Volume 23, Issue 1-2

An accurate determination of the two- and three-dimensional electro-elastic fields of periodically as well as arbitrarily distributed interacting quantum wires (QWRs) and interacting quantum dots (QDs) of arbitrary shapes within a piezoelectric matrix is of particular interest. Both the QWR/QD and the barrier may be made of materials with distinct general rectilinear anisotropy in elastic, piezoelectric, and dielectric constants. The lattice mismatch between the QWR/QD and the barrier is accounted by prescribing an initial misfit strain field within the QWR/QD. Previous analytical treatments have neglected the distinction between the electro-mechanical properties of the QWR/QD and those of the barrier. This simplifying assumption is circumvented in the present work by using a novel electro-mechanical equivalent inclusion method in Fourier space (FEMEIM). Moreover, the theory can readily treat cases where the QWRs/QDs are multiphase or functionally graded (FG). It was proven that for two-dimensional problems of either a periodic or an arbitrary distribution of FG QWRs in a transversely isotropic piezoelectric barrier, the elastic and electric fields are electrically and elastically impotent, respectively, and no electric field would be induced in the medium provided that the rotational symmetry and polarization axes coincide. Some numerical examples of more frequent shapes and different distributions of indium nitride QDs/QWRs within transversely isotropic aluminum nitride barrier are solved.

Carbon nanotubes (CNTs) were fabricated using low-pressure chemical vapor deposition and then embedded in epoxy polymer at several weight ratios, 0, 0.75, 1.5, and 3 wt%, for tensile testing and Young’s modulus determination using an Instron machine. The tensile strength and Young’s modulus of the epoxy resin were increased with the addition of CNTs to a certain extent, and then decreased with the increase in the weight fraction of CNTs. The best properties occurred at 1.5 wt% of CNTs. Scanning electron microscopy was used to reveal the dispersion status of CNTs in the nanocomposites.

The phenomenon of super-deep penetration of solid microparticles into solid targets under shock has not been interpreted convincingly until now. The concept of highly excited states, developed by V.E. Panin and others, has opened a new path for the interpretation of this phenomenon. According to this concept, under the condition of a highly excited state, the number of allowable structure states in crystals significantly exceeds the number of atoms, i.e., in crystals, new degrees of freedom arise. Highly excited crystals become, in essence, a superposition of several structures. Therefore, in highly excited states, the material of target may be looked at as a system of weakly interacting particles. The application of the theory of a system of weakly interacting particles in this article shows that when the velocity of penetrating particles exceeds the velocity of the thermal motion of particles of the target material, the friction coefficient is inversely proportional to the third power of the relative velocity of penetrating particles. In this way, the effect of losing friction in the penetration of solid particles into solid targets is interpreted.

The present paper deals with the reflection of waves incident at the surface of a transversely isotropic micropolar medium under the theory of thermoelasticity of GN types II and III. The wave equations are solved by imposing proper conditions on the components of displacement, stresses, and temperature distribution. It is found that there exist four different waves, viz. quasi-longitudinal displacement (qLD) wave, quasi-transverse displacement (qTD) wave, quasi-transverse microrotational (qTM) wave, and quasi-thermal (qT) wave. The amplitude ratios of these reflected waves are presented, when different waves are incident. Numerically simulated results have been depicted graphically for the different angles of incidence with respect to the frequency. Some special cases of interest also have been deduced from the present investigation.

Penalty functions, used in computational mechanics, can provide an interpretation of the effects of the spatial gradients in continuum mechanics. In particular, the use of mass penalties and the use of microinertia terms in gradient elasticity lead to the identical systems of equations. Thus, an alternative perspective on the long-range interactions due to gradient activity is provided. This is illustrated with a numerical example.

The use of an extension of gradient elasticity through the inclusion of spatial derivatives of fractional order to describe the power law type of non-locality is discussed. Two phenomenological possibilities are explored. The first is based on the Caputo fractional derivatives in one dimension. The second involves the Riesz fractional derivative in three dimensions. Explicit solutions of the corresponding fractional differential equations are obtained in both cases. In the first case, stress equilibrium in a Caputo elastic bar requires the existence of a nonzero internal body force to equilibrate it. In the second case, in a Riesz-type gradient elastic continuum under the action of a point load, the displacement may or may not be singular depending on the order of the fractional derivative assumed.