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Dynamic properties of screw-bolts connections of sowing machine

Snitynskyy Volodymyr, Kernytskyy Ivan, Diveyev Bohdan, Horbay Orest, Burtak Volodymyr, Humenyuk Ruslan

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

2019

Vol. 28, No. 4

584--593

A vehicle is a complicated system under the influence of vibration caused by an inequality of the road surface, variable speed, unbalance of the rotating elements. The main factors influencing the relaxation of threaded connections (TC) are the amplitude, frequency and gradient of vibration. Although the frequencies of these oscillations are distributed over a wide range, the general effects of dynamic loading on bolted connections are similar. Main effects: (1) loosening the nut/bolt and (2) failure due to fatigue failure. The analysis of the technological process of agricultural machinery shows that the main external factors influencing their work are the profile of the surface of the field, the hardness and moisture of the soil, the speed of the unit, the instability of the engine, the traction of the wheels of the tractor and others. To study the integrity of TC, which is tested on the stand, consider the design scheme of nonlinear oscillations of the design in the presence of gaps in the TC. The study was conducted in two modes of movement of the drill: with tightened bolts and weakened bolts. For the survey, the method of spectral analysis of multidimensional periodically non-stationary random signals was used. In the process of testing, the dynamic loading of bolted joints installed on the respective knots and components of the drill was evaluated. From the conducted research it follows that the maximum vibrations acting on the TC of the drill may be in the vicinity of high-frequency resonances of TC. In parallel, nonlinear mathematical models of the oscillations of the seeder and the weakened TC were developed. The theoretical results qualitatively correspond to the experimental data.

Experimental tests and prediction of the effect of welding technology on fatigue limit of butt joints in 18G2A steel.

Szubryt M., Skorupa M.

Advances in Manufacturing Science and Technology

2005

Vol. 29, nr 2

55-64

A methodology of estimating the fatigue limit of butt joints in 18G2A steel using the Basquin-Morrow equation is presented and the prediction approach is validated through comparisons with the fatigue test results. Three welding processes, namely the manual welding with covered electrodes (manual metal arc welding further referred to as MMA welding), the automated welding in an active gas shielding (metal active gas welding further referred to as MAC welding) and the highly efficient welding in an active gas shielding (transferred ionised molten energy further referred to as T.I.M.E.) have been considered. The main goal of the research was to investigate the effect of the welding process on fatigue limit of the welds and to check the capability of the theoretical model applied to predict the fatigue limit for the specific process of welding.

Przedstawiono wyniki obliczeń wytrzymałości zmęczeniowej złączy doczołowych ze stali 18C2A z wykorzystaniem zależności Basquina-Morrowa oraz ich weryfikację w badaniach eksperymentalnych. Połączenia wykonano trzema metodami spawania: ręcznego elektrodami otulonymi (MMA), zautomatyzowanego w osłonie gazów aktywnych (MAG) i wysoko wydajnego w osłonie gazów aktywnych (T)ME). Określono wpływ technologii spawania na wytrzymałość zmęczeniową badanych połączeń. Ustalono poprawność przyjętych modeli teoretycznych w prognozowaniu wytrzymałości zmęczeniowej połączeń spawanych.