EFFECT OF ELASTICITY ON THE SHAPE OF MEASURED SHEAR SIGNALS IN A TWO-DIMENSIONAL ASSEMBLY OF DISKS

A Molecular Dynamics approach has been used to compute the shear force resulting from the shearing of disks. Two-dimensional mono-disperse disks have been put in an horizontal and rectangular shearing cell with periodic boundary conditions on right and left hand sides. The shear is applied by pulling the cover of the cell either at a constant rate or by pulling a spring, linked to the cover, with a constant force. Depending on the rate of shearing and on the elasticity of the whole set-up, we showed that the measured shear force signal is either irregular in time, regular in time but not in shape, or regular in shape.