A“Sequential Design of Simulations”approach for exploiting and calibrating discrete element simulations of cohesive powders

The flow behaviours of cohesive particles in the ring shear test were simulated and examined using discrete element method guided by a design of experiments methodology.A full factorial design was used as a screening design to reveal the effects of material properties of partcles.An augmented design extending the screening design to a response surface design was constructed to establish the relations between macroscopic shear stresses and particle properties.It is found that the powder flow in the shear cell can be classified into four regimes.Shear stress is found to be sensitive to particle friction coefficient,surface energy and Young’s modulus.A considerable fluctuation of shear stress is observed in high friction and low cohesion regime.In high cohesion regime,Young’s modulus appears to have a more significant effect on the shear stress at the point of incipient flow than the shear stress during the pre-shear process.The predictions from response surface designs were validated and compared with shear stresses measured from the Schulze ring shear test.It is found that simulations and experiments showed excellent agreement under a variety of consolidation conditions,which verifies the advantages and feasibility of using the proposed“Sequential Design of Simulations”approach.