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A. F. Plankensteiner, D. Duschlbauer, O. Coube, H. E. Pettermann, H. J. Böhm:
"Numerical and Experimental Analysis of Pore Shape Evolution of Sintered Molybdenum under Triaxial Loading Condition";
Vortrag: Pm Tec 2003, Las Vegas, NV; 08.07.2003 - 12.07.2003; in: "Advances in Powder Metallurgy and Particulate Metals - 2003", MPIF, Princeton, NJ, (2003), ISBN: 1-878954-96-2; S. 108 - 119.

The densification process of porous media (Molybdenum) is investigated by means of an axisymmetric unit cell. The investigated microgeometries are based on a body centered cubic arrangement and differ in the initial void density and the relative size of the spherical voids to each other. Triaxialities of X = -1/3 and X = -4/3 are considered in combination with the deformation modes "sphere to needle" and "sphere to crack".
It is found that triaxialities of X = -4/3 and the deformation mode "sphere to crack" achieve much higher densification rates with respect to equivalent logarithmic strains and total strain energy densities than do triaxialities of X = -1/3 and the deformation mode "sphere to needle", respectively. In the case of differently sized voids the small void closes faster than the large void. The ratio of the radii of the voids is found to have little influence on the compaction behaviour.
Results are presented in terms of void shape and density evolutions, total energy densities, as well as evolution of the cross sectional areas by adopting material parameters for Molybdenum at 1000°C. Experimental verification is done for room temperature conditions in terms of overall stress strain characteristics. For a specific case cross sectional areas obtained via experimental hot upsetting tests at 1000°C are compared to corresponding unit cell results. For all verification cases good agreement is found.