圆盘式开沟机作业功耗仿真分析及试验验证

Experimental verification and simulation analysis on power consumption of disc type ditcher

为探明土壤条件和工作参数对圆盘式开沟机作业功耗的影响规律,该文采用光滑粒子流体动力学方法构建了土壤-开沟刀盘的有限元模型,利用ANSYS软件中的显示动力模块LS-DYNA对开沟刀盘土壤切削过程进行仿真分析,得出开沟刀盘在土壤切削过程中功率消耗的变化规律。结合正交试验设计和数值模拟技术,研究土壤坚实度、刀盘转速和开沟深度对圆盘式开沟机作业功耗的影响规律,得出影响作业功耗的因素主次顺序是土壤坚实度>开沟深度>刀盘转速。采用多变量单目标优化方法,建立关于土壤坚实度、刀盘转速和开沟深度的作业功耗模型,利用Matlab软件对功耗模型进行求解,得出当土壤坚实度为120 N/cm^2,刀盘转速为225 r/min,开沟深度为405 mm时,作业功耗最小为32.4 k W。通过土槽试验对优化结果进行验证,结果表明:理论值与试验值的相对误差为5.68%,作业功耗模型和优化结果具有较高的准确性。该研究可为圆盘式开沟机选择节省功耗的参数组合提供参考。

In order to investigate the general rule of soil conditions and working parameters on power consumption of disc type ditcher, LS-DYNA software which transient dynamic finite element analysis using explicit time integration was employed to simulate the process of soil cutting in this paper, and MAT147 model was used as constitutive model to build soil model, then with given specific parameters, the characteristics of yellow loam in north China was simulated. Due to the complexity of construction for ditching part, the model was initially set up in Soildworks, then imported into LS-DYNA. In order to shorten the operation time, the secondary characteristics such as chamfer, fillet and connection, etc, was omitted. Aiming to study the physical process of soil cutting, we stimulated the finite element model of soil cutting by using Smoothed Particle Hydrodynamics. The deformation of soil was generated when subjected to extrusion of blade. As the amount of deformation was big enough, the soil would be broken. According to the results of simulation, the relationship between power consumption and time of ditching part in soil cutting process was obtained. Any two blades mounted in disk were simultaneously used to assure cutting smoothness and steady. As such, the second blade has been inserted into soil before the first one departed from soil. The total power assumption included kinetic energy from rotational motion of ditching part and internal energy from interaction with soils. At the beginning of soil cutting, power consumption increased quickly, which was caused by a great deal of power consumption needed during the process of soil deformation and broken. According to the results of simulation, it was found that the cutting power consumed was from 0 to 24.2 kW during the time of 0 to 13 ms, the consumption reached maximum 36.26 kW, when cutting motion arrived at the time of 26 ms. After that, the power consumption tended to be stable, indicating that the binding force tended to be less after the soil particle was destroyed. The cutting force was then maintained at steady state, so the power consumption subsequently changed slowly and maintained about 32.5 kW. Orthogonal simulation experiment was carried out with soil firmness, rotation speed of cutting wheel and ditching depth as experiment factors and with power consumption of rotary ditching part as assessment index. It can be concluded that soil firmness, rotation speed of cutting disk and ditching depth had a larger effect on power consumption. Using range analysis method and variance analysis method to determine the importance index for power consumption, the results were： soil firmness, ditching depth, rotation speed of cutting disk. The mathematical model of impact factor and performance index was then established using MATLAB software, the minimum power consumption was 32.5 kW when the parameters of soil firmness, rotary velocity and ditching depth were 120 N/cm2, 225 r/rain and 405 ram, respectively. Finally, the field test was conducted to verify the accuracy of simulation results and optional parameters, it has shown that the relative error between theoretical and testing values was 5.68% showing that the simulated value was basically coincided with testing value, which proved that the modeling and simulating methods adopted met the content requirement. The results provide reference for the product designers to select economic power consumption parameters and working conditions with different working parameters.