DISCRETE ELEMENT INVESTIGATION OF STRESS FLUCTUATION IN GRANULAR FLOWAT HIGH-STRAIN RATES

The high rate shear of a granular material is investigated by the use of a discrete mesodynamic method. The simulation describes a Couette f low geometry without gravity. A collection of frictional and perfectly smooth particles are subjected to strain rates ranging from 2/3 X 10( 1) to 2/3 X 10(4) l/s at solids concentrations ranging from 75% to 87% in a two-dimensional geometry. Normal stresses at the base of the gra nular sample are recorded. Large fluctuations in individual transmitte d stresses are observed. The behavior of this stress profile compares well with previous experimental results. A near linear relation betwee n normal stress and the strain rate is observed. The mechanism of stre ss transfer, stress chain formation, and random particle collision, th rough the depth of the sample, is seen to depend on solids concentrati on. Friction affects both the magnitudes of normal stresses and the ch aracteristics of the granular flow. [S1063-651X(98)13902-8].