Constitutive model for the elastic–plastic analysis of porous sintered materials

Analyses of the fundamental parameters of cold die compaction of powder metallurgy

“…On the other hand, previously published work, indicated that the value of the internal friction is approximately i = 0.08-0.15. This value is an estimation, and will be used in the present theoretical calculations (Doraivelu et al, 1984;Kuhn and Downey, 1971;Gurson, 1977;Green, 1972;Coube and Riedel, 2000;Shima, 2000;Zavaliangos, 2000;Li et al, 1994;Justino et al, 2004;Al-Qureshi et al, 2005). The theoretical porosity and density can be predicted from Eqs.…”

“…It seems, however, that all the previously developed expressions depend totally or partially on experimental factors, due to the unknown parameters. Studies were performed involving the simulation of powder compaction using the FEM and based on the elastic-plastic behaviour of large displacement, where the powder is considered as a continuum which exhibits plastic deformation under applied external pressure (Doraivelu et al, 1984;Kuhn and Downey, 1971;Gurson, 1977;Green, 1972;Coube and Riedel, 2000;Shima, 2000;Zavaliangos, 2000;Li et al, 1994;Justino et al, 2004). New components to be produced by the P/M process are governed by tooling design and manufacturing parameters.…”

A model for the simulation of powder compaction processes

“…These models are based on the classical von Mises model in which some modifications are introduced in order to account for the influence of the hydrostatic pressures on the yield criterion, see Justino et al [4]. Granular material models are based on a multiple yield criterion approach and are naturally sensitive to the hydrostatic stress and consider the cohesion and friction among particles of the granular matter.…”

On the mechanics of cold die compaction for powder metallurgy

“…But it seems that all the previously developed expressions depend totally or partially on experimental factors, due to the unknown parameters. Studies were performed involving the simulation of powder compaction using the FEM and based on the elastic-plastic of large displacement, where the powder is considered as a continuum which exhibits plastic deformation under applied external pressure [9][10][11][12][13][14][15][16][17]. Greek letters β density factor ε effective strain µ container-compacted powder interface µ i internal coefficient of friction-restricted movements coefficient ρ, ρ g , ρ p , ρ t powder density at any stage, green, tap, and theoretical densities σ effective stress in compression of the bulk material σ r radial stress σ yc yield compressive stress σ z axial compressive stress σ 0 normal yield stress…”