Development of Powered Groundnut Harvester for Small and Medium Holdings in North Kordofan State in Western Sudan

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Figure 2. Digger with 20 cm length and 10 rear base width

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2.2.1.2. Material Definition for Mesh Generation

Since digger material is 1020 steel which characterized by plasticity, stress stiffening, large deflection and large strain capability, solid 45, 8 nodes element type and elastic isotropic material model were used for meshing.

2.2.1.3 Boundary Conditions

Digger model was constrained at its top rear end and its upper surface was subjected to arbitrary load of 100 kPa.

2.2.1.4. Solution for Boundary Problem and Post-Processing

The reaction of digger is linear problem, so, the contour plot was read and the principal stress in X direction and shear stress in XZ plane were recorded for each digger design and the output of simulation were demonstrated in Figure 3, Figure 4, Figure 5, Figure 6 and Table 1.

Table 1. Stress distribution on surface of different digger

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Figure 3. Shear stress in XZ plane on 25 cm long digger

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Figure 4. Stress in X direction on 25 cm long digger

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Figure 5. Shear stress in XZ plane on 20 cm long digger

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Figure 6. Stress in X direction on 20 cm long digger

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Figure 7. Machine dimensions

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Figure 8. Motion transmission system

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Table 2. Specification of the machine

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2.2.2. Machine Fabrication

The results of computer simulation in Table 1 showed that the optimum dimensions of digger that demonstrated the lowest stresses distribution were 20 cm length and 10 cm base width, therefore, these dimensions were adopted to manufacture the machine diggers. The machine with specifications in Table 2 was fabricated in a workshop of agricultural machineries in Elobied Industrial Area. The machine and motion transmission system part and dimensions were shown in Figure 7 and Figure 8 (a and b)

2.2.3. Soil Test

Soil samples were taken from two different locations in North Kordofan State at depth 30 cm, the moisture content on dry base and soil bulk density for the samples were determined. Tri-axial soil test apparatus and shear box were used to measure soil cohesion and internal angle of friction, while soil adhesion measurement apparatus was used to determine soil adhesion pressure with steel and the soil physical and mechanical properties were shown in Table 1.

Table 3. Soil physical and mechanical properties

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2.2.4. Measurements of Field Performance Parameters

The field work was conducted in two the locations, the experiment was carried out in 8 plots grown with groundnut in each location, the area of the plot was 100 m x 4.6 m.

2.2.4.1. Measurement of Time

The machine was operated in the plot and the time was recorded using stop watch. The turning time at ends of the plot was determined.

Total time was computed by adding effective time to turning time and other field stops time.

2.2.4.2. Fuel Consumption Measurement

The fuel consumption rate was detected as follows:

The machine started working the plot with full tank, after finishing the plot, the tank was refilled using measuring cylinder. The amount of fuel used to refill the fuel tank was recorded. The fuel consumption rate was calculated as follows:

(8.5)

Where,

FCR = fuel consumption rate, L / ha.

CR = reading of cylinder, ml.

A = area, m2.

C1 = conversion factor, ^[10].

2.2.4.3 Measurement of Speed

The digging velocity was the calculated as follow

(1)

Where,

S = digging speed, km / h.

D = travelling distance, m.

t = time, s.

C2 = conversion factor, [3.6].

2.2.4.4. Measurement of Theoretical Field Capacity

Theoretical field capacity in each plot was computed using the following equation

(2)

Where,

TFC = theoretical field capacity, ha/h.

S = digging speed, km / h.

W = working width, m.

C₃ = conversion factor, ^[10].

2.2.4.5. Measurement of Effective Field Capacity

Effective field capacity was calculated as follows

(6.3)

Where,

EFC = effective field capacity, ha/h.

A = plot area, m².

T = time, sec.

C₄ = conversion factor, [0.36].

2.2.4.6. Measurement of Field Efficiency

(7.3)

3. Results and Discussion

The views and motion transmission system of the fabricated harvesting machine were shown in Plate 1, Plate 2 and Plate 3. Field time and fuel consumption rate were demonstrated in Table 4 while field speed, field capacities and efficiency were shown in Table 5.

Plate 1. Side view of the machine (diggers and rotating cylinder at raised position)

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Plate 2. Frond view of the machine

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Plate 3. Second phase motion transmission (from middle gear to rotating cylinder)

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Table 4 showed that the effective time and total time recorded by the machine in sandy soil were lower than effective time and total time recorded in clayey sand soil by 0.050 hr. It was also demonstrated that fuel consumption rate in sandy soil was lower than that in clayey sand soil by 0.7 L / ha. Since the clayey sand soil is characterized by higher bulk density, cohesion and adhesion force as compared to sandy soil, therefore, the field time and fuel consumption rate in clayey soil were higher than in sandy soil and the differences between soil types were found to be significant at 0.05 level.

Table 4. Field time and Fuel consumption in two locations

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Table 5. Field speed, capacities and efficiency in two locations

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