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Keywords: pressure vessels, stress concentration, clothoidal-spherical head, general-ellipsoidal head.

Summary

The paper presents the problem of stress concentration in a cylindrical pressure vessels with special shapes of meridian of dished head subject to internal pressure. Clothoidal-spherical and general-ellipsoidal heads are considered. Proposed shapes of the meridian are continuous at the junction between the head and the circular cylindrical shell. No shear force and bending moment occurs at the junction region because of this property. Therefore the membrane stress state in the vessel is not disturbed. The analytical formulas describing the shape of the clothoidal-spherical and the general-ellipsoidal are derived. By using these formulas the main dimensionless radii of curvature are calculated. Based on boundary disturbance theory for shell of revolution the stress state in the cylindrical vessel is analytically described. The equivalent dimensionless stresses in the vessel are formulated and presented in figures. Using the finite element method (FEM) method for selected cases of relative convexity of clothoidal-spherical and general-ellipsoidal heads the stress distribution analysis is carried out. Results of the FEM analysis show a good relationship with the analytical ones. The stress concentration is measured by a factor defined as the ratio of the maximal equivalent stress in the pressure vessel achieved in the FEM analysis and the stress of the cylindrical shell under membrane state. The stress concentration factor depends on the relative convexity of the head and decreases for higher values of relative convexity. Maximal concentration of stresses in vessel for both kinds of heads is observed in the cylindrical part of the junction region. The clothoidal-spherical and general-ellipsoidal, heads stress concentration factor is lower than in standard heads.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 138 Strength Shaping of Dished Heads of Pressure Cylindrical Vessels L. Wittenbeck and K. Magnucki Institute of Applied Mechanics, Poznan University of Technology, Poland doi:10.4203/ccp.88.138 purchase the full-text of this paper Full Bibliographic Reference for this paper L. Wittenbeck, K. Magnucki, "Strength Shaping of Dished Heads of Pressure Cylindrical Vessels", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 138, 2008. doi:10.4203/ccp.88.138 Keywords: pressure vessels, stress concentration, clothoidal-spherical head, general-ellipsoidal head. Summary The paper presents the problem of stress concentration in a cylindrical pressure vessels with special shapes of meridian of dished head subject to internal pressure. Clothoidal-spherical and general-ellipsoidal heads are considered. Proposed shapes of the meridian are continuous at the junction between the head and the circular cylindrical shell. No shear force and bending moment occurs at the junction region because of this property. Therefore the membrane stress state in the vessel is not disturbed. The analytical formulas describing the shape of the clothoidal-spherical and the general-ellipsoidal are derived. By using these formulas the main dimensionless radii of curvature are calculated. Based on boundary disturbance theory for shell of revolution the stress state in the cylindrical vessel is analytically described. The equivalent dimensionless stresses in the vessel are formulated and presented in figures. Using the finite element method (FEM) method for selected cases of relative convexity of clothoidal-spherical and general-ellipsoidal heads the stress distribution analysis is carried out. Results of the FEM analysis show a good relationship with the analytical ones. The stress concentration is measured by a factor defined as the ratio of the maximal equivalent stress in the pressure vessel achieved in the FEM analysis and the stress of the cylindrical shell under membrane state. The stress concentration factor depends on the relative convexity of the head and decreases for higher values of relative convexity. Maximal concentration of stresses in vessel for both kinds of heads is observed in the cylindrical part of the junction region. The clothoidal-spherical and general-ellipsoidal, heads stress concentration factor is lower than in standard heads. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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