Theoretical background for the bionic substantiation of parameters of the stubble cultivator working bodies

In the southern regions of Russia, the technology of cultivation of grain crops in the variant of partial sowing has been widely used. In this regard, it became necessary to create effective working bodies of a stubble cultivator that would have fundamentally new resource-saving ways of influencing the area under cultivating and meet the requirements of modern advanced technologies. The shapes of the working bodies surfaces of the cultivators were improved taking into account the mechanic-bionic approach. The main parameters of the toothed cutting surface were determined by the method of bionic comparisons, with a scarab beetle as a bionic prototype. Use of the serrated shape of the cutting edge is consistent with the bionic principle of multi-contact exposure and leads to the fact that the tops of the teeth become stress concentrators and, with a significantly smaller indentation force, cause soil destruction processes, which reduces the energy costs of cutting the soil layer. The optimal curvilinear shape of the working surface made in the form of a logarithmic spiral, is characterized by a constant value of the angle between the normal and the radius vector, and the value of this angle, equal to the angle of internal friction of the soil φ2, will ensure the sliding of the soil and plant residues with minimal energy consumption. The number (n = 4), height (h = 5...7 mm) and tooth placement step (S = 10...12 mm) of the bit tip of the stubble cultivator are analytically justified. The shape of the profile of the working surface of the stubble cultivator bit in the form of a logarithmic spiral with a variable angle of crumbling is proposed. The studies were conducted in the period from September to October 2018 in the soil channel of the research Laboratory of Bionic Agroengineering of the Department of Mechanization and Technical Service in Agro-Industrial Complex. They have shown the decrease in the traction resistance of the proposed working body of the stubble cultivator by 16.5% in comparison with the traction resistance of the serial sample

Theoretical prerequisites for the bionic substantiation of spring soil leveler working bodies parameters

In the system of measures for pre-sowing tillage, special attention should be given to leveling the soil, ensuring an increase in the uniformity of seeding in depth, which has a significant impact on increasing yields. The main solution to this problem is to improve the design of aligners using a mechanical-bionic approach for the analytical description of the optimal forms and parameters of their working bodies. The design of the working body of the spring soil leveler is proposed, the cutting edges of the undercutting wings of which have ridges and hollows in the form of a logarithmic curve with a positive convexity of curvature inside the depressions, developed by the bionic prototype of the mole cricket (Gryllotalpa). Using the methods of agricultural mechanics, the theoretical dependence of the rational depth of the working bodies and the value of the tractive resistance of spring soil leveler on the travel speed, design parameters and physical-mechanical soil properties, which are proved by the results of experimental research on the south carbonated middle loamy black earth have been established. The experimental spring soil leveler provided the reduction of traction resistance by 7...8% (40...49 N) and had the best stability of motion in depth by an average of 1.5 times (± 0.5 cm) in comparison with the serial model of the working bodies of the leveler VPN-5.6 A

Substantiation of parametres of springs vibro tines

The most energy-intensive operation in cultivation of agricultural crops is a soil treatment, which spent up to 40% energy. Among the system of measures to reduce the energy intensity of tillers most important is the use of vibration of working bodies. Vibration of working bodies can be carried out using a forced drive. However, the energy costs of a forced drive to work sometimes exceed the energy costs of passive working bodies. Therefore, it is more appropriate to imparting elastic vibration tillage working bodies due to variable soil resistance in accordance with the phases of deformation and destruction of the soil. The most effective is a vibro-impact effects of the working body on the ground with the use of vibro-impact self-adjusting mechanisms. The object of theoretical study is selected construction of cultivators' paws on the resilient C-shaped stand, the upper part of which is designed as a helical coil spring with hemispherical strikers. When making parameters of vibro spring force action it was considered in view of the current soil resistance. In justifying the design parameters and operating conditions it were used theoretical methods and agricultural mechanics, continuum mechanics, elasticity theory, integral and differential calculus. Given the known forces of resistance to movement through the soil of cultivators paws with vibro-impact spring and sediment spring, taking into account the radius of hemispheric drummers on coils of vibro-impact springs theoretical dependences for definition of key parameters of vibro-impact springs were obtained: wire radius, the radius of the vibro-impact spring, and the number of its active coils. Taking into account the maximum permissible load vibro-impact spring should be used for the manufacture of spring wire. Vibro-impact spring will contribute to self-oscillation

Vibration control of linear split Stirling cryogenic cooler for airborne infrared application

Modern infrared imagers often rely on the split Stirling cryogenic coolers the linear compressors of which are the wellknown sources of harmonic disturbance. The traditional method of their passive isolation fails to meet the restraints on the static and dynamic deflections which are originated by the combined action of the airborne g-loading and harsh random vibration. The vibration protection system, which combines a stiff and heavily damped vibration isolator with tuned dynamic absorber, is studied and optimised for use in the design of an airborne infrared device. Such a design is aimed, primarily, at essential dynamic suppression of the harmonic force which is produced by the linear compressor and, secondarily, at minimisation of environmental vibration loads transmitted through the infrared device to the linear compressor. Experimental testing backed up the theoretical results

Vibro-Impact Response of a Cracked Bar

The presence of a crack in a structure affects its dynamic behaviour under working conditions. Cracks introduce nonlinearities into the system; the use of such nonlinearities for damage detection should be investigated. A model of a one-dimensional cracked cantilever bar subjected to longitudinal harmonic excitation is used to analyse a vibro-impact response as a way to monitor structural health. The effect of contact nonlinearity due to crack's faces interaction is considered. This nonlinear information is obtained based on a combination of the analytical technique and the Matlab-Simulink computation. The procedure uses a numerical approximation for dynamic compliance operators and a nonlinear model of contact faces interaction implemented numerically as a nonlinear feedback. Nonlinear resonant phenomena due to vibro-impact interaction in the cracked bar are obtained and analysed. A distribution of the higher harmonics along the bar length, generated due to the nonlinear response of the crack, is revealed as a function of the distance from the crack. Recommendations on structural health monitoring of cracked bars due to contact nonlinearity are presente

Substantiation of the arrangement and parameters of the loosening compacting discs of tillage rollers with a bionic approach

The article presents the methods and results of bionic modeling in agricultural mechanics, which made it possible to substantiate the arrangement and parameters of the working bodies of the loosening compacting discs of tillage rollers adapted to the soil environment using the regularities of the arrangement of thorns on wide rings of the tail in the biological prototype of the girdle tail (Cordylidae). Based on the principle of multi-contact action of the teeth and toothed plates of the roller discs on the soil layer, the coefficient of the arrangement of the discs on the roller is equal to 0.22 ... 0.24, as well as the number of toothed plates and teeth on the working surface of the loosening compacting disc of the roller, which is in the range of 6 ... 12, which is consistent with the arrangement of spines along the circumference of the wide rings on the tail of the girdle. The results of experimental studies, confirming the decrease in the traction resistance of the proposed working bodies of the loosening compacting discs of tillage rollers for surface tillage are presented

Дощування та краплинне зрошення: особливості застосування в сучасних умовах

The article deals with the current state and use of sprinkler equipment and drip irrigation systems in modern conditions. Authors show the factors to be taken into account when restore and develop irrigation in Ukraine.Висвітлено існуючий стан і особливості застосування дощувальної техніки та систем краплинного зрошення в сучасних умовах. Наведено фактори, які мають бути враховані при відновленні та розвитку зрошення в Україні

Dynamics of an impact oscillator near a degenerate graze

We give a complete analysis of low-velocity dynamics close to grazingfor a generic one degree of freedom impact oscillator. This includes nondegenerate (quadratic) grazing and minimallydegenerate (cubic) grazing, corresponding respectively to nondegenerateand degenerate chatter. We also describe the dynamics associatedwith generic one-parameter bifurcation at a more degenerate (quartic)graze, showing in particular how this gives rise to the often-observedhighly convoluted structure in the stable manifolds of chattering orbits.The approach adopted is geometric, using methods from singularity theory