Study On Vibration Excavation Perpendicular To Cutting Direction And Its Drag Reduction

The main problem potato harvesters face is that excavation resistance is excessively large,which would give rise to the lack of power as well as the accelerating abrasion of excavating device so that the cost would increase.Compared with fixed excavator,the vibratory one could relatively reduce excavation resistance to some extent.The excavation resistance of vibratory excavator is affected by traction speed,penetration angle,vibration frequency and amplitude.It is of great significance to analyze the influence of different traction speed,penetration angle,vibration frequency and amplitude on excavation resistance.Aiming at reducing excavation resistance,vibratory excavating device perpendicular to cutting direction was designed.And numerical simulation on soil cutting process of vibratory excavating device was conducted to get obtain the excavation resistance.Excavation resistance at different parameters was analyzed in order to study the influence of traction speed,penetration angle,vibration frequency and amplitude and figure out the optimal parameter combination.The excavation resistance at optimal parameter combination was compared with that of fixed excavator and the effect of vibratory excavating was studied.The main contents are as follows:(1)Soil parameters affecting the excavation resistance were studied and soil water content was detected.Soil crushing method and yield criterion were studied to determine the soil constitutive model adopted in the numerical simulation of soil excavation.The characteristics of vibratory excavator and the principle of vibratory excavating were analyzed,which provided the theoretical basis for the design of vibratory excavating device perpendicular to cutting direction.(2)According to potato planting mode and excavator design requirements,vibratory excavating device perpendicular to cutting direction was designed.The excavator amplitude calculation model was established and its amplitude was calculated,and trajectory equation of excavator was established and kinematic simulation was carried out.Kinematic simulation result was compared with the results of amplitude calculation and trajectory equation of excavator,the calculation and simulation results proved consistent,which showed the accuracy of excavator amplitude calculation model and trajectory equation.In addition,according to modal analysis,the driving frequency and the first-order natural frequency were found greatly different so that resonance would not come up.Thus the device structure was reasonable.(3)Numerical simulation analysis process of soil cutting was established.The model boundary condition and load were set by means of MAT147 soil constitutive model and vibratory excavator model.Soil cutting process of vibratory excavator was numerically simulated by means of software LS-DYNA,and excavation resistance was obtained,and it showed that the reason why excavation resistance was cyclically changed was that the motion of excavator was cyclical.(4)Analysis on excavation resistance at different parameters was carried out.Influence of traction speed,penetration angle,vibration frequency and amplitude on the excavation resistance was analyzed through single-factor test.Through multi-factor orthogonal test and range analysis,the results showed that order of the influence of excavation resistance is: vibration frequency> amplitude> traction speed>penetration angle,and the optimal parameter combination was obtained when the excavation resistance was minimum.Under the optimal parameter combination condition,numerical simulation on fixed excavator was carried out,and it was found that the excavation resistance of vibratory excavation was reduced by 37.1% in comparison to that of fixed excavator.