Computational and Experimental Method for Assessing the Thermal Strength of High-Loaded Diesel Engines

The article discusses the reasons of fatigue failure of pistons of high-loaded diesel engines. A deformation-kinetic criterion is proposed, generalized to non-isothermal loading, which allows more correct calculation of the number of thermal loading cycles before the appearance of fatigue damage. For a specific implementation of the proposed criterion, a calculated assessment of the piston stress-strain rate was carried out using the FEM. The boundary conditions for the calculation were obtained by thermometry of the piston head on a non-motorized thermal stand (TS). Comparison of the calculated and experimental values of the number of thermal cycles before the appearance of cracks on the edge of the combustion chamber (CC) of pistons made by casting and isothermal stamping is given.

Shape Optimization of a Column under Generalized Load with a Force Directed towards Positive Pole

In this paper, the issue of shape optimization of a column subjected to the generalized load with a force directed towards the positive pole (L. Tomski’s load, specific load) was considered. Based on the Hamilton’s principle, the differential equations of movement and boundary conditions describing the system were formulated. Taking into account a kinetic criterion of stability loss and a condition of constant total volume, the scope of changes in natural frequency as a function of an external load was determined with selected geometrical and physical parameters of the loading structure. On the basis of obtained results, values of geometrical parameters of individual column segments were determined, at which the maximum critical load value was obtained. In order to find the maximum critical force, which is a function of many variables, the simulated annealing algorithm was used.

Methods of Achieving Stylistic Unity Between Portrait, Costume, and The Theatre Play Space

Creating stylistic unity within a theatre play is more than just a complex process. The original interpretation of the language forms, specific to each artist that becomes part of this creative act, lies within the final aesthetic product. This article starts by analysing the concept of form and movement as a result of syncretism on various levels, from style and movement, to expression and feelings. To achieve this, the author describes the aesthethics of form emphasising the meaning of stylistic unity in achieving the artistic vision of a show. The paper defines compositional laws and theatrical methods that make the muppet play become a harmonic visual ensemble and stylistic unity. Some of these are: stage props and background; the kinetic criterion of moving forms; the ergonomic criterion of forms in space; the criterion of materiality - in creating the clothing and the costume design.

Quasi-optimization of the slender geometrically nonlinear supporting system with non-prismatic element under the specific load

This paper is devoted to the issue of free vibrations of a geometrically nonlinear column with a nonprismatic element modelling the supporting structure subjected to the specific load. The boundary problem was formulated on the basis of the Hamilton’s principle and its solution was obtained using the Lindstedt - Poincare’s small parameter method (a perturbation method). Within the range of the kinetic criterion of the static equilibrium, an influence of the shape of a rod of variable crosssection on the values of free vibrations and the bifurcation load of the system was determined. Presented quasi-optimization issue has been reduced to defining the ranges of physical and geometrical parameters where an increase of the bifurcation load is the biggest in comparison with the reference system.

THE STABILITY AND FREE VIBRATIONS OF A COLUMN SUBJECTED TO A CONSERVATIVE LOAD GENERATED BY A HEAD WITH A PARABOLIC CONTOUR

The boundary value problem concerning the free vibrations of a slender system subjected to a specific load has been formulated and solved in this work. Heads with parabolic contour have been used to realize the specific load for the first time. The boundary value problem has been formulated using Hamilton's principle. The critical load and the characteristic curves in the plane load–natural frequency have been determined on the basis of the kinetic criterion of stability. Numerical calculations have been assigned to different values of the parameters of the considered system for which the parabolic parameter and the parameter of the roller radius are ranked. The roller is the head of the receiving load. The accuracy of the mathematical model was confirmed on the basis of experimental research based on frequency and modal analysis.

Theory of Phase Transformations in the Mechanics of Solids and its Applications for Description of Fracture, Formation of Nanostructures and Thin Semiconductor Films Growth

The brief review of the current state of the theory of first-order phase transitions is given. The basic processes of nucleation and evolution of nanostructure ensembles on crystal surfaces are considered. The general equations describing nanoparticle size distribution, evolution of their average radius and density are deduced. The influence of mechanical pressure on nucleation and property of quantum dots and nanopores is considered. The equations describing new phase nucleation under condition of mechanical pressure caused by distinction in density of an old and new phase are resulted. The kinetic theory of micropore nucleation in solids under loading is described. The kinetic criterion is received of nucleation of micropores and microcracks in fragile solids under the influence of stretching pressure.

Suppression Criterion of the Phase Growth Based on Extremal Principles of Nonequilibrium Thermodynamics

The suppression criterion of the binary phase growth due to addition of a third component is considered. In this case the analysis of the two possible criteria of the first phase growth are considered: first – kinetic criterion based on the balance of components fluxes and second - thermodynamic criterion which is based on the maximal rate of the entropy production principle. We demonstrate that in the case of a model system the thermodynamic criterion lead to a bigger value of the critical thickness of the phases which are suppressed by the growth of the investigated phase.