Abstract: In this paper a 3-D finite element (FE) investigation of soil-blade interaction is described. The effects of blade’s shape and rake angle are examined both numerically and experimentally. The soil is considered as an elastic-plastic granular material with non-associated Drucker-Prager material model. Contact elements with different properties are used to mimic soil-blade sliding and soil-soil cutting phenomena. A separation criterion is presented and a procedure to evaluate the forces acting on the blade is given and discussed in detail. Experimental results were derived from tests using soil bin facility and instruments at the University of Saskatchewan. During motion of the blade, load cells collect data and send them to a computer. The measured forces using load cells had noisy signals which are needed to be filtered. The FE results are compared with experimental results for verification. This technique can be used in blade shape optimization and design of more complicated blade’s shape.
Abstract: Evaluating and measuring the performance parameters of wheels and tillage equipments under controlled conditions obligates the use of soil bin facility. In this research designing, constructing and evaluating a single-wheel tester has been studied inside a soil bin. The tested wheel was directly driven by the electric motor. Vertical load was applied by a power bolt on wheel. This tester can measure required draft force, the depth of tire sinkage, contact area between wheel and soil, and soil stress at different depths and in the both alongside and perpendicular to the direction of traversing. In order to evaluate the system preparation, traction force was measured by the connected S-shaped load cell as arms between the wheel-tester and carriage. Treatments of forward speed, slip, and vertical load at a constant pressure were investigated in a complete randomized block design. The results indicated that the traction force increased at constant wheel load. The results revealed that the maximum traction force was observed within the %15 of slip.
Abstract: Offset Double-Disk Opener (DDO) is a popular
furrow opener in conservation tillage. It has some limitations such as
negative suction to penetrate in the soil, hair pinning and mixing seed
and fertilizer in the slot. Because of importance of separation of seed
and fertilizer in the slot, by adding two horizontal mini disks to DDO
a modified opener was made (MDO) which placed the fertilizer
between and under two rows of seed. To consider performance of
novel opener an indoor comparison test between DDO and MDO was
performed at soil bin. The experiment was conducted with three
working speeds (3, 6 and 8 km h-1), two bulk densities of soil (1.1
and 1.4 Mg m-3) and two levels of residues (1 and 2 ton ha-1). The
experimental design consisted in a (3×2×2) complete randomized
factorial with three replicates for each test. Moisture of seed furrow,
separation of seed and fertilizer, hair pinning and resultant forces
acting on the openers were used as assessing indexes. There was no
significant difference between soil moisture content in slots created
by DDO and MDO at 0-4 cm depth, but at 4-8 cm the in the slot
created by MDO moisture content was higher about 9%. Horizontal
force for both openers increased with increasing speed and soil bulk
density. Vertical force for DDO was negative so it needed additional
weight for penetrating in the soil, but vertical force for MDO was
positive and, which can solve the challenge of penetration in the soil
in DDO. In soft soil with heavy residues some trash was pushed by
DDO into seed furrow (hair pinning) but at MDO seed were placed at
clean groove. Lateral and vertical separation of seed and fertilizer
was performed effectively by MDO (4.5 and 5 cm, respectively)
while DDO put seed and fertilizer close to each other. Overall, the
Modified Offset Double-disks (MDO) had better performance. So by
adapting this opener with no-tillage drillers it would possible to have
higher yield in conservation tillage where the most appropriate
opener is disk type.