共查询到20条相似文献,搜索用时 31 毫秒
1.
Holm Altenbach Victor A. Eremeyev Leonid P. Lebedev Leonardo A. Rendón 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(3):217-227
Acceleration waves in nonlinear thermoelastic micropolar media are considered. We establish the kinematic and dynamic compatibility
relations for a singular surface of order 2 in the media. An analogy to the Fresnel–Hadamard–Duhem theorem and an expression
for the acoustic tensor are derived. The condition for acceleration wave’s propagation is formulated as an algebraic spectral
problem. It is shown that the condition coincides with the strong ellipticity of equilibrium equations. As an example, a quadratic
form for the specific free energy is considered and the solutions of the corresponding spectral problem are presented. 相似文献
2.
The general Hoyle–Youngdahl and Love solutions in the three-dimensional theory of inhomogeneous linear elastic materials are
proposed. Following a brief historical outline of various general solutions existing in the classical linear elasticity of
homogeneous isotropic media, key steps of the derivation of the Hoyle–Youngdahl and Love solutions are presented. The procedure
is then generalized to the case of inhomogeneous elastic materials with elastic constants depending on the z-coordinate. The significance of the solutions and their relevance to modeling of functionally graded materials is discussed
in brief 相似文献
3.
The modified nonlinear relations for the estimation of elastic constants of Al2O3–NiAl composite material are developed. The concept of microstructure and interconnectivity of phases at the interface is
used. Hashin–Shtrikman relations are described in their actual form and modified version of Hashin–Shtrikman relations for
bulk and shear moduli are discussed. These relations for elastic and mechanical properties are applied mainly for Al2O3–NiAl composite material. Theoretical predictions using modified relations are compared with Hashin–Shtrikman bounds and experimental
results of elastic properties for Al2O3–NiAl matrix-inclusion-based composite. It is found that the predicted values of elastic and mechanical properties using modified
relations are quite close to the experimental results. 相似文献
4.
Summary The compliance tensor related to orthotropic media is spectrally decomposed and its characteristic values are determined.
Further, its idempotent tensors are estimated, giving rise to energy orthogonal states of stress and strain, thus decomposing
the elastic potential in discrete elements. It is proven that the essential parameters, required for a complete characterisation
of the elastic properties of an orthotropic medium, are the six eigenvalues of the compliance tensor, together with a set
of three dimensionless parameters, the eigenangles θ, ϕ and ω. In addition, the intervals of variation of these eigenangles
with respect to different values of the elastic constants are presented. Furthermore, bounds on Poisson's ratios are obtained
by imposing the thermodynamical constraint on the eigenvalues to be strictly positive, as specified from the positive-definite
character of the elastic potential. Finally, the conditions are investigated under which a family of orthotropic media behaves
like a transversely isotropic or an isotropic one.
Received 5 January 1999; accepted for publication 22 June 1999 相似文献
5.
Peter Voinovich 《Shock Waves》2009,19(5):443-444
A wide spread error related to the compressibility of elastic media is reproduced in the paper by Włodarczyk and Zielenkiewicz
(Shock Waves 18:465–473, 2009) leading to erroneous results and conclusions. 相似文献
6.
F. A. Bakhyshov V. M. Mirsalimov 《Journal of Applied Mechanics and Technical Physics》2006,47(4):588-595
Based on the balanced strength principle, a problem of determining the optimal interference for fitting elastic inclusions
into holes of an isotropic elastic plate weakened by a doubly periodic system of circular holes is solved. A closed system
of algebraic equations is derived, which allows solving this problem. The resultant interference increases the load-carrying
capacity of the composite plate being bent.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 153–161, July–August, 2006. 相似文献
7.
The ray method is used to develop a procedure for studying the kinematics and dynamics of the interaction of discontinuous
waves with interfaces between elastic media. The critical states of such interactions are analyzed. For the cases of a free
surface and two surfaces contacting with and without sliding, it is established that the kinematic and dynamic conditions
for critical states to occur are satisfied simultaneously
Translated from Prikladnaya Mekhanika, Vol. 45, No. 2, pp. 79–90, February 2009. 相似文献
8.
M. Mond I. Rutkevich E. Zaretsky 《Archive of Applied Mechanics (Ingenieur Archiv)》2001,71(4-5):317-326
Summary The role of free electrons in the stability of strong shock waves in metals under spontaneous acoustic emission is investigated.
For that purpose, a three-term form of the equation of state is employed in order to describe the cold pressure, the thermal
atomic pressure and the thermal pressure of free electrons. The equation of state enables the calculation of the sound velocity
behind the shock, which in turn is utilized in the Dyakov–Kontorovich criteria for the shock stability. The integral over
the Fermi–Dirac distribution function that describes the specific internal energy of free electrons is replaced by a model
algebraic function that possesses correct asymptotic limits at low and high temperatures. It is shown that strong shock waves
in all metals are prone to instability under spontaneous emission. However, the threshold for that instability is shifted
to higher Mach numbers if free electrons are taken into account. It is further shown that the stabilizing effect of free electrons
is vastly overestimated if the expressions for degenerate electron gas are employed for temperatures that are larger than
the Fermi temperature.
Received 22 November 1999; accepted for publication 12 July 2000 相似文献
9.
S. V. Selivanova 《Journal of Applied Mechanics and Technical Physics》2008,49(5):809-822
An invariant (with respect to rotations) formalization of equations of linear and nonlinear elasticity theory is proposed.
An equation of state (in the form of a convex generating potential) for various crystallographic systems is written. An algebraic
approach is used, which does not require any geometric constructions related to the analysis of symmetry in crystals.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 5, pp. 127–142, September–October, 2008. 相似文献
10.
The literature regarding the free vibration analysis of Bernoulli–Euler and Timoshenko beams under various supporting conditions
is plenty, but the free vibration analysis of Reddy–Bickford beams with variable cross-section on elastic soil with/without
axial force effect using the Differential Transform Method (DTM) has not been investigated by any of the studies in open literature
so far. In this study, the free vibration analysis of axially loaded and semi-rigid connected Reddy–Bickford beam with variable
cross-section on elastic soil is carried out by using DTM. The model has six degrees of freedom at the two ends, one transverse
displacement and two rotations, and the end forces are a shear force and two end moments in this study. The governing differential
equations of motion of the rectangular beam in free vibration are derived using Hamilton’s principle and considering rotatory
inertia. Parameters for the relative stiffness, stiffness ratio and nondimensionalized multiplication factor for the axial
compressive force are incorporated into the equations of motion in order to investigate their effects on the natural frequencies.
At first, the terms are found directly from the analytical solutions of the differential equations that describe the deformations
of the cross-section according to the high-order theory. After the analytical solution, an efficient and easy mathematical
technique called DTM is used to solve the governing differential equations of the motion. The calculated natural frequencies
of semi-rigid connected Reddy–Bickford beam with variable cross-section on elastic soil using DTM are tabulated in several
tables and figures and are compared with the results of the analytical solution where a very good agreement is observed. 相似文献
11.
T. V. Gavrilyachenko M. I. Karyakin 《Journal of Applied Mechanics and Technical Physics》2000,41(2):377-381
The torsion problem of a cylinder with a circular transverse cross section twisted by end moments that are equal in magnitude
and opposite in direction is considered for various models of nonlinearly elastic compressible media. The problem is solved
by the semi-inverse method of elasticity theory. The Poynting effect, which consists of variation in the length of a shaft
in torsion, is treated qualitatively and quantitatively. The results of the numerical and asymptotic (only terms that are
quadratic relative to the displacement gradient are conserved) solutions for various models of the nonlinearly elastic behavior
of materials are compared. An analysis of the results shows that in some cases, the quasilinear model is not applicable for
studying the behavior of nonlinearly elastic compressible media.
Rostov State Construction University, Rostov-on-Don 344022. Rostov State University, Rostov-on-Don 344090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 2, pp. 188–193, March–April, 2000. 相似文献
12.
T. J. T. Spanos 《Transport in Porous Media》2009,79(1):135-148
It has been known since the time of Biot–Gassman theory (Biot, J Acoust Soc Am 28:168–178, 1956, Gassmann, Naturf Ges Zurich
96:1–24, 1951) that additional seismic waves are predicted by a multicomponent theory. It is shown in this article that if
the second or third phase is also an elastic medium then multiple p and s waves are predicted. Futhermore, since viscous dissipation
no longer appears as an attenuation mechanism and the media are perfectly elastic, these waves propagate without attenuation.
As well, these additional elastic waves contain information about the coupling of the elastic solids at the pore scale. Attempts
to model such a medium as a single elastic solid causes this additional information to be misinterpreted. In the limit as
the shear modulus of one of the solids tends to zero, it is shown that the equations of motion become identical to the equations
of motion for a fluid filled porous medium when the viscosity of the fluid becomes zero. In this limit, an additional dilatational
wave is predicted, which moves the fluid though the porous matrix much similar to a heart pumping blood through a body. This
allows for a connection with studies which have been done on fluid-filled porous media (Spanos, 2002). 相似文献
13.
B. D. Annin N. I. Ostrosablin 《Journal of Applied Mechanics and Technical Physics》2008,49(6):998-1014
Papers dealing with the generalized Hooke’s law for linearly elastic anisotropic media are reviewed. The papers considered
are based on Kelvin’s approach disclosing the structure of the generalized Hooke’s law, which is determined by six eigenmoduli
of elasticity and six orthogonal eigenstates.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 131–151, November–December, 2008. 相似文献
14.
I. Yu. Tsvelodub 《Journal of Applied Mechanics and Technical Physics》2009,50(4):698-700
Plane problems of determining the stress-strain state of an isotropic elastic domain with a rigid inclusion are considered.
It is shown that the stress field in the inclusion is uniquely determined. This field is uniform for a plane with an elliptic
inclusion, and the stresses at infinity and in the inclusion are related by mutually single-valued formulas.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 183–186, July–August, 2009. 相似文献
15.
J. J. Rushchitsky 《International Applied Mechanics》2007,43(12):1347-1352
It is shown that uniform compression/tension and simple shear as universal deformations are quite useful in studying Signorini’s
nonlinear theory of hyperelastic materials. They make it possible to formulate restrictions for the elastic constants of the
theory and to explain the Poynting effect
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Translated from Prikladnaya Mekhanika, Vol. 43, No. 12, pp. 54–60, December 2007. 相似文献
16.
Vladimir Kobelev 《Meccanica》2006,41(6):653-660
Failure of a composite is a complex process accompanied by irreversible changes in the microstructure of the material. Microscopic
mechanisms are known of the accumulation of damage and failure of the type of localized and multiple ruptures of the fibers
delamination along interphase boundaries, and also mechanisms associated with fracture of fibers. In this work, we propose
a mathematical model of the local mechanism of failure of a composite material randomly reinforced with a system of short
fibers. We implement the Cosserat moment model of crack tip for filament material, reinforced with whiskers or in fiber- reinforced
polycrystalline materials. It is assumed that the angular distribution of the fibers is isotropic and the elastic characteristics
of the fibers are considerably higher than the elastic constants of the matrix. We implement the homogenization procedure
for the effective Cosserat constants similarly to the effective elastic constants. The singular solution in the vicinity of
the crack tip in the Cosserat moment model is found. Using this solution, we examine the bending stresses in the filaments
due to effective moment stresses in the material. The constructed model describes the phenomenon of fracture of the fibers
occurring during crack propagation in those composites. The following assumptions are used as the main hypotheses for the
micromechanical model. The matrix contains a nucleation crack. When the load is increased the crack grows and its boundary
comes into contact with the reinforcing fibers. A further increase of the stress causes bending of the fiber. When~the fiber
curvature reaches a specific critical value, the fiber ruptures. If the stress at infinity is given, the fibers no longer
delay the development of failure during crack propagation The degree of bending distortion of the fiber in the vicinity of
the boundary of the crack is determined by the moment model of the material. The necessity to take into account the moment
stresses in the failure theory of the reinforced material was stressed in [Muki and Sternberg (1965) Zeitschrift f angew Math
und Phys 16:611–615; Garajeu and Soos (2003) Math Mech Solids 8(2):189–218; Ostoja-Starzewski et al (1999) Mech Res Commun
26:387–396]. The moment Cosserat stresses were accounted also for inhomogeneous biomechanical materials by Buechner and Lakes
(2003) Bio Mech Model Mechanobiol 1: 295–301. We should also mention the important methodological studies [Sternberg and Muki
(1967) J Solids Struct 1:69–95; Atkinson and Leppington (1977) Int J Solids Struct 13: 1103–1122] concerned with the moment
stresses in homogeneous fracture mechanics. 相似文献
17.
Summary In this paper, the eigen-equations governing antiplane stress singularities in a bonded piezoelectric wedge are derived analytically.
Boundary conditions are set as various combinations of traction-free, clamped, electrically open and electrically closed ones.
Application of the Mellin transform to the stress/electric displacement function or displacement/electric potential function
and particular boundary and continuity conditions yields identical eigen-equations. All of the analytical results are tabulated.
It is found that the singularity orders of a bonded bimaterial piezoelectric wedge may be complex, as opposed to those of
the antiplane elastic bonded wedge, which are always real. For a single piezoelectric wedge, the eigen-equations are independent
of material constants, and the eigenvalues are all real, except in the case of the combination C–D. In this special case,
C–D, the real part of the complex eigenvalues is not dependent on material constants, while the imaginary part is.
Received 26 March 2002; accepted for publication 2 July 2002 相似文献
18.
M. Abu-Hilal 《Archive of Applied Mechanics (Ingenieur Archiv)》2003,72(9):637-650
Summary The transverse vibrations of elastic homogeneous isotropic beams with general boundary conditions due to a moving random
force with constant mean value are analyzed. The boundary conditions considered are: pinned–pinned, fixed–fixed, pinned–fixed,
and fixed–free. Based on the Bernoulli beam theory, the problem is described by means of a partial differential equation.
Closed-form solutions for the variance and the coefficient of variation of the beam deflection are obtained and compared for
three types of force motion: accelerated, decelerated and uniform. The effects of beam damping and speed of the moving force
on the dynamic response of beams are studied in detail.
Received 3 December 2001; accepted for publication 30 April 2002 相似文献
19.
The natural vibrations of a corrugated elastic orthotropic cylindrical shell with a directrix perpendicular to its edges that
are free are examined
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 12, pp. 97–114, December, 2006. 相似文献
20.
We found the colorimetric reaction of Tiron (1,2-dihydroxybenzene-3,5-disulfonic acid) and molybdate suitable for optical quantification of chemical reaction during fluid–fluid mixing in laboratory chambers. This reaction consists of two colorless reagents that mix to rapidly form colored, stable, soluble products. These products can be digitally imaged and quantified using light absorbance to study fluid–fluid mixing. Here we provide a model and equilibrium constants for the relevant complexation reactions. We also provide methods for relating light absorbance to product concentrations. Practical implementation issues of this reaction are discussed and an example of imaged absorbances for fluid–fluid mixing in heterogeneous porous media is given. 相似文献