實船 上甲板 開口部의 應力集中과 疲勞壽命 評價 : 실선 상갑판 개구부의 응력집중과 피로수명 평가

백점기 釜山大學校 工科大學 1990 工科大學 硏究 報告 Vol.40 No.-

最終强度를 기준으로 한 船體上甲板構造의 信賴性評價 : 최종강도를 기준으로 한 선체상갑판구조의 신뢰성평가

백점기 釜山大學校 工科大學 1990 工科大學 硏究 報告 Vol.40 No.-

HAZ 연화부를 가진 TMCP형 고장력강판의 압축최종강도에 관한 연구 - 제 2 보

백점기,고재용 대한용접접합학회 1991 대한용접·접합학회지 Vol.9 No.2

The use of high tensile steel plates is increasing in the fabrication of ship and offshore structures. The softening region which has lower yield stress than base metal is located to prevent cracking in the conventional high tensile steel. Also, thermo mechanical control process(TMCP) steel with low carbon equivalent has the softening region which occurs in the heat affected zone when high heat input weld is carried out. The softening region in the high tensile steel gives rise to serious effect on structural strength such as tensile strength, fatigue strength and ultimate strength. In order to make a reliable structural design using high tensile steel plates, the influence of the softening on plate strength should be evaluated in advance. In the previous paper, the authors discussed the ultimate compressive strength of 50HT steel square plates with softening region. In this paper, the ultimate compressive strength with varying the yield stress of softening region and the aspect ratio of the plate is investigated by using the elasto-plastic large deformation finite element method.

복잡한 형상의 초기처짐을 가진 판의 압축최종강도

백점기,P. T. Pedersen 부산대학교 1994 生産技術硏究所論文集 Vol.47 No.

A simplified procedure for prediction of the ultimate compressive strength of plate elements with complex shape of the initial deflection is described. The procedure consists of the elastic large deflection theory and the rigid-plastic analysis based on the collapse mechanism taking into account large deformation effects. By taking only one component for the selected deflection function, the computer time for the elastic large deflection analysis will be drastically reduced. The validity of the procedure is checked by comparing the present solutions with the finite-element results for actual ship panels with complex shapes of measured initial deflection. It is concluded that the proposed procedure provides quite accurate solutions for the ultimate loads with extremely short computer time. 본 논문에서는 복잡한 형상의 초기처짐을 가진 선체 판요소의 압축최종강도를 효율적으로 계산할 수 있는 방법을 개발하였다. 본 계산법에서는 먼저 탄성대처짐해석과 소성붕괴해석을 별도로 수행한 뒤 이들 해석결과를 조합하여 그 교차점을 최종강도로 간주한다. 이때 판부재에 존재하는 복잡한 형상의 초기처짐을 Fourier급수로 전개하여 나타내며, 탄성대처짐해석은 초기처짐항간의 상관효과를 무시하여 한개의 초기처짐항만을 고려하여 수행함으로써 수치계산시간을 극단적으로 줄였다. 물론 탄성대처짐해석은 모든 초기처짐항에 대하여 개별적으로 수행하며, 압축최종강도의 해는 각 초기처짐항에 대해 계산된 값중의 최소치를 취하면 된다. 본 계산법의 정도와 유용성은 복잡한 형상의 초기처짐을 가진 실제 선체 판부재를 대상으로 탄소성 대변형 유한요소해석법에 의해 계산된 결과와 비교하여 검증하였으며, 그 결과 본 계산법은 극히 짧은 계산시간내에 높은 정도의 결과를 준다는 것을 확인하였다.

이중 선체 화학 운반선의 충돌 강도 평가

백점기,이제명,이경언,원석희,김철홍,고재용,Paik, Jeom-Kee,Lee, Jae-Myung,Lee, Kyung-Ern,Won, Suk-Hee,Kim, Chelo-Hong,Ko, Jae-Yong 한국항해항만학회 2004 한국항해항만학회지 Vol.28 No.6

선박의 충돌ㆍ좌초 등과 같은 사고는 이들 사고의 방지를 위한 꾸준한 노력에도 불구하고 끊임없이 발생하고 있다. 환경오염방지와 해상에서의 안전성확보에 대한 요구가 지속적으로 증가함에 따라, 선박안전과 해양환경오염을 야기할 수 있는 잠재적인 위험을 최소화시키고 궁극적으로 사고발생확률을 경감시키고자 하는 노력이 아주 중요하게 되고 있다. 본 논문에서는, 본 연구실에 의해 수행된 선박의 좌초ㆍ충돌 문제에 대한 최근의 연구결과를 정리한다. (최, 1999; 백, 1999; 최, 1999; 연, 2003; 강, 2002; 연, 2002) 충돌ㆍ좌초사고 문제에 있어서 유용한 도구로 알려져 있는 유한요소법의 활용상의 주의점, 즉 사용요소의 크기와 파괴기준 그리고 해석에 사용하는 재료 물성치 설정에 대한 주의 깊은 고찰을 바탕으로 실제 충돌문제에 대한 수치시뮬레이션을 수행하였다. 실제 선박을 대상으로 하는 시리즈해석 수행을 목표로, 46,000 dwt Product/chemical carrier를 대상으로 운항속도, 충돌각도, 적재조건 등의 변화를 고려한 충돌성능 분석을 비선형 유한요소해석법을 이용하여 수행하였다. 해석결과를 이용하여 사고 시나리오별 흡수에너지-진압량 관계를 정량적으로 도출하였고, 이를 근거로 하는 선박의 내충돌성능 평가용 설계기준을 제안하였다. Ship collisions and grounding continue to occur regardless of continuous efforts to prevent such accidents. With the increasing demand for safety at sea and for protection of the environment, it is of crucial importance to be able to reduce the probability of accidents, assess their consequences and ultimately minimize or prevent potential damages to the ships and the marine environment. Numerical simulations for actual collision problem are conducted with a special attention with respect to finite element size, fracture criteria and material properties, which require a careful consideration to improve the accuracy. A parametric analysis varying colliding speed, angle, design loading condition is conducted using nonlinear finite element analysis method for 46,00 dwt Product/chemical carrier. The relationship between the absorbed energy and indentation are derived quantitatively using the insights observed from this study, and a novel design concept for assessing the anti-collision performance are proposed.

표준논단 - 세계표준을 주도하는 자, 세계를 지배한다

백점기,Baek, Jeom-Gi 기술표준원 2008 기술표준 Vol.83 No.-

增分 Galerkin法에 의한 固定板의 座屈 및 座屈後 擧動 解析

白点基,李晩承,金昌烈 부산대학교 공과대학 1991 工大論文集 Vol.42 No.-

In the previous papers [1-2], the first author developed Incremental Galerkin Method(IGM) in order to analyse the elastic large deflection behaviour of simply supported plates. In this method, the incremental expression of the differential equation which governs the large deflection behaviour of plates with initial deflection is derived. Then the incremental governing equation is solved by using Galerkin method. IGM may be very useful tool in both accuracy and computing time when buckling and post-buckling behaviour of plates with initial deflection is analyzed. Also, using IGM the influence of initial imperfections affecting the large deflection behaviour can be investigated. In the present study, the use of IGM is extended to clamped plates. An accurate Fourier Series function which stands for the deflected shape of clamped plates is assumed. Using the assumed deflection function, the incremental governing equation is solved. A computer program is completed based on the present theory. The preparation of the input data for the use of the computer program is very simple. Then the computer program is applied to the analysis of buckling and post-buckling behaviour of a clamped square plate. A comparison of large deflection behaviours between simply supported and clamped plates is made. It is concluded that the present method gives an accurate solution in the short computing time.

Considerations of the Initial Crack Damage Effect on the Advanced Idealized Plate Unit

백점기,서흥원,Paik, Jeom-K.,Suh, Heung-W. The Society of Naval Architects of Korea 1994 대한조선학회 논문집 Vol.31 No.2

This paper attempts to incorporate the initial crack damage effect into the existing idealized plate unit. For this purpose, a new concept which indicates the equivalent, reduced material properties due to initial cracks at the structural unit level, not at he microscopic aspect, is suggested, and a simplified mechanical plate model for the initially cracked plate in axial tension is formulated as a function of initial crack length, based on the finite-element solutions obtained by crack propagation analysis.

Ultimate Compressive Strength-Based Safely and Reliability Assessment of the Double Skin Upper Deck Structure

백점기,Jeom-K. Paik The Society of Naval Architects of Korea 1991 대한조선학회 논문집 Vol.28 No.1

A practical procedure for the ultimate compressive strength-based safety and reliability assessment of the double skin upper deck structure is described. The external compressive stress acting on the upper deck structure which is due to the still water and wave-induced sagging moment is approximately estimated by using the existing rule of classification society. The ultimate compressive stress of double skin structure under the action of sagging moment is analyzed by using idealized structural unit method. Here an idealized plate element subjected to uniaxial load is formulated by idealizing the nonlinear behaviour of the actual element taking account of the initial imperfections in the form of initial deflection and welding residual stress. The interaction effect between the local and global failure in the structure is also taken into consideration. The accuracy of the present method is verified comparing with the present solution and the existing numerical and experimental results for unit member and welded box columns. The safety of the structure is evaluated using the concept of conventional central safety factor and the reliability assessment is made by using Cornel's MVFOSM method. The present procedure is then applied to upper deck structure of double skin product oil carrier. The influence of the initial imperfections and the yield stress of the material on the safety and reliability of the structure is investigated.

이상화구조요소법에 의한 골조구조물의 최종강도해석에 관한 연구

백점기,임화규 한국전산구조공학회 1991 전산구조공학 Vol.4 No.1

본 연구에서는 이상화구조요소법을 적용하여 골조구조물의 비선형해석을 높은정도로서 짧은 계산시간에 수행할 수 있는 해석이론과 컴퓨터프로그램을 개발하였다. 이를 위해 골조구조물을 구성하는 보-기둥(Beam-Column)부재에 대한 이상화구조요소를 부재에 존재하는 초기결함의 영향도 고려하여 정식화한다. 요소의 접선탄성강성행렬은 에너지원리를 적용하여 명시적인 형태로 도출하며, 최종강도조건은 요소에 소성붕괴메카니즘이 형성될때를 기준으로 정식화한다. 또한, 요소의 최종강도후 강성행렬도 근사적인 방법을 이용하여 명시적인 형태로 도출한다. 본해석법의 정도와 유용성은 단위부재 및 골조구조모형에 대한 기존의 실험 및 수치해석결과등과 비교하여 확인한다. This paper presents an efficient and accurate method for nonlinear analysis of frame structures by idealized structural unit method. The main idea behind the present method is to minimize the computational effort by reducing the number of unknowns. An explicit form of the tangential elastic stiffness matrix of the element is derived by the principle of virtual work. The ultimate limit state of the element is judged on the basis of the formation of a plastic hinge mechanism. The elasto-plasto-plastic stiffness matrix of the element is derived by plastic node method and the post-ultimate stiffness equation is formulated under a simple analytic consideration. A comparison between the present solution and the existing experimental and other numerical result for unit column member and simple frame structure is made. If is clear from the result of this study that the present method is very useful because the computing time required is very small while giving the accurate solution.