Cylindrical shells are often used in ship structures at deck plating with a camber, side shell plating at fore and aft parts, and bilge structure part. It has been believed that such curved shells can be modelled fundamentally by a part of a cylinder under axial compression. From the estimations wit...
Cylindrical shells are often used in ship structures at deck plating with a camber, side shell plating at fore and aft parts, and bilge structure part. It has been believed that such curved shells can be modelled fundamentally by a part of a cylinder under axial compression. From the estimations with the usage of cylinder models, it is known that, in general, curvature increases the buckling strength of a curved shell subjected to axial compression, and that curvature is also expected to increase the ultimate strength. We conduct series of elasto-plastic large deflection analyses in order to clarify the fundamentals in buckling and plastic collapse behaviour of cylindrical shells under axial compression. From the numerical results, we derive design formula for predicting the ultimate strength of cylindrical shell, based on a series of the nonlinear finite element calculations for all edges, simply supporting plating, varying the slenderness ratio, curvature and aspect ratio, as well as the following design formulae for predicting the ultimate strength of cylindrical shell. From a number of analysis results, fitting curve can be developed to use parameter of slenderness ratio with implementation of the method of least squares. The accuracy of design formulae for evaluating ultimate strength has been confirmed by comparing the calculated results with the FE-analysis results and it has a good agreement to predict their ultimate strength.
Cylindrical shells are often used in ship structures at deck plating with a camber, side shell plating at fore and aft parts, and bilge structure part. It has been believed that such curved shells can be modelled fundamentally by a part of a cylinder under axial compression. From the estimations with the usage of cylinder models, it is known that, in general, curvature increases the buckling strength of a curved shell subjected to axial compression, and that curvature is also expected to increase the ultimate strength. We conduct series of elasto-plastic large deflection analyses in order to clarify the fundamentals in buckling and plastic collapse behaviour of cylindrical shells under axial compression. From the numerical results, we derive design formula for predicting the ultimate strength of cylindrical shell, based on a series of the nonlinear finite element calculations for all edges, simply supporting plating, varying the slenderness ratio, curvature and aspect ratio, as well as the following design formulae for predicting the ultimate strength of cylindrical shell. From a number of analysis results, fitting curve can be developed to use parameter of slenderness ratio with implementation of the method of least squares. The accuracy of design formulae for evaluating ultimate strength has been confirmed by comparing the calculated results with the FE-analysis results and it has a good agreement to predict their ultimate strength.
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문제 정의
To achieve the advanced buckling and ultimate strength design of cylindrical shell, we would need more sophisticated methods than existing simplified approaches to evaluate buckling and ultimate strength. The aim of the present study is to develop more advanced design formulae to predict their ultimate strength for cylindrical shell.
가설 설정
3. The definition of cylindrical shell.
2. To develop the design formulae to evaluate ultimate strength of the cylindrical shell.
(1) The ultimate strength of a cylindrical shell under axial compression is sensitive to geometrical initial imperfection.
제안 방법
We conduct series of elasto-plastic large deflection analysis in order to clarify the fundamentals in buckling and plastic collapse behaviour of cylindrical shells under axial compression. According to numerous FE-results, we derived design formula for predicting the ultimate strength of cylindrical shell, based on a series of the nonlinear finite element calculations for all edges simply supporting plating varying the slenderness ratio, curvature and aspect ratio, as well as the following design formulae to predict the ultimate strength of cylindrical shell.
(2004) performed a series of elasto-plastic large deflection analyses to investigate buckling and plastic collapse behaviour of ship’s bilge strakes, which are unstiffened curved plates under axial compression. On the basis of the calculated results, a simple formula was derived to calculate buckling and ultimate strength and to simulate stress-average strain relationship of the bilge structure under axial compression. It was found that the bilge structure with a conventional shape and size reaches the ultimate strength by yielding before buckling.
10 shows the relationships between ultimate strength and slenderness ratio with varying flank angles. From the series analysis results, fitting curve can be developed to use parameter of slenderness ratio with implementation of the method of least squares. Fig.
이론/모형
Tran and Davaine (2011) developed a method for predicting the ultimate strength of a cylindrical shell subjected to uniform axial compression. The methodology is based on the formal procedure adopted by Eurocode 3, for all types of stability verification. A series of numerical simulations were carried out in order to clarify and examine the fundamental buckling behaviour of curved panels.
This is expressed as a percentage of the original Young’s elastic modulus. Cylindrical shell geometries were modelled with the ANSYS 14.0 code using standard structural shell element namely SHELL181. This element is suitable for analysing thin to moderately-thick shell structures.
성능/효과
11 illustrates the comparative results between FE-analysis and design formula as obtained from equation (4), (5) and (6). The developed design formula has a good agreement to predict the ultimate strength of cylindrical shell under axial compression and the difference ratio is approximately 1.7 %.
(3) The effect of aspect ratio has little influence on the ultimate strength of cylindrical shell with the flank angle over 20 degrees.
참고문헌 (7)
Det Norske Veritas AS(2013), Buckling Strength of Shells, Section 3, Buckling Resistance of Cylindrical Shells, January, 2013, pp. 13-25.
Maeno, Y., H. Yamaguchi, Y. Fujii and T. Yao (2004), Buckling/plastic collapse behaviour and strength of bilge circle and Its contribution to ultimate strength of ship's hull girder, Proc. International Offshore and Polar Engineering Conference, Toulon, France, May 23-28, 2004, p. 296.
Park, J. S., M. Fujikubo, K. Iijima and T. Yao(2009), Prediction of the secondary buckling strength and ultimate strength of cylindrically curved plate under axial compression, The international Journal Society of Offshore and Polar Engineers(IJOPE-ASME), July, 2009, pp. 740-747.
Smith, C. S. and P. C. Davidson(1987), Strength and stiffness of ship's plating under in-plane compression and tension, Transaction of Royal Institution of Naval Architects, pp. 277-296.
Timoshenko, S. and S. Woinowsky-Krieger(1959), Theory of Plates and Shells (Engineering Societies Monographs) 2nd Edition, 1959.
Tran, K. L. and L. Davaine(2011), Stability of cylindrical steel panels under uniform axial compression, Proceedings of the Annual Stability Research Council, Pittsburgh, Pennsylvania, May 10-14, 2011.
Tran K. L., C. Douthe, K. Sab, J. Dallot and L. Davaine(2014), Buckling of stiffened curved panels under uniform axial compression, Journal of Construction Steel Research, May 20, 2014, pp. 140-147.
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