Computerized Buckling Analysis Of Shells

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.

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.

This collection of papers, written by friends and colleagues of Josef Singer, presents a comprehensive and timely review of the theoretical mechanics of thin shell-structures. Topics of great current interest such as the buckling of composite plates and shells, the plastic buckling of thin-walled structures and the optimum design of buckling sensitive curved composite panels are examined by experts, using a great diversity of approaches, whereby theoretical predictions are compared with experimental results whenever possible.Other topics reviewed include the buckling and post-buckling behaviour of imperfect shells under different external static or dynamic loads and a variety of boundary conditions. Papers dealing with the vibration and the dynamic response of thin elastic bodies are also presented.A strong emphasis is made on the practical applications aspect in the theories presented. Thus engineers, research workers and students who are involved with the design and analysis of shell structures made of different materials, and subjected to various static and dynamic loads will find this volume an invaluable source of reference.

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".