Numerical Simulation of Uprooting of Cassava Root

Based on the methods including modified Mohr-Coulomb yield criterion, Lagrange and smoothed particle hydrodynamics (SPH), the cassava stem - root - soil system dynamics simulation model is established by ANSYS/LS-DYNA. The interaction mechanisms between uprooted cassava root and soil are discovered. The processes of soil shearing and the changing processes of root's stress are analyzed. The studies show that (1) the effects of root being extruded on the soil expand gradually from inside to outside in the process of uprooting, and the uprooted force reaches the maximum value when the soil appears ring shear rupture; (2) after the uprooted force reaches the maximum value, the root's effective stress still increases gradually with the increasing of its bending deformation until the soil is separated,and root's maximum effective stress appears in the combination of the root and stem where is the most easily to be broken;(3)when the maximum uprooted force on cassava root is analyzed, the interaction of a disc and its extension on the soil is regarded as the mechanical model of maximum uprooted force on cassava root.