimate Strength Behavior Analysis on the Ship's Plate under Combined Load(Lateral Pressure Load and Axial Compressive Load) (조합하중을 받는 선체판부재의 최종강도거동 해석)

  • Park Jo-Shin;Ko Jae-Yong;Lee Jun-Kyo;Bae Dong-Kyun
    • Proceedings of KOSOMES biannual meeting
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    • 2005.05a
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    • pp.147-154
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    • 2005
  • The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact Hence, for more rational and safe design of ship structures, it is of crucial importance to better understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

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Secondary Buckling Behavior Analysis on the Ship's Plate under Combined Load(Lateral Pressure Load and Axial Compressive Load) (조합하중을 받는 선체판부재의 2차좌굴거동 해석)

  • Park Joo-Shin;Ko Jae-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.12 no.1 s.24
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    • pp.67-74
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    • 2006
  • The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion rf the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design rf ship structures, it is of crucial importance to better understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated secondary buckling behavior through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

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Development of Designed Formula considering Buckling under Longitudinal and Transverse Axial Compressive Load (종횡방향 압축하중이 작용하는 유공판의 좌굴을 고려한 설계식 개발)

  • Park, Joo-Shin;Ko, Jae-Yong;Lee, Jun-Kyo
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.29 no.1
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    • pp.55-60
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    • 2005
  • Plate that have cutout inner bottom and girder and floor etc. in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and change of freight, piping etc.. Because cutout's existence gnaws in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, perforated plate elastic buckling strength and ultimate strength is one of important design criteria which must examine when decide structural elements size at early structure design step of ship. Therefore, and, reasonable elastic buckling strength about perforated plate need design ultimate strength. Calculated ultimated strength change several aspect ratioes and cutout's dimension, and thickness in this investigation. Used program applied ANSYS F.E.A code based on finite element method.

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Characteristic of Buckling and Ultimate Strength of the Perforated Stiffened Plate (유공보강판의 좌굴 및 극한강도 특성에 관한 연구)

  • Park Joo-Shin;Ko Jae-Yong;Oh Kyoung-Gun
    • Journal of Navigation and Port Research
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    • v.30 no.6 s.112
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    • pp.439-446
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    • 2006
  • In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.

A Study on the Lateral Pressure Effect under Axial Compressive Load of Ship Platings (종방향 압축력을 받는 선체판부재의 횡압력 영향에 관한 연구)

  • Park Joo-Shin;Ko Jae-Yong;Lee Jun-Kyo
    • Journal of Navigation and Port Research
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    • v.29 no.6 s.102
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    • pp.515-522
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    • 2005
  • The ship plating is generally subjected to. combined in-plane load and lateral pressure loads, In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to. water pressure and cargo. These load components are nat always applied simultaneously, but mare than one can normally exist and interact. Hence, far mare rational and safe design of ship structures, it is af crucial importance to. better understand the interaction relationship af the buckling and ultimate strength far ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except far the impact load due to. slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to. the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.