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.

Research of a Truck Train Movement when Driving Semitrailer by Slowdowning of Wheels of One Axis Pin on the Model

Abstract: A free-running model of a truck train, which simulates a truck train consisting of a tow truck MAN TGS 19.360 and a biaxial semitrailer Utility VS2DС with a steerable front axis, has been developed. A semitrailer model is active with the wheel drive enables to control its movement by slow downing one of the wheels. The model was equipped with all necessary control equipment. It proved that driving a semitrailer by slow downing one of its wheels is identical to driving a semitrailer front axis with direct drive and a driver transmission ratio of 0.5. Differences in all cases have not exceeded 12% that is slowingdown one of the wheels of a semitrailer is reasonable for driving a truck train with a long base semitrailer.

Adhesive properties and adhesive joints strength of graphite/epoxy composites

Abstract: The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure The single-lap adhesive joints of epoxy composites were considered Adhesive properties were described by surface free energy Owens-Wendt method was used to determine surface free energy The epoxy two-component adhesive was used to preparing the adhesive joints Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (048 mm) Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 095 The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (095 confidence level) It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy

Impact of AC Current Density on Material Corrosion of Distribution Pipelines

Abstract: Abstract Vliv střídavého indukovaného proudu na korozní rychlost oceli St3 a 17GS byl pozorován v simulovaných půdních elektrolytech typických pro Ukrajinu. Ocel St3 je citlivější na přirozené korozní napadení v půdě i na napadení vyvolané střídavým proudem. Byla stanovena nejhorší prostředí z hlediska koroze v elektrolytech obsahujících chloridy či směs chloridů se sírany.

Lifetime estimation of superheater header

Abstract: The safe operation of thermal power plants (TPPs) is largely determined by the reliability of main components of steam systems of power units, to which belong the headers of boiler superheaters. The aim of the study is to estimate the residual lifetime of superheater header starting from the initial defect size and up to the maximum allowable one. The above-mentioned lifetime is affected by the fluctuations of temperature under steady mode of operation of TPP superheater header. Superheaters headers operate in a steamy environment under the pressure of 15.5 MPa at temperature of 545 oС. The header is a thick-walled cylinder with a length of 2314 mm, outer diameter of 325 mm and thickness of 50 mm. The header contains three rows of 27 holes with a diameter of 22 mm and step of 80 mm in the axial direction and 57.6 mm in the circular. The header is made of 12Cr1MoV steel. To estimate the residual lifetime of header, the registered operational data of steam temperature in header were used. The temperature range of header under quasi-stable operational mode was divided into three classes: the temperature range (1) T 30 °C. The local minima and maxima were determined using the obtained steam temperature history. The stresses in the wall of header for the given temperature fluctuations were calculated by finite element method (FEM). The residual durability was evaluated taking into account the effect of thermo-mechanical stresses and also the stresses caused by internal steam pressure. The stress intensity factors at the crack tip in the ligament between the holes of superheater collector were estimated by FEM. Based on the analysis of header defects, the proposed front shape was taken in the form of semi-ellipse. The crack growth at 500 ° C was modelled by Paris equation. The number of cycles for a crack to grow from the initial crack depth of 25 mm up to final size of 35 mm is calculated, taking into account the mean of temperature fluctuations. With the increase of temperature difference between the external and internal header surfaces from 10 °С to 50 °С, the number of cycles, that is necessary for the crack to reach 35 mm in depth, decreases approximately in 25 times. It was calculated, that the average value of temperature fluctuations is 15°С for the 2 nd class, and is 46.2 °С for the 3 rd class. It takes 112000 and 10200 hours of operation for the crack to grow from initial depth of 25 mm to final defect depth of 35 mm at temperature fluctuations of 2 nd and 3 rd class, respectively. The lifetime of header can be extended due to the decrease of fluctuations of temperature range and their frequency.

Ground state energy of metallic ferromagnet in a generalized Hubbard model

Abstract: In the present work ferromagnetic ordering in the Hubbard model generalized by taking into account the inter-atomic exchange interaction and correlated hopping in partially filled narrow band is considered. In the case of weak electron-electron interaction the ground state energy and condition of ferromagnetic state realization are found using the Green function technique. The obtained results indicate the important role of correlated hopping.