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

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/min and 405 mm, 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.