bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of Flutter of Suspension Bridges
Authors: Preidikman S. , Mook D. T.
Published: April 2009

A method for simulating the spontaneous, wind-excited vibrations of suspension bridges is described. The approach is based on a numerical model that treats the bridge and flowing air as elements of a single dynamic system; and all of the governing equations are integrated numerically, simultaneously, and interactively. It is shown that the present simulation predicts the same onset of flutter as the analysis of Fung. Unlike Fung’s analysis, the present analysis provides the solution in the time domain, is not restricted to periodic motions or linear equations of motion, and provides post-onset behavior as long as the effective angles of attack are not large enough to produce stall. As a consequence, the present analysis can be a very effective tool for the design of flutter-suppressing control systems. Because the equations are solved numerically, nonlinear supports do not present a problem. In the present work, it is shown how the nonlinear springs lead to limit-cycle responses.
Finite Strain Viscoplasticity Based on Unified Constitutive Equations and Decomposition of Logarithmic Strain: Applications to Shells
Authors: Sansour C. , Kollmann F. G.
Published: April 2009

The paper is concerned with a formulation of large strain viscoplasticity based on the concept of unified constitutive models as well as on an additive decomposition of a logarithmic strain tensor. The constitutive model due to Bodner and Partom is modified as to fit within the theoretical framework presented. A basic feature of the formulation is the fact that the additive structure of the infinitesimal theory is preserved in the finite strain range. Based on an essential result, a closed form of the tangent operator is derived which is very efficient from the numerical point of view. As an application, finite shell deformations are considered. The shell theory used allows for the application of three-dimensional constitutive laws and is geometrically exact. The computations are based on an enhanced strain functional where the right Cauchy-Green tensor is enhanced. Two examples of large shell deformations including loading-unloading cycles are presented.
Application of an Adjoint Method to Aerodynamic Design
Authors: Santos Luis Carlos de Castro
Published: April 2009

The theoretical development and implementation of an optimization technique based on optimal control method is presented for the two-dimensional full-potential flow model. This technique, in comparison with the classical finite-differences approach (brute force), provides major savings in the overall computational cost. The reduction on computational effort is due to the fact that the gradient of a cost function can be evaluated by a closed form equation after the solution of an adjoint equation. Since this adjoint equation is similar to the full-potential equation itself, the same solution algorithm is applied. Inverse design problems are solved using optimization in both subsonic and transonic flows. Also wave drag minimization is successfully accomplished.
Direct Measurement of Skin Friction in Complex Fluid Flows
Authors: Schetz Joseph A.
Published: April 2009

This paper describes methods for the direct measurement of skin friction in fluid flows under a very wide variety of conditions. The challenges involved in different flow situations are highlighted, and representative instrument designs and measurement results are presented. The test conditions considered span the range from incompressible to hypersonic speeds; ambient to very high temperature including combusting flows; smooth, rough, and porous surfaces with and without injection and test times from 10-6 to essentially continuous runs. Both 2D and 3D flows are discussed. Accuracies of +/- 3-5% are presently attainable in the simplest cases, while +/- 10-15% is more typical for complex, 3D, high-speed flows at high temperatures. The final topic discussed is simultaneous measurements of skin friction and heat flux with the possible further additions of surface pressure and temperature.
Stresses in a Thin Piezoelectric Element Bonded to a Half-Space
Authors: Seemann Wolfgang E.
Published: April 2009

In this paper, a thin piezoceramic element is considered which is bonded to an elastic or a rigid half-space. Such a model may be an approximation of the interaction between piezoceramic elements and elastic structures like beams and plates. For an elastic half-space, the determination of the shear stress in the bonding layer leads to a singular integral equation. A half-space which is very stiff may be modeled as a rigid substrate. For this case, displacement functions are introduced. Hamilton’s principle for electromechanical systems allows the use of Lagrange multipliers to incorporate the condition of a stress free upper surface of the piezoceramic element. The stresses in the bonding layer and in the piezoceramic element are estimated by this method and compared with Finite Element results. Though the singularity near the ends of the piezoceramic element cannot be modeled by both methods, stress concentrations can clearly be seen for the shear stress as well as for the normal stress. As infinite stresses due to the singularity do not occur in reality, the results allow an estimation of the bonding stresses except in the near vicinity of the edges. The knowledge of these stresses is important to prevent failure due to delamination.
Continuum Model for Ion Gating in Cochlear Hair Cells
Authors: Steele Charles R.
Published: April 2009

The details of ion flow in cells are important for the macro mechanical response of sensory organs, as in the inner ear of vertebrates. A continuum model for the flow of an ionized fluid through a pore in an elastic wall is considered. With this, the electro-mechanical behavior is readily computed. An interesting result is that two equilibria exist for the flow through a pore with a soft elastic entrance region. At one equilibrium point, the entrance opening is more restricted and the corresponding ion flow rate is much lower. Thus it appears that the tendency of ion channels to pop from an open to a closed state may be a consequence of basic fluid-elastic interaction. With the simple continuum model, various effects can be explored. One is the presence of an external spring force, corresponding to the force of the tip fiber between stereocilia. Another is the effect of an adjacent membrane and pore. The input physical parameters are reasonable and the results for flow rate are consistent with experimental measurements.
Self-Locking Satellite Boom With Flexure-Mode Joints
Authors: Szyszkowski W. , Fielden K. , Johnson D. W.
Published: April 2009

Dynamic analysis, numerical simulation, and experimental results of the deployment of a self-locking lightweight satellite boom are presented. The joints that connect the two segments of the boom are made of flexible semi-cylindrical shells. During the deployment, the shells undergo large deflections and large rotations, up to π radians. The boom is to be launched in the folded configuration and then deployed from a rotating satellite. In the straight configuration, after locking the joints, the boom should be stiff enough to precisely position a heavy sensor in a required location. Several models of the boom are considered for analysis. In order to optimize the sensor trajectory and the locking sequence, a model that includes stiffness of the joints but neglects flexibility of the links is developed. The joints, which are prone to instabilities and snap-through behavior, are analyzed using large deflection quasistatic approach. Finally, nonlinear dynamics FEA is performed to simulate the deployment of the complete boom. The simulation is compared with experimental results obtained from the preliminary tests.
Pulsating Flow in a Channel With a Backward-Facing Step
Authors: Valencia Alvaro
Published: April 2009

The incompressible laminar flow in a channel with a backward-facing step is studied for steady cases and for pulsating inlet flow conditions. For steady flows, the influrnce of the inlet velocity profile, the height of the step, and the Reynolds number on the reattachment length is investigated. A parabolic entrance profile was used for pulsating flow. It was found with amplitude of oscillation of one by Re = 100 that the primary vortex breakdown through one pulsatile cycle and the wall shear stress in the separation zone varied markedly with pulsating inlet flow.
In-Plane Shear Strength Determination of Composite Materials in Laminated and Sandwich Panels
Authors: Vinson J. R.
Published: April 2009

A simple test procedure is available to determine the in-plane shear strength of laminated composite materials, as well as other orthotropic and isotropic advanced material systems. The test apparatus is simple, inexpensive, and the flat rectangular plate test specimen is not restricted in size or aspect ratio. In addition to its use for laminated composite materials, the test can also be used for foam core sandwich panels. In sandwich panels, the tests can be used to determine the in-plane shear strength of the faces, the core and/or the adhesive bond between face and core. The shear stresses developed vary linearly in the thickness direction and are constant over the entire planform area.
General Reduced Order Analytical Model for Nonlinear Dynamic Analyses of Beams With or Without Lumped Masses
Authors: Crespo da Silva M. R. M.
Published: April 2009

A set of reduced order differential equations of motion that are suited for analyzing the nonlinear dynamics of beams subjected to external excitations is developed using a variational formulation. The beam may have arbitrary property variations along its span, may carry any number of concentrated masses, and may have multiple supports. It may also be subjected to a base excitation in the form of a prescribed displacement imposed to the supports. The distributed and/or concentrated forces acting on the system may have a nonzero time average so that the equilibrium solution of the system does not necessarily coincide with its undeformed state. Because the first approximation to the elastic deformation of the beam is governed, in general, by partial differential equations with variable coefficients, the solution for the bending displacements at that level is obtained numerically. An analytical methodology is used to formulate, in a mathematically consistent manner, the reduced order nonlinear differential equations explicitly. Specific examples are then used in order to assess the combined effect of the nonlinear terms on the dynamic response of a beam subjected to both static and dynamic loads.
Spatial Coherence in the Wake of a Flat Plate
Authors: Da´vila Jose´ B. , Hajj Muhammad R. , Miksad Richard W. , Powers Edward J.
Published: April 2009

Spatial coherence of the streamwise velocity fluctuation was measured in the wake of a flat plate in a wind tunnel. The measurements were made in the context of determining the role of wavenumber resonance in quadratic interactions among resonant frequency modes. Frequency domain results show that sum-interaction modes targeted by coupled mode pairs are spatially coherent. This suggests that spatial coherence measurements can be combined with bispectral measurements to determine mode energy transit and direction.
Effective Elastic Moduli of Composite Materials: Reduced Parameter Dependence
Authors: Dundurs John , Jasiuk Iwona
Published: April 2009

In this paper, we focus on the effective elastic constants of composite materials and pay attention to the possibility of reducing the number of independent variables. Surprisingly, this important issue has hardly been explored before. In our analysis, we rely on a new result in plane elasticity due to Cherkaev, Lurie, and Milton (1992), and use Dundurs constants (Dundurs, 1967, 1969). As an example, we consider a result for the effective elastic moduli of a composite containing a dilute concentration of perfectly-bonded circular inclusions.
Design Sensitivity of Buckled Thin-Walled Composite Structural Elements
Authors: Alma´nzar Leonel I. , Godoy Luis A.
Published: April 2009

This paper presents a theory and applications to account for changes in the fundamental, buckling, and post-buckling states when design parameters of a composite material are modified. The influence of micro-mechanical parameters (the volume fraction and the fiber orientation) and of cross-sectional dimensions is investigated. A numerical example for columns made of composite materials is presented. Sensitivity is studied for local buckling loads. Explicit expressions are obtained for the sensitivities in the form of perturbation expansions. A beam under transverse load is also investigated, and geometric design parameters employed to investigate sensitivity. The information from the sensitivity analysis can be used to improve a design by modification of the buckling load.
Quasi-Analytic Sensitivity Analysis of a Unified Viscoplastic Constitutive Model for a Solder Alloy
Authors: Eisenberg Martin A. , Krempl Erhard , Maciucescu Luca
Published: April 2009

Unified constitutive models for the consistent description of inelastic thermomechanical response of engineering alloys to widely varying control conditions are strongly nonlinear; there are numerous constants to be determined; and successful use depends critically on expert professional judgment. These circumstances are not unlike those associated with the design of complex systems dependent on successful interaction of multidisciplinary teams. Introduced in this paper is a paradigm for design of constitutive models motivated by modern system design methodologies. Specifically, a quasi-analytic sensitivity analysis is applied to a special form of a viscoplasticity-based overstress model (VBO) for the uniaxial, isothermal, high-homologous temperature mechanical response of a solder alloy. Parameter sensitivity is demonstrated via linear algebraic equations. The technique is a critical first step to application of sophisticated techniques of multidisciplinary design optimization (MDO) to constitutive modeling.
Electrical Nonlinearity in Fracture of Piezoelectric Ceramics
Authors: Fulton Chandler C. , Gao Huajian
Published: April 2009

The structural reliability of piezoelectric ceramics in smart sensors and actuators is hindered by the lack of an appropriate fracture mechanics model. Recent experimental observations of their cracking behavior under combined electrical and mechanical loads contradict predictions made by the linear theory. Evidently, a fracture criterion suitable for piezoelectrics must account for material nonlinearity. Because these materials are typically mechanically brittle, we expect electrical ductility to be the dominant effect. By adopting a multiscale viewpoint, we identify a region of electrical nonlinearity near the crack tip in which the mechanical response of the material remains linear. The equilibrium equations for a fully anisotropic solid have closed-form solutions if the material’s behavior is assumed to be entirely linear outside of the plane of the crack. This approximation is equivalent to Dugdale’s model of the plastic zone in cracked metal sheets. The energy release rate derived using this load for specimens with cracks perpendicular to the poling direction. A remarkable feature of our model is that the energy release rate is strictly independent of the form of the nonlinear electrical constitutive relation. In fact, the material may even experience domain switching in the Dugdale zone without affecting the fracture criterion determined by our formulation.
Thermal-Mechanical Response of Stiffened Composite Cylinders
Authors: Herakovich Carl T. , Mirzadeh Farshad
Published: April 2009

A two-dimensional, curvilinear, isoparametric finite element is used to provide a discrete layer analysis of deformations and stresses in stiffened composite cylinders subjected to thermal-mechanical loading. Individual layers of the cylinder and the stiffener are modeled explicitly, providing an accurate and detailed representation of deformations and stresses including interlaminar stresses. Several skin and stiffener laminates are studied for fabrication induced residual thermal effects, applied axial strain, and internal pressure loadings. The analysis shows that local curvatures and interlaminar stress concentrations are present near the skin/stiffener joint. Interlaminar stresses are also present along the free edge of the stiffener.
Material Instabilities for Large Deformations of the Generalized Blatz-Ko Material
Authors: Horgan C. O.
Published: April 2009

One of the most widely used constitutive models for compressible isotropic nonlinearly elastic solids is the generalized Blatz-Ko material for foam-rubber and its various specializations. For this model, a discussion of necessary and sufficient conditions for ellipticity of the governing three-dimensional displacement equations of equilibrium is provided. When the parameter f occurring in the generalized Blatz-Ko model is in the range 0 ≤ f < 1, it is shown that ellipticity is always lost at sufficiently large stretches, while for f = 1, the equilibrium equations are globally elliptic. The implications of these results for material instabilities in a variety of physical problems are discussed.
Fuzzy Optimization of Complex Systems Using Approximation Concepts
Authors: Jensen Hector A. , Sepulveda Abdon E.
Published: April 2009

This paper presents a methodology for the efficient solution of fuzzy optimization problems. Design variables, as well as system parameters are modeled as fuzzy numbers characterized by membership functions. An optimization approach based on approximation concepts is introduced. High quality approximations for system response functions are constructed using the concepts of intermediate response quantities and intermediate variables. These approximations are used to replace the solution of the original problem by a sequence of approximate problems. Optimization techniques for non-differentiable problems which arise in fuzzy optimization are used to solve the approximate optimization problems. Example problems are presented to illustrate the ideas set forth.
Zero-Pressure-Gradient Turbulent Boundary Layer
Authors: George William K. , Castillo Luciano
Published: April 2009

Of the many aspects of the long-studied field of turbulence, the zero-pressure-gradient boundary layer is probably the most investigated, and perhaps also the most reviewed. Turbulence is a fluid-dynamical phenomenon for which the dynamical equations are generally believed to be the Navier-Stokes equations, at least for a single-phase, Newtonian fluid. Despite this fact, these governing equations have been used in only the most cursory manner in the development of theories for the boundary layer, or in the validation of experimental data-bases. This article uses the Reynolds-averaged Navier-Stokes equations as the primary tool for evaluating theories and experiments for the zero-pressure-gradient turbulent boundary layer. Both classical and new theoretical ideas are reviewed, and most are found wanting. The experimental data as well is shown to have been contaminated by too much effort to confirm the classical theory and too little regard for the governing equations. Theoretical concepts and experiments are identified, however, which are consistent-both with each other and with the governing equations. This article has 77 references.
Strain Rate Effects in Composites
Authors: Sierakowski R. L.
Published: April 2009

A review of the high strain rate behavior of filamentary composite materials is presented. The experimental techniques used for evaluating the dynamic performance of composites are discussed, as well as results obtained by researchers for various types of filamentary composites. Areas of research needed for expanding the information base for composites as well as the testing devices needed to obtain composite test data are chronicled. This review article contains 120 references.
Differential Quadrature Method in Computational Mechanics: A Review
Authors: Bert Charles W. , Malik Moinuddin
Published: April 2009

The differential quadrature method is a numerical solution technique for initial and/or boundary problems. It was developed by the late Richard Bellman and his associates in the early 70s and, since then, the technique has been successfully employed in a variety of problems in engineering and physical sciences. The method has been projected by its proponents as a potential alternative to the conventional numerical solution techniques such as the finite difference and finite element methods. This paper presents a state-of-the-art review of the differential quadrature method, which should be of general interest to the computational mechanics community.
Simulation of Multi-Dimensional Gaussian Stochastic Fields by Spectral Representation
Authors: Shinozuka Masanobu , Deodatis George
Published: April 2009

The subject of this paper is the simulation of multi-dimensional, homogeneous, Gaussian stochastic fields using the spectral representation method. Following this methodology, sample functions of the stochastic field can be generated using a cosine series formula. These sample functions accurately reflect the prescribed probabilistic characteristics of the stochastic field when the number of terms in the cosine series is large. The ensemble-averaged power spectral density or autocorrelation function approaches the corresponding target function as the sample size increases. In addition, the generated sample functions possess ergodic characteristics in the sense that the spatially-averaged mean value, autocorrelation function and power spectral density function are identical with the corresponding targets, when the averaging takes place over the multi-dimensional domain associated with the fundamental period of the cosine series. Another property of the simulated stochastic field is that it is asymptotically Gaussian as the number of terms in the cosine series approaches infinity. The most important feature of the method is that the cosine series formula can be numerically computed very efficiently using the Fast Fourier Transform technique. The main area of application of this method is the Monte Carlo solution of stochastic problems in structural engineering, engineering mechanics and physics. Specifically, the method has been applied to problems involving random loading (random vibration theory) and random material and geometric properties (response variability due to system stochasticity).
Fluid Loaded Structures With One Dimensional Disorder
Authors: Photiadis Douglas M.
Published: April 2009

This paper reviews the problem of the vibration of fluid loaded structures with one dimensional disorder. There are two aspects which are important in understanding the behavior of such systems: the nature of the fluid loading and the effects arising from irregularity. These two areas of investigation have been pursued simultaneously by the structural acoustics and condensed matter physics communities, and only recently have attempts been made to use the results from both fields. The key results from these areas which have been employed in the analysis of disordered fluid loaded structures are reviewed, and the recent research results in this area are described.
Bearing Capacity of Floating Ice Covers Subjected to Static, Moving, and Oscillatory Loads
Authors: Kerr Arnold D.
Published: April 2009

This review article presents a survey of analyses and tests of bearing capacity of floating ice covers when subjected to (1) Static loads of short duration, (2) Static loads of long duration, (3) Moving loads, and oscillatory loads that cause ice fatigue. Shortcomings of the available analyses and conducted tests are pointed out. This article, which contains 163 references, concludes with suggestions for future research.
Recent Developments in Modeling of Liquid Phase Electroepitaxy: A Continuum Approach
Authors: Dost Sadik
Published: April 2009

Liquid phase electroepitaxy (LPEE) is a low temperature, solution growth technique which has been proven to be successful in growing high quality, thick compound and alloy semiconducting single crystal layers. The availability of such high quality alloy layers would open new horizons in the production of optoelectronic and high-speed devices. Due to the technological importance of this crystal growth technique, some theoretical models for its growth process have been developed recently to provide needed information to experimentalists to develop growth configurations for reproducible desired single crystals. These models have shed light on various aspects of the LPEE growth process. This review article, with 71 references, provides the reader with an overview of recently developed macroscopic continuum models for the LPEE growth process of binary and ternary semiconductors. Fundamental equations of these models are obtained from the basic principles of electrodynamics and thermomechanics of the continuum. The models include various thermoelectric effects observed in LPEE and also incorporates microscopic surface phenomena such as surface kinetics. Results of numerical simulations are presented, and compared with available experimental data. The significance of research results are discussed.
Contact Mechanics of Rough Surfaces in Tribology: Single Asperity Contact
Authors: Bhushan Bharat
Published: April 2009

Contact modeling of two rough surfaces under normal approach and with relative motion is carried out to predict the real area of contact which affects friction and wear of an interface. The contact of two macroscopically flat bodies with microroughness is reduced to the contact at multiple asperities of arbitrary shapes. Most of deformation at the asperity contact can be either elastic or elastic-plastic. In this paper, a comprehensive review of modeling of a single asperity contact or an indentation problem is presented. Contact analyses for a spherical asperity/indenter on homogeneous and layered, elastic and elastic-plastic solids with and without tangential loading are presented. The analyses reviewed in this paper fall into two groups: (a) analytical solutions, primarily for elastic solids and (b) finite element solutions, primarily for elastic-plastic problems and layered solids. Implications of these analyses in friction and wear are discussed.
Turbulence in the Ocean, Atmosphere, Galaxy, and Universe
Authors: Gibson Carl H.
Published: April 2009

Flows in natural bodies of fluid often become turbulent, with eddy-like motions dominated by inertial-vortex forces. Buoyancy, Coriolis, viscous, self-gravitational, electromagnetic, and other force constraints produce a complex phase space of wave-like hydrodynamic states that interact with turbulence eddies, masquerade as turbulence, and preserve information about previous hydrodynamic states as fossil turbulence. Evidence from the ocean, atmosphere, galaxy and universe are compared with universal similarity hypotheses of Kolmogorov (1941, 1962) for turbulence velocity u, and extensions to scalar fields θ like temperature mixed by turbulence. Universal u and θ spectra of natural flows can be inferred from laboratory and computer simulations with satisfactory accuracy, but higher order spectra and the intermittency constant u of the third Kolmogorov hypothesis (1962) require measurements at the much larger Reynolds numbers found only in nature. Information about previous hydrodynamic states is preserved by Schwarz viscous and turbulence lengths and masses of self-gravitating condensates (rarely by the classical Jeans length and mass), as it is by Ozmidov, Hopfinger and Fernando scales in hydrophysical fields of the ocean and atmosphere. Viscous-gravitational formation occurred 104-105 y after the Big Bang for supercluster, cluster, and then galaxy masses of the plasma, producing the first turbulence. Condensation after plasma neutralization of the H-4He gas was to a primordial fog of sub-solar particles that persists today in galactic halos as dark matter. These gradually formed all stars, star clusters, etc (humans!) within.
Natural Mode Method: A Practicable and Novel Approach to the Global Analysis of Laminated Composite Plates and Shells
Authors: Argyris John , Tenek Lazarus
Published: April 2009

An overview of the natural mode method is presented, as applied in the linear and geometrically nonlinear analysis of multilayered composite plates and shells of arbitrary geometry. The method is particularly suitable for the finite element analysis of thin and moderately thick composite shell structures using simple 3-node triangular plate and shallow shell elements which are based on the definition of total strain, as well as physical decomposition principles, and involve only exact integrations. The triangular elements comprise 12 degrees of freedom on the natural coordinate. Numerical examples have shown that they address a well-balanced trade-off between accuracy and economy; as such they are intended for the analysis of large and complex composite shell structures and for use in interdisciplinary topics such as efficient sensitivity analysis and design optimization where complexity and economy must be considered in the computations. A brief history of the evolution of the natural mode technique is also given. Areas of application include static, vibration, buckling, postbuckling, and nonlinear dynamic and chaotic response topics under both load and temperature. This review article includes 36 references.
Optimal Structural Design Under Creep Conditions
Authors: Z˙yczkowski Michał
Published: April 2009

Optimal design of structures, or rather just of simple structural elements working under creep conditions, belongs to the most recent branches of structural optimization. It was initiated by four papers published in the years 1967-1968 (Reitman, Prager, Nemirovsky, and Z˙yczkowski). The most important differences with respect to elastic design are as follows: factor of time appearing in the constraints, a great variety of constitutive equations of creep or viscoplasticity, creep rupture hypotheses, creep buckling theories, various definitions of creep stiffness, etc. Moreover, the constraints related to stress-relaxation are quite new. So, it is almost impossible to establish a sufficiently general theory, and various types of problems must be treated separately by appropriate methods. On the other hand, the problems of optimization under creep conditions are important in view of metal structures working at elevated temperatures, structures made of plastics, concrete, etc. This review article gives a classification of problems and then a review of results obtained for bars, columns, arches, trusses, frames, plates, and shells. Over thirty percent of these results were obtained at the Cracow University of Technology. This is an extended and updated version of an earlier review article published in AMR41(12), December, 1988, discusses specific features of the branch of optimal structural design under consideration, as well as perspectives for future research. This review article contains 187 references.
Recent Studies on the Dynamic Plastic Behavior of Structures - An Update
Authors: Jones Norman
Published: April 2009

This article contains a brief review of the literature, published since the previous Applied Mechanics Reviews article in 1989 [1], on the dynamic plastic response of basic structural members made from ductile metallic type materials. The external dynamic loads cause large inelastic strains in the structural members which dominate material elastic effects. Thus, the external dynamic energy is absorbed plastically and, generally speaking, produces large permanent deformations. This field of research is of interest for the structural crashworthiness and collision protection of land, sea and air transportation systems, as well as the design of energy absorbing systems, and provides vital input into safety calculations and hazard assessments throughout industry.
Inclusion Problems
Authors: Mura T. , Shodja H. M. , Hirose Y.
Published: April 2009

The present review on inclusion problems emphasizes papers primarily published after 1982. Materials associated with inclusions are composite materials, precipitated or transformed alloys, porous media, and polycrystals. The inclusion problems deal with the following subjects of these materials: (1) stress fields caused by non-elastic strains (eigenstrains) and; (2) stress disturbances due to heterogeneity and inhomogeneities of materials under applied stresses; (3) average elastic moduli and average thermal properties; (4) nonelastic constitutive equations; (5) behavior of inclusions including nucleation, growth, and collapse of voids; (6) cracks and inclusions including the transformation toughening, crack growth through composites and stress intensity factors; (7) sliding and debonding inclusions; and (8) dynamic effects of inclusions. The present review is an update to the review paper, which appeared in Applied Mechanics Reviews, Volume 41 (1988), and includes opinions of some of the experts who made significant contributions to the field of inclusion problems. It is our hope that we cited all the important papers relevant to the subject of inclusion problems. The first author would welcome anyone’s comments and any references which were not included in this review.
Recent Approaches in Constitutive Behavior and Testing of Structural Adhesives
Authors: Sancaktar Erol
Published: April 2009

Adhesively bonded joints are complex composite structures with at least one of the constituents, namely the adhesive, most often, being a composite material itself due to the presence of secondary phases such as fillers, carriers, etc. The joint structure possesses a complex state of stress with high stress concentrations, and often, singularities due to the terminating adhesive layer where the substrates may possess sharp corners. With these issues in mind, this article discusses the following: Typical joint stress distributions; Stress concentrations and the effect of joint scarf angle on stress concentrations; Singularity methods; Reductions in stress concentrations due to viscoelastic adhesive behavior, as well as increases in joint strength due to rate dependent viscoelastic adhesive behavior; Geometrical methods to reduce stress concentrations; Bulk adhesive as composite material; The concept of the interphase; Damage models; The effects of cure and processing conditions on the mechanical behavior.
Dusty Shock Waves - An Update
Authors: Ben-Dor G.
Published: April 2009

A review of our original article [1] is given. It describes the state-of-the art of the subject of the propagation and attenuation of planar shock waves in dust-gas suspensions. In addition, it includes a brief description of the Dust Entrainment Phenomenon. This relatively new subject in the general area of Dusty Shock Wave has been getting more and more attention in the past few years.
Progress in Gas-Side Fouling of Heat-Transfer Surfaces: 1989-1995
Authors: Marner W. J.
Published: April 2009

Gas-side fouling is the deposition of an insulating layer of material onto a heat-transfer surface in the presence of a dirty gas stream. This review updates an extensive overview of gas-side fouling presented about six years ago in Applied Mechanics Reviews, Marner (1990). Four major topics are covered in this review: (a) various aspects of gas-side fouling, (b) gas-side fouling mechanisms of which the most important is transport to the surface, (c) experimental studies including gas-side fouling measuring devices, and (d) analytical studies including deposition, heat transfer, and pressure drop models. Gas-side fouling is an extremely complex, multifaceted phenomenon and substantial work continues in an attempt to better understand the processes involved.
Thermal Management of Electronic Equipment: Research Needs in the Mid-1990s and Beyond
Authors: Nakayama Wataru
Published: April 2009

As electronic devices and equipment are finding their ways into diverse applications, their physical integrity becomes a matter of utmost concern. The thermal design criteria customarily assumed in many of previous heat transfer research programs have to be replaced by those on the thermomechanical load in compact systems. Attempts to find thermal and stress fields in critical parts of components, however, are beset by geometrical complexities and multiple length and time scales involved in transport processes in electronic equipment. Modeling of complex systems is the subject left for further rationalization. Also needed is the foresight about possible hardware morphologies taken by electronic equipment in the future. In view of possible saturation of 2D packaging technology, heat transfer studies for 3D packaging are worth being undertaken. Common to different scenarios of hardware development is the need to critically review the methodology and focuses of fundamental heat transfer research.
Biomimetics: Advancing Man-Made Materials Through Guidance From Nature - An Update
Authors: Srinivasan A. V. , Haritos G. K. , Hedberg F. L. , Jones W. F.
Published: April 2009

An update is provided on progress resulting from research programs supported by the Air Force Office of Scientific Research (AFOSR) in biomimetics. The goal of these programs remains constant: to obtain significant improvements in aerospace materials and systems through the understanding and description of the evolutionarily-optimized structure and function of biological systems. The programs fall into three general categories: Biomimetic Materials Design, Biomimetic Processing, and Biomimetic Precision Sensing. Biomimetic material design efforts have focused on new concepts for the design of advanced composites with optimized mechanical properties to weight ratios, by studying the constituent properties, percentage, distribution, morphology, and contribution in biological materials. Types of biological materials under AFOSR-funded study include compact bone, tendon, and mollusk shells. Biomimetic processing programs have addressed biopolymer-mediated growth mechanisms of inorganic crystals with potential for highly selective control of electro-optical and electromagnetic properties, and also explored porous proteins as templates for nanolithography. Biomimetic precision sensing programs have addressed receptor composition and transduction mechanisms for auditory sensing in cochlea, and are most recently investigating receptor composition and transduction mechanisms for infrared sensing in snakes. Future considerations for research programs include better understanding of mechanisms involved in growth of biological materials in order to understand, describe, and more effectively mimic the complexities of their composition.
Multibody Dynamics Since 1990
Authors: Huston R. L.
Published: April 2009

This is a review of multibody dynamics research reported in the technical literature since 1990. It is an update of an earlier review appearing in 1991. In the five to six years since the writing of that first review, it is found that the literature has greatly expanded, attesting to a major increase in research efforts, with the greatest increase occurring in flexible and constrained multibody dynamics. In this review, the state-of-the-art of the research is briefly outlined and a discussion about unresolved issues and research opportunities is presented.
Nonlinear Dynamic Response of Membranes: State of the Art - Update
Authors: Jenkins Christopher H.
Published: April 2009

This paper is an update of an earlier review on the mechanics of membrane structures. It provides more than 120 new references and includes topics not discussed earlier, such as under-constrained pneumatic envelopes. Thoughts on future research directions are given.
Nonlinear Vibrations of Plates: An Update of Recent Research Developments
Authors: Sathyamoorthy M.
Published: April 2009

This paper comprises a survey on the nonlinear vibration analysis of plates, with emphasis on research carried out since 1987. Most of the research reviewed here deals with the effects of geometric nonlinearity on the vibration behavior of plates. Complicating factors such as material nonlinearity, geometric imperfections, transverse shear and rotatory inertia effects, and magnetic fields on the vibration behavior are included. Recent developments in the analytical and numerical methods of solution of isotropic, orthotropic as well as laminated, composite plates are presented. Experimental, analytical, and numerical investigations are included for all the cases reviewed and some general remarks are presented along with suggestions for future research directions.
Update to: Approaches to the Automatic Generation and Control of Finite Element Meshes
Authors: Shephard Mark S.
Published: April 2009

This paper updates the status of efforts on the development of automatic mesh generation techniques for general three-dimensional domains. The technical areas reviewed include: (i) issues associated with automatic mesh generation of CAD geometric models, (ii) local mesh modification procedures for improving mesh quality, (iii) advances in tetrahedral mesh generators, (iv) generation of anisotropic meshes, (v) hexahedral mesh generators, and (vi) implementation of automatic mesh generators on parallel computers.
Recent Developments and Applications of the Stochastic Averaging Method in Random Vibration
Authors: Zhu W. Q.
Published: April 2009

Comprehensive surveys on the stochastic averaging method in random vibration until the late 1980s were given by Roberts and Spanos (1986) and Zhu (1988). The present paper reviews the recent developments and applications of the stochastic averaging method in random vibration since then. A major new development of the stochastic averaging method in recent years is the generalization of the method to multi-degree-of-freedom, quasi-Hamiltonian systems.
Micromechanical Analysis of Composites by the Method of Cells - Update
Authors: Aboudi Jacob
Published: April 2009

The micromechanical method of cells and the generalized method of cells are briefly summarized. Recent applications of these methods by various investigators are reviewed.
Wall/Vortex-Ring Interactions
Authors: Verzicco R. , Orlandi P.
Published: April 2009

This review article presents a state-of-the-art review of the ring and wall interactions in the case of normal and oblique collisions. The different approaches used to study this flow and the results obtained are described and discussed. These techniques span from flow visualizations to LDV measurements, direct numerical simulations, particle-in-cell vortex methods and viscous and inviscid interactions. The relevance of these basic flows to the comprehension of wall-turbulence is also described. Finally, further developments, such as interaction with a grooved surface and with a deformable wall, and in Non-Newtonian fluids, are suggested.
Molecular Characteristics of Extended-Spectrum-β-Lactamase-Producing
Escherichia coli
Isolates Causing Bacteremia in the Calgary Health Region from 2000 to 2007: Emergence of Clone ST131 as a Cause of Community-Acquired Infections
Authors: Pitout Johann D. D. , Gregson Daniel B. , Campbell Lorraine , Laupland Kevin B.
Published: April 2009

A study was designed to characterize extended-spectrum-β-lactamase (ESBL)-producing
Escherichia coli
isolates causing bacteremia over an 8-year period (2000 to 2007) in a large well-defined geographical region. Molecular characterization was done by using isoelectric focusing; PCR; and sequencing of the
bla
CTX-M
-,
bla
TEM
-,
bla
OXA
-,
bla
SHV
-, and plasmid-mediated quinolone resistance determinants. Genetic relatedness was determined by pulsed-field electrophoresis with XbaI and multilocus sequence typing. A total of 67 patients with incident bloodstream infections were identified, and the majority presented with community-acquired infections involving the urinary and biliary tracts. Of the 67 ESBL-producing
E. coli
isolates recovered, 60 (90%) were positive for
bla
CTX-M
genes; 32 (48%) produced CTX-M-15, 25 (37%) produced CTX-M-14, 1 (2%) produced CTX-M-24, 1 (2%) produced CTX-M-2, and 1 (2%) produced CTX-M-3, while 2 (3%) produced TEM-52 and 5 (7%) produced SHV-2. Twenty-four (36%) isolates were positive for
aac(6′)-Ib-cr.
The majority of isolates were resistant to ciprofloxacin (60 [90%] isolates) and gentamicin (40 [60%] isolates). The occurrence of ESBL-producing isolates was stable during the first 5 years, but there was a substantial increase from 2005 to 2007, mostly due to clone ST131, which produces CTX-M-15 and CTX-M-14, in blood cultures submitted from the community. Our results illustrated that
E. coli
clone ST131, which coproduces CTX-M-15, OXA-1, TEM-1, and
aac(6′)-Ib-cr
, has emerged as an important cause of community-onset bacteremia caused by ESBL-producing
E. coli
isolates; and this is the first study to identify CTX-M-14 in
E. coli
clone ST131.
Hypersusceptibility to Azole Antifungals in a Clinical Isolate of
Candida glabrata
with Reduced Aerobic Growth
Authors: Vandeputte Patrick , Tronchin Guy , Rocher Françoise , Renier Gilles , Bergès Thierry , Chabasse Dominique , Bouchara Jean-Philippe
Published: April 2009

Petite mutations have been described in
Saccharomyces cerevisiae
and pathogenic yeasts. However, previous studies of the phenotypic traits of these petite mutants reported that they express azole resistance. We describe a clinical isolate of
Candida glabrata
with a striking association between increased susceptibility to azoles and respiratory deficiency. This isolate was obtained from a urine sample together with a respiration-competent
C. glabrata
isolate which exhibited azole resistance. The respiratory status of the two isolates was confirmed by cultivation on glycerol-containing agar and oxygraphy. Flow cytometry revealed the normal incorporation of rhodamine 123, and mitochondrial sections with typical cristae were seen by transmission electron microscopy for both isolates. Together, these results suggested a nuclear origin for the reduced respiratory capacity of the hypersusceptible isolate. The sterol contents of these isolates were similar to the sterol content of a reference strain. Sequencing of the
ERG11
and
PDR1
genes revealed that the sequences were identical in the two isolates, demonstrating their close relatedness. In addition to silent mutations, they carried a nonsense mutation in
PDR1
that led to the truncation of transcription factor Pdr1p. They also overexpressed both
PDR1
and one of its targets,
CDR1
, providing a possible explanation for the azole resistance of the respiration-competent isolate. In conclusion, in addition to azole resistance, which is a common feature of
C. glabrata
mitochondrial petite mutants, the mutation of a nuclear gene affecting aerobic growth may lead to azole hypersusceptibility; however, the mechanisms underlying this phenotype remain to be determined.
Sitafloxacin Activity against
Helicobacter pylori
Isolates, Including Those with
gyrA
Mutations
Authors: Murakami Kazunari , Okimoto Tadayoshi , Kodama Masaaki , Tanahashi Jin , Fujioka Toshio , Ikeda Fumiaki , Muraoka Hiroe , Takigawa Motoko , Saika Takeshi , Hasegawa Miyuki , Kobayashi Intetsu
Published: April 2009

Sitafloxacin showed MICs of less than or equal to 0.5 μg/ml against 105 isolates of
Helicobacter pylori
, including 44 isolates with mutations in the
gyrA
gene. The highest MICs for garenoxacin and levofloxacin were 8 and 64 times, respectively, higher than the highest MICs observed for sitafloxacin.