Simulation of soil-tool interaction using smoothed particle hydrodynamics (SPH)

Abstract

Numerical techniques in soil-tool interaction play a critical role in the applications of optimal design and optimal control of soil-engaging components. However, one of the greatest challenges in the simulation of soil-tool interaction is the complex dynamic behaviors of the soil in the regime of large deformations, and the analysis and evaluation of forces at the soil-tool interface. Recently smoothed particle hydrodynamics (SPH) has shown its advantages in modeling large deformation problems with deformable boundaries and moving interfaces. In this paper, an SPH model of soil-tool interaction based on the elastoplastic constitutive is established. Firstly, the cutting process and soil-tool interaction for both non-cohesive and cohesive soil are simulated based on a shear failure model and a contact algorithm. The simulation results for non-cohesive soil and cohesive soil in different operating conditions are discussed separately, and the results for different operating conditions are compared. In addition, interactions between soil and inclined short flat blades are also simulated to estimate the cutting force during the tillage process. The predicted soil configuration and cutting force are in good agreement with our experiments and with the results in published literature. The cutting forces for non-cohesive soil exhibit similar trends and average values throughout the process. For cohesive soil, the cutting force curve has a wavy trend and the average value in a stable state is greater than for non-cohesive soil. In order to further validate the feasibility and precision of the presented model, different tillage conditions (cutting angles and depths), internal friction angles for non-cohesive soil, different cohesion for cohesive soil, and different friction coefficient of the cutting blade are all discussed. This work has demonstrated that the proposed model is accurate in soil-tool interaction simulations and can also provide an accurate description of the shear fragmentation of cohesive soil. It helps to contribute to a better understanding of the tillage process that is fundamental and essential for the optimal design of the soil-engaging components.