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One of the current and widely used non-destructive testing methods for monitoring and determining the elastic properties of materials is nanoindentation. In this case, to interpret the test results, a non-trivial task arises of constructing an adequate mathematical model of the indentation process. As a rule, in many cases, analytical formulas are used that are obtained from an elastic linear formulation of problems about the introduction of a non-deformable stamp into a homogeneous elastic half-space. Currently, the numerical formulation of the problem makes it possible to obtain and use a numerical solution obtained taking into account the complete plastic nonlinear behavior of the material. In this work, a study of contact problems on the introduction of a spherical and conical indenter into an elastoplastic homogeneous half-space was carried out. To verify the numerical solution, the problem of introducing a spherical and conical indenter into an elastic homogeneous half-space was also solved and compared with known analytical solutions. Issues of convergence and tuning of numerical methods, the influence of plasticity and the applicability of analytical solutions are explored. Problems are solved numerically using the finite element method in the Ansys Mechanical software package.

This work is devoted to the study of gas-dynamic processes in the operation of climate control systems in the cabins of vehicles (HVAC), focusing on pressure values. This research examines the issue of assessing the required values of air overpressure inside the locomotive cabin, which is necessary to prevent gas exchange between the interior of the cabin and the outside air through leaks in the cabin, including protection against the penetration of harmful substances. The pressure boost in the cabin depends, among other things, on the external air pressure on the locomotive body, the power of the climate system fan, and the ratio of the input and output deflectors. To determine the external air pressure, the problem of train movement in a wind tunnel is considered, the internal and external fluids domain is considered, and the air pressure on the cabin skin is determined using numerical methods CFD based on the Navier–Stokes equations, depending on the speed of movement. The finite-volume modeling package Ansys CFD (Fluent) was used as an implementation. The values of excess internal pressure, which ensures the operation of the climate system under different operating modes, were studied numerically and on the basis of an approximate applied formula. In particular, studies were carried out depending on the speed and movement of transport, on the airflow of the climate system, and on the ratio of the areas of input and output parameters. During a numerical experiment, it was found that for a train speed of 100 km/h, the required excess pressure is 560 kPa, and the most energy-efficient way to increase pressure is to regulate the area of the outlet valves. [ABSTRACT FROM AUTHOR]

Current developments in vehicles have generated great interest in the research and optimization of heating, ventilation, and air conditioning (HVAC) systems as a factor to reduce fuel consumption. One of the key trends for finding solutions is the intensive development of electric transport and, consequently, additional requirements for reducing energy consumption and modifying climate systems. Of particular interest is the optimal functioning of comfort and life support systems during air recirculation, i.e., when there is a complete or partial absence of outside air supply, in particular to reduce energy consumption or when the environment is polluted. This work examines numerical models of airfields (temperature, speed, and humidity) and also focuses on the concentration of carbon dioxide and oxygen in the cabin, which is a critical factor for ensuring the health of the driver and passengers. To build a mathematical model, the Navier–Stokes equations with energy, continuity, and diffusion equations are used to simulate the diffusion of gases and air humidity. In the Ansys Fluent finite volume analysis package, the model is solved numerically using averaged RANS equations and k-ω turbulence models. The cabin of a mainline locomotive with two drivers, taking into account their breathing, is used as a transport model. The problem was solved in a nonstationary formulation for the design scenario of summer and winter, the time of stabilization of the fields was found, and graphs were constructed for different points in time. A comparative analysis of the uniformity of fields along the height of the cabin was carried out with different locations of deflectors, and optimal configurations were found. Energy efficiency values of the climate system operation in recirculation operating modes were obtained. A qualitative assessment of the driver's blowing directions under different circulation and recirculation modes is given from the point of view of the concentration of carbon dioxide in the breathing area. The proposed solution makes it possible to reduce electricity consumption from 3.1 kW to 0.6 kW and in winter mode from 11.6 kW to 3.9 kW and save up to 1.5 L/h of fuel. The conducted research can be used to develop modern energy-efficient and safe systems for providing comfortable climate conditions for drivers and passengers of various types of transport. [ABSTRACT FROM AUTHOR]

Mathematical and computer finite element model in the ACELAN package of resonant impact on a spike was developed and a full-scale experiment was carried out. Two installations are considered, one based on a cantilever, the free end of which acts on the spike, and the second is a semi-passive round bimorph. Excitation of vibrations is carried out using an actuator based on piezoceramic elements. In the first installation, low-frequency vibrations of the stem with a spike are excited and the resonance frequency is determined at which only an spike with grain performs intense vibrations. The second installation is designed to excite high-frequency vibrations at which resonant movements of the grains themselves arise. The purpose of both installations is to separate the grain from the spike using resonance phenomena.

The work is devoted to the study of the dynamics of the grain mass in a field stripper for grain separation. At the first stage, a model of the movement of the air mass in the considered installation is built and based on a mathematical model that takes into account the turbulence of the movement of the air mass, using the method of finite volumes in the ANSYS package, the field of velocities and pressures is calculated. At the second stage, the movement of a fragment of the grain mass in this flow is considered, its trajectory is built taking into account the interaction with the upper deck of the installation. The performed calculations allow us to choose rational geometric and kinematic parameters at which no stagnant zones appear in the chamber, the grain mass interacts with the upper one, which contributes to the release of grain in the installation chamber.

Considered by this article are static and dynamic deformation of the stem with the ear of wheat and of the individual grain. The purpose of the article is to determine the factors of influence on the ear of wheat to isolate the grain The ear fluctuations are considered within the Euler-Bernoulli bar theory. The first stage studies the dynamics of the plant as a whole, the second stage studies the dynamics of an individual grain in a moving system associated with the ear. The model of the ear and the grain fluctuation uses the mechanical characteristics of elastic bonds and elastic bodies, which are determined by spring stiffness's, elastic moduli, etc. The natural frequencies shows that at the value of natural frequencies of grain fluctuations 131,6 Hz and 1274,9 Hz the grain itself fluctuates predominantly, and at frequencies 1622,8 Hz, 7367.3 Hz, 9396.0 Hz and 13491,0 Hz the flakes vibrate. [ABSTRACT FROM AUTHOR]

"Supervised autonomy" is a term that best describes the autonomous agricultural machines currently being envisioned. Such machines will be able to work autonomously, but require human supervision. The topic of interface design, however, has not received sufficient attention by designers. The goal of this study was to investigate the importance of live video for remote supervision of autonomous agricultural machines. The study was conducted using an autonomous agricultural machine control interface simulator, which provided information of machine status using graphical indicators (which interpreted and displayed sensor information) and live video (which was presented as seen by the camera). The participants of the study performed the role of the supervisor of an autonomous agricultural machine. The importance of live video was assessed by comparing the participant's performance during trials with and without video. Information about the gaze direction was obtained with an eye-tracking system. The results showed that graphical indicators are the preferred source of machine status information, and live video is a secondary source. At the beginning of the experiment, participants split their attention evenly between the graphical indicators and the live video, but by the end of the experiment, their focus was on the graphical indicators 70% of the time. More than 75% of the participants indicated that the live video helped them to understand machine functions better and they felt more secure when the video footage was present. The participants suggested that live video should be available either full time or on demand. Control interface designers should consider including live video on the interface for autonomous agricultural machines to provide additional decision-making support to the supervisor. [ABSTRACT FROM AUTHOR]