Study of psychological status of tsu students from exercise therapy group

The present article contains the results of ascertaining study, aimed at identification of the psychological characteristics of students engaged in groups of exercise therapy. It has been established that students with poor health differ greatly in psychometric characteristics from the group of students who do not have any problems with their health. These differences are most pronounced in the findings obtained by means of questionnaires of constructive thinking and level of subjective control. Students who train in the groups of exercise therapy, need special forms of organization of the educational process involving psychological methods

FRICTION BEHAVIOR OF ALUMINUM BRONZE REINFORCED BY BORON CARBIDE PARTICLES

A promising composite material for tribotechnical applications based on aluminum bronze with reinforcing boron carbide particles fabricated by a special electron beam additive deposition technique was studied experimentally and numerically. Tribological experiments showed that reinforcing by carbide particles allowed reducing the coefficient of friction from 0.26 to 0.19 and improving the wear resistance by 2.2 times. Computer modeling reveals two main factors playing a significant role in the friction behavior of the studied metal matrix composite: the mechanical effect of reinforcing ceramic inclusions and effective hardening of the metal matrix due to the peculiarities of the 3D electron beam printing. The mechanical effect of hardening inclusions determines a more rounded shape of wear particles, preventing wedging, and thereby increasing the stability of friction. Strengthening the metal matrix leads to reducing the number of wear particles

A DISCRETE ELEMENT FORMALISM FOR MODELLING WEAR PARTICLE FORMATION IN CONTACT BETWEEN SLIDING METALS

The paper describes an advanced discrete-element based mechanical model, which allows modelling contact interaction of ductile materials with taking into account fracture and surface adhesion by the cold welding mechanism. The model describes these competitive processes from a unified standpoint and uses plastic work of deformation as a criterion of both local fracture and chemical bonding of surfaces in contact spots. Using this model, we carried out a preliminary study of the formation of wear particles and wedges during the friction of rough metal surfaces and the influence of the type of forming third body (interfacial) elements on the dynamics of the friction coefficient. The qualitative difference of friction dynamics in the areas of the contact zone characterized by different degrees of mechanical confinement is shown

Development of discrete element approach to modeling heterogeneous elastic-plastic materials and media

A general approach to realization of models of elasticity and plasticity of isotropic materials within the framework of discrete element method (DEM) is proposed in the paper. It is based on building many-body potentials/forces of discrete element interaction, which provide response of element ensemble correctly conforming to the response of simulated solids. Developed formalism makes possible realization of various rheological models in the framework of DEM to study deformation and fracture of solid-phase media of various nature

Study of the influence of morphology and strength of interphase boundaries on the integral mechanical properties of NiCr-TiC composite

Sintered metal-ceramic materials are characterized by high mechanical and tribological properties. A key element of the internal structure of the metal-ceramic composites which have an important, and in many cases, a decisive influence on the integral mechanical properties of these materials is the interphase boundary. In this paper, based on numerical simulation we show the influence of morphology and strength properties of interfaces for integral mechanical properties of the dispersion-reinforced composite NiCr-TiC (50 : 50). Computer simulation results indicate that the phase boundary significantly contributes to the integral mechanical characteristics of a composite material and to the nature of the initiation and development of cracks

Role of vortex-like motion in fracture of coating-substrate system under contact loading

Deformation of a heterogeneous material containing internal interfaces or/and free surfaces is accompanied by collective vortex motion near these boundaries. One should expect that rotational motion in nanomaterials takes place at different scales, from the atomic scale to the macroscopic one. Nevertheless such a fundamental factor as elastic vortex motion in material formed during dynamic loading still remains out of discussion. The aim of this paper is revealing the role of vortex displacements in contact interaction of the strengthening coating with a hard counter-body by means of 3D modeling using movable cellular automata (MCA). MCA method is an efficient numerical method in particle mechanics, which assumes that the material is composed of a certain amount of elementary objects interacting among each other according to many-particle forces. In this paper MCA method is applied to 3D modeling deformation of the coating-substrate system under its contact loading by the rigid indenter. Main attention of the research is focused on the role of vortex structures in the velocity fields in elastic and non-elastic deformation of the strengthening coating and substrate. The mechanical properties of the model coating correspond to multifunctional nanostructured film and the properties of the substrate, to nanostructured titanium. The loading is performed by a hard conical indenter with various ratios of normal and tangential components. The peculiarities of the velocity vortex formation and propagation, as well as interaction with the structural elements are studied

Elastic vortex displacements as precursors of mechanical stress relaxation in heterogeneous materials

Deformation of heterogeneous material containing internal interfaces or/and free surfaces is accompanied by collective vortex motion near such boundaries. Nevertheless, such fundamental factor as elastic vortex motion in material formed during dynamic loading still remains out of the discussion. The aim of this paper is to reveal the role of vortex displacements in contact interaction of heterogeneous coatings with hard counter-body by means of 3D computer simulation using movable cellular automata. The research is mainly focused on the role of vortex structures in the velocity field in elastic and non-elastic deformation of the coating. The peculiarities of the velocity vortex formation and propagation, as well as interaction with the structural elements are studied

Theoretical investigation of the dynamics of friction stir welding process by movable cellular automaton method

The paper is devoted to development of a new approach to study of friction stir welding (FSW) process on the mesoscopic scale. This approach is based on computer-aided simulation by movable cellular automaton (MCA) method. In the framework of developed formalism of MCA method the dynamics of the friction stir welding process of duralumin plates was investigated. It was shown that ratio of rotation velocity to velocity of translation motion of rotating tool greatly influences the quality of welded joint. Optimal choice of the ratio of these parameters could significantly decrease volume content of pores and microcracks in the welded joint

МЕТОД ДИАГНОСТИКИ СЕРДЕЧНО-СОСУДИСТОЙ СИСТЕМЫ НА ОСНОВЕ ОДНОМЕРНОЙ МОДЕЛИ ГЕМОДИНАМИКИ

A method of screening a cardiovascular system state using original software, which realizes ma-thematical analysis of oscillometry data in terms of biomechanical model of hemodynamics, is de-scribed. The screening, based on the proposed method, allows to expand the possibilities of classical oscillometry and to obtain the important information about the state of heart and blood vessels as well as the adaptability of humans (particularly, athletes) under various physiological loads.Описывается метод первичной диагностики состояния сердечно-сосудистой системы с ис-пользованием оригинального программного обеспечения, реализующего математический анализ ос-циллометрических данных на основе одномерной биомеханической модели гемодинамики. Проводимый предложенным методом скрининг позволяет расширить возможности классической осциллометрии и получить важную информацию о состоянии сердца и сосудов, включая оценку адаптационных возможностей обследуемых (в частности, спортсменов) при различных физиологических нагрузках