@article{SnarskiiShamoninChamonineYuskevichetal., author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Yuskevich, Pavel and Savelev, Dmitrii V. and Belyaeva, Inna A.}, title = {Induced anisotropy in composite materials with reconfigurable microstructure: Effective medium model with movable percolation threshold}, series = {Physica A: Statistical Mechanics and its Applications}, volume = {560}, journal = {Physica A: Statistical Mechanics and its Applications}, number = {December}, publisher = {Elsevier}, doi = {10.1016/j.physa.2020.125170}, abstract = {In composite materials, with field-dependent restructuring of the filler material (changes in the mutual arrangement of inclusions), the presence of an external magnetic field induces anisotropy of the dielectric properties, even if the composite is isotropic in the absence of an external field. A modified effective medium approximation is proposed for the calculation of the components of effective permittivity within a class of composites with reconfigurable microstructure, where both phases (the filler and the matrix) are isotropic and the inclusions have spherical shape. The effective physical properties are calculated in the parallel and perpendicular directions to an applied field. The appearance of the anisotropy of the permittivity is simulated by the introduction of two not-equal, possibly variable (field-dependent) percolation thresholds. The implications, of the proposed theoretical approach, are demonstrated for the case of the dielectric properties of magnetoactive elastomers (MAEs). In MAEs with soft polymer matrices, the mutual arrangement of micrometer-sized magnetic inclusions can significantly change in an applied magnetic field. A reasonable agreement between theory and experiment at a measurement frequency of 1 kHz is found, and is improved in comparison to the previous models. The components of the effective permittivity tensor, characterizing the dielectric properties along the direction of the applied magnetic field and in the orthogonal direction, grow with an increasing field. This growth is more pronounced for the permittivity component in the field direction. The possible extensions of the theoretical model and future directions of research are discussed. The presented theoretical approach can be useful for the application-driven development of a number of smart materials, in particular electro- and magnetorheological gels, elastomers and fluids.}, language = {en} } @article{SnarskiiKalitaShamoninChamonine, author = {Snarskii, Andrei A. and Kalita, Viktor M. and Shamonin (Chamonine), Mikhail}, title = {Renormalization of the critical exponent for the shear modulus of magnetoactive elastomers}, series = {Scientific Reports}, volume = {8}, journal = {Scientific Reports}, publisher = {Nature}, doi = {10.1038/s41598-018-22333-6}, pages = {1 -- 8}, abstract = {It is shown that the critical exponent for the effective shear modulus of a composite medium where a compliant polymer matrix is filled with ferromagnetic particles may significantly depend on the external magnetic field. The physical consequence of this dependence is the critical behavior of the relative magnetorheological effect.}, language = {en} } @article{SnarskiiZhenirovskyyShamoninChamonine, author = {Snarskii, Andrei A. and Zhenirovskyy, M. I. and Shamonin (Chamonine), Mikhail}, title = {The effective properties of macroscopically nonuniform ferromagnetic composites: Theory and numerical experiment}, series = {Journal of Experimental and Theoretical Physics}, volume = {96}, journal = {Journal of Experimental and Theoretical Physics}, publisher = {Springer}, doi = {10.1134/1.1545385}, pages = {66 -- 77}, abstract = {Various theoretical models (self-consistent field, local linearization, and percolation theory methods and an analytic solution of the linear problem for an ordered medium) for calculating the magnetostatic properties of two-phase composites containing one ferromagnetic phase were considered. The concentration and field dependences of the effective magnetic permeability were found. A method for determining the coercive force and remanent magnetization as functions of the ferromagnetic phase concentration was suggested. Numerical experiments were performed for composites with a periodic distribution of circular inclusions. The results were compared with the analytically calculated effective magnetic permeability.}, language = {en} } @article{SnarskiiShamoninChamonineZhenirovskyyetal., author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Zhenirovskyy, M. I. and Trautner, Ralph}, title = {Effect of disorder on the conductivity of two-phase strongly inhomogeneous highly filled composites}, series = {Theoretical and Mathematical Physics}, volume = {50}, journal = {Theoretical and Mathematical Physics}, publisher = {Springer}, doi = {10.1134/1.1854818}, pages = {11 -- 18}, abstract = {The effect of the "stir" of a structure (small deviations from strict periodicity) on effective conductivity is considered. For determinate and random deviations, concentration and field dependences of the effective conductivity are found. Numerical experiments with determinate deviations are carried out for the cases of linear (with respect to the field) inclusions embedded in both a linear and nonlinear matrix. The numerical results are compared with the effective conductivity calculated analytically.}, language = {en} } @article{SnarskiiShamoninChamonineYuskevich, author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Yuskevich, Pavel}, title = {Effect of magnetic-field-induced restructuring on the elastic properties of magnetoactive elastomers}, series = {Journal of Magnetism and Magnetic Materials}, journal = {Journal of Magnetism and Magnetic Materials}, number = {517, January}, publisher = {Elsevier}, doi = {10.1016/j.jmmm.2020.167392}, abstract = {Composite materials where magnetic micrometer-sized particles are embedded into a compliant polymer matrix are known as magnetorheological (or magnetoactive) elastomers (MAEs). They are distinguished by huge variations in their physical properties, when in a magnetic field, which is commonly attributed to the restructuring of the filler. The process of the magnetic-field-induced restructuring in a magnetorheological elastomer is interpreted as progression towards percolation. Such a physical model was previously used to explain the dependence of the magnetic permeability and dielectric permittivity of MAEs on the magnetic field strength. Based on this hypothesis, the magnetorheological effect in MAEs is considered theoretically. The theoretical approach is built upon a self-consistent effective-medium theory for the elastic properties, extended to the variable (field dependent) percolation threshold. The proposed model allows one to describe the large variations (over several orders of magnitude) of the effective elastic moduli of these composite materials, known as the giant magnetorheological (MR) and field-stiffening effects. The existence of a giant magnetic Poisson effect is predicted. The relation of the proposed model to the existing theories of the MR effect in MAEs is discussed. The results can be useful for applications of MAEs in magnetic-field-controlled vibration dampers and isolators.}, language = {en} } @article{SnarskiiShamoninChamonineYuskevich, author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Yuskevich, Pavel}, title = {Effective medium theory for the elastic properties of composite materials with various percolation thresholds}, series = {Materials}, volume = {13}, journal = {Materials}, number = {5}, publisher = {MPDI}, address = {Basel}, doi = {10.3390/ma13051243}, pages = {1 -- 19}, abstract = {It is discussed that the classical effective medium theory for the elastic properties of random heterogeneous materials is not congruous with the effective medium theory for the electrical conductivity. In particular, when describing the elastic and electro-conductive properties of a strongly inhomogeneous two-phase composite material, the steep rise of effective parameters occurs at different concentrations. To achieve the logical concordance between the cross-property relations, a modification of the effective medium theory of the elastic properties is introduced. It is shown that the qualitative conclusions of the theory do not change, while a possibility of describing a broader class of composite materials with various percolation thresholds arises. It is determined under what conditions there is an elasticity theory analogue of the Dykhne formula for the effective conductivity. The theoretical results are supported by known experiments and show improvement over the existing approach. The introduction of the theory with the variable percolation threshold paves the way for describing the magnetorheological properties of magnetoactive elastomers. A similar approach has been recently used for the description of magneto-dielectric and magnetic properties.}, language = {en} } @article{KalitaSnarskiiShamoninChamonineetal., author = {Kalita, Viktor M. and Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Zorinets, Denis}, title = {Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers}, series = {Physical review E}, volume = {95}, journal = {Physical review E}, number = {3}, publisher = {American Physical Society}, doi = {10.1103/PhysRevE.95.032503}, abstract = {The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016)]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Pade approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles.}, language = {en} } @article{BodnarukKalitaKulyketal., author = {Bodnaruk, Andrii V. and Kalita, Viktor M. and Kulyk, Mykola M. and Lozenko, Albert F. and Ryabchenko, Sergey M. and Snarskii, Andrei A. and Brunhuber, Alexander and Shamonin (Chamonine), Mikhail}, title = {Temperature blocking and magnetization of magnetoactive elastomers}, series = {Journal of Magnetism and Magnetic Materials}, volume = {471}, journal = {Journal of Magnetism and Magnetic Materials}, number = {February}, publisher = {Elsevier}, doi = {10.1016/j.jmmm.2018.10.005}, pages = {464 -- 467}, abstract = {The magnetization of a magnetoactive elastomer (MAE) with microparticles of soft magnetic carbonyl iron embedded in a highly elastic matrix has been studied. It is shown that at high temperatures its magnetization curve has the form of a specific hysteresis loop. This hysteresis is attributed to the influence of displacement of magnetized particles in the elastically soft elastomer matrix under the effect of magnetic forces, leading to the change of magnetic interaction between the particles. In this case, there is a maximum in the field dependence of the magnetic susceptibility, the occurrence of which has been associated with the competition between rearrangement of particles, when they are displaced in a magnetic field, and saturation of particles' magnetization. When the MAE is cooled below approximately 225 K, both the magnetic hysteresis and the maximum in the field dependence of the magnetic susceptibility disappear. When the MAE material is cooled below the solidification temperature of the elastomer matrix, the displacements of the magnetic particles during magnetization are blocked by the rigid matrix. The magnetization reversal of the MAE is reversible. This means that the shape of subsequent magnetization loops remains constant and the sample returns into the initial non-magnetized state after the magnetic field is turned off.}, language = {en} } @article{SnarskiiZorinetsShamoninChamonineetal., author = {Snarskii, Andrei A. and Zorinets, Denis and Shamonin (Chamonine), Mikhail and Kalita, Viktor M.}, title = {Theoretical method for calculation of effective properties of composite materials with reconfigurable microstructure}, series = {Physica A: Statistical Mechanics and its Applications}, volume = {535}, journal = {Physica A: Statistical Mechanics and its Applications}, number = {December}, publisher = {Elsevier}, doi = {10.1016/j.physa.2019.122467}, abstract = {We propose a theoretical approach for calculating effective electric and magnetic properties of composites, with field dependent restructuring of the filler. The theory combines the effective medium approximation, extended to a field-dependent (variable) percolation threshold, with an approximate treatment of the nonlinearity of material properties. Theoretical results are compared with experiments on magnetorheological elastomers, which in the context of investigated phenomena are often called magnetoactive elastomers (MAEs). In MAEs with soft polymer matrices, the mutual arrangement of inclusions changes in an applied magnetic field. This reorganization of the microstructure leads to unconventionally large changes of electrical and magnetic properties. The obtained theoretical results describe observed phenomena in MAEs well. For the magnetodielectric effect, qualitative agreement between theory and experiment is demonstrated. In the case of magnetic permeability, quantitative agreement is achieved. The theoretical approach presented can be useful for the development of field-controlled smart materials and design of intelligent structures on their basis, because the field dependence of physical properties can be predicted. (C) 2019 Elsevier B.V. All rights reserved.}, language = {en} } @article{SnarskiiPodlasovShamoninChamonine, author = {Snarskii, Andrei A. and Podlasov, Sergii and Shamonin (Chamonine), Mikhail}, title = {Isotropic inertia tensor without symmetry of mass distribution}, series = {American Journal of Physics}, volume = {89}, journal = {American Journal of Physics}, number = {10}, publisher = {AIP Publishing}, doi = {10.1119/10.0005416}, pages = {916 -- 920}, abstract = {Conventional calculations of the inertia tensor in undergraduate physics course are usually done for highly symmetrical bodies. Students might therefore get the impression that the moment of inertia about any axis through the center of mass is the same only for bodies with the highest degree of symmetry relative to this point, e.g., for spheres. A simple, seemingly counterintuitive example is presented, showing that the moment of inertia of a non-regular body, here an assembly of material points, can be the same about any axis passing through its center of mass.}, language = {en} }