Self-balancing performance and simulation analysis of multi-group vibrating sholvels of oscillatory subsoiler

Abstract: Oscillation tillage could reduce the drag resistance and power consumption during tillage. But the oscillation has a bad effect on tractor driver. In order to do vibration analysis, a four-tine oscillatory subsoiler and a tractor model were designed using 3D modeling software in this study. In the process of oscillation tillage, the tillage forces and inertia force were unbalanced, these force transferred to the tractor and driver, and negatively impact them to some extent. These vibrations prevent the spreading use of oscillatory subsoiler. Therefore, it is necessary to conduct a vibration optimization test. The simulation optimization test could avoid the real car test in the dangerous working environment. A simulation model of the tractor-subsoiler system was established based on ADAMS. The modeling process had four parts, including introduction of 3D model, adding constraints, loading, defining the contact force and friction between tire and ground. During the contact force definition part, on the basis of the wheel damping coefficient-cut depth curve and the adhesion coefficient-slip rate curve of a running tractor, the contact force and friction force between tire and soil was defined by using the STEP function. This could improve the accuracy of the simulation model. During the contact force definition part, related research had shown that the maximum draft occurred during the period tine had their top face active (cutting) and the minimum draft occurred during the period tine had their underside active (backward). The statistical results showed that a sinusoidal force relationship was between these two peaks. In order to get the actual draft force of the tine during oscillation tillage, a single group tine oscillation tillage test was carried out in the soil bin, and the single tine draft force curve was obtained using statistical software. After that, the optimization tests were started. During the tests, the experimental index was the vibrations at the tractor driver's seat. The working parameters to be considered were each tine's initial phase angle of oscillation. The tests result showed that the theoretical and simulation analysis verifies each other. The mean value of the supporting force in the rear wheel of the tractor was 27.8 kN, 26.4 kN, respectively, the error was 1.4kN, and the tendency of the main vibration curve was consistent. The optimization goal was to reduce the root mean square of weighed acceleration on the tractor seat. According to the evaluation index of whole body vibration of agricultural wheeled tractor driver (GB/T13876-2007), the influence of vibration on the driver was evaluated by using the mean square root of weighted acceleration. By using the power spectral density function in MATLAB, the mean square root of the total weighted acceleration of the driving seat was calculated. Related research showed that the relative changes of the initial phase angle of the various groups affected the vibration size of the seat. During the test of four-group vibrating shovels of oscillatory subsoiler, we fixed one of the break shovel initial phase angle of 0°. The other three groups break shovel initial phase angle range of 0-360 °. The relative changes of multi-group vibrating shovels' initial phase angle can influence seat's vibration. The test for three factors can be used to consider the influence of four-group initial phase angles. As such, the test could reduce the test factors and test times. Using optimal design in Design-Expert software, the quartic order regression model was founded. According to the regression analysis, the variance analysis was obtained, and the R-squared, Adj R-squared, Pred R-squared were 0.8948, 0.8411, and 0.765, respectively, and the regression model was good. Six groups for the optimal solution of initial phase angle combination were obtained by using the regression model. Compared with the un-optimized combination, the vibration reduction ratio was over 90%, and the self-balance of the oscillatory subsoiler was realized.