Longitudinal Imperfections on Thin Walled Cylindrical Shells

Mahyar Maali,Hossein Showkati,Abdulkadir Cuneyt Aydın,Seied Mahdi Fatemi,Merve Sagıroglu

doi:10.4172/2165-784x.1000309

Abstract

Buckling and post-buckling are among the most important failure factors in thin walled structures. The loadcarrying behavior of cylindrical thin-walled shell structures under external pressure load is strongly dependent upon the nature and magnitude of the initial imperfections. These imperfections are invariably caused by an assortment of manufacturing processes like installing or welding. One of the most important imperfections caused by welding that has been reported to have an essential detrimental effect on the buckling resistance of these shells under external pressure load is longitudinal imperfections. Buckling and post buckling capacity of the shells depend on the H/R and t/ R ratios (H the height, R the radius and t the thickness of a cylindrical shell). The present work discusses the finiteelement models labeled as SS (Shallow Slim), DS (Deep Slim), ST (Shallow Thick) and DT (Deep Thick). The samples of first group are modiﬁed to include a line longitudinal imperfection, amplitudes of 0.5t, 1t, 2t, 3t, 4t and 8t in depth (t is the thickness of cylindrical shell). The results presented are in agreement with international codes and theories concerning buckling.

Highlights

Buckling and collapse are two structures of thin-walled cylindrical shells
The comparison between the results of Eq (6) and the results of the to-radius ratio (t/R)=0.0016 models reveal that the obtained initial buckling load of the Riks analysis is 26%-36% greater than the Donnell theory
D) The height of the cylinder (H) is higher; the buckling load capacity is low in linear analyses

Summary

Introduction

Buckling and collapse are two structures of thin-walled cylindrical shells. Buckling of a cylindrical shell depends on the scores of variables, for example, the geometric properties, the material properties and the type of the applied load. Rolling and construction have much effect on buckling and postbuckling capacity of the cylindrical shells. Hornug and Saal [8] searched on real-size tanks to examine the effects of imperfections on the buckling load of cylindrical shells. Schneider and Brede [9] studied the effects of geometric imperfections on the buckling resistance of cylindrical shells. Maali et al [10] studied the buckling behavior of conical shells and showed the stiffening effect of weld-induced imperfections on the buckling strength. In 2013, Fatemi et al [5] conducted experiments on imperfect cylindrical shells under uniform external pressure and showed the detrimental effects on the buckling of weld-induced geometric imperfections. Niloufari et al [11] conducted experiments on imperfect steel tanks under hydrostatic pressure and showed the detrimental effects on buckling and post buckling of weld-induced geometric imperfections. Eurocode 3, ECCS and DINI18800 [12-18] have all set limitations for rolling- and welding-induced imperfections

Methods

Results

Discussion

Conclusion