Discrete element modeling of cultivator sweep-to-soil interaction: Worn and hardened edges effects on soil-tool forces and soil flow

Abstract

Simulation of tool-to-soil interaction provides opportunities to accelerate new equipment design and evaluate performance of tillage tools. Simulation based evaluation of worn tillage tools performance on soil flow has not been done. Discrete Element Modelling (DEM) has a potential to simulate worn tool to soil interaction problems, where worn tools CAD can be generated using 3D scanning. The DEM parameters of Hertz-Mindlin with Parallel Bond model were calibrated to match draft force and soil failure zone measured from a tool bar moving at 0.22 m/s and 38 mm cutting depth. The draft force and soil forward failure zone were predicted at 7% and 24% relative errors compared to measured values, respectively. Using the optimized DEM soil model, the interaction of three 3D reconstructed sweeps (new sweep, carbide treated-worn, untreatedworn) with soil were simulated to compare their geometric wear dimensional loss, performance on soil forces and soil flow. Results showed that the carbide treated-worn sweep had similar soil draft force and soil forward failure distance as the new sweep. The untreated-worn sweep showed lower vertical force (less suction) and its wing induced soil failure zone (front and lateral) showed poor soil tilth quality compared with the carbide treated-worn sweep and the new sweep.

Applications of Discrete Element Method in the Research of Agricultural Machinery: A Review

“…There are two common methods for calibrating the contact and constitutive parameters [15,49]. The first is determining the parameters directly with test apparatus; the second is comparing the simulated dynamic or mechanistic behaviors with the experimental ones through a repose angle test (Figure 2a), direct shear test (Figure 2b), triaxial pressure test (Figure 2c), and tillage test, by changing the parameter value until the error between the simulation and experimental results was controlled in a limited range, optimal parameter values could be obtained [17,27,29,[50][51][52]. Friction coefficient is one of the most important parameters influencing soil dynamic behavior, including the static and rolling friction coefficient between soil particles, and the static and rolling friction coefficient between soil particles and the contact materials.…”

“…Table 1 summarizes the commonly used soil contact models and key model parameters in the published literature. Steel [53] Elasticity modulus [18] Particle stiffness [16] Hertz-Mindlin with bonding Norfolk sandy loam soil [52] Clay soil in South China [31] Loam clay soil [32] [ 53,54] [53] Steel [53] Steel [54] Steel [54] Between soil particles [55] Between soil particle and contact material [55] Shear modulus [53] Poisson's ratio [53] Bond normal stiffness [52] Bond shear stiffness [52] Critical stress of the bond [32] PBCM * Sandy loam soil [22,56] Sandy soil [56] Sandy soil [27,57] [56]…”

Microstructure and Soil Wear Resistance of D517 Coating Deposited by Electric Spark Deposition

“…According to the soil adhesion mechanics [39], the soil adhesion Fq can be used in the formula to indicate: 𝐹 𝑞 = 𝑓′ 𝑚 (𝑁 𝑚 + 𝑆 ∑ 𝑁 𝑛𝑖 ) + 𝑆 ∑ 𝑁 𝑛𝑗 + 𝐹 𝑓 (5) Where the Nm is the gravity of the soil to the sample, Nni is the force of the normal direction adhesion, Nnj is the tangential direction adhesion force, Ff is the viscous force between the moisture in the dimples and the soil water film, f'm is the proportional coefficient between normal force and tangential resistance, and S is the contact area between soil and metal Figure 9b shows the weight loss of the D517 coatings as a function of the test time under the accelerated wear simulation tests. Additionally, the normalized 65 Mn was tested as reference.…”

“…The accumulation of soil abrasion would lead to passivated outer corners and reduce contour [4]. The wear rate is mainly influenced by soil mechanical conditions, the working surface structure of the parts, and the component materials of the agricultural parts [5]. Therefore, it would be helpful to obtain the wear regularity and understand the wear mechanism of the furrow openers in the soil for improving the wear resistance of furrow openers.…”

Comparative assessment of discrete element methods and computational fluid dynamics for energy estimation of the cultivator working bodies

“…At the same time the spread of data obtained by DEM-modeling for different values of the static friction coeffi cient goes up to 20%. Studies on the infl uence of the static friction coeffi cient on the tractive resistance of the working instrument in DEM-modeling is presented in the works of [17,[28][29][30].…”