EMERGENCE OF PARAMETRIC VIBRATIONS AND RESONANCES IN THE CULTIVATORS WITH AN ELASTIC SUSPENSION OF TILLAGE TOOLS
National University of Bioresources and Wildlife Management of Ukraine
The research devoted to the vibration process of cultivator’s tillage tools on the soil cultivated demonstrated the possibility of significant (20% and more) re-duction of cultivating machines’ tractive resistance, as well as improvement of agrotechnical performance of the soil cultivation. Calculations of rational parame-ters for tillage tools interaction with the soil (during which the decrease in tractive resistance is observed) may be conducted on the basis of two concepts of energy transfer between the tillage tools and the cultivated environment. The first con-cept – the key resonance appears in the system, that means that oscillation frequen-cy of cultivator share matches with the oscillation frequency of the soil. This con-cept refers to the linear problems. The second concept – considering significant nonlinearity of share and visco-elastic-plastic substance of the environment, it should be considered as the most favorable conditions for the occurrence of sub-resonance, that is, the oscillation frequency of share almost equals (asymptotically) to the frequency of oscillation of the soil. Appropriate suspension settings can be selected by using the theory of parametric oscillations. Such periodically variable parameter is the elastic stiffness of the suspension, provided that the characteristic of the restoring force is nonlinear. In the article the conditions for the occurrence and stability of parametric vibrations and resonances in the elastic suspension cul-tivator shares are described, and found the values of the wavelength of the cleavage of the soil are defined which depend on the speed of tillage aggregate and the natu-ral frequency of the system. It is also defined within the model equations of Mathieu-Hill and Meissner the analytical relations describing the instability areas of parametric variations, which become possible in the cultivators with an elastic suspension of the tillage tools.
Keyword(s): Parametrical vibrations, resonances, cultivator, resilient suspension, tillage
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Agricultural Engineering ISSN 1392-1134 / eISSN 2345-0371
This journal is published under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License. Responsible editor: Dr A. Žunda.