Elastoplastic constitutive model parameter determination for dry cohesive powders with finite element application to low pressure powder compression

A basic elastoplastic model (modified Cam-clay) was applied to a dry cohesive powder, flour. Five constitutive parameters for the modified Cam-clay model were previously determined using triaxial tests. To apply the elastoplastic constitutive model, a test cylinder was built that uniaxially compacted the test powder under constant axial displacement. Hoop and vertical strains in the cylinder wall were measured at three levels during compaction. Predicted vertical and hoop strains using a finite element model (FEM), were adequate for all three levels. The FEM also predicted stress distribution in the powder mass, which proved useful in identifying potential regions of stress concentration and large shear stresses in the powder mass.