振动深松机多组振动深松铲自平衡性能及仿真分析

振动深松具有减阻的优势,但振动对拖拉机及驾驶员的不利影响制约其推广,该文对振动深松机多组振动深松铲进行自平衡性能分析。在优化试验中,多组深松铲振动作业时的剧烈振动易造成试验设备损坏,仿真试验可避免危险工作环境下的实车试验。对拖拉机-振动深松机系统进行受力分析,并基于ADAMS建立其仿真模型,建模过程包括导入三维模型、定义轮胎与地面之间接触力和摩擦力等。理论与仿真分析相互验证,得到拖拉机后轮所受支持力均值分别为27.8、26.4 kN,误差为1.4 kN,并且二者主振动曲线变化趋势一致。采用加权加速度均方根值评价振动对驾驶员的影响。通过MATLAB编程,利用功率谱密度函数,计算得到驾驶座质心总加权加速度均方根值。利用Design-Expert软件设计试验并优化得到6组振动影响较小的四组振动松土铲作业初始相位角组合,减振比率超过90%,实现了振动深松机作业时的自平衡。

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.