The energy required for tillage processes accounts for a significant proportion of total energy used in crop production.In many tillage processes decreasing the draft and upward vertical forces is often desired for re...The energy required for tillage processes accounts for a significant proportion of total energy used in crop production.In many tillage processes decreasing the draft and upward vertical forces is often desired for reduced fuel use and improved penetration,respectively.Recent studies have proved that the discrete element modelling(DEM)can effectively be used to model the soil–tool interaction.In his study,Fielke(1994)[1]examined the effect of the various tool cutting edge geometries,namely;cutting edge height,length of underside rub,angle of underside clearance,on draft and vertical forces.In this paper the experimental parameters of Fielke(1994)[1]were simulated using 3D discrete element modelling techniques.In the simulations a hysteretic spring contact model integrated with a linear cohesion model that considers the plastic deformation behaviour of the soil hence provides better vertical force prediction was employed.DEM parameters were determined by comparing the experimental and simulation results of angle of repose and penetration tests.The results of the study showed that the simulation results of the soil-various tool cutting edge geometries agreed well with the experimental results of Fielke(1994)[1].The modelling was then used to simulate a further range of cutting edge geometries to better define the effect of sweep tool cutting edge geometry parameters on tillage forces.The extra simulations were able to show that by using a sharper cutting edge with zero vertical cutting edge height the draft and upward vertical force were further reduced indicating there is benefit from having a really sharp cutting edge.The extra simulations also confirmed that the interpolated trends for angle of underside clearance as suggested by Fielke(1994)[1]where correct with a linear reduction in draft and upward vertical force for angle of underside clearance between the ranges of-25 and-5°,and between-5 and 0°.The good correlations give confidence to recommend further investigation of the use of DEM to model the different types of tillage tools.展开更多
The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,includi...The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,including diesel fuel(B0)and three biodiesel blends made of canola oil(B10:10%biodiesel+90%petro-diesel blend;B20:20%biodiesel+90%petro-diesel blend;B30:30%biodiesel+90%petro-diesel blend).The performance characteristics evaluated were PTO power,engine torque,engine fuel consumption,and specific fuel consumption.Due to sharp slopes in measured quantities around the nominal engine speed(2200 r/min),compared to the standard regression method,the spline regression models suited well to the experimental data with coefficient of determination R2=0.99 for PTO power and engine torque.R2 varied between 0.97 and 0.99 for fuel consumption and 0.91 and 0.95 for specific fuel consumption.The weaker correlation found for specific fuel consumption could be attributed to profound fluctuations in measured data causing atypical pattern in the corresponding graphs around the nominal engine speed.It was concluded that splines were useful to accurately predict the measured PTO power and engine torque.Neither standard methods nor splines were sufficient to obtain very good regression models for specific fuel consumption.展开更多
基金The authors acknowledge the support of the University of South Australia–Australia for granting of a post graduate scholarship to Mustafa Ucgulthe Australian Grains Research and Development Corporation(GRDC)project USA00005 for funding the computer and software.
文摘The energy required for tillage processes accounts for a significant proportion of total energy used in crop production.In many tillage processes decreasing the draft and upward vertical forces is often desired for reduced fuel use and improved penetration,respectively.Recent studies have proved that the discrete element modelling(DEM)can effectively be used to model the soil–tool interaction.In his study,Fielke(1994)[1]examined the effect of the various tool cutting edge geometries,namely;cutting edge height,length of underside rub,angle of underside clearance,on draft and vertical forces.In this paper the experimental parameters of Fielke(1994)[1]were simulated using 3D discrete element modelling techniques.In the simulations a hysteretic spring contact model integrated with a linear cohesion model that considers the plastic deformation behaviour of the soil hence provides better vertical force prediction was employed.DEM parameters were determined by comparing the experimental and simulation results of angle of repose and penetration tests.The results of the study showed that the simulation results of the soil-various tool cutting edge geometries agreed well with the experimental results of Fielke(1994)[1].The modelling was then used to simulate a further range of cutting edge geometries to better define the effect of sweep tool cutting edge geometry parameters on tillage forces.The extra simulations were able to show that by using a sharper cutting edge with zero vertical cutting edge height the draft and upward vertical force were further reduced indicating there is benefit from having a really sharp cutting edge.The extra simulations also confirmed that the interpolated trends for angle of underside clearance as suggested by Fielke(1994)[1]where correct with a linear reduction in draft and upward vertical force for angle of underside clearance between the ranges of-25 and-5°,and between-5 and 0°.The good correlations give confidence to recommend further investigation of the use of DEM to model the different types of tillage tools.
文摘The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,including diesel fuel(B0)and three biodiesel blends made of canola oil(B10:10%biodiesel+90%petro-diesel blend;B20:20%biodiesel+90%petro-diesel blend;B30:30%biodiesel+90%petro-diesel blend).The performance characteristics evaluated were PTO power,engine torque,engine fuel consumption,and specific fuel consumption.Due to sharp slopes in measured quantities around the nominal engine speed(2200 r/min),compared to the standard regression method,the spline regression models suited well to the experimental data with coefficient of determination R2=0.99 for PTO power and engine torque.R2 varied between 0.97 and 0.99 for fuel consumption and 0.91 and 0.95 for specific fuel consumption.The weaker correlation found for specific fuel consumption could be attributed to profound fluctuations in measured data causing atypical pattern in the corresponding graphs around the nominal engine speed.It was concluded that splines were useful to accurately predict the measured PTO power and engine torque.Neither standard methods nor splines were sufficient to obtain very good regression models for specific fuel consumption.
