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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Society of Naval Architects of Korea
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Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 33, Issue 4 - Nov 1996
Volume 33, Issue 3 - Aug 1996
Volume 33, Issue 2 - May 1996
Volume 33, Issue 1 - Feb 1996
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A Study on Stress Concentration Factor at Fillet Welded Joint
S.W. Kang ; W.I. Ha ; J.S. Shin ; J.S. Jae ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 1~7
The stress concentration factor gives the significant effect the fatigue strength of welded joints. The model used herein is the type of the load carrying fillet welded cruciform joint with full or partial penetration. In order to obtain the stress concentration factor at the weld toe of fillet joint, the reasonable element size of the toe part is investigated and the stress analysis for the series models by FEM under tensile load is performed. On the basis of the calculation results, the estimated formulae for the stress concentration factor(Kt) at weld toe part of the fillet welded joint, which the effect of toe radius, flank angle and other parameters are taken into account, is derived.
An Empirical Formulation for Predicting the Ultimate Compressive Strength of Plates and Stiffened Plates
J.K. Paik ; J.M. Lee ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 8~21
The aim of this study is to derive an empirical formula for predicting ultimate strength of plates and stiffened plates subjected to uniaxial compression. The test data of ultimate compressive strength for unstiffened and stiffened plates previously obtained by others have been collected. Many test data are necessary so that the derived formula will be available in wide range of plate dimensions. Additional collapse tests for a plate specimen with one flat bar stiffener, varying dimensions of plate and stiffener were performed in this study. On the basis of the present and previous experimental data, a more useful empirical formula than the existing ones was derived by applying the least square method.
Prediction of Residual Deformation and Stress Distribution for a Thermo-Elastic-Plastic Beam Using a Simplified Numerical Analysis
S.H. Jun ; K. Choi ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 22~34
Regarding the plate bending process by line heating method, in this study a simplified numerical analysis is performed for a beam model to predict its residual deformation and stress distribution. Using the modified strip theory and beam finite element method, a PC-based simulation program is developed for a thermo-elastic-plastic beam. The plate bending problem can be approximately replaced by a beam model using distributed springs to account for the effect of adjacent strips. The spring constants are chosen as the best fit with experiments. In this paper, it is assumed that the temperature distribution is already given and the temperature-dependent material properties are considered. To verify the simulation program, the results using present numerical algorithm are compared with other published experimental results and similar numerical studies. The comparison shows good agreement. The present PC-based computer program also shows good efficiency in computing time.
A Study on the Design of Ship′s Bow Form using Surface Panel Method
Jae-Hoon Yoo ; Hyo-Chul Kim ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 35~47
A surface panel method treating a boundary-value problem of the Dirichlet type is presented to design a three dimensional body with free surface corresponding to a prescribed pressure distribution. An integral equation is derived from Green's theorem, giving a relation between total potential of known strength and the unknown local flux. Upon discretization, a system of linear simultaneous equations is formed including free surface boundary condition and is solved for an assumed geometry. The pseudo local flux, present due to the incorrect positioning of the assumed geometry, plays a role f the geometry corrector, with which the new geometry is computed for the next iteration. Sample designs for submerged spheroids and Wigley hull and carried out to demonstrate the stable convergence, the effectiveness and the robustness of the method. For the calculation of the wave resistance, normal dipoles and Rankine sources are distributed on the body surface and Rankine sources on the free surface. The free surface boundary condition is linearized with respect to the oncoming flow. Four-points upwind finite difference scheme is used to compute the free surface boundary condition. A hyperboloidal panel is adopted to represent the hull surface, which can compensate the defects of the low-order panel method. The design of a 5500TEU container carrier is performed with respect to reduction of the wave resistance. To reduce the wave resistance, calculated pressure on the hull surface is modified to have the lower fluctuation, and is applied as a Dirichlet type dynamic boundary condition on the hull surface. The designed hull form is verified to have the lower wave resistance than the initial one not only by computation but by experiment.
Scaling and Dynamic Effects on the Plate Cutting Response
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 48~55
The aim of the present study is to investigate the scaling and dynamic erects on the plate cutting response. A series of cutting tests for unstiffened and longitudinally stiffened steel plate specimens in a quasi-static condition were carried out, varying the plate thickness. Based on the previous as well as the present test results, the scaling effect of Plate thickness on the cutting response is investigated. Dynamic erects are also clarified from the devious theoretical and experimental results. The Cowper-Symonds constitutive equation originally derived for mild steel is modified to consider the influence of strain-rate sensitivity on yield strength of high tensile steel.
Optimum Structural Design of Sandwich Plates Considering the Shear Buckling
C.D. Jang ; M.S. Cho ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 56~65
Recently, with development of mechanics of materials, as pursuing the high speed of the ships, there has been an increasing demand on the composite construction which satisfies high strength and low weight at the same time. A sandwich element is a type of composite construction, which is composed of thin, strong, stiff and relatively high density faces and a thick, light, and weaker core material. As the second moment is increased by faces separated from the neutral axis farther, a sandwich element is most effective light structural form. In this study, Rayleigh-Ritz Energy Method is adopted, which can analyze sandwich plate relatively simply and exactly. Stresses and buckling loads are analyzed exactly, when uniform lateral pressure load, inplane compression and inplane shear are acting at the sandwich plate. Including a wrinkling stress, this study can be applied to the initial design and minimum weight design of sandwich plates.
Secondary Buckling Behaviour of Plate under Inpane Compressive Loading
J.Y. Ko ; T. Yao ; J.K. Paik ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 66~80
Recently, HT steel has been widely used in structure, and this enables to reduce the plate thickness. To use the HT steel effectively for a ship hull, the plate thickness becomes thin so that plate buckling may take place. Therefore, precise assessment of the behaviour of plat above primary buckling load is important. The plate under the load, that is called, secondary buckling load may undergo abrupt changes in wave form after primary buckling. This is very important when the collapse strength of the whole structures is considered. From this point of view, this paper discusses secondary buckling behaviour of thin plate under inplane compressive loading. A elastic large deflection analysis of plates with initial imperfection is performed assuming uniaxial compression, respectively, and the influence of secondary buckling is investigated. It is known that square plate is not influenced by non-symmetrical deflection coefficient but influenced by symmetrical deflection coefficient. Also, it has been found that rectangular plate(
=a/b) is influenced by all deflection coefficient, and the reduction of inplane stiffness of the plate after primary buckling is continued.
Plate Forming Automation System of Steel Plates by Line Heating Method(II)
Joo-Sung Lee ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 81~93
In this paper reviewed are the past studies on the plate forming and introduced is the computer aided marking data generation system which should precede the automation system for plate forming by line heating method. The developed computer aided marking data generation system has been applied to a real surface which is frequently found in the bow and the stern area of a ship. From its application results, the estimated surface by the present marking data generation system is very close to the given surface and the generated marking data also shows reasonably good agreement with those in the real practice in ship yard at present. shows very good agreement. When the marking data generation system has been complemented through more applications to real surface models, then it can be practically used in the real practice in ship yard.
A New Interpretation on the Additive and Multiplicative Decompositions of Elastic-Plasmic Deformation Gradient Tensor
Y.Y. Nam ; J.G. Shin ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 94~102
An interpretation for the additive and multiplicative decomposition theory of the deformation gradient tensor in finite deformation problems is presented. the conventional methods have not provided the additive deformation velocity gradient. Moreover the plastic deformation velocity gradients are not free from elastic deformations. In this paper, a modified multiplicative decomposition is introduced with the assumption of coaxial plastic deformation velocity gradient. This strategy well gives the additive deformation velocity gradient in which the plastic deformation velocity gradient is not affect4d by the elastic deformation.
Minimum Weight Design of Transverse Frames of Oil Tankers by Generalized Slope Deflection Method
Chang-Doo Jang ; Seung-Soo Na ;
Journal of the Society of Naval Architects of Korea, volume 33, issue 3, 1996, Pages 103~111
A generalized slope deflection method has already been developed by the authors from the existing one, and applied to the 3-dimensional structural analysis of tankers idealized as frame models to verify the effectiveness of the method from the analysis viewpoint. In this study, a minimum hull weight design program of tankers is developed to verify the effectiveness of the method from the design viewpoint by the combination of generalized slope deflection method and optimization method considering discrete design variables. By this program, it is possible to determine the scantling of each member of actual tankers that give minimum weight under given constraints. Also, a considerable weight saving has been found compared with existing ship.