Laser shock peening (LSP) is used to enhance surface quality of the metallic structures by the generation of compressive residual stresses on it. This work studies the effect of the main LSP parameters on residual stress fields by the finite-element method. The specimen under investigation is a square plate with a thickness of 3 mm made of Ti-6Al-4V. The performed analysis enhances understanding of LSP application to structures manufactured from this material and this information can be useful for a choice of optimal peening parameters. The effect of the spot size and shape, the pulse energy, the number of peen layers, overlapping of spots and temporal variation of the mechanical pressure induced by plasma is considered and analyzed. A 3D finite-element model based on the Johnson-Cook constitutive relation is developed and verified by the results of residual stress measurements performed for the LSP-treated samples under different conditions. From the obtained results the following main conclusions can be drawn: pulse energy provides the more significant effect although the resulting residual stresses profile tends to some saturation curve; temporal pressure pulse shape and its total duration also substantially alter the residual stress field; the least significant parameter is the spot shape.

Artificial ground freezing is an efficient technique which allows one to sink the mine shafts under complex hydrogeological conditions. The aim of artificial ground freezing is a creation of a temporary wall of frozen soil around the intended excavation. To estimate an optimal thickness of an ice-soil wall, the Vyalov’s formula is widely used by engineers. The article is devoted to analysis of Vyalov’s formula on the basis of the numerical simulation. The numerical simulation has been conducted by the finite element method. For the simulation of a stress-strain state of an ice-soil wall a new computational scheme has been proposed. The scheme is based on Vyalov’s design layout for a vertical shaft sinking and takes into account a soil layer beyond the excavation bottom. A mechanical behavior of frozen soil is described by Vyalov’s constitutive relations. As a result, it has been shown that values of the wall thickness given by Vyalov’s formula do not agree with the ones obtained by the numerical simulation. In order to conform results given by Vyalov’s formula and the numerical simulation, two modifications of the formula have been proposed.

The exhaustion of constructive ways for increasing the service life of parts has led to the development of new methods which can improve their material properties during operation under various loading conditions. Laser shock peening (LSP) induces compressive residual stress field which prevents fatigue crack initiation and propagation in components. Characteristics of laser impact and treatment patterns play an important role in efficiency of LSP application for improvement of fatigue properties. This work is devoted to the experimental examination of two LSP patterns to reveal the most optimal scheme from fatigue live improvement point of view. Proposed LSP pattern allowed one to increase the fatigue life of specimens with semi-circular notch by an order of magnitude. The numerical simulation of the LSP was performed to visualize the residual stress field of treated specimen after loading and to give the interpretation of the experimentally observed improvement of fatigue life.

An intensive development of infrastructure in the far North and application of the artificial ground freezing technology for construction of civil and industrial buildings require an accurate description of frost heave caused by freezing of pore water in soils. It is important to understand this processes at the developing stage for the aim of safety exploitation of constructions. The present work is devoted to an experimental and theoretical study of the frost heave in laboratory samples of water saturated sand. Artificial freezing of the sample is performed in a chest freezer. During freezing measurements of temperature and strain are carried out by a control system consisting of a set of thermocouples and fiber optic sensors based on Bragg gratings. To analyze the obtained experimental data, a thermo-hydro-mechanical model has been developed. Water saturated soil is supposed to be three phase porous media consisting of a drained skeleton, water and ice. The model includes the energy conservation equation, the mass balance equations for moisture and ice content, the equilibrium equation and the constitutive relations taking into account an influence of the phase transition of water on heat and mass transfer and the additional volumetric strain. The numerical solution of the nonlinear partial differential equations of the model is performed by the finite element method. The feature of the model is a possibility to take into account the crystallization kinetics on the frost heave of the freezing saturated soil. As a result of the study, a good qualitative and quantitative agreement between a temperature measurement in the volume of the sample and the results of the simulation has been obtained. A comparison of the fiber-optic sensors readings with the results of the numerical simulation has shown that the calculated values are slightly deviated from the experimental ones. On the basis of the measurements analysis and the numerical results it can be concluded that the frost heave proceeds in a long time after the phase transition starts within the temperature range below the temperature of water freezing.

For heat rejection, small air-cooling towers are widely used in mine ventilation systems. However, the thermal efficiency of the cooling towers can be significantly affected by their geometrical arrangement and crosswind conditions. In certain ambient conditions, heated air coming from an exit of one tower can flow to intakes of other towers, which leads to a reduction in the thermal efficiency of the entire ventilation system. The aim of this study was to investigate the influence of crosswind speed and tower spacing on the temperature and moisture content of intakes of cooling towers. For this purpose, a three-dimensional CFD model of the non-isothermal turbulent flow of moist air around cooling towers is proposed. The model is based on the Reynolds-averaged Navier–Stokes equations with a standard turbulence model which are supplemented by heat transfer and moisture transport equations. The investigation of the effects of the crosswind speed and the tower spacing was carried out for two cooling towers by multiparametric numerical simulation using the CFD model. It was shown that the upstream tower protects the downstream one from the effect of the crosswind. The increase in the crosswind speed causes a rise in temperature and moisture content at the intakes of the downstream tower. The increase in the tower spacing, in general, contributes to a decrease in air temperature at the intakes of the downstream tower. However, at low crosswind speed, the heat transfer at the intakes can rise with the tower spacing due to a reduction in the protection possibilities of the upstream tower. Results of the numerical simulation of airflow around three cooling towers indicated that the increase in the number of cooling towers contributes to a rise in temperature and moisture content at the intakes.