A mechanical model of single wheat straw with failure characteristics based on discrete element method.

Owing to the complicated process of using the discrete element method (DEM) to simulate the interaction between straw and machinery, existing straw models do not exhibit failure properties. This affects simulation accuracy because some of the interaction processes are not being simulated. To solve these problems, a mechanical model of wheat straw with failure characteristics was developed based on the Hertz–Mindlin (no-slip) contact model and bonded-particle model (BPM). In this model, two types of bonding keys with different bonding parameters were used to bond straw stems. The bonding parameters of the straw model were calibrated using tension, compression, three-point bending, and shear tests, and response surface method. By calculating and solving the regression equation of the Box–Behnken design, the bond parameters (normal and tangential stiffness per unit area, and critical normal and tangential stresses) were calibrated as Bond1 and Bond2. The model can simulate the breaking, fracture, flexural, and shear behaviours of straw during tension, compression, bending, and shearing. The simulated tensile strength, compressive strength, modulus of elasticity, and shear strength of the model were 9.84%, 1.99%, 10.21% and 15.57% different from their respective experimental average values. The results show that the straw model can accurately reflect the mechanical properties of wheat straw with failure properties, which not only helps to improve the accuracy of straw simulation but also provides a reference for modelling the interaction between straw, or other crops, and mechanical equipment. • An innovative mechanical model of wheat straw with destructibility was constructed. • Two bonding keys with different parameters were newly used to bond the straw unit. • Bonding parameters were calibrated by tension, compression, bending and shear tests. • Tensile, compressive and shear strength, and modulus of elasticity were verified. • Model can reflect the mechanical properties while having destructive properties. [ABSTRACT FROM AUTHOR]