Simulation of the dynamic behaviour of a tractor-oscillating subsoiler system

A two-tine oscillatory subsoiler was developed at the University of South Australia for fracturing the compacted soil layers between grapevines using small tractors. As the soil forces exerted on the tines were unbalanced, the tillage forces, torque peaks through the power-take-off and the inertia of the tines transferred vibrations to the tractor and its driver. These vibrations currently prevent the commercial use of soil loosening settings that require the lowest engine power to be used.A simulation model is presented that calculates the dynamic behaviour of the tractor-oscillating subsoiler system with the focus being on the vibrations at the tractor driver’s seat. The model considers the three oscillatory tillage phases of soil cutting, backing-off and catching-up, with positive and negative oscillation angles; tine inertia and the various tyre stiffness and damping parameters.The results of the simulation were compared to field measurements and a good correlation of both the magnitude of root mean square (RMS) acceleration and the response to change in the oscillatory tillage parameters of amplitude, frequency and oscillation angle were obtained.