Asymptotic Methods In The Buckling Theory Of Elastic Shells

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 presents a collection of articles reporting the current challenges in solid and fracture mechanics. The book is devoted to the 90th birthday of academician Nikita F. Morozov—a well-known specialist in the field of solid and fracture mechanics.

A consistent theory for thin anisotropic layered structures is developed starting from asymptotic analysis of 3D equations in linear elasticity. The consideration is not restricted to the traditional boundary conditions along the faces of the structure expressed in terms of stresses, originating a new type of boundary value problems, which is not governed by the classical Kirchhoff-Love assumptions. More general boundary value problems, in particular related to elastic foundations are also studied. The general asymptotic approach is illustrated by a number of particular problems for elastic and thermoelastic beams and plates. For the latter, the validity of derived approximate theories is investigated by comparison with associated exact solution. The author also develops an asymptotic approach to dynamic analysis of layered media composed of thin layers motivated by modeling of engineering structures under seismic excitation. Contents:Plane Problem for a Rectangular Elastic StripThe Winkler-Fuss ModelDirect Asymptotic Integration of 3D Elasticity Equations for Orthotropic PlatesMatching of the Outer Solution and the Boundary Layer for an Orthotropic PlateElastic Plates of General AnisotropyNon-Classical Boundary Value Problems for Anisotropic PlatesTwo-Layer Anisotropic Plates. The Modulus of a Layered FoundationAsymptotic Analysis of the Outer Problem for an Orthotropic ShellBoundary Layer in Orthotropic ShellsNon-Classical Boundary Value Problems for Anisotropic ShellsSpatial Dynamic Problems for Anisotropic Plates Readership: Researchers and specialists in applied mathematics and mechanical engineering, undergraduates and graduate students. Keywords:Asymptotic Theories;Beams;Plates;Shells;Problems of Elasticity Theory;Layered Thermoelastic Thin Structures;Elastic Foundations;Non-Classical Boundary Problems for Anisotropic Beams, Plates and Shells;Singularly Perturbed Systems;Boundary LayerKey Features:The book exposits consistent theory for composite thin walled elastic structures. The obtained results are applied to justification and refinement of ad hoc engineering structural theoriesThe effective solutions of a variety of boundary value problems are obtainedThere is a clear potential for numerous advanced industrial applications

This book presents the various approaches in establishment the basic equations of one- and two-dimensional structural elements. In addition, the boundaries of validity of the theories and the estimation of errors in approximate theories are given. Many contributions contain not only new theories, but also new applications, which makes the book interesting for researcher and graduate students.

The construction of solutions of singularly perturbed systems of equations and boundary value problems that are characteristic for the mechanics of thin-walled structures are the main focus of the book. The theoretical results are supplemented by the analysis of problems and exercises. Some of the topics are rarely discussed in the textbooks, for example, the Newton polyhedron, which is a generalization of the Newton polygon for equations with two or more parameters. After introducing the important concept of the index of variation for functions special attention is devoted to eigenvalue problems containing a small parameter. The main part of the book deals with methods of asymptotic solutions of linear singularly perturbed boundary and boundary value problems without or with turning points, respectively. As examples, one-dimensional equilibrium, dynamics and stability problems for rigid bodies and solids are presented in detail. Numerous exercises and examples as well as vast references to the relevant Russian literature not well known for an English speaking reader makes this a indispensable textbook on the topic.

There have been stability theories developed for beams, plates and shells — the most significant elements in mechanical, aerospace, ocean and marine engineering. For beams and plates, the theoretical and experimental values of buckling loads are in close vicinity. However for thin shells, the experimental predictions do not conform with the theory, due to presence of small geometric imperfections that are deviations from the ideal shape.This fact has been referred to in the literature as ‘embarrassing’, ‘paradoxical’ and ‘perplexing’. Indeed, the popular adage, “In theory there is no difference between theory and practice. In practice there is”, very much applies to thin shells whose experimental buckling loads may constitute a small fraction of the theoretical prediction based on classical linear theory; because in practice, engineers use knockdown factors that are not theoretically substantiated.This book presents a uniform approach that tames this prima-donna-like and capricious behavior of structures that has been dubbed the ‘imperfection sensitivity’ — thus resolving the conundrum that has occupied the best minds of elastic stability throughout the twentieth century.

The object of this book is to clarify the whole aspect of the basic problems concerning the elastic stability of of circular cylindrical shells under typical loading conditions. The book deals with buckling, postbuckling and initial postbuckling problems under one of the three fundamental loads, that is, torsion, pressure and compression. The emphases are placed on the accurate analysis and comprehensive numeral results for the buckling problem, experimental verification of the theoretical analysis for the postbuckling problem and clarification of the range of applicability of the perturbation method for the analysis of initial postbuckling behaviors and imperfection sensitivity. The problems under typical combined loads as well as the influence of the contained liquid are also clarified.

The book presents mathematical and mechanical aspects of the theory of plates and shells, applications in civil, aero-space and mechanical engineering, as well in other areas. The focus relates to the following problems:• comprehensive review of the most popular theories of plates and shells,• relations between three-dimensional theories and two-dimensional ones,• presentation of recently developed new refined plates and shells theories (for example, the micropolar theory or gradient-type theories),• modeling of coupled effects in shells and plates related to electromagnetic and temperature fields, phase transitions, diffusion, etc.,• applications in modeling of non-classical objects like, for example, nanostructures,• presentation of actual numerical tools based on the finite element approach.