Document Type: Research Paper

**Authors**

Department of Mechanical Engineering, Pondicherry Engineering College

**Abstract**

One of the common failure modes of thin cylindrical shell subjected external pressure is buckling. The buckling pressure of these shell structures are dominantly affected by the geometrical imperfections present in the cylindrical shell which are very difficult to alleviate during manufacturing process. In this work, only three types of geometrical imperfection patterns are considered namely (a) eigen affine mode imperfection pattern, (b) inward half lobe axisymmetric imperfection pattern extended throughout the height of the cylindrical shell and (c) local geometrical imperfection patterns such as inward dimple with varying wave lengths located at the mid-height of the cylindrical shell. ANSYS FE non-linear buckling analysis including both material and geometrical non-linearities is used to determine the critical buckling pressure. From the analysis it is found that when the maximum amplitude of imperfections is 1*t*, the eigen affine imperfection pattern gives out the lowest critical buckling pressure when compared to the other imperfection patterns considered. When the amplitude of imperfections is above 1*t*, the inner half lobe axisymmetric imperfection pattern gives out the lowest critical buckling pressure when compared to the other imperfection patterns considered.

**Keywords**

[1] Ross C.T.F., Little A.P.F., Adeniyi K.A., 2005, Plastic buckling of ring-stiffened conical shell under eternal hydrostatic pressure, Ocean Engineering 32:21-36.

[2] Ross C.T.F., Little A.P.F., Allsop R., Smith, C., Engelhardt M., 2007, Plastic General instability of ring-reinforced conical shells under uniform external pressure, Marine Technology 44(4): 268-277.

[3] Schiender W., Brede A., 2005, Consistent equivalent geometric imperfections for the numerical buckling strength verification of cylindrical shells under uniform external pressure, Thin-Walled Structures 43(2): 175-188.

[4] Timoshenko P.S., Gere M.J., 1965, Theory of Elastic Stability, McGraw-Hill Publications, Second Edition, Singapore.

[5] Brush D.O., Almroth B.O., 1975, Buckling of Bars, Plates and Shells, Chapter 5, McGraw-Hill, New York.

[6] Bushnell D., 1985, Computerized Buckling Analysis of Shells, Martinus Nijhoff Publishers, Doedrecht.

[7] Teng J.G., Song C.Y., 2001, Numerical models for nonlinear analysis of elastic shells with eigen mode-affine imperfections, International Journal of Solids and Structures 38: 3263-3280.

[8] Featherston C.A., 2003, Imperfection sensitivity of curved panels under combined compression and shear, International Journal of Non-Linear Mechanics 38: 225-238.

[9] Kim Seung-Eock, Kim Chang-Sung, 2002, Buckling strength of the cylindrical shell and tank subjected to axially compressive loads, Thin-Walled Structures 40: 329-353.

[10] Khelil, 2002, Buckling of steel shells subjected to non-uniform axial and pressure loadings, Thin-Walled Structures 40: 955-970.

[11] Pircher M., Berry P.A., Ding X., Bridge R.Q., 2001, The shape of circumferential weld-induced imperfections in thin-walled steel silos and tanks, Thin-Walled Structures 39(12): 999-1014.

[12] Koiter W.T., 2001, Elastic stability and post-buckling behaviour, Journal of Structural Engineering 127(10): 1129- 1136.

[13] Khamlichi A., Bezzazi M., Limam A., 2004, Buckling of elastic cylindrical shells considering the effect of localized axisymmetric imperfections, Thin-Walled Structures 42: 1035-1047.

[14] Schiender W., 2006, Stimulating equivalent geometric imperfections for the numerical buckling strength verification of axially compressed cylindrical steel shells, Comput. Mech. 37: 530-536.

[15] Hutchinson J.W., Tennyson R.C., Muggeridge D.B., 1971, Effect of local axisymmetrical imperfection on the buckling behavior of a circular cylindrical shell under axial compression, AIAA Journal 9: 48-52.

[16] Amazigo J.C., Budiansky B., 1972, Asymptotic formulas for the buckling stresses of axially compressed cylinders with localized or random axisymmetric imperfections, ASME Transactions, Journal of Applied Mechanics 39: 179-184.

[17] Shen H.-S., Li Q.S., 2002, Thermo mechanical post buckling of shear deformable laminated cylindrical shells with local geometric imperfections, International Journal of Solids and Structures 39: 4525-4542.

[18] Song C.Y., Teng J.G., Rotter J.M., 2004, Imperfections sensitivity of thin elastic cylindrical shells subjected to axial compression, International Journal of Solids and Structures 41: 7155-7180.

[19] Arbocz J., Stranes J.H., 2004, On a verified high-fidelity analysis for axially compressed cylindrical shells, in: 45th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics& Materials Conference, 19-22 April 2004, Palm Springs, California, AIAA 2004-1712.

[20] ANSYS 10 User Manual.

Volume 1, Issue 2

Spring 2009

Pages 148-158