International Union of Theoretical and Applied Mechanics Buckling of Structures Symposium Cambridge/USA June 17-21, 1974 Editor Bernard Budiansky Springer-Verlag Berlin Heidelberg New York 1976 Professor Bernard Budiansky Harvard University Cambridge, Massachusetts, U.S.A. With 214 Figures ISBN 978-3-642-50994-0 ISBN 978-3-642-50992-6 (eBook) DOl 10.1007/978-3-642-50992-6 Library of Congress Cataloging in Publication Data: Symposium on Buckling of Structures, Harvard University. 1974. Buckling of structures. At head of title: International Union of Theoretical and Applied Mechanics. Bibliography: p. Inclndes index. 1. Jlnckling (Mechanics) - Congresses. 2. Struc tural stabilit~-- Congresses. 1. Jlndiansky, Beruard. II. International Union of Theoretical and App lied Mechanics. III. Title. TA656.2.S95. 1974. 624'.176. 75-31726. This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned. specifically those of translation, reprinting, re-use of illustratious, broadcasting, repro duction by pbotocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyrigbt Law where copies are made for otber than private use, a fee is payable to the pub lisher, the amonnt of the fee to be determined by agreement with the publisber. © by Springer-Verlag, Berlin/Heidelberg 1976. Softcover reprint of the hardcover 1st edition 1976 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that sucb names arc exempt from the relevant protective laws and regulations and therefore free for general use. Preface 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. San ders in making local arrangements for the symposium; and, finally, the dedicated secretarial and administrative services provided by Marion Remillard and Parian Temple, without whom nothing would have worked, are most gratefully acknowledged. Cambridge, Mass., October 1975 Bernard Budiansky Participants (Authors denoted by asterisks) Akkas, N. Ankara, Turkey *Almroth, B. O. Palo Alto, California, U.S.A. *A mazigo, J. C. Troy, New York, U.S.A. *A nderson, M. S. Hampton, Virginia, U.S.A. *Arbocz, J. Pasadena, California, U.S.A. *A ugusti, G. Florence, Italy *Babcock, Jr., Ch. D. Pasadena, California, U.S.A. Basdekas, N. Arlington, Virginia, U.S.A. Batdorf, S. B. Los Angeles, California, U.S.A. Bauld, N. R. Clemson, South Carolina, U.S.A. Besseling, J. F. Delft, Netherlands Billington, D. P. Princeton, New Jersey, U.S.A. Blaauwendraad, J. Gouda, Netherlands Brown, E. H. London, England Brush, D. O. Davis, California, U.S.A. *Budiansky, B. Cambridge, Massachusetts, U.S.A. Bufler, H. Stuttgart, Germany Bushnell, D. Palo Alto, California, U.S.A. Calladine, C. R. Cambridge, England Ceradini, G. Rome, Italy *Chilver, A. H. Cranfield, England Como, M. Cosenza, Italy Danielson, D. A. Charlottesville, Virginia, U.S.A. Dickie, J. F. Manchester, England Dill, E. H. Seattle, Washington, U.S.A. *Duszek, M. K. Warsaw, Poland Dym, C. L. Cambridge, Massachusetts, U.S.A. Ebner, H. Aachen, Germany *Esslinger, M. Braunschweig, Germany *Gallagher, R. H. Ithaca, New York, U.S.A. Galletly, G. D. Liverpool, England *Hansen, H. R. Oslo, Norway *Hayman, B. Leicester, England Hedgepeth, J. M. Santa Barbara, California, U.S.A. Herrmann, G. Stanford, California, U.S.A. *Hoff, N. J. Stanford, California, U.S.A. Huang, N. C. Notre Dame, Indiana, U.S.A. Huseyin, K. vVaterloo, Ontario, Canada *Hutchinson, J. W. Cambridge, Massachusetts, U.S.A. *Johns, K. C. Sherbrooke, Quebec, Canada Participants V Jones, N. Cambridge, Massachusetts, U.S.A. Kalnins, A. Bethlehem, Pennsylvania, U.S.A. Kempner, J. Brooklyn, New York, U.S.A. Khot, N. S. Dayton, Ohio, U.S.A. Knets,1. Riga, U.S.S.R. *Koiter, W. T. Delft, Netherlands *Kozarov, 1\'I. lVL Sofia, Bulgaria *Leckie, F. A. Leicester, England *Leipholz, H. H. E. \Vaterloo, Ontario, Canada *Leonard, R. VY. Hampton, Virginia, U.S.A. Libove, C. Syracuse, New York, U.S.A. Lukasiewicz, S. \Varsaw, Poland McIvor, 1. K. Ann Arbor, Michigan, U.S.A. *Massonnet, Ch. Liege, Belgium Masur, E. F. Chicago, Illinois, U.S.A. Nachbar, W. La Jolla, California, U.S.A. *Needleman, A. Cambridge, Massachusetts, U.S.A. *van der Neut, A. Delft, Netherlands Niordson, F. 1. Lyngby, Denmark Ohtsubo, H. Tokyo, Japan *Pedersen, P. T. Lyngby, Denmark Pian, T. H. H. Cambridge, Massachusetts, U.S.A. *Pignataro, M. Rome, Italy Plaut, R. H. Providence, Rhode Island. U.S.A. Pomerantz, J. Arlington, Virginia, U.S.A. Rehfield, L. W. Atlanta, Georgia, U.S.A. Reissner, E. La Jolla, California, U.S.A. Rhodes, J. Glasgow, Scotland Riks, E. Amsterdam, Netherlands Roorda, J. \Vaterioo, Ontario, Canada *Roren, E. l\'1. Q. Oslo, Norway Samuelson, L. A. Bromma, Sweden Sanders, J. L., Jr. Cambridge, Massachusetts, U.S.A. Seide, P. Los Angeles, California, U.S.A. *Sewell, M. J. Reading, England Simitses, G. J. Atlanta, Georgia, U.S.A. Simmonds, J. G. Charlottesville, Virginia, U.S.A. *Singer, J. Haifa, Israel Stein, M. Hampton, Virginia, U.S.A. Supple, W. J. Guildford, England *Tennyson, R. C. Downsview, Ontario, Canada *Thompson, J. M. T. London, England Thurston, G. A. Denver, Colorado, U.S.A. Tillman, S. C. Manchester, England *Tulk, J. D. London, England *Tvergaard, Y. Lyngby, Denmark Uetani, K. Kyoto, Japan Valid, R. Chatillon, France de Veubeke, B. F. Liege, Belgium Wierzbicki, T. \Varsaw, Poland *Williams, F. W. Birmingham, England *Yamaki, N. Sendai, Japan Zyczkowski, ill. Krakow, Poland Contents I. Opening Lecture W. T. Koiter: Current Trends in the Theory of Buckling . . . . . . . . 1 II. Buckling and Post-Buckling Calculations F. W. Williams, W. H. Wittrick, R. J. Plank: Critical Buckling Loads of some Prismatic Plate Assemblies. . . . . . . . . . . . . . . . .. 17 P. T. Pedersen: On the Collapse Load of Cylindrical Shells ..... 27 R. H. Gallagher: Finite Element Representations for Thin Shell Instability Analysis ..................................... 40 B. O. Almroth, E. Meller, F. A. Brogan: Computer Solutions for Static and Dynamic Buckling of Shells .................... 52 III. Plasticity and Creep N. J. Hoff: Theory and Experiment III the Creep Buckling of Plates and Shells ...................................... 67 R. B. Rikards, G. A. Teters: Nonsymmetric Creep Buckling of Cylindrical Shells under Axial Compression and External Pres- sure 78 F. A. Leckie, B. Hayman: Creep Instability of Thick Shell Struc- tures .................................................. 86 M. J. Sewell: A Plastic Flow Rule at a Yield Corner 95 J. W. Hutchinson, B. Budiansky: Analytical and Numerical Study of the Effects of Initial Imperfections on the Inelastic Buckling of a Cruciform Column .......................... 98 Contents VII M. K. Duszek: Stability Analysis of Rigid Plastic Structures at the Yield-Point Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 100 I V. Mode Interaction A. van der Neut: Mode Interaction with Stiffened Panels 117 W. T. Koiter, M. Pignataro: An Alternative Approach to the In teraction between Local and Overall Buckling in Stiffened Panels 133 J. M. T. Thompson, J. D. Tulk, A. C. Walker: An Experimental Study of Imperfection-Sensitivity in the Interactive Buckling of Stiffened Plates ...................................... 14H V. Tvergaard, A. Needleman: Mode Interaction in an Eccentric- ally Stiffened Elastic-Plastic Panel under Compression ...... 160 V. Stochastics . J. C. Amazigo: Buckling of Stochastically Imperfect Structures.. 172 G. Augusti, A. Baratta: Reliability of Slender Columns: Compari- son of Different Approximations .......................... 183 K. C. Johns: Some Statistical Aspects of Coupled Buckling Struc- tures .................................................. 199 VI. Dynnmics H. H. E. Leipholz: Some ltemarks on Liapunov Stability of Elas- tic Dynamical Systems .................................. 208 M. Kozarov, M. Kishkilov: An Investigation of the Stability and Vibration of a Hyperbolic Shell of one Sheet under Axisymmet- ric Loading ............................................ 217 VII. Experiments J. Singer, A. Rosen: The Influence of Boundary Conditions on the Buckling of Stiffened Cylindrical Shells .... . . . . . . . . . . . .. 227 R. C. Tennyson: The Effect of Shape Imperfections and Stiffening on the Buckling of Circular Cylinders ....................... 251 M. Esslinger, B. Geier: Calculated Postbuckling Loads as Lower Limits for the Buckling Loads of Thin-Walled Circular Cylinders 274 VIII Contents ,J. Arbocz, Ch. D. Babcock, Jr.: Prediction of Buckling Loads Based on Experimentally Measured Initial Imperfections. . . .. 291 N. Yamaki: Experiments on the Postbuckling Behavior of Circu- lar Cylindrical Shells under Torsion ........................ 312 V III. Design A. H. Chilver: Design Philosophy in Structural Stability 331 R. W. Leonard, M. S. Anderson, \V. L. Heard, Jr.: Design of a Mars Entry "Aeroshell" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 346 R. Maquoi, C. Massonnet: Interaction between Local Plate Buck- ling and Overall Buckling in Thin-Walled Compression Mem- bers-Theories and Experiments .......................... 365 E. M. Q. Roren, H. R. Hansen: Buckling Design in Ship Struc- tures .................................................. 383 Current Trends in the Theory of Buckling W. T. Koiter Technische Hogeschool, Delft, .Netherlands Abstract Some current trends in buckling theory are reviewed. Particular attention is given to multi-mode bifurcation buckling, the associated imperfection-sensitivity and the correlation of experimental evidence with theory. 1. Introduction The task of a speaker in an opening lecture at a meeting of selected experts in a particular field of science is hardly to be envied. In most aspects of his topic the audience comprises members with far more specialized expertise than the lecturer has at his command, and the eaRY way out, a retreat into generalities, is not likely to be welcomed. Having accepted the challenge, however, I shall try and review some CUl'rent trends in the theory of buckling as I see them. I had the good fortune to read the abstracts of your papers which our chairman kindly made available to me, and this may reduce to some extent the inevit able personal bias in my talk. The simplest possible model of a column, depicted in Fig. 1 a, consists of a rigid bar supported on an elastic hinge. This simple model is employed in several elementary text-books, including the author's [28] which, incidentally, enjoys sales comparable to a volume of poetry. The perfect column, with zero eccentricity of the applied load (e = 'XL = 0), loses its stability and buckles by bifurcation at the critical load 1\ = DIL. The post-buckling behaviour depends on nonlinearities in the spring characteristic. Various possible load-deflection curves are shown in Fig. 1 b, and the relationship between the load and the overall shortening is exhibited in° F ig. 1 c. In cases of an unstable descending post-buckling path (ex =1= or ex = 0, (3 < -1/6) the column is sensitive to geometric imperfections or load eccentricity. The associated drop in critical load is shown in Fig. 1 d, and the buckling load FI at the bi furcation point is replaced by the snap load at a limit point. In the absence of a descending post-buckling path of the perfect column, how ever, no loss of stability occurs in the column with imperfections or 2 W. T. Koiter a load eccentricity. The presence of the buckling load PI of the perfect column appears here only in the form of a marked increase of the deflection when the load P approaches and passes the value PI" Post-buckling equilibrium paths and the influence of imperfections F IF i I I i L a F F F CJ. = 0 , f3 < -116 a=O,{3>-1I6 e b F F*IF, CI.. = 0 ,/3> -116 F. I ....... \ .............. e&= 0, f:l < -116 " a=O, f3 < -116 ,n=312 ....... a;>! 0 l(lX>O,n=2 ,1/L c d Fig. 1. a) Simplest column model eccentricity e = uL, spiral spring, + ltf = D [0 - or.02 ,803]; b) Load-deflection curves; c) Load-shortening curve for perfect column. d) Imperfection-sensitivity (1 - F*IF1)n = const· lui FIFr