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The present theoretical investigation studies the effect of small multilobed initial deviations from the exact shape upon the deformations and the critical time of a thin-walled circular cylindrical shell which was manufactured with initial axisymmetric deformations. To facilitate the analytical work, the actual solid wall of the shell is imagined to be replaced by an equivalent sandwich wall. The general equilibrium equations derived for shallow shells are expressed in terms of the stresses and deviations corresponding to the equivalent sandwich model. The radial displacement as well as the meridional, circumferential and membrane shear stresses are expressed by finite Fourier series for each face of the sandwich model. A closed form solution is found for the multilobed deformation rates and for the critical time as well. A numerical integration of the deformation rates shows, for a given cylinder, that the multilobed creep buckling deformations grow much faster than the axisymmetric. (Modified author abstract).
This volume contains the written texts of the papers presented at a Symposium on Buckling of Structures held at Harvard University in June 1974. This symposium, one of several on various topics sponsored annually by the International Union of Theoretical and Applied Me chanics (IUTAM), was organized by a Scientific Committee consisting of B. Budiansky (Chairman), A. H. Chilver, W. T. Koiter, and A. S. Vol' mir. Participation was by invitation of the Scientific Committee, and specific lecturers were invited to speak in the areas of experimental research, buckling and post-buckling calculations, post-buckling mode interaction, plasticity and creep effects, dynamic buckling, stochastic problems, and design. A total of 29 lectures were delivered, including a general opening lecture by Professor Koiter, and there were 93 reg istered participants from 16 different countries. Financial support for the symposium was provided by IUTAM, in the form of partial travel support for a number of participants, and also by the National Science Foundation, the National Aeronautics and Space Administration, and the Air Force Office of Scientific Re search, for additional travel support and administrative expenses. Meeting facilities and services were efficiently provided by the Science Center of Harvard University, and administrative support was gen erously provided by the Division of Engineering and Applied Physics of Harvard University. The scientific chairman enjoyed the invaluable assistance of his colleagues Professors J. W. Hutchinson and J. L.
* Edited by Josef Singer, the world's foremost authority on structural buckling. * Time-saving and cost-effective design data for all structural, mechanical, and aerospace engineering researchers.
On December 2-5, 1991, a Symposium on Thermal Stresses, Dynamics and Stability honoring Professor Bruno A. Boley on the occasion of his 65th birthday was held in Atlanta, Georgia during the Winter Annual Meeting of the American Society of Mechanical Engineers. The papers presented during the Symposium by some of Professor Boley's former students and colleagues cover those areas of applied mechanics where most of his contributions have been made over the years. These papers have been written in tribute to Professor Boley's distinguished scientific career and out of genuine affection and respect for him. The present volume consists of those Symposium papers that belong to the areas of Dynamics and Stability and constitute recent advances in the field. A special issue of the Journal of Thermal Stresses has been reserved for publication of the Symposium papers on Thermal Stresses, under the editorship of Professor R. B. Hetnarski. The present volume begins with a biographical sketch and bibliography of Professor Boley, along with a list of his doctoral students. Thirteen papers on dynamics and stability follow. The first four papers deal with wave propagation and vibration studies in solids and structures. The next two papers study wave propagation in fluids, while the seventh paper is concerned with the dynamic response of random media. Two papers dealing with structural vibrations exhibiting instability and one dealing with dynamic buckling delamination are presented next. The last three papers are concerned with instability in solids and structures.
The Thirteenth International Congress of Theoretical and Applied Mechanics was held in Moscow from Monday, 21 August, to Saturday, 26 August 1972. About 2500 participants from 37 countries all over the world attended the congress that was convened by the Congress Committee of the International Union of Theoretical and Applied Mechanics. The local or ganization lay in the hands of the Organizing Committee, established by the USSR National Committee on Theoretical and Applied Mechanics. The USSR Academy of Sciences rendered partial financial help to the organization of th8 congress. The Organizing Committee was assisted by the Institute of Problems of Mechanics of the USSR Academy of Sciences, by the Research Institute for Mechanics of Moscow University, and by the Computing Center and the Institute of Applied Mathematics of the USSR Academy of Sciences. The Bureau of IUTAM had allocated a considerable sum for partial financial support of young scientists attending the congress. The Thirteenth Congress was officially opened on Monday morning at the Kremlin Palace of Congresses by Academician N. 1. Muskhelishvili, President of the Congress, and Professor W. T. Koiter, President of IUTAM. Greeting addresses were offered by: Mr. K. N. Rudnev, Minister, member of the Council of Ministers of the USSR, Academician M. V. Keldysh, President of the USSR Academy of Sciences, Mr. L. N.
Test equipment suitable for the study of the creep buckling of axially compressed circular cylindrical shells was developed and built. With the aid of this equipment, thirty-one electroformed nickel cylinders of radius-to-thickness ratios ranging from 30.6 to 96.4 were tested at a temperature of 650F. The loading of each specimen was interrupted usually once, and in some cases twice, to permit an exact measurement of the creep deformations produced by the axial compression. Diagrams showing the deformed shapes of eight generators of each specimen are presented at two or three stages of the creep buckling process. Inspection of the figures reveals that specimens of this kind either buckle axisymmetrically, or begin the creep buckling process in a axisymmetric manner but change over to a multilobed pattern in later stages of the deformations. (Author).
Experimental results obtained with 31 nickel circular cylindrical shell specimens are evaluated in the light of the theory. The test results have already been reported in SUDAAR No. 415. The experimental creep buckling times obtained in axial compression at a temperature of 650F were found to be in reasonable agreement with the theoretical formulas. (Author).
A review is presented of the fundamental considerations that enter into the calculation of the buckling of plates and shells whose material deforms in consequence of nonlinear creep. Results are given of analyses that have been carried out for flat plates subjected to edge-wise compression and for circular cylindrical shells subjected to uniform axial compression, to a uniform external pressure and to a constant bending moment. The character of the behavior of these structural elements after buckling is also discussed. (Author).