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

The work is devoted to the development of a solid-phase technology for obtaining high-temperature layered composites from Nballoys. The following are presented: one of the options for the formation of the initial multilayer package and its diffusion welding (1), the microstructure of the obtained composites (2) and the results of testing composites (3) for strength at room temperature and temperatures up to 1350°C, taking into account the structure anisotropy, crack resistance and tests for creep with two options for processing the obtained experimental data.

The microstructure and characteristics of the heat resistance of layered composites of Nb–V alloys and intermetallic compounds with aluminum are presented. The composites obtained by diffusion welding under pressure of packages of aluminum foils and foils of niobium alloys with 5, 10, and 15 at. % vanadium had structures representing an alternation of viscous-plastic layers and reinforcing layers of aluminides. The composites were characterized by a viscous-plastic nature of fracture and higher values of strength at room temperature and temperatures up to 1300°C, in comparison with composites without vanadium.

In many applications, FGM rotating discs are subjected to severe operating temperature and high rotational speeds. In such conditions the incidence of creep is inevitable. To study some aspects of this phenomenon, using the Sherby’s law the creep relaxation of a group of FGM rotating discs is modeled. Results show that even thought the temperature is uniform entirely, the stress variation leads to a phase transformation and so the creep mechanism is changed. In this paper the effect of this change of creep mechanism on the steady state creep behavior of FGM rotating discs made of Al-SiC is studied.

Polymer-based products are widely used as load-carrying components in different structural applications due to the ease of manufacture, installation, and long lifetime properties. In mining and tunnelling industry, fast-setting, thin polymer-based products are in demand as an underground support liner. Researchers have agreed that the time-dependent material properties of underground support liners have significance for short to long term applications. Although some creep tests were performed in literature, there is no available study on the numerical analysis/simulation of the creep behaviour of underground support liners. In this study, viscoelastic mathematical
models developed for two different underground support liners were analyzed in ABAQUS finite element numerical modelling software with a developed subroutine. After the implementation, tensile creep test specimens were modelled to verify the new subroutine. There are two main purposes of the simulation of experiments; Firstly, to verify that the subroutine works in accordance with the actual behaviour of the material, secondly, to obtain realistic creep behaviour results for cases where experiments were not performed. As a result, a good  agreement was obtained between the mathematical model predictions and numerical results for different stress levels. The proposed subroutines may create a basement for future numerical studies.

This paper presents a two-dimensional numerical algorithm for creep analysis of the elastic beams under uniform torsion. Torque is assumed to be constant during the whole creep process. Tangential stresses are calculated following the warping function distribution. Material creep behaviour is simulated using the effective stress function. Analysis takes in consideration the torque acting on cross-sectional surface independently on the beam length. The proposed numerical algorithm enables the stress analysis to be carried out regardless of the cross-sectional shapes. Viscoelastic effects of the material are modelled by the creep power law formula. Numerical algorithm was developed in Python code and its effectiveness is validated through the benchmark example.

This paper presents creep buckling finite element modeling of steel beam-type structure. For beams under sustained loads the loss of stability may occur during a period of exploitation of structure even for loads lower than critical buckling load. For that reason stability is characterized by critical buckling time instead the critical buckling load. The simulation is performed using four nodded Kirchoff- Love theory based shell finite elements. For a space frame, as the test example, critical buckling times are calculated for different levels of applied load, temperature conditions and steel chemical composition.