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Showing papers in "Applied Mechanics Reviews in 2010"


Journal ArticleDOI
TL;DR: In this article, the authors present the analysis of new trends and recent results carried out during the last 10 years in the field of fractional calculus application to dynamic problems of solid mechanics.
Abstract: The present state-of-the-art article is devoted to the analysis of new trends and recent results carried out during the last 10 years in the field of fractional calculus application to dynamic problems of solid mechanics. This review involves the papers dealing with study of dynamic behavior of linear and nonlinear 1DOF systems, systems with two and more DOFs, as well as linear and nonlinear systems with an infinite number of degrees of freedom: vibrations of rods, beams, plates, shells, suspension combined systems, and multilayered systems. Impact response of viscoelastic rods and plates is considered as well. The results obtained in the field are critically estimated in the light of the present view of the place and role of the fractional calculus in engineering problems and practice. This articles reviews 337 papers and involves 27 figures. DOI: 10.1115/1.4000563

491 citations


Journal ArticleDOI
TL;DR: In this article, the dynamics and control of low-frequency unsteadiness, as observed in some aerodynamic applications, were addressed, and a coherent and rigorous linearized approach was presented, which enables both to describe the dynamics of commonly encountered open-flows and to design open-loop and closed-loop control strategies, in view of suppressing or delaying instabilities.
Abstract: This review article addresses the dynamics and control of low-frequency unsteadiness, as observed in some aerodynamic applications. It presents a coherent and rigorous linearized approach, which enables both to describe the dynamics of commonly encountered open-flows and to design open-loop and closed-loop control strategies, in view of suppressing or delaying instabilities. The approach is global in the sense that both cross-stream and streamwise directions are discretized in the evolution operator. New light will therefore be shed on the streamwise properties of open-flows. In the case of oscillator flows, the unsteadiness is due to the existence of unstable global modes, i.e., unstable eigenfunctions of the linearized Navier-Stokes operator. The influence of nonlinearities on the dynamics is studied by deriving nonlinear amplitude equations, which accurately describe the dynamics of the flow in the vicinity of the bifurcation threshold. These equations also enable us to analyze the mean flow induced by the nonlinearities as well as the stability properties of this flow. The open-loop control of unsteadiness is then studied by a sensitivity analysis of the eigenvalues with respect to base-flow modifications. With this approach, we manage to a priori identify regions of the flow where a small control cylinder suppresses unsteadiness. Then, a closed-loop control approach was implemented for the case of an unstable open-cavity flow. We have combined model reduction techniques and optimal control theory to stabilize the unstable eigenvalues. Various reduced-order-models based on global modes, proper orthogonal decomposition modes, and balanced modes were tested and evaluated according to their ability to reproduce the input-output behavior between the actuator and the sensor. Finally, we consider the case of noise-amplifiers, such as boundary-layer flows and jets, which are stable when viewed in a global framework. The importance of the singular value decomposition of the global resolvent will be highlighted in order to understand the frequency selection process in such flows. © 2010 by ASME.

252 citations


Journal ArticleDOI
TL;DR: Symplectic elasticity as discussed by the authors is a new concept and solution methodology in elasticity and applied mechanics based on the Hamiltonian principle with Legendre's transformation, which can be found in many numerical and analytical works.
Abstract: Symplectic Elasticity: Theory and Applications Many of the early works on symplectic elasticity were published in Chinese and as a result, the early works have been unavailable and unknown to researchers worldwide. It is the main objective of this paper to highlight the contributions of researchers from this part of the world and to disseminate the technical knowledge and innovation of the symplectic approach in analytic elasticity and applied engineering mechanics. This paper begins with the history and background of the symplectic approach in theoretical physics and classical mechanics and subsequently discusses the many numerical and analytical works and papers in symplectic elasticity. This paper ends with a brief introduction of the symplectic methodology. A total of more than 150 technical papers since the middle of 1980s have been collected and discussed according to various criteria. In general, the symplectic elasticity approach is a new concept and solution methodology in elasticity and applied mechanics based on the Hamiltonian principle with Legendre's transformation. The superiority of this symplectic approach with respect to the classical approach is at least threefold: (i) it alters the classical practice and solution technique using the semi-inverse approach with trial functions such as those of Navier, Levy, and Timosh-enko; (ii) it consolidates the many seemingly scattered and unrelated solutions of rigid body movement and elastic deformation by mapping with a series of zero and nonzero eigenvalues and their associated eigenvectors; and (iii) the Saint–Venant problems for plane elasticity and elastic cylinders can be described in a new system of equations and solved. A unique feature of this method is that bending of plate becomes an eigenvalue problem and vibration becomes a multiple eigenvalue problem.

186 citations


Journal ArticleDOI
TL;DR: A critical survey on homogenization theory and related techniques applied to micromechanics is presented and the classical as well as the emerging analytical and computational techniques are presented.
Abstract: In this paper, we present a critical survey on homogenization theory and related techniques applied to micromechanics. The validation of homogenization results, the characterization of composite materials and the optimal design of complex structures are issues of great technological importance and are viewed here as a combination of mathematical and mechanical homogenization. The mathematical tools for modeling sequentially layered composites are explained. The influence of initial and boundary conditions on the effective properties in nonlinear problems is clarified and the notion of stability by homogenization is analyzed. Multiscale micromechanics methods are outlined and the classical as well as the emerging analytical and computational techniques are presented. Computation of effective static and dynamical properties of materials with linear or nonlinear constitutive equations is closely related to the development of generalized theories such as the strain-gradient mechanics. Selected applications of these techniques are outlined. Moreover, the extension of kinetic techniques in homogenization and the related inverse imaging problem are presented.

174 citations



Journal ArticleDOI
TL;DR: In this article, a review of recent research studies on the buckling of carbon nanotubes is presented, where the main factors, such as dimensions, boundary conditions, temperature, strain rate, and chirality, influencing buckling behaviors are discussed.
Abstract: This paper reviews recent research studies on the buckling of carbon nanotubes. The structure and properties of carbon nanotubes are introduced to the readers. The various buckling behaviors exhibited by carbon nanotubes are also presented herein. The main factors, such as dimensions, boundary conditions, temperature, strain rate, and chirality, influencing the buckling behaviors are also discussed, as well as a brief introduction of the two most used methods for analyzing carbon nanotubes, i.e., continuum models and atomistic simulations. Summary and recommendations for future research are also given. Finally, a large body of papers is given in the reference section. It is hoped that this paper provides current knowledge on the buckling of carbon nanotubes, reviews the computational methods for determining the buckling loads, and inspires researchers to further investigate the buckling properties of carbon nanotubes for practical applications.

142 citations


Journal ArticleDOI
TL;DR: In this article, various experimental methods devised to measure permeability as a porous material property in composites are reviewed, as well as issues related to these methods and some associated permeability models.
Abstract: Accurate measurement of permeability is critical for fluid flow modeling in porous media. Various experimental methods devised to measure permeability as a porous material property in composites are reviewed. Liquid flow and gas flow methods of permeability measurement for in-plane and transverse directions specifically for fiber-reinforced composites are discussed, as well as issues related to these methods and some associated permeability models. Alternative methods of permeability determination based on cross transport phenomenon are reviewed as well. DOI: 10.1115/1.4001047

101 citations



Journal ArticleDOI
TL;DR: A literature review on the design and performance of antimotion structures/devices such as breakwaters, submerged plates, oscillating water column breakwaters and air-cushion, auxiliary attachments, and mechanical joints for mitigating the hydroelastic response of very large floating structures (VLFS) under wave action is presented in this article.
Abstract: Presented herein is a literature review on the design and performance of antimotion structures/devices such as breakwaters, submerged plates, oscillating water column breakwaters, air-cushion, auxiliary attachments, and mechanical joints for mitigating the hydroelastic response of very large floating structures (VLFS) under wave action. Shapes of VLFS that could minimize the hydrodynamic response of the structure are also discussed. The analytical, numerical, and experimental methods used in studying the effect of these antimotion structures/devices toward reducing the hydroelastic responses of VLFS are also reviewed.

82 citations


Journal ArticleDOI
TL;DR: In this article, two principal concepts of nonlinear normal vibrations modes (NNMs) namely the Kauderer-Rosenberg and Shaw-Pierre concepts are analyzed and properties of NNMs and methods of their analysis are presented.
Abstract: Two principal concepts of nonlinear normal vibrations modes (NNMs), namely the Kauderer–Rosenberg and Shaw–Pierre concepts, are analyzed. Properties of the NNMs and methods of their analysis are presented. NNMs stability and bifurcations are discussed. Combined application of the NNMs and the Rauscher method to analyze forced and parametric vibrations is discussed. Generalization of the NNMs to continuous systems dynamics is also described.

68 citations


Journal ArticleDOI
TL;DR: In this article, a comprehensive view of the research area is sought by critically examining the ex-perimental and numerical approaches adopted in studies of this problem in the literature, and areas of further research are highlighted.
Abstract: Natural convection in triangular enclosures is an important problem. It displays well thegeneric attributes of this class of convection, with its dependence on enclosure geometry,orientation and thermal boundary conditions. It is particularly rich in its variety of flowregimes and thermal fields as well as having significant practical application. In this pa-per, a comprehensive view of the research area is sought by critically examining the ex-perimental and numerical approaches adopted in studies of this problem in the literature.Different thermal boundary conditions for the evolution of the flow regimes and thermalfields are considered. Effects of changes in pitch angle and the Rayleigh number on theflow and thermal fields are examined in detail. Although most of the past studies are inthe laminar regime, the review extends up to the recent studies of the low turbulent re-gime. Finally, areas of further research are highlighted. [DOI: 10.1115/1.4004290]Keywords: buoyancy-induced flows, flow fields, triangular enclosures

Journal ArticleDOI
TL;DR: In this article, the experimental and computational simulations indicate that BN nanotubes are highly flexible and high necking angles in BN are correlated with unfavorable bonding in Bn and N-N atoms.
Abstract: Boron nitride (BN) nanotubes have structural and mechanical properties similar to carbon nanotubes and are known to be the strongest insulators. Great interest has been focused on understanding the mechanical properties of BN nanotubes as a function of their structural and physical properties. Yet, the published data have not been reviewed and systematically compared. In this paper, we critically review the mechanical properties of BN nanotubes from both experimental and simulation perspectives. The experimental reports include thermal vibrations, electric induced resonance method, and in situ force measurements inside transmission electron microscopy. The modeling and simulation efforts encompass tight bonding methods and molecular dynamics. Replacing the covalent sp2 bond (C–C) by ionic bond (B–N) results in differences in the mechanical properties of BN nanotubes in comparison to carbon nanotubes. The experimental and computational simulations indicate that BN nanotubes are highly flexible. High necking angles in BN nanotubes are assumed to be correlated with unfavorable bonding in B–B and N–N atoms.

Journal ArticleDOI
TL;DR: In this paper, a unified treatment of masonry structures is presented, presenting an overall and comprehensive up-to-date insight in the analysis of Masonry constructions while providing basic and advanced concepts and tools already available or original.
Abstract: The prevalent feature that characterizes masonry structures and makes them dissimilar from modern reinforced concrete and steel structures is quite definitely their inability to resist tensile stresses. Therefore, it is natural that the material model that is intended to be an “analog” of real masonry cannot resist tensile stress but possibly behaves elastically under pure compression, opening a perspective on the adoption of the no-tension (NT) material constitutive assumption. Founded on the NT theory, the basic direction and aim of the present work is to propose a unified treatment of masonry structures presenting an overall and comprehensive up-to-date insight in the analysis of masonry constructions while providing basic and advanced concepts and tools already available or original. The note is intended to lead to several notable results including, just to mention some of the outcomes, that the St. Venant’s postulate does not hold in NT solids, no energy is dissipated by fracture, special accommodations for discontinuous loads are needed, and the relevant developments are provided, among other significant outcomes such as the identification of operative procedures for engineering solutions of structural problems. In the first part of the paper, the basics for the foundation of a NT material theory are illustrated, and the relevant principles for structural analysis, mainly identified in the classic energy theorems and suitably adapted to the material at hand, are formulated. In (apparently) simple cases, closed-form solutions can be obtained, or, at least, the solution process can be prepared after a preliminary screening of the equilibrium scenario. The application to two-dimensional no-tension elasticity is then illustrated in the last section, with reference to two sample cases. The first example proves that the solution in a NT panel acted on by vertical loads on the top is clearly identified in terms of stress, but if discontinuities are present in the load pattern, these reflect in some strong singularities in the deformation field that requires to deepen the problem. The second example is concerned with a NT-elastic half-plane, and a technique to find approximate solutions is outlined and carried on in detail. In Part II of the note, it is demonstrated that discontinuous or lumped load patterns can be looked at as frontier cases: They are not in contrast, but in some sense they are not natural to NT solids. Still in Part II, it is shown how the equilibrium problem can be managed both through the strain and the stress approach.



Journal ArticleDOI
TL;DR: In this paper, the authors review the history and previous works, distinguishing Saint-Venant type decay from Toupin-type decay, and argue that the latter is not a formulation of the former.
Abstract: Toupin’s Theorem plays the most influential role in the history of development concerning Saint-Venant’s Principle. We now review the history and the previous works, distinguishing Saint-Venant type decay from Toupin-type decay and arguing that Toupin’s Theorem is not a formulation of Saint-Venant’s Principle; Saint-Venant’s Principle stated by Love can be disproved mathematically from Toupin’s Theorem, so Toupin’s Theorem is mathematically inconsistent with Saint-Venant’s Principle; Modified Saint-Venant’s Principle can be proved or formulated, though Saint-Venant’s Principle in its general form stated by Boussinesq and Love is not true.