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

This paper presents investigations of vibrations of cantilever beams with piezoelectric layers. The paper discusses the contemporary engineering and scientific software systems in order to select the appropriate for the study of mechanical and electrical dynamic behavior of piezoelectric beams.The system COMSOL has been chosen and a study with it has been stated with a static analysis and an eigenvalue analysis. Conclusions are made and a frequency response and time dependent investigations are planned to be done.

The paper is devoted to objectification and determination of the influence of hand-arm vibrations with selected machinery. We permanently meet with vibrations, but especially when performing work activities. When working with machinery, a person is constantly exposed to vibrations and they can very negatively affect the health of the person. The aim of the paper is to compare measured vibration values with the manual of the device and then to determine the maximum time exposure for work activities to avoid the employee being at risk of working with the device. Comparison of a final hand-arm vibration will be assessed by means of the hand-arm exposure calculator and software for a specific measuring device – vibration analyzer of the 4447 type. The proposed method – an extended risk matrix – is used to assess the risks of hand-arm vibration.

On the manufactured enlarged version of the flotation device with a high-pressure rotary pulsating aerator (HFRPA), investigations and tests were conducted on refractory finely minified gold-bearing ore samples. The experiment and practice of flotation with the developed by the authors HFRPA showed that the pressure fluctuations created by the aerator ensure the efficiency of the functional use of the two periods. Which is the dissolution of additional gases in the high-pressure compression period, which ensures the aeration process with the required amount of dissolved gases and pseudo cavitation emission of gases in the medium rarefaction period, and this provides aeration with gas separation from the aqueous phase directly on hydrophobic mineral micro particles, i.e. micro dispersions selective flotation.

The article deals with a problem of fatigue load calculations when designing the aircraft wing. Much of fatigue damage is done to the wing by occasional air gusts in turbulent atmosphere. Therefore, the author considers the pattern of continuous atmospheric turbulence that gives an idea of low-altitude gusts. It is at low altitudes that nonstandard flights are performed for which it is wrong to use the statistical data on fatigue damage available from the previously operated airplanes of the same class. The method is offered to determine the equivalent bending moments along the wing span in discrete flight modes and within the entire routine flight. The above method takes into account the profile parameters of routine flights, the dynamic vibrations of the wing and fatigue characteristics of the structural material. To prove the reliability of the method the calculation results have been compared to those of medium-range aircraft testing flights.

The vibrations caused by road-building machinery affect drivers equally harmful to the three axes of the coordinate system.
Assessment of exposure to vibration hand-arm system is based on the calculation of daily exposure value for the 8-hour A (8).