EMERGENCE OF PARAMETRIC VIBRATIONS AND RESONANCES IN THE CULTIVATORS WITH AN ELASTIC SUSPENSION OF TILLAGE TOOLS

Abstract

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.