Determining Patterns in Thermoelastic Interaction Between A Crack and A Curvilinear Inclusion Located in A Circular Plate

A two-dimensional mathematical model of the thermoelastic state has been built for a circular plate containing a curvilinear inclusion and a crack, under the action of a uniformly distributed temperature across the entire piece-homogeneous plate. Using the apparatus of singular integral equations (SIEs), the problem was reduced to a system of two singular integral equations of the first and second kind on the contours of the crack and inclusion, respectively. Numerical solutions to the system of integral equations have been obtained for certain cases of the circular disk with an elliptical inclusion and a crack in the disk outside the inclusion, as well as within the inclusion. These solutions were applied to determine the stress intensity coefficients (SICs) at the tops of the crack. Stress intensity coefficients could later be used to determine the critical temperature values in the disk at which a crack begins to grow. Therefore, such a model reflects, to some extent, the destruction mechanism of the elements of those engineering structures with cracks that are operated in the thermal power industry and, therefore, is relevant. Graphic dependences of stress intensity coefficients on the shape of an inclusion have been built, as well as on its mechanical and thermal-physical characteristics, and a distance to the crack. This would make it possible to analyze the intensity of stresses in the neighborhood of the crack vertices, depending on geometric and mechanical factors. The study's specific results, given in the form of plots, could prove useful in the development of rational modes of operation of structural elements in the form of circular plates with an inclusion hosting a crack. The reported mathematical model builds on the earlier models of two-dimensional stationary problems of thermal conductivity and thermoelasticity for piece-homogeneous bodies with cracks

Influence of preparation conditions on the microstructure of ZnO thin film prepared by electrodeposition

The effect of electrochemical deposition duration and the heat treatment at 450 °С within 1 hour on the microstructure of ZnO thin films, including their phase composition, lattice parameters, microstrain, grain size and surface morphology is investigated. The empirical relationships allowing to predict the molar composition and the ZnO/FTO thickness ratio depending on the specific charge passing through the substrate during the film formation process have been obtained. According to scanning electron microscopy, there is a consolidation of the film crystallites after the heat treatment leading to formation of hexagonal nanorods. An average size of the crystallites before the heat treatment is 0.727 μm, and after the heat treatment it is 0.455 μ

Influence of preparation conditions on the microstructure of ZnO thin film prepared by electrodeposition

The effect of electrochemical deposition duration and the heat treatment at 450 °С within 1 hour on the microstructure of ZnO thin films, including their phase composition, lattice parameters, microstrain, grain size and surface morphology is investigated. The empirical relationships allowing to predict the molar composition and the ZnO/FTO thickness ratio depending on the specific charge passing through the substrate during the film formation process have been obtained. According to scanning electron microscopy, there is a consolidation of the film crystallites after the heat treatment leading to formation of hexagonal nanorods. An average size of the crystallites before the heat treatment is 0.727 μm, and after the heat treatment it is 0.455 μ

Influence of annealing on microstructure and optical properties of hot wall deposited PbxSn(1−x)S thin films

PbxSn(1 − x)S (0.05 < x < 0.20) thin films with the thickness of 2 μm were deposited on glass substrates using hot wall vacuum deposition method at the vacuum pressure of 5 × 10−4 Pa, wall temperature of 600°С, substrate temperature of 300°С and subsequently annealed at 450 °C in vacuum at 5 × 10−4 Pa. The microstructure and optical properties of the as-deposited and annealed films were examined in relation to the film composition. The explanations of lattice parameter deviations from the bulk crystals for both as-deposited and annealed PbxSn(1 − x)S thin films are discussed. The PbxSn(1 − x)S thin films exhibit a preferred orientation around the [111] direction. The annealing decreases the film microstrain values and increases the grain size and the degree of preferred orientation. Thermal probe measurements showed the sulfur-deficient films to be p-type and the sulfur-rich films to be n-type. The PbxSn(1 − x)S films exhibit direct allowed transitions with energy band gap Eg(d) increasing with the increase of Pb mole fraction. The Eg(d) values for as-deposited films range from 0.95 to 0.98 eV and for annealed films they variy from 0.90 to 0.94 eV