Indoor Soil Bin Research Articles

Analysis of the movement behaviour of soil between subsoilers based on the discrete element method

The identification of the movement behaviour of soil in the area under the combined effect of two subsoilers (i.e., the area between two subsoilers) is one of the key issues in determining a reasonable inter-subsoiling shovel distance. The present study established a working model of subsoiling using the discrete element method (DEM). Based on this model and an indoor soil-bin experiment, the present study focused on investigating the micro-movement and macro-disturbed behaviour of soil in the area under the combined effect of two subsoilers. The results show the following. (1) The range of transverse and longitudinal disturbance of soil decreased with increasing distance between the soil and subsoiler. The range of disturbance of the soil in the shallow layer was the widest, followed by the range of disturbance of the soil in the middle layer and the range of disturbance of the soil in the deep layer. The simulated and experimental values of the mean displacement of the soil in the shallow layer (tracer blocks with a side length of 10 mm) were 34.81 mm and 34.55 mm, respectively (error: 0.75%). (2) The force on the soil particles in the deep layer was the greatest, followed by the force on the soil particles in the middle layer and the force on the soil particles in the shallow layer. The force on and the velocity of movement of the soil particles at different locations decreased with increasing distance between the soil and subsoiler. (3) The discrete element simulation could accurately simulate the disturbance process of the soil subjected to subsoiling. The sectional profiles of the disturbed soil obtained from the simulation and experiment were consistent with each other. The relative error between the simulated and experimental values of the soil looseness and the soil disturbance coefficient was 14.45% and 12.06%, respectively. Based on the DEM combined with an indoor soil-bin experiment, the present study determined the movement behaviour of the soil in the area under the combined effect of two subsoilers. The results of the present study can facilitate in-depth investigations of the subsoiling shovel–soil interaction and provide a basis for making decisions to optimise subsoiler arrangements.

Measurement and modelling of soil displacement from sweeps with different cutting widths

Soil dynamic properties are important performance indicators for soil-engaging tools. In this study, soil displacement and cutting forces of selected sweeps were measured and simulated. The sweeps had different cutting widths: 153, 280, and 330 mm, and they were tested in an indoor soil bin with a sandy loam soil at a working depth of 50 mm and a travel speed of 1.53 m s−1. A discrete element model was developed using PFC3D (Particle Flow Code in Three Dimensions) to simulate soil-sweep interactions. With the measured soil cutting forces, the model particle stiffness was calibrated to be 3 × 103 N m−1. Results from modelling and measurements showed a general trend of the highest displacements around the centre of the path of sweep, reducing at the further distance away from the centre. Among all directions, measured soil displacements were the highest in the forward direction, up to 608 mm. Measured results showed that forward soil displacements were smaller for smaller sweeps, and lateral soil displacements were lower at a greater depth regardless of the sweeps. Simulated forward and lateral displacements did not contradict these results. Among all the sweeps, the 153-mm wide sweep had significantly higher vertical displacements at all depths as compared to the other sweeps, demonstrated by both measurements and simulations. Overall, the simulated soil displacements were lower than the measured values in all three directions. The accuracy of the model needs to be improved for predictions of soil displacements.

Soil disturbance and cutting forces of four different sweeps for mechanical weeding

Sweeps are the most common tools for mechanical weeding for row-crops. However, how their soil disturbance characteristics are associated with the weeding performance has not been well documented in the literature. The main objective of this study was to evaluate the weeding performance of selected inter-row sweeps through laboratory tests. Four different sweeps, namely: Fin, Conventional, ¾-conventional, and Narrow-wing, were tested in an indoor soil bin at a working depth of 40mm and a travel speed of 8kmh−1 in a sandy loam soil. Soil disturbance characteristics (uprooting and cutting width, burial width, and burial depth), soil cutting forces (draft and vertical), and weeding rates were measured. Based on the ANOVA outputs, all these variables were significantly affected by the treatments at p<0.05, except for the draft force. The ¾-conventional and Conventional sweeps had higher vertical forces than the other sweeps. The Conventional and ¾-conventional sweeps produced an uprooting and cutting width of approximately 260mm, and the Fin and Narrow-wing sweeps resulted in an approximately 7.2% larger uprooting and cutting width. The Fin sweep had the smallest burial width (zero), while the ¾-conventional sweep had the largest burial width (308mm). This trend was also observed for the burial depth. In general, the burial depth decreased exponentially from the centre of the sweep path over the lateral distance. The Fin and ¾-conventional sweeps had over 70% weed kill and these two sweeps are recommended as the best choices for row-crop weed control.

Evaluation of Inter-Row Sweeps with Different Working Widths

Abstract. Little information is available on the performance of inter-row sweeps. The aim of this study was to evaluate the potential of inter-row sweeps for mechanical weed control. Sweeps with different working widths (153, 280, and 330 mm) were tested at different working speeds (0.70, 1.53, and 2.22 m s-1) and a constant working depth (50 mm) in an indoor soil bin with a sandy loam soil. Measurements included soil disturbance characteristics: distance of soil throw (L), width of disturbed soil (W), mass of soil throw (M), height of soil ridge (H), and draft force (Fd). Results showed that L increased linearly with the working speed, but L was not affected by the working width of the sweeps. In contrast, W was slightly affected by the speed, but it was significantly increased if a wider sweep was used. Effects of working speed on M and H depended on the sweep width, and the smallest sweep traveling at 2.22 m s-1 resulted in the highest M and H. Draft force was higher for a wider sweep and a higher working speed. Considering the potential weeding efficiency (defined as the ratio of W and Fd), the width of sweep would not make any differences, and a lower working speed would result in better performance. Keywords: Draft force, Inter-row, Soil disturbance, Speed, Sweep, Weeding.

Bionic Design for Reducing Adhesive Resistance of the Ridger Inspired by a Boar's Head.

The main feature of the boar's head used to root around for food is the front part, which is similar to the ridger in terms of function, load, and environment. In this paper, the boar's head was selected as the biological prototype for developing a new ridger. The point cloud of the head was captured by a 3D scanner, and then, the head surface was reconstructed using 3D coordinates. The characteristic curves of the front part of the boar's head were extracted, and then, five cross-sectional curves and one vertical section curve were fitted. Based on the fitted curves, five kinds of bionic ridgers were designed. The penetrating resistances of the bionic ridgers and traditional ridger were tested at different speeds in an indoor soil bin. The test results showed that bionic ridger B had the best penetrating resistance reduction ratio of 16.67% at 4.2 km/h velocity. In order to further evaluate the performance of the best bionic ridger (bionic ridger B), both the bionic ridger and traditional ridger were tested in a field under the same working conditions. The field results indicate that the bionic ridger reduces penetrating resistance by 6.91% compared to the traditional ridger, and the test results validate that the bionic ridger has an effect on reducing penetrating resistance.

Instrumented Soil Bin for Testing Soil-Engaging Tools

Abstract. An indoor soil bin was developed in this study for testing soil-engaging tools. The design criteria included that the soil bin had to be compact, well controlled in its operational parameters, instrumented to measure soil cutting forces, and be safe to operate. The test tool could travel at any specific speed, up to 8 km h-1. A compact dynamometer was designed for the soil bin for measuring soil cutting forces in three directions. The calibration results of the dynamometer showed a linear relationship between the loads and the output voltages, with coefficients of determination of 0.99. The cross sensitivity between the directions was from 0.31% to 4.7%. The soil bin and the dynamometer were tested using a disc operated at three values of tilt angle of 0°, 10°, and 20°. The test results showed that the soil bin allowed precise control of the tool travel speed and working depth in the designed ranges. Forces of the disc had an increase in vertical and lateral forces, and decrease in draft force, with the increase in tilt angle. These trends are in line with other studies in the literature. The results proved the full-functioning status of the soil bin and the dynamometer. Keywords: Calibration, Design, Disc, Dynamometer, Soil bin, Test, Tilt angle.

A pressure measurement method based on profiling elastic press roller

A novel method was introduced based on a type of profiling elastic press roller to solve the problem that soil compaction pressure is difficult to monitor in real time. The pressure real-time values were acquired through the measurement of the profiling elastic press roller’s eccentricity. In order to evaluate the relationship between the profiling elastic press roller’s eccentricity and the pressure, the study was conducted in an indoor soil bin, in July 2015. Three experimental treatments with soil volumetric moisture content 14.9%, 22.7% and 29.7%, were used in clay soils. The relationship between the profiling elastic press roller’s eccentricity and soil cone index, and the relationship between the static pressure and soil cone index, were investigated. With the equivalent relationship of the cone index, the data was curve fitted and the model equation was established between eccentricity and pressure, in the topsoil layer in which the depth is 0–0.1m. The correlation coefficient values (R2) of the model equation all reached 0.99 at three experimental treatments, indicating the high degree of correlation. In order to evaluate the pressure measurement method, the validation experiments were conducted. The relationship was compared between the cone index predicted from the press roller measurements and the cone index measured from the manual measurements. The results showed that the dots of scatter diagram are all concentrated around the 1:1 ratio line, with high R2 values, at three volumetric moisture contents. These experiments indicate that the predictions were very consistent with the manual measurements, indicating the pressure measurement method based on the profiling elastic press roller can be used into real-time pressure monitoring.

Design and Tests of Biomimetic Blades for Soil-rototilling and Stubble-breaking

Biomimetic blades for soil-rototilling and stubble-breaking were designed learning from the geometrical structure of the tips of toes of mole rat (Scaptochirus moschatus). The orientation, the number and the central angle of the biomimetic structure were taken as the testing factors. The optimal structure of the biomimetic blade was determined through the tests of soil-rototilling and stubble-breaking operation in an indoor soil bin. The optimal combination of the biomimetic structure parameters is that three arc concave teeth are equally arranged on the front cutting edge with a central angle of 60°. The results of comparative tests between the optimal biomimetic blade and a conventional universal blade show the torque acting on the biomimetic blade is lower during soil-rototilling and stubble-breaking operations. The results of field tests show that the working quality of the biomimetic blades meets the requirements of the national standard of China. Tests of soil-rototilling show that, when the orientation of the biomimetic structure was at low and middle levels, the torque of biomimetic blades decreased from 34.17 N·m to 31.03 N·m. The torque also decreased with the increase of the number of biomimetic structure. The average torques were 34.57 N·m, 33.44 N·m and 31.37 N·m, respectively. The maximum different value between two levels of central angle was 0.41 N·m. Tests in field indicate that for soil-rototilling operation, the tillage depth is deeper than 80 mm, the soil-crushing rate (length of soil block less than 40 mm) is over 50 %, and the vegetation coverage rate is over 55 %. For stubble-breaking operation, the stubble-breaking depth is deeper than 70 mm, the stubble-breaking rate (length of stubble less than 40 mm) is over 60%, and the stubble coverage rate is over 80%, which can meet the stubble-breaking requirement of corn.

A 3D Finite Element Simulation Analysis of the Soil Forces Acting on a Rotary Blade

Proper prediction of tillage force is difficult, inconvenient, and time-consuming in field work since many external factors should be taken into consideration. The need for a sound modeling technique to predict tillage force is the motivation for the present work. The finite element method (FEM) is a proven and effective approach for modeling soil-tool interaction. In this study, 3D dynamic simulation models using FEM of a conventional rotary blade were established to predict the effects of rotational speed and direction. The soil was modeled as an elastic-plastic material with elastic parameters such as Young’s modulus, Poisson’s ratio, and the Drucker-Prager criterion, which were obtained from triaxial tests. A general contact algorithm was used to simulate the interaction between the rotary blade and the soil. Two rotational directions and three rotational speeds were analyzed by the finite element model and experimentally verified in an indoor soil bin. A relatively good general correlation was obtained between the finite element simulation and the experimental results. The simulation and experimental results both indicated that applied torque on the rotor shaft increases with rotary speed, and the torque of up-cut rotary tillage is larger than that of down-cut tillage.

Bioinspired design of a ridging shovel with anti-adhesive and drag reducing

Learning from the microstructure of the convex (concave) and ridging (triangle and arc-shaped) shapes of fresh lotus leaves and shark skin, bionic ridging shovels was designed with the characteristics of adhesion and resistance reduction. Ten ridging shovel models were established, and the interaction process with the soil by ANSYS is discussed. Stress analysis results showed that the bionic ridging shovel was more obvious in visbreaking and in the resistance reduction effect. An indoor soil bin experiment with the bionic ridging shovel and the prototype ridging shovel was operated as follows: the ridging resistance of the three types of ridging shovel was tested under the condition of two soil moistures (18.61% and 20.9%) and three different ridging speeds (0.68, 0.87, and 1.11 m/s). In this article, the structure, the mechanism, and their relationship to the functions are discussed. The results of this study will be useful in practical application in the field of agricultural machinery toward practical use and industrialization.

Study on Geometrical and Working Properties of the Parabolic Moldboard

Three forms of model parabolic bulldozing plate were designed and manufactured. Their macroscopic soil-engaging surface directrixes consist of parabolic curve and the cutting angle were 50°, 55°and 60°respectively. The working resistance was measured by a homemade indoor soil bin. The parabolic moldboard model with a cutting angle of 55° has the least working resistance. On this basis, the parametric equations of three kinds of macroscopic soil-engaging surface of parabolic type moldboard were established. The intrinsic geometrical quantities of the macroscopic soil-engaging surfaces, including the first base quantity (E, F, &amp; G) and the second base quantity (L, M, &amp; N), were calculated. Compared with the working resistance test results of the three moldboard models, it is found that there is a specific range of E value in first base quantities and L value in second base quantities which can make the soil-engaging surface to obtain lower resistance. This research provides a reference for the resistance-reducing and energy-saving design of macroscopic soil-engaging surface of moldboard.

Soil disturbance and draft force of selected seed openers

“Soil stepping” is a problem resulting from the accumulation of soil on top of seeds as the result of the excessive soil thrown by adjacent openers. The objective of this study was to characterise soil stepping associated with three different seed openers (hoe, winged hoe, and spoon) when operated at target depths of 25 and 50mm in an indoor soil bin with a sandy loam soil (70gkg−1 sand, 16gkg−1 silt, and 14gkg−1 clay). Soil surface roughness, furrow cross-section, soil throw width, draft force, and vertical force were measured in a soil condition that had an average penetration resistance of 209kPa, an average bulk density of 1184kgm−3, and an average soil moisture content of 25.8%. Soil disturbance characteristics and force requirements increased with the working depth of opener. Averaged for both working depths, the spoon opener created the largest furrow width (113mm) and had the greatest soil throw (450mm). For the controlled soil condition in which the evaluations were conducted, the critical spacing was 219, 255, and 285mm for the hoe, winged hoe, and spoon opener, respectively. These results demonstrated that different openers caused different extents of soil stepping, and the hoe opener was least susceptible to soil stepping. Considering both soil stepping and draft force requirement, the hoe opener showed better performance than the winged hoe and spoon openers.

The behavior of tillage tools with acute and obtuse lift angles

An experimental investigation was conducted to study the trend of draft force against forward speed and working depth for a range of lift angles beyond acute angles for a simple plane tillage tool. The experiments were performed in an indoor soil bin facility equipped with a tool carriage and a soil preparation unit propelled by an integrated hydraulic power system. The system was also equipped with electronic instrumentation including an Extended Octagonal Ring Transducer (EORT) and a data logger. The factorial experiment (4×3×3) with three replications was used based on Randomized Complete Block Design (RCBD). The independent variables were lift angle of the blade (45, 70, 90 and 120°), forward speed (2, 4 and 6 km h-1) and working depth (10, 25 and 40 cm). The variance analysis for the draft force shows that all independent variables affect the draft force at 1% level of significance. The trend of the draft force against working depth and forward speed had almost a linear increase. However, the trend of the draft force against the lift angle is reversed for lift angles &gt;90. This finding, conflicts with the results of analytical and numerical studies which extrapolate the results achieved for acute lift angles to obtuse lift angles and have not been reported experimentally.

RHEOLOGICAL PROPERTIES OF PADDY SOIL UNDER VARIOUS PRESSURE, WATER CONTENT AND TOOL SHAPES

In this study Burger’s four element model was used to analyze rheological parameter of paddy soil of t he Southern China. Two types of tool shape include cir cular shape (with an area of 12.56 cm 2 ) and rectangular shape (with an area of 12.56 cm 2 ) were use to measure the rheological parameter of paddy soil under different loading pressure (7.65, 10.20 and 12.75 k g) and soil water content (27 and 30%), the test wa s carried out an indoor soil bin. The results show th at the Burger model possesses an excellent prospect ive for proper representation of the time dependent behavio r of a stress-strain time graph curve can well imit ate the tool structural change during the soil deformation under different soil water content. Overall results show that, the soil water content has great impact on soil def ormation under different loading pressure, where pr oper tool shapes can control the soil deformation under diffe rent pressure. Soil water content on rheological pa rameter (Em, Ek, λm and λk) were predominantly significant, while loading on rheological parameter (Em, Ek, λm and λk) were not significant. The difference in the mean values among the different levels of M.C and Load has significant difference (p = <0.01) on rheological p arameter in different tool shapes.

Simulation of Bionic Anti-Drag Subsoiler with Exponential Curve Feature Using Discrete Element Method

Subsoiling, as an important mode of conservation tillage, can break plowpan and increase permeability and water retention ability of soil which increase the crop yield. Subsoiler, as a key component of subsoiling, significantly effects on the tillage resistance. Reduction of working resistance of subsoiler can decrease output power of tractor and then further reduce the cost of subsoiling operation. The existing subsoilers have problem of overlarge subsoiling resistance. The conventional methods to resolve such problem include optimal design of the structural parameters of subsoiler and application of oscillation subsoiling device, but those methods not only make the structure of subsoiler more complex, but also increase the cost of agricultural production. Based on biomimetics principles, the upper surface outline of the claw of the house mouse (mus musculus), which has exponential function curve feature, was applied to the structural design of cutting soil edge of subsoiler shaft. Accordingly, the bionic subsoiler which has exponential function curve feature was designed and manufactured. The comparative experiments were conducted using the two types of subsoilers which have exponential function curve shape and parabola type in tillage depth at 300mm and 350mm with the forward velocitys of 0.5m/s and 1.0m/s in the indoor soil bin. The horizontal tillage resistances of the two types of subsoilers were measured using remote-measuring system of agricultural machinery dynamic parameters under different experimental conditions. The results showed that the horizontal tillage resistances increased with the increase of tillage depth and forward velocity. The horizontal tillage resistances of bionic anti-drag subsoiler (BAS) were obviously less than those of parabola type subsoiler (PTS) under same experimental conditions and the reduction was in the range of 8.5-38.2%. It indicated that the cutting soil edge of shaft with exponential function curve structure has remarkable anti-drag property. The simulations of tillage processes of the two types of subsoilers were conducted using discrete element method (DEM), the stress fields and velocity fields were obtained under different simulation conditions. The results showed that the directions of stress fields and velocity fields of the two types of subsoilers have forward and upward variation trend, but the directionality of contact stress of PTS was nonuniform compared with BAS, and such results lead to an increase in soil disturbance. The intensities of stress field and velocity field of BAS were obviously less than those of PTS under same experimental conditions, The results of simulation were consistent with the results of tillage experiments, indicating that the bionic subsoiler with exponential function curve feature has significant anti-drag property. The exponential function curve can be applied to the structural design of cutting soil edge of subsoiler aiming to reduce tillage resistance.

Development of an In-Door Tire Soil Bin Testing Facility Experimental Setup

The field testing may give the real conditions, but the uncontrolled environment may affect the results. In a soil bin, all driving conditions are controlled. Therefore a scaled soil bin was designed and established at MTC. The single wheel tester concludes the dynamic weight equal to that measured statically. Using an indoor soil bin, and measuring sensors the instantaneous wheel speed representing the theoretical speed and free wheel speed representing the actual speed were measured and recorded. Using the signals from two speed sensors, the instantaneous wheel slip is calculated. Also the dynamic sinkage due to wheel motion is measured using ultrasonic sensor. This paper presents a detailed experimental measuring of instantaneous wheel slip and dynamic sinkage on two surfaces; soft dry sand and hard surface. A theoretical control algorithm was developed and implemented. The control system using rotary valve and pressure sensor to control the tire pressure (inflation/deflation) based on the wheel slip ratio and dynamic sinkage.

Effect of travel speed and vertical load on the subsoil force and displacement under a smooth steel roller

A smooth steel roller was tested in an indoor soil bin. Subsoil forces and displacements were measured at depths of 50, 100, 150, and 200mm. Roller operating conditions included roller travel speed, the vertical load, and number of passes. Three travel speeds, 1, 3, and 5kmh−1 and three vertical loads 20, 40, and 60kN were tested. The draft needed to move the roller was also recorded. For multiple passes, subsoil forces were increased by 30% if vertical load increased by 50%; while the roller draft increased by 20%. For a single pass, no significant differences detected between the subsoil forces at speeds of 1 and 3kmh−1; when the roller traveled at 5kmh−1 with a vertical load of 60 kN, the subsoil force was approximately reduced by 30% compared to those at lower travel speeds. For both single and multiple passes, increasing travel speed did not significantly increase subsoil forces and displacement below 150-mm depth; however, the power required to drive the roller was significantly increased. Higher travel speed was more effective in creating larger subsoil displacement and subsoil forces within 100-mm from the soil surface. For similar effects below 100-mm, lower travel speed was found appropriate.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils: Part 2: Draught and Vertical Force Induced on Plough by Brittle Fracture

A method is proposed for soil improvement of salt-affected soils. Large soil clods are produced in subsoil by deep tillage to cut off capillarity from groundwater and to prevent the rise of salts to the soil surface. In this paper, the draught and vertical force induced on this plough body by brittle fracture (not by shear failure) was analysed to get the large soil clods in an indoor soil bin with a soil with cement. The results showed that the normal mean peak draught was about 1 kN, and the downward vertical peak force was about 10 kN at 200 mm in the operating depth. When the blade length was short (50 mm or 80 mm) and huge soil clods were produced, the peak draught and vertical force increased to about 2 kN and 20 kN respectively. When the blade length was long (200 and 250 mm) and the operating depth was deep (150 and 200 mm), the peak draught increased abnormally to 4–5 kN. The peak vertical force also increased abnormally to 30–40 kN. The proper length of the plough blade was determined to be 130 mm because of the smallest draught and downward vertical force.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils: Part 3: Field Experiments

A method is proposed for soil improvement of salt-affected soils to till down to about 600 mm in depth by a special plough. The goal is to cut off the capillary rise of the groundwater by creating a coarse layer of tilled subsoil. Earlier, a plough configuration to produce soil clods with the proper size in the subsoil was determined in an indoor soil bin. In this paper, we designed and tested prototypical plough bodies in field experiments. A plough blade length less than 130 mm produced large soil clods and a blade length more than 130 mm generated small ones. With any length, deeper operating depth caused larger soil clods to form. The proper specifications of the third and fourth plough bodies of the special plough are as follows: the plough blade length is 130 mm, the operating width is 300 mm, the operating depth is 200 mm and the cutting angle is 20°.

Deep Tillage Plough down to 600 mm for Improvement of Salt-affected Soils: Part 1: Configuration of Plough for Production of Large Soil Clods in Subsoil

A method is proposed for soil improvement of salt-affected soils. Soil clods of desired size are produced in subsoil by deep tillage to cut off capillarity from groundwater and to prevent the rise of salts to the soil surface. In this paper, the plough configuration to produce soil clods with the proper size by brittle fracture was analysed in an indoor soil bin. The results showed that when brittle fracture (tensile failure) took place in the soil, a horizontal crack in the soil was produced at the tip of the plough blade, followed by an another upward crack toward the soil surface with the angle of about 40°. A short blade length (50 and 80 mm) and deep ploughing (150 and 200 mm) of the deep tillage plough generated unwanted huge soil clods of about 25 kg. In order to generate proper soil clods, the ideal rake angle should be 20°, and the ideal blade length was 130 mm.