Issue 37

G. Cricrì et alii, Frattura ed Integrità Strutturale, 37 (2016) 333-341; DOI: 10.3221/IGF-ESIS.37.44 340 1 MN MX X Y Z 1.032 1.042 1.052 1.062 1.071 1.081 1.091 1.101 1.11 1.12 JUL 19 2011 16:59:06 NODAL SOLUTION STEP=6 SUB =105 TIME=6 SVAR10 (AVG) DMX =5.996 SMN =1.032 SMX =1.12 Figure 8 : Relative density,  r at final step of compaction process (  = 0.1). 0 0.2 0.4 0.6 0.8 1 1.2 0 100 200 300 400 500 600 Relative density  r Loading pressure [MPa] Maximum rel. density Minimum rel. density Average rel. density 0 0.2 0.4 0.6 0.8 1 1.2 0 100 200 300 400 500 600 Relative density  r Loading pressure [MPa] Maximum rel. density Minimum rel. density Average rel. density Figure 9 : Relative maximum, minimum and average density vs loading pressure (  = 0.1 and  = 0.05) C ONCLUSIONS n the present work, the behaviour of metal powder during die compaction process is described, by using a cap-cone model of yield surfaces in order to simulate material strain hardening capability. Material model was implemented in ANSYS FEM code by subroutine USERMAT. Several numerical simulations were performed considering a simple 2D axialsymmetric geometry to evaluate the forces acting on the die walls, in addition to metal powder behaviour analysis. The obtained outcomes were used to describe an adequate characterization of the pressed object, in terms of stress and density distribution. In particular, FEM analyses highlighted that increasing friction coefficient the density gradient becomes higher and higher whilst the stress field of the compacted powders grows slowly. Although the presented constitutive material model has provided with satisfactory results, comparable with those available in literature relating to similar tests, it may be subject to further developments that make it possible to consider the relation between relative density and other parameters, such as cohesion and internal friction. R EFERENCES [1] Calì, C., Cricrì, G., Perrella, M., An advanced creep model allowing for hardening and damage effects, Strain, 46-4 (2010) 347-357. DOI: 10.1111/j.1475-1305.2009.00682.x I