• Title/Summary/Keyword: 선체외판 변형

Search Result 12, Processing Time 0.022 seconds

Direct Fairing for Geometric Modeling of Hull Surface (선형의 기하학적 모델링을 위한 직접순정법에 관한 연구)

  • W.D. Kim;J.H. Nam;K.W. Kim
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.28 no.1
    • /
    • pp.1-11
    • /
    • 1991
  • When a geometric modeling of a hull form for ship design and hull production is done, a hull fairing is a tedious process which wastes a lot of time, but it is unavoidable because hull consist of the sculptured surfaces. This paper presents the mathematical method of the direct fairing to overcome the tediousness of cross fairing. Bi-cubic B-spline surface description was adopted for the representation of the hull surface. The fairing process was executed by minimizing the strain energy in a shell plate. The color-encoded Gaussian curvature and strain energy were visualized on the screen to illustrate the fairness of the surface. The geometric information generated from the faired hull surface model was interfaced with the basic design calculation package and the hull production system.

  • PDF

Study on Effect of Shell Plate Deformation to Radar Cross Section of Warship (선체외판의 변형이 수상함 RCS에 미치는 영향 연구)

  • Kim, Kook-Hyun;Cho, Dae-Seung
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.48 no.6
    • /
    • pp.509-515
    • /
    • 2011
  • The radar cross section (RCS) of warships is a crucial design factor to improve the survivability in terms of not only low observablity of the platform but also efficiency of on-board sensors and jamming devices against enemy threat. In design stage, numerical models are generated in order to quantitatively assess RCS, of which hull surfaces are modeled with the finite number of the flat plate. However, in practice, hull surfaces are permanently deformed by various kinds of loads such as winds and ocean waves faced during operations. In this paper, the effect of these shell plate deformation to RCS is numerically investigated. For this purpose, RCS calculations are carried out for various kinds of numerical models, such as single plates, dihedrals, large-sized undulate plates, and virtual warships, with some extent of permanent deformation. The results are compared with those of corresponding models without permanent deformation. It is concluded that the permanent deformation of hull surface highly influences RCS characteristics of warships, therefore they should be considered in the RCS analysis.

Heating-Plan Heuristics for Forming Curved Shell Plate of Ship Structure (선체 외판 부재의 곡 성형을 위한 가열 계획 생성 휴리스틱)

  • Gang, Byeong-Ho;Park, Gi-Yeok;Kim, Ung;Ryu, Gwang-Ryeol;Lee, Jeong-Hwan;Do, Yeong-Chil;Kim, Dae-Gyeong;Kim, Se-Hwan
    • Proceedings of the Korea Inteligent Information System Society Conference
    • /
    • 2007.11a
    • /
    • pp.570-578
    • /
    • 2007
  • 선체 외판 부재의 곡 성형 과정은 주로 가열(열간가공)에 의해 수행된다. 이 가열 작업은 작업자의 경험과 지식에 크게 의존하는 매우 어려운 작업이다. 본 논문에서는 선체 외판의 곡 성형을 위한 가열 계획을 자동으로 수립할 수 있는 휴리스틱을 소개한다. 현장 전문가의 지식에 기반한 이 휴리스틱은 크게 가열 선을 생성하는 부분과 외력을 주는 도구를 배치하는 부분으로 구성된다. 가열 선은 대상 부재의 현재 곡면과 설계된 목적곡면과의 비교를 통해 생성되고, 가우스 커널 함수를 통해 스무딩(smoothing)된다. 현장에서는 열간가공 시 의도하지 않은 변형을 막으면서 작업시간을 줄이고자 외력을 이용한다. 외력의 위치와 방향은 가열 선 군집화를 통해 추출된 대표 가열 선을 기준으로 결정된다. 가상의 인공 곡면과 현장의 실제 부재를 대상으로 실험한 결과, 이 휴리스틱이 숙련된 전문가가 수립한 가열 계획과 유사한 가열 계획을 수립할 수 있음을 확인하였다.

  • PDF

FRP 선박의 Mouldless 건조방식

  • Kim, Hyo-Cheol;Kim, Jae-Seong;Lee, Jae-Gyu
    • Journal of Korea Ship Safrty Technology Authority
    • /
    • v.5
    • /
    • pp.10-19
    • /
    • 2000
  • 소형어선이나 일반적인 활주형선형은 부분적인 형상 수정을 거치게 되면 3차원 곡면으로 이루어진 선체의 외판을 2차원 평면상에 전개하여 표현할 수 있다는 특성을 가지고 있다. 이러한 점을 활용하여 전개도형에 따라서 제작된 얇은 FRP 판재를 선 요소들로 정의된 형틀 상에서 변형시켜 선체의 형상을 만들고 그 내부에 추가로 FRP를 적층 함으로서 선체를 완성하는 방법을 제안하고자 한다.

  • PDF

Estimation of buckling and collapse behaviour for continuous stiffened plate under combined transverse axial compression and lateral pressure (조합하중을 받는 연속보강판의 좌굴 및 붕괴거동 평가)

  • Park, Joo-Shin;Choi, Joung-Hwan;Hong, Kwan-Young;Lee, Gyoung-Woo
    • Journal of Navigation and Port Research
    • /
    • v.33 no.1
    • /
    • pp.27-33
    • /
    • 2009
  • Estimation of the buckling and ultimate strength of a continuous stiffened plate subjected to combined transverse compression and lateral pressure is of high importance to ensure the safety of ship structures, particularly for the bottom plating under a deep draft condition For example, bottom plating of bulk carriers is subjected to transverse thrust caused by the bending of double bottom structure and the direct action of pressure on the side shells. Most of experimental tests, theoretical approach and numerical researches have been performed on the buckling and ultimate strength behaviour of plates or stiffened plates under combined compression and lateral pressure. With regard to stiffened panels, however, most of studies have been concerned with the load conditions of combined longitudinal thrust and lateral pressure, while fewer studies have been performed for the combined transverse thrust and lateral pressure. In addition, the previous researches are mainly concerned with an isolated rectangular plate simply supported along the all edges, whereas actual ship plating is continuous across the transverse frames and heavy girders. In the present paper, a series of elastoplastic large deflection FEA on a continuous stiffened plate is performed and then clarify the characteristic of collapse mode and explain the effect of transverse compression.

Simulation of Plate Deformation by Triangle Heating Process (삼각가열에 의한 판 변형의 시뮬레이션)

  • Chang-Doo Jang;Dae-Eun Ko;Sung-Choon Moon;Yong-Rok Seo
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.38 no.4
    • /
    • pp.66-74
    • /
    • 2001
  • Plate bending process is indispensible in shipbuilding. The process includes press bending process and heating process. Especially the heating process is carried out exclusively by skillful workers. Many researches have been made to automate the heating process. This study was carried out as a fundamental study to develop a efficient analysis method for triangle heating and focused on clarifying the deformation characteristics of plate by triangle heating and essential elements effect on the deformation. In this paper, we proposed an analysis model for thermal-elastic-plastic analysis and simulated the deformation by triangle heating using ANSYS based on the experimental results of Jang et al.(2001). Also, we showed the deformation characteristics more clearly by comparing the deformation due to triangle heating and line heating in case that the total heat input is same. Finally, we investigated the change characteristics of deformation elements according to the volumetric heat input.

  • PDF

Analysis of Ship Hull Plate Bending By Roll Bending Machine (Roll bending machine에 의한 선체외판의 곡면가공 해석)

  • Kim, You-Il;Shin, Jong-Gye;Lee, Jang-Hyun
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.33 no.4
    • /
    • pp.142-149
    • /
    • 1996
  • Pyramid type three roll bending machines are widely used in roll-bending process to produce singly curved plate. In forming singly curved plate, controlling the vertical displacement of the center roller is most important to acquire the shape required and automation system of the process. In this paper roller bending process is modeled as an elastic-plastic phenomenon and analyzed using beam theory and finite element method. In finite element analysis the workpiece is modeled by using beam elements and plane strain elements respectively. Through the analyses vertical center roller displacement is obtained to get constant curvature distribution along arc length. The relationship between center roller displacement and curvature in steady state as well as residual stress and strain along plate thickness direction are calculated through finite element analysis.

  • PDF

An Experimental Study of Characteristics of Plate Deformation by Heating Process (열간가공에 의한 판의 변형특성에 관한 실험적 연구)

  • Chang-Doo Jang;Dae-Eun Ko;Byeong-Il Kim;Jeong-Ung Park
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.38 no.2
    • /
    • pp.62-70
    • /
    • 2001
  • As the ship hull is a compound-curved structure, plate bending process is indispensible. The process includes press bending process for forming major 1st curvature and heating process for forming the rest curvature. Especially the heating process that is above 50 percents of entire bending work is carried out exclusively by skillful workers. Many researches have been made to automate the heating process but most of these are about line heating process and researches for triangle heating process are rare. This study is a fundamental study to develop a efficient analysis method for triangle heating and focused on clarifying the deformation characteristics of plate by triangle heating. In this paper, we carried out heating experiments and analysed the deformation characteristics of plate to explain the deformation characteristics of plates rationally by showing the phase transformed high temperature region. Also we investigated the heating effect on the hull material properties by mechanical tests.

  • PDF

A Material characteristics of 490MPa steel by Line Heating Method (490MPa급 강재의 선상가열에의한 재질특성)

  • Cho, Sung-Kyu;Ko, Sang-Ki;Choi, Wong-Kyu;Kim, Jung-Hak
    • Proceedings of the KWS Conference
    • /
    • 2009.11a
    • /
    • pp.58-58
    • /
    • 2009
  • 선박의 선체부분인 선수, 선미 등을 이루고 있는 곡형 외판의 제작은 강판을 원하는 형상으로 성형하기 위하여 벤딩롤러 및 유압프레스를 이용한 냉간가공과 산소-프로판가스 화염을 적용한 선상가열, 삼각가열을 이용한 열간가공으로 크게 구분할 수 있다. 선상가열을 이용한 곡면가공의 원리는 가열토치를 이용하여 강판을 가열하면 가열부는 팽창하게 되고 냉각시에는 수축하게 된다. 이 때 두께방향으로의 소성변형으로 인한 수축량의 차이로 인해 굽혀지게 된다. 최근에는 선박이 고기능 및 대형화로 인해 3차원 곡형 외판 형상이 복잡해지고, 강도를 향상시키기 위하여 합금원소(C, Nb, V, Ti)를 첨가하거나 열처리(노말라이징)를 이용한 고장력강재인 중후판의 적용이 증가하고 있다. 이러한 고강도강재를 선상가열공정으로 제작한 곡형 외판재는 가열, 냉각의 열사이클로 인해 취화되어 인성이 저하 될 수 있다. 본 연구에서는 Normalizing 열처리재인 490MPa급 강재를 이용하여, 현장에서 작업자의 미숙련으로 인해 발생 할 수 있는 최대의 가혹한 조건과 재질에 큰 영향을 미치지 않는 범위를 선정하여 선상가열시의 가열, 냉각조건에 따른 강재의 재질특성을 조사하고자 한다. 이를 위해 가열시 가열부위의 정확한 온도 측정에 역점을 두었으며, 각각 다른 선상가열 조건에 따른 시편을 제작하기 위하여 선상가열 실험장치를 제작하였다. 선상가열 실험 결과 최고가열온도 $1300^{\circ}C,\;950^{\circ}C$에서 수냉 조건인 경우 급격한 인성저하 현상이 발생하며 비록 공냉이라 하더라도 결정립 조대화로 인성 저하가 발생하였다. $800^{\circ}C$가열 후 수냉개시온도를 $700^{\circ}C$이하로 수냉한 경우에는 인성 저하 현상이 개선되고 있음을 알 수 있다.

  • PDF

Realtime Simulation of Deformation due to Line Heating for Automatic Hull Forming System (곡가공 자동화 시스템을 위한 선상가열에 의한 변형의 실시간 시뮬레이션)

  • Dae-Eun Ko;Chang-Doo Jang;Seung-Il Seo;Hae-Woo Lee
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.36 no.4
    • /
    • pp.116-127
    • /
    • 1999
  • Line heating is a method widely used in forming ship hull surface. From the viewpoint of mechanics it is large deformation thermal elasto-plastic problem of arbitrary shaped plate. Many researches have been carried out to resolve this problem. Especially, Jang et al.[1] proposed a simplified thermal elasto-plastic analysis method to predict effectively the deformation of plate due to line heating. In this paper, we improved the method of Jang et al.[1] by considering tension yielding in temperature decreasing stage and verified with experimental results. FEA program using MITC4 degenerated shell element was made to deal with elastic large deformation problem. The newly proposed method can be used in the simulation and control of forming hull surface for higher productivity with simplicity and efficiency.

  • PDF