FEM-SPG coupling modelling and reinforced soil effect of maize root-soil composite

Root-soil composites, formed by root stubble remaining in the field and the surrounding soil, are major factors affecting the quality of maize seeding operations under conservation tillage system. Addressing this problem requires the development of efficient stubble management equipment. A dynamic simulation model of the cutting effect of a blade is established by coupling finite element method (FEM) and smoothed particle Galerkin (SPG) models. After drawing 3D solid models, soil was discretised into SPG particles, and stubble was divided into finite meshes and given different material properties respectively based on their measured data. Based on the mechanical properties of fibre-reinforced composite material, soil and stubble model were bonded as a composite by contact setting. The coupling between FEM and SPG and the non-uniqueness problem of this contact model were dealt with by the co-nodes. Direct shear simulations at two positions of the maize root-soil composite were carried out using SPG-FEM model and verified experimentally by in-situ tests. Test results showed that shear stress and force predicted by SPG-FEM model were in good agreement with the measured results. The results showed that the reinforcement ability of roots to soil was related to their contact area with soil and distribution uniformity. The effective circumference was shown to be able to predict the depth of maximum shear strength of root-soil composite. These current research results are useful for improving the reliability of numerical simulations of crop root-soil composite and optimising agricultural operation components.