Vibrational dynamics in 2D crystal lattices of borophene

Vibration dynamics of crystalline borophene is considered in the framework of the Born–von Karman model. The vibrations perpendicular to the plane of 2D borophen lattice (flexural modes) are studied.

Numerical investigation on effect of internal flow on vortex-induced vibration dynamics of a full-scale mining riser

The dynamics of a full-scale pipe conveying fluid inside is investigated based on the finite element method (FEM). During the numerical simulation, the Euler–Bernoulli beam equations are used to model the motion of the full-scale pipe while the effect of internal flow is considered. And the semi-empirical time-domain model is applied to simulate the external hydrodynamic forces exerted on the pipe. Then the typical vortex-induced vibration (VIV) characteristics of the full-scale pipe considering both internal and external flows are analyzed. The results show that with the increase of the internal flow velocity, the natural frequencies of the full-scale pipe decrease and the in-line (IL) and cross-flow (CF) dominating modes are increased. Furthermore, the dominating frequencies in both IL and CF directions are not notably changed. And the IL and CF root-mean-square (RMS) values of amplitudes fluctuate at around the stable values due to the stable external hydrodynamic forces. It should be noticed that the IL and CF RMS strain values of the full-scale pipe are increased, especially for high external and internal flow velocities. The maximal RMS strain values in both IL and CF directions appear next to the pipe top, which could have an influence on the motion of the ship on the sea surface.

Minimizing tool vibrations when turning metals, as a method of energy-efficient cutting

Taking into account the interrelated vibration dynamics of cutting and the temperature in the cutting zone allows you to determine the most successful state or cutting mode in terms of energy costs. Purpose of the work: by forming a consistent model, determine the most convenient mechanism for the mode of operation of the cutting system, in which the further wear of the cutting wedge will be stabilized, the cutting force will also be stabilized, as well as the temperature in the cutting zone and the vibration of the tool. The paper examines: The process of metal processing by cutting on a lathe for the case of longitudinal turning of the product. Research methods: The research consists of a series of field experiments on real equipment using a modern measuring stand STD. 201-1, as well as using an experimental complex developed by us. Results and discussion. The results of processing experimental data, in particular, the results of measuring cutting forces, temperature and tool vibrations, are presented. The mechanism of stabilization of the processing process due to the relationship between temperature and vibrations during cutting and the formation of a quasi-stationary cutting mode is experimentally proved. It is assumed that due to the practical application of the results obtained in the work, it will be possible to increase the energy efficiency of metal processing by reducing the energy cost of vibration of the cutting wedge.