International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The creation and calculation of computer models of various products under load with the properties of UFG materials in the normal and irradiated state was performed. To model the UFG properties of non-irradiated AISI-321 steel, hardening curves were constructed based on the Hall-Petch equation for the base state of the material at a grain size of 1500 nm and for two UFG states (with grain sizes of 700 and 200 nm). To simulate the properties of irradiated AISI-321 steel, plastometric tests were performed using uniaxial compression of cylindrical samples at constant values of the strain rate of 1 s-1 and the temperature of 20°C on the “Gleeble 3800” plastometric unit. Fast neutron fluence with the following values was selected as a variable parameter: 0.5∙1018 n/cm2, 1∙1018 n/cm2, 0.5∙1019 n/cm2, 1∙1019 n/cm2. The maximum operating pressure of 340 MPa was used as a static load. The simulation results showed that for both parts, the use of the material in the UFG state is the most appropriate solution.

This paper investigates stress state in connection of pipes with flat ends used in pressurized pipelines and steam boiler connections. Flat ends are designed according standard EN 12952-3 and later numerically checked using linear elastic material model. These analyses showed areas with increased stress. Therefore, additional analyses were performed using linear elastic-ideally plastic material. The maximal pressure loads are obtained for series of pipes with flat ends and compared to calculated results according EN 12952-3 norm.

Professional activity of police officers is often related to extreme situations stimulating the emergence and development of stress conditions. Police officers, who were not trained in dealing with stress, in extreme situations, can act in a professionally inappropriate manner and put at risk (including risk of death) those involved in a situation, including police officers themselves, and deteriorate the efficiency of resolving the situation of offence. Lack of skills on how to cope with stress significantly undermines normal activity of police officers. The article discusses the theoretical basis of the authors’ developed ideomotoric training program designed for police officers, as well as its validation results. The program aims to decrease the negative consequences of being emotionally involved in stressful situations and to enhance the individual resistance to stress among police officers. The special attention is focused on professional reliability improvement among police officers resulting from participation in the ideоmotoric training program.

The analysis of stress-strain state of the bisector of the corner of the blank at a drawing of box-shaped parts. Analytical dependences for the meridional and circumferential stress on the bisector of the angle. It is shown that an increase in the limit drawing ratio compared with an extract of the cylindrical part is a consequence of the growth in absolute value of district compressive stresses. It was found that the maximum value of the coefficient of drawing of box-shaped parts cannot exceed the value of – K=exp(1+1/√3)≈ 4,84.

Based on the analysis of the initial equations of the plastic state,established the distribution of strains in the initial and final stages of axisymmetric drawing. The dependencies to assess the accuracy of linear and diametrical sizes taking into account volumetric of strain state.

The theoretical and experimental study of stress-strain state and density distribution into the billet at equal-channel angular pressing has been conducted. It has shown clearly that deformation zone takes a substantial volume with dramatic non-uniformity of stress- strain state after the first pass of equal-channel angular pressing at the backpressure of 90 MPa. The presence of turbulence zone that ensures structure fragmentation of material has established by microhardness indentation. A possibility of production of high-density billets after the second pass at the backpressure of 150 MPa with high mechanical properties and more uniform stress-strain state, free of loosening and cracks has presented.

Results of the theoretical analysis of invariant criteria for evaluating the stress-strain state under specific mechanical schemes stresses and deformations on forming operations and their impact on the sustainable flow of processes of plastic deformation are presented

The paper deals with an experimental measurement of the fatigue operating life of a specimen from the aluminium AlMgSi07 alloy on a built testing equipment, into which the welded joint was implemented. An importance of the measurement is in a comparison of achieved results with the same material, which was not subjected to welding. The result of the research is verification of the influence of welding on the fatigue operating life of the concrete material at torsion stress.

The analysis of two-layer sheet bending moment package under plane strain conditions, taking into account the strain hardening. Approximate analytical dependence for the largest radial compressive stress and the relative displacement of the radius of the neutral surface of the inner layer. The possibility of increasing the permissible degree of deformation and reduce the relative radius of curvature of the inner layer.

The paper is focused on the analysis of tracked vehicle propulsion mechanism during a movement of the vehicle. Propulsion mechanisms of tracked vehicles are highly loaded by dynamics stress. This stress arises by vehicle movement on a terrain and by vibration of tracks. Analysis of this stress is essential in the process of development or optimization (modernization) of the vehicle. Simulating technology was chosen for analysis of selected vehicle, because analysis of propulsion mechanism stress of tracked vehicle is complex process. Utilization of simulating technologies enables extensive analysis of vehicle behaviour including analysis of stress of main parts of the vehicle.

The article deals with determining of fatigue lifetime of aluminium alloy EN AW 2007.T3 during by multiaxial cyclic loading. The theoretical part deals with the fatigue and with the criteria for evaluation of multiaxial fatigue lifetime, in region low-cycle and high-cycle fatigue. The experimental part deals with modeling of combined bending – torsion loading and determining the number of cycles to fracture in region low-cycle and high-cycle fatigue and also during of loading with the sinusoidal wave form under in phase φ = 0° and out phase φ = 90°.

The work presents the research of permanent strain occurred when metallurgical transformations take place even under small stress applied externally lower than the yield stress of weaker phase. Four tool steel grades were tested: THG2000 (Uddeholm, Sweden), 20X13, 40X13 and 95X18 (GOST). All steel grades differ in carbon content and amount of alloying elements and behave differently when transformation plasticity occurs. This phenomenon was observed during bending test when bending stress was 100MPa and was less than 10 % of yield strength of the steel. The steel specimens were heated to 950-1050 °C temperature and then bent during air quenching. Plastic deflections were observed though all cooling process that involved martensitic transformation as well. Different effect of compression and tensile stresses on microstructure evolution during martensitic transformation was determined as both type of stresses formed in bent specimens.