Buckling Of Shells

Thin shells are very popular structures in many different branches of engineering. There are the domes, water and cooling towers, the contain ments in civil engineering, the pressure vessels and pipes in mechanical and nuclear engineering, storage tanks and platform components in marine and offshore engineering, the car bodies in the automobile industry, planes, rockets and space structures in aeronautical engineering, to mention only a few examples of the broad spectrum of application. In addition there is the large applied mechanics group involved in all the computational and experimental work in this area. Thin shells are in a way optimal structures. They play the role of·the "primadonnas" among all kinds of structures. Their performance can be extraordinary, but they can also be very sensitive. The susceptibility to buckling is a typical example. David Bushnell says in his recent review paper entitled "Buckling of Shells - Pitfall for DeSigners": "To the layman buckling is a mysterious, perhaps even awe inspiring phenomenon that transforms objects originally imbued with symmetrical beauty into junk".

This report describes the work performed by Lockheed Palo Alto Research Labora tory, Palo Alto, California 94304. The work was sponsored by Air Force Office of Scientific Research, Bolling AFB, Washington, D. C. under Grant F49620-77-C-0l22 and by the Flight Dynamics Laboratory, Air Force Wright Aeronautical Laboratories, Wright-Patterson AFB, Ohio under Contract F3361S-76-C-31OS. The work was completed under Task 2307Nl, "Basic Research in Behavior of Metallic and Composite Components of Airframe Structures". The work was admini stered by Lt. Col. J. D. Morgan (AFOSR) and Dr. N. S. Khot (AFWAL/FIBRA). The contract work was performed between October 1977 and December 1980. The technical report was released by the Author in December 1981. Preface Many structures are assembled from parts which are thin. For example, a stiffened plate or cylindrical panel is composed of a sheet the thickness of which is small com pared to its length, breadth, and stiffener- spacing, and stiffeners the thickness of which is small compared to their _ heights and lengths. These assembled structures, loaded in compression, can buckle overall, that is sheet and stiffeners can collapse together in a general instability mode; the sheet can buckle locally between stiffeners; the stiffeners can cripple; and a variety of complex buckling interactions can occur involving local and overall deformations of both sheet and stiffeners. More complex, built-up structures can buckle in more complex and subtle ways.

Thin-walled metal shell structures are highly efficient in their use of material, but they are particularly sensitive to failure by buckiling. Many different forms of buckling can occur for different geometries and different loading conditions. Because this field of knowledge is both complex and industrially important, it is of great interest and concern in a wide range of industries. This book presents a compilation and synthesis of a wealth of research, experience and knowledge of the subject. Information that was previously widely scattered throughout the literature is assembled in a concise and convenient form that is easy to understand, and state-of-the-art research findings are thoroughly examined. This book is useful for those involved in the structural design of silos, tanks, pipelines, biodigestors, chimneys, towers, offshore platforms, aircraft and spacecraft. Buckling of Thin Metal Shells is essential reading for designers, researchers and code writers involved with thin-walled metal shell structures.

This book contains solutions to the most typical problems of thin elastic shells buckling under conservative loads. The linear problems of bifurcation of shell equilibrium are considered using a two-dimensional theory of the Kirchhoff-Love type. The explicit approximate formulas obtained by means of the asymptotic method permit one to estimate the critical loads and find the buckling modes.The solutions to some of the buckling problems are obtained for the first time in the form of explicit formulas. Special attention is devoted to the study of the shells of negative Gaussian curvature, the buckling of which has some specific features. The buckling modes localized near the weakest lines or points on the neutral surface are constructed, including the buckling modes localized near the weakly supported shell edge. The relations between the buckling modes and bending of the neutral surface are analyzed. Some of the applied asymptotic methods are standard; the others are new and are used for the first time in this book to study thin shell buckling. The solutions obtained in the form of simple approximate formulas complement the numerical results, and permit one to clarify the physics of buckling.

This book contains eight chapters treating the stability of all major areas of the flexural theory. It covers the stability of structures under mechanical and thermal loads and all areas of structural, loading and material types. The structural element may be assumed to be made of a homogeneous/isotropic material, or of a functionally graded material. Structures may experience the bifurcation phenomenon, or they may follow the postbuckling path. This volume explains all these aspects in detail. The book is self-contained and the necessary mathematical concepts and numerical methods are presented in such a way that the reader may easily follow the topics based on these basic tools. It is intended for people working or interested in areas of structural stability under mechanical and/or thermal loads. Some basic knowledge in classical mechanics and theory of elasticity is required.

This report describes the work performed by Lockheed Palo Alto Research Labora tory, Palo Alto, California 94304. The work was sponsored by Air Force Office of Scientific Research, Bolling AFB, Washington, D. C. under Grant F49620-77-C-0l22 and by the Flight Dynamics Laboratory, Air Force Wright Aeronautical Laboratories, Wright-Patterson AFB, Ohio under Contract F3361S-76-C-31OS. The work was completed under Task 2307Nl, "Basic Research in Behavior of Metallic and Composite Components of Airframe Structures". The work was admini stered by Lt. Col. J. D. Morgan (AFOSR) and Dr. N. S. Khot (AFWAL/FIBRA). The contract work was performed between October 1977 and December 1980. The technical report was released by the Author in December 1981. Preface Many structures are assembled from parts which are thin. For example, a stiffened plate or cylindrical panel is composed of a sheet the thickness of which is small com pared to its length, breadth, and stiffener- spacing, and stiffeners the thickness of which is small compared to their _ heights and lengths. These assembled structures, loaded in compression, can buckle overall, that is sheet and stiffeners can collapse together in a general instability mode; the sheet can buckle locally between stiffeners; the stiffeners can cripple; and a variety of complex buckling interactions can occur involving local and overall deformations of both sheet and stiffeners. More complex, built-up structures can buckle in more complex and subtle ways.