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Showing papers in "Applied Mechanics Reviews in 1998"


Journal ArticleDOI
TL;DR: In this paper, a review of contributions to the theory of thermoelasticity with thermal relaxation and the temperature-rate dependent thermodynamic properties is presented, and a glance is made at the new theory which includes the so-called dual-phase-lag effects.
Abstract: This review article is a continuation of a previous article by the author, Thermoelasticity with second sound: A review, which appeared in this journal in March, 1986 (Appl Mech Rev 39(3) 355-376). Here, attention is focused on papers published during the past 10-12 years. Contributions to the theory of thermoelasticity with thermal relaxation and the temperature-rate dependent thermoelasticity theory are reviewed. The recently developed theory of thermoelasticity without energy dissipation is described, and its characteristic features highlighted. A glance is made at the new thermoelasticity theory which includes the so-called dual-phase-lag effects. There are 338 references.

1,019 citations


Journal ArticleDOI
TL;DR: In this paper, a methodology for solving numerically, for engineering purposes, boundary and initial boundary value problems by a peculiar approach characterized by the following features: the continuous formulation is centered on integral equations based on the combined use of single-layer and double-layer sources, so that the integral operator turns out to be symmetric with respect to a suitable bilinear form.
Abstract: This review article concerns a methodology for solving numerically, for engineering purposes, boundary and initial-boundary value problems by a peculiar approach characterized by the following features: the continuous formulation is centered on integral equations based on the combined use of single-layer and double-layer sources, so that the integral operator turns out to be symmetric with respect to a suitable bilinear form. The discretization is performed either on a variational basis or by a Galerkin weighted residual procedure, the interpolation and weight functions being chosen so that the variables in the approximate formulation are generalized variables in Prager’s sense. As main consequences of the above provisions, symmetry is exhibited by matrices with a key role in the algebraized versions; some quadratic forms have a clear energy meaning; variational properties characterize the solutions and other results, invalid in traditional boundary element methods enrich the theory underlying the computational applications. The present survey outlines recent theoretical and computational developments of the title methodology with particular reference to linear elasticity, elastoplasticity, fracture mechanics, time-dependent problems, variational approaches, singular integrals, approximation issues, sensitivity analysis, coupling of boundary and finite elements, and computer implementations. Areas and aspects which at present require further research are identified, and comparative assessments are attempted with respect to traditional boundary integral-elements. This article includes 176 references.

292 citations


Journal ArticleDOI

244 citations


Journal ArticleDOI
TL;DR: A detailed overview of structural and mechanical systems with friction can be found in this paper, where the authors trace examples from the earliest prehistoric technologies and the formulation of dissipation laws in mechanics and conclude with examples of friction oscillators and stick-slip.
Abstract: This article gives a historical overview of structural and mechanical systems with friction. Friction forces between sliding surfaces arise due to complex mechanisms and lead to mathematical models which are highly nonlinear, discontinuous and nonsmooth. Humankind has a long history of magnificent usage of friction in machines, buildings and transportation. Regardless, our state of knowledge of the friction-influenced dynamics occurring in such systems as well as in our daily lives was, until recently, rather primitive. To represent our understanding of friction in nonlinear dynamics, we first trace examples from the earliest prehistoric technologies and the formulation of dissipation laws in mechanics. The work culminates with examples of friction oscillators and stick-slip. This review article contains 304 references.

229 citations



Journal ArticleDOI
TL;DR: This article is specifically focused on the application of piezoelectric materials, magnetostrictive materials and shape memory alloys to intelligent material systems used to control the deformation, vibration and fracture of composite materials and structures.
Abstract: This article presents a review of recent important developments in the field of intelligent material systems. Intelligent material systems, sometimes referred to as smart materials, can adjust their behavior to changes of external or internal parameters analogously to biological systems. In these systems, sensors, actuators and controllers are seamlessly integrated with structural materials at the macroscopic or mesoscopic level. In general, sensors and actuators are made of functional materials and fluids such as piezoelectric materials, magnetostrictive materials, shape memory alloys, polymer hydrogels, electro- and magneto-rheological fluids and so on. This article is specifically focused on the application of piezoelectric materials, magnetostrictive materials and shape memory alloys to intelligent material systems used to control the deformation, vibration and fracture of composite materials and structures. This review article contains 188 references.

186 citations



Journal ArticleDOI
TL;DR: In this paper, the authors present a review of the current level of understanding in this field, including the correlations between failure mode and energy absorption, the principal material, geometric, and physical parameters relevant to crashworthy design and methods of predicting the energy absorption capability of polymer composites.
Abstract: The controlled brittle failure of thermosetting fiber-reinforced polymer composites can provide a very efficient energy absorption mechanism. Consequently, the use of these materials in crashworthy vehicle designs has been the subject of considerable interest. In this respect, their more widespread application has been limited by the complexity of their collapse behavior. This article reviews the current level of understanding i this field, including the correlations between failure mode and energy absorption, the principal material, geometric, and physical parameters relevant to crashworthy design and methods of predicting the energy absorption capability of polymer composites. Areas which require further investigation are identified. This review article contains 70 references.

153 citations


Journal ArticleDOI
TL;DR: The evidence for superior performance of airlift bioreactors is overwhelming, and many hybridoma cultures and plant cell suspensions have given good results, and in wastewater treatment, airlift devices have far outperformed conventional systems.
Abstract: Major aspects of design and operation of pneumatically agitated bioreactors are reviewed. The focus is on considerations that are relevant to industrial practice. Airlift bioreactors are emphasized. The treatment covers hydraulics, hydrodynamics, gas-liquid and solid-liquid mass transfer, heat transfer, mixing, and suspension. Newtonian and non-Newtonian systems are discussed. Applications in microbial fermentations, animal and plant cell culture, biotransformations with immobilized enzymes, and treatment of wastewater are outlined. Comparisons with more conventional bioreactor technologies are made. Design features for sterile processing in airlift systems are detailed. The evidence for superior performance of airlift bioreactors is overwhelming. Excellent productivities have been demonstrated with yeasts, bacteria, and filamentous fungi. Processes that produce highly viscous broths, including several biopolymer producing fermentations, have been proven in airlift devices. Similarly, many hybridoma cultures and plant cell suspensions have given good results. As a general rule, volumetric productivity of airlift bioreactors equals or betters that of conventional stirred tanks. Typically, this level of performance is achieved at substantially lower power input than in stirred vessels. Furthermore, the probability of mechanical failure and likelihood of loss of sterility are lower with airlift bioreactors. In wastewater treatment, too, airlift devices have far outperformed conventional systems. Airlift bioreactors accept higher BOD loadings, produce less sludge, and the degradation rate is faster; performance improves with increasing scale of operation. This review article includes 328 references.

147 citations








Journal ArticleDOI
Abstract: The fundamental aspects of isotropic turbulence are reviewed in reviewed in order to gain a betterinsight into the physical processes of turbulence. After first reviewing the Kolmogorov energyspectrum and the energy cascade, the Kolmogorov hypothesis of local isotropy is discussed in depth.Then, the detailed physical processes involving energy transfer and interacting scales in isotropicturbulence, including triad interactions, are reviewed. The inertial range and self-similarity are alsodiscussed along with tile response of the small scales to large-scale anisotropy and the final stagesof the decay process. Results from direct and large-eddy simulations of isotropic turbulenceincluding a discussion of subgrig scale modeling--are then discussed in detail to illustrate these points. The article closes with a review of self-preservation in isotropic turbulence and a discussion of the prospects for future research. It contains 155 references.

Journal ArticleDOI
TL;DR: In this paper, a review of nonlocal theories in solid mechanics from the viewpoint of wave motion is given, where the influence of two essential qualities of solids, nonlocality and nonlinearity, is discussed.
Abstract: This review article gives a brief overview on nonlocal theories in solid mechanics from the viewpoint of wave motion. The influence of two essential qualities of solids—nonlocality and nonlinearity—is discussed. The effects of microstructure are analyzed in order to understand their role in nonlocal theories. The various models are specified on the level of one-dimensional unidirectional motion in order to achieve mathematical clarity of interpreting physical phenomena. Three main types of evolution equations are shown to govern deformation waves under such assumptions. Based on the dispersion analysis, weak, true, and strong nonlocalities are distinguished. There are 75 references included with this article.



Journal ArticleDOI
TL;DR: Eigensolution techniques for linear undamped eigenproblems of the form AΦ = CΦΛ, where A and C are frequently symmetric and positive definite are discussed.
Abstract: This article reviews the solution procedures used to extract eigenvalues and eigenvectors from linear dynamic systems using the finite element method. The main focus of this review article is on eigensolution techniques that provide only a partial eigensolution. Such eigensolvers extract only a small subset (normally the lowest) of the eigenvalues and eigenvectors present in the discretized system. They represent the most efficient approach to extracting eigenvalues and eigenvectors from large degree of freedom systems. The techniques covered include the subspace iteration method, the Lanczos method, the conjugate gradient method, the Ritz vector method, the substructure synthesis methods (including component mode synthesis), and the condensation techniques (including dynamic substructuring). Each subsection contains a variety of references that cover the current state of research as well as the origin of each technique. A brief critique of the eigensolution procedures used for solving small (less than 250 degree of freedom) eigenproblems is also included for completeness. The discussion is generally limited to eigensolution techniques for linear undamped eigenproblems of the form AΦ = CΦΛ, where A and C are frequently symmetric and positive definite. A brief review of eigensolvers for the nonsymmetric eigenproblem, such as that arising in damped structures, is included at the end. This review article contains 320 references.




Journal ArticleDOI
TL;DR: In this article, a multifractal formalism is employed to describe intermittency, and the results of the multifractal approach are compared with predictions of other models of intermittent and non-intermittent turbulence.
Abstract: Many phenomena depend on the features of the fine-scale structure of turbulence, including its intermittency. This article discusses the problem of the turbulent “shear” in biotechnology including the effect of the shear stress on particles (cells, flocs, cells immobilized on microcarriers). Traditionally, the effect of intermittency has not been taken into account in the shear problem and the theory of isotropic turbulence introduced by Kolmogorov (1941) based on average values of the rate of kinetic energy dissipation, velocity fluctuactions, rates of strain, turbulent stresses etc. has been applied. In this paper a multifractal formalism is employed to describe intermittency; the results of multifractal approach are then compared with predictions of other models of intermittent and non-intermittent turbulence. The multifractal model of intermittent turbulence has been used to derive equations describing flow-particle interactions, including: equations describing turbulent stresses acting upon particles in the inertial and viscous subranges of turbulence; mass transfer to small particles suspended in turbulent fluid; turbulent rupture of flocs; particles encounters in turbulent flow including the average number of collisions per unit time in the inertial and viscous subranges of turbulence and the severity of collisions; mechanical stress generated by bubble coalescence. Generally, the article shows how the traditional approach to the shear problem in turbulence, based on the Kolmogorov theory, can be extended by including the influence of intermittency. This review article includes 47 references.


Journal ArticleDOI
TL;DR: In this paper, the authors trace the development of applied mechanics and its relation to science and engineering by reviewing first the history of mechanics from 1600 to 1900, the physics of the 19th century, and the engineering education in the same period.
Abstract: This article traces the development of applied mechanics and its relation to science and engineering by reviewing first the history of mechanics from 1600 to 1900, the physics of the 19th century, and the engineering education in the same period. The review is followed by a discussion on modern physics and modern engineering, and the formation of applied mechanics as a discipline in science and one in engineering, which is classified into 94 subjects in 10 categories by Applied Mechanics Reviews. The article concludes with a chart to summarize the relation between science and engineering, and the interactions of applied mechanics with other disciplines. There are 15 references included in this article.Originally published in Applied Mechanics Reviews, Vol. 51, No. 2, February 1998



Journal ArticleDOI
TL;DR: In this paper, the authors present a state-of-the-art review concerning the mechanics of reinforced soil and reinforced soil structures, including rigidplastic, elasto-plastic and rheological.
Abstract: Reinforced soil (RS) is a composite material built of a soil matrix reinforced with other materials such as metal strips, geosynthetics etc. RS has been increasingly used in civil engineering, either as a cheaper alternative to classical geotechnical structures, or as an independent technical solution. The aim of this article is to present a state-of-the-art review concerning the mechanics of RS and mechanics of RS structures. Research on both subjects was initiated by pioneering works of H Vidal in the 1960s. First, a brief introduction is presented followed by a review of mechanical models of RS, including rigid-plastic, elasto-plastic, and rheological. Then, the methods of analysis of RS structures are discussed. These methods include the limit states approach, determination of stresses, creep etc. Some research needs are also outlined. The article is presented in the form of a tutorial review which also includes a state-of-the-art review and a basic bibliographical survey. There are 200 references.