Transient localizations in metals using microstructure-based yield surfaces

摘要

Classical constitutive models of phenomenological plasticity/viscoplasticity rely heavily on yield functions to distinguish plastic flow from reversible elastic deformation. Physically based yield functions are utilized here for body-centred cubic (bcc) and face-centred cubic (fcc) types of metal structures in investigating necking and dynamic shear localizations over a wide range of temperatures and strain rates. The consistency model is employed in determining the increment of the viscoplastic multiplier and consequently a proper definition for the continuum elasto-viscoplastic tangent modulus is derived. Mesh-independent results are obtained using the finite element analysis in investigating the localization behaviour for tantalum, vanadium and niobium for bcc metals and OFHC copper for fcc metals.