VISCOPLASTIC BEHAVIOR OF POROUS METALLIC MATERIALS SATURATED WITH LIQUID .2. EXPERIMENTAL IDENTIFICATION ON A SN-PB MODEL ALLOY

The rheological behaviour of a model Sn-Pb alloy in the semi-solid sta te is investigated. The tensorial constitutive equation that was propo sed in Part I for viscoplastic porous metallic materials saturated wit h liquid is used. In particular, the three characteristic functions ap pearing in the viscoplastic potential that describes the porous solid phase rheology are experimentally identified. Three stress states are exploited to identify the functions: undrained triaxial compression, d rained hydrostatic densification and shear deformation in a Couette rh eometer. Undrained tests for which the interstitial liquid pressure is measured show that a viscoplastic potential with a densification/dila tation boundary situated on the J(I) = 0 axis (first invariant) is not valid. Finally, triaxial drained compression is used to partially val idate the coupling, introduced in the viscoplastic potential formulati on, between hydrostatic and deviatoric properties. (C) 1997 Elsevier S cience Ltd.