(208g) Experimental Validation of a 3-D Finite Element Method Roll-Compaction Model

This study compares the FEM-predicted density distribution of roll-compacted ribbons to those measured experimentally.  The following steps were undertaken to ensure one-to-one comparisons of model and measured results: (i) an air powered piston feeder configuration that applied a known, uniform stress on the powder was manufactured to replace the roll compactor feed auger; (i) all model boundary conditions, such as the powder/roll and powder/cheekplates friction angles, were based on experimentally-measured values; and (iii) density-dependent stress-strain constitutive parameters were used in the simulations to describe the powder mechanical behavior.  Results show that model results agree well with the experimentally measured counterparts.  Discrepancies between the two quantities were the result of cantilevered roll shaft supports that caused the experiments to be performed with non-parallel rolls.  This effect made the experimentally-measured ribbon densities slightly asymmetrical against the roll half-width.  Such trends were not captured by the simulations since the model assumed perfectly parallel rolls.  Model shortcomings include its inability to resolve yield paths when the roll gap is too small (< 1.00 mm) and the ribbon’s springback response downstream of the roll minimum gap width.