Bulletin of the Russian Academy of Sciences: Physics最新文献

In this study, methods for enhancing the structural strength of conical orthopedic transtibial exoprosthetic sockets are investigated through the implementation of non-planar reinforcement using structured rods made of continuous carbon fiber. Numerical modeling based on progressive failure analysis according to an instantaneous damage law, incorporating material property degradation models, effectively demonstrated the damage accumulation process in the examined structures.

Magnetohydrodynamic (MHD) stirring of liquid metal is used in the continuous casting of round aluminum ingots to improve an ingot structure during its crystallization. The MHD stirrers developed for this purpose excite the vortex flow of liquid metal in both vertical and horizontal directions. Such bidirectional MHD stirrers have two rotating and travelling magnetic field inductors, which is a decisive factor in design of these stirrers. In this paper, we describe the MHD stirrer with small dimensions and with only one inductor, namely, a rotating magnetic field inductor, which induces in the liquid metal not only its rotation, but also flows in the vertical direction. In this paper, the verification of the used mathematical model is performed. The results of numerical modeling of the considered designs showed that the proposed design with inclined poles can be comparable in efficiency with MHD stirrers of classical construction. This indicates the relevance of further research into the efficiency of the proposed design.

A numerical simulation has been carried out to evaluate the effect of Rayleigh damping on the efficiency of passive suppression of free and forced harmonic vibrations of a thin plate using piezoelectric element connected to a passive electric circuit of different configurations. The solution is constructed using a finite element algorithm, which is developed in the context of the proposed mathematical formulation. It has been found that the efficiency of the considered method of vibration damping decreases with increasing contribution of another dissipative mechanism existing in the system.

We investigated the mechanical response of planar auxetic lattice metamaterials with various cell geometries under thermal loading. The dependance of the structures’ deformation behavior on both the geometry and quantity of the unit cells was established. Specifically, the influence of unit cell shape (auxetic and trapezoidal) and connecting element type (straight and arc) on thermal expansion was analyzed. The obtained results can be used for designing metamaterials with tailored thermomechanical response.

The dependence of reconstructed velocity fields on time delays for two cases with different types of tracers in a typical nozzle flow is studied. Cases with water droplets that vary substantially in size and small oil droplets are considered. Increasing the initial interrogation window has been shown to be quite efficient for reconstructing the velocity field in cases of relatively large time delays exceeding the optimal time delay value. It is shown that the loss of information with an increase in time delay is a gradual process.

Viscoelastic properties of elastomer composites were studied depending on the filler type (carbon black, nanodiamonds, graphene, carbon nanotubes). The samples were subjected to cyclic loading with the amplitude and rate of deformation decreasing at each subsequent cycle (plus stops for relaxation). An analysis of dissipative cyclic losses during loading and unloading was carried out, and their share due to softening of the material due to the Mullins effect was also determined.

We discussed mathematical modeling and research of current density and magnetic field strength distributions in single- and multi-frequency coaxial cables during high-frequency electrical energy transmission.

A nonlinear equation is obtained for the dynamics of a hyperelastic rod, the deformation of the material thereof is described by a neo-Hookean potential. The following quasi-harmonic processes are studied: the generation of a longitudinal double-frequency wave, the formation of a wave package with its amplitude envelope having the properties of a soliton.

Active vibration diagnostics is a promising method for assessing the mechanical condition of large-scale structures. The main element of the vibration diagnostic system is the actuator. It is used to generate diagnostic signals in the structure. Previously, the authors developed an actuator based on piezoceramics. Dynamic deformation of piezoceramics is usually described by linear relations, although it is known that at high values of electric field strength it exhibits nonlinear properties. Therefore, a series of experiments was carried out that allowed us to determine the limits of applicability of a conservative linear model of a piezoceramic actuator.

We presented an experimental study of the regularities of multiple localization of plastic deformation under conditions of the Portevin–Le Chatelier effect during compression of “inclined” cylindrical samples made of AMg6 alloy. An analysis of statistical distributions of intervals of plastic flow stress fluctuations was performed. Calorimetric studies of samples with different degrees of deformation were conducted.