Ternopil Ivan Pul'uj National Technical University

About: Ternopil Ivan Pul'uj National Technical University is a based out in . It is known for research contribution in the topics: Deformation (engineering) & Fracture toughness. The organization has 134 authors who have published 187 publications receiving 1019 citations.

Prediction of transport vehicles’ durability with consideration of corrosive surface cracks propagation in structural elements

Abstract: Support frameworks of transport vehicles operate under varying terrain conditions under the influence of extreme climate and corrosive environments. When transporting cargo, dust is deposited on the surface of metal structures. The combination of dust and moisture creates an aggressive environment resulting in intense corrosion damage. The damage is caused by the defects of corrosion pitting, which occur on the surface and transform into corrosion cracks. Based on energy approaches, with the application of wellknown results for the mathematical description of electrochemical reactions and the principles of fragile fracture mechanics, an analytical model of durability is proposed for the first time. The model determines the residual life of maximum loaded elements of undercarriages with surface cracks under the action of dynamic loads and corrosive environments. For this case, a set of mathematical relations in the form of a non-linear differential equation was developed, as well as the initial and final conditions for determining the life of vehicles’ structural elements with corrosive surface cracks. The analytical model implementation is proven by solving the problem of determining the residual life of a vehicle’s element, i.e., a steel plate, weakened by a semi-elliptical surface crack, which is under the action of dynamic loads in a 3% sodium chloride solution. The insignificant increase in the crack’s initial size is proven to greatly reduce the period of its subcritical growth. The developed model was applied to define the residual life of thin-walled elements of structures with surface cracks.

Influence of high intensity ion beam irradiation on impact toughness of 12Cr1MoV steel

Abstract: The impact toughness of non-treated and irradiated 12Cr1MoV steel Charpy specimens has been studied in the range of temperatures from 20 C to 600 C. It was revealed that the ion beam treatment of steel deteriorates the impact toughness by 5–40 % at the tested temperature range. The physical regularities of irradiation effect on microhardness and hardness of the treated surface were investigated. It was also found out that irradiated specimens fracture via more brittle mechanism, which is related to both more severe stress–strain state at the notch tip and gradient alteration of properties in the subsurface layer.

A New Two-Pole Approximation in the Hubbard Model. Metal-Insulator Transition

Abstract: A new two-pole approximation, which allows to describe the transition from an insulating state to a metallic one at increase of bandwidth, and also the observable in some compounds transition from a metalic state to an insulating one with increasing temperature, is presented. The case of a paramagnetic narrow-band material at half-filling is considered. Single-particle Green function and energy spectrum of electron system are calculated. The expressions for energy gap width and the concentration of polar states (holes or doublons) are obtained. The conditions for metallic and insulating states are found.

The device for remote measurements of geometric dimensions and positions

Abstract: A non-contact technique for measurement of geometric dimensions and positions in the monochrome light is presented along with the assessment of measurement performance by automatic processing of measurement.

On metallic ferromagnetism of a generalized Hubbard model with correlated hopping

Abstract: In the paper a possibility of metallic ferromagnetic state realization in a generalized Hubbard model with more complete accounting of electron-electron interactions, in particular, the correlated hopping and exchange interaction integrals is investigated. Recently obtained by means of mean-field approximation single electron energy spectrum is used for the description of finite temperature properties of the system. In the paper the expression for the critical temperature of ferromagnet-paramagnet transition is found, the behaviour of temperature dependencies of magnetization and paramagnetic susceptibility is analyzed. Taking into account the correlated hopping allows to explain some peculiarity of ferromagnetic behaviour of transition metals, their alloys and compounds.