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

The effect of nozzle diameter on the mechanical properties of polymers reinforced with short fibers is critical for optimizing both print quality and structural performance in fiber-reinforced composites 3D‑printed using fused filament fabrication. This study investigated three types of polymer composites based on acrylonitrile butadiene styrene reinforced with carbon, glass, and basalt short fibers. The study involved experiments on monofilament samples before and after manufacturing process to evaluate and compare the effective tensile strength and stiffness properties of filaments reinforced with different materials.

The results of studying kinetics of strength decrease for two types (polyethylene and polyamide) of polymer fibers at X-ray irradiation. A structural-kinetic model of radiation induced changes in strength of fibers is considered, which accounts for the opposite effect of degradation and crosslinking of macromolecules on the oriented polymer (fiber) strength.

We present a version of the numerical analysis of the relationship between maximum strains on the ground surface and in an underground pipeline based on the results of solving the corresponding problem of the stress–strain state that arises as a result of the appearance of cavities of different geometries in the soil mass.

We proposed methods for developing predictive models of concrete gravity dam crest displacement. A deterministic finite element analysis (FEA) model is presented along with a method for identifying its mechanical properties. Performance of FEA model is compared to booster regression trees statistical model with hyperparameter tuning. Resulting models demonstrate excellent accuracy.

The study of multiphase systems based on magnetic fluids under external magnetic influence is a relevant direction in the development of contactless methods for controlling non-magnetic objects. This work aims to investigate non-magnetic inclusions in magnetic fluid. The results have been obtained through experimental methods and computer simulations using FEMM software.

We investigated the possibility of accelerating the numerical simulation of transient processes in ANSYS software when calculating superelastic dampers based on shape memory alloys. The work compares two approaches to three-dimensional modeling of dampers: the superelasticity model and the thermomechanical model, demonstrating their satisfactory agreement. It is noted that simulating slender structures, typical of superelastic dampers, in a three-dimensional formulation requires significant computational time. As a solution, the use of beam finite elements with a thermomechanical model is proposed. It is shown that this approach provides reliable results while substantially reducing computation time and is optimally suited for analyzing typical beam-like damper configurations.

A series of seven samples of water-based magnetic fluid stabilized with a double surfactant layer was synthesized. The magnetic properties of the synthesized samples were determined as a function of their concentration. The obtained concentration dependences of the initial static magnetic susceptibility for all samples are described by a third-degree polynomial of the Langevin susceptibility with a negative cubic term, which contradicts the existing theoretical models.

We investigated the application of distributed fiber-optic sensors (DFOS) based on Rayleigh scattering for high-resolution strain measurements in heterogeneous materials under four-point bending tests. Experiments on potassium salt compare full-length and two-point bonding strategies, showing that bonding configuration significantly affects the measured strain variability and interpretation of material behavior. The strain profile over the height of the specimen during the four-point bending test was registered using DFOS and used to estimate the position of the neutral axis. The results highlight both capabilities and limitations of DFOS in geomechanical applications.

The shell structures made of prepreg-based composite materials are of particular interest in space applications. Due to incomplete matrix cure, the material retains elasticity sufficient for shaping structures directly in space conditions. Once the structure is fully deployed, the material is fully cured under heating by radiant energy, which makes it rigid and strong. The main sources of radiation in Earth orbits are the Sun and the Earth. The amount of radiation emitted by the Earth is less (but not negligible) than that of the Sun. The aim of this paper is to assess quantitatively the degree of impact of the Earth’s radiation on a space object in low Earth orbit. Emphasis is placed on studying the dependence of this impact on the position of an object relative to the Earth, including the change of day and night, and on its location over different parts of the planet (poles, equator).

Safe operation of a structure is provided by monitoring its deformation behavior. An important part of it is the vibration response characterized by amplitude-frequency and phase parameters. In this study, the natural frequencies and mode shapes of load-bearing elements of a building structure are evaluated by using FEM. Based on the long-term monitoring of the vibration response on one of the load-bearing reinforced concrete beams, the evolution of the natural frequencies of the structure was obtained. It should be noted that these structural elements were damaged and repaired, which determined the interest of the study. The results of in-situ and numerical experiments are analyzed with respect to the current seasonal changes.