Constitutive modeling of semisolid deformation for the assessment of dilatant shear bands

•A new constitutive model was developed in order to study the localization in semi-solid materials.•A new description is proposed for the rheological behavior of semi-solid materials.•Both proposed constitutive model and shear localization analysis were fairly well correlated with the experimental results. A new constitutive model is proposed to investigate the shear localization in semisolid materials. It is based on the development of a viscosity-type equation to express the homogeneous part of the semisolid flow curve. An instability analysis was performed by examining the necessary condition for the growth of a perturbation in the homogeneous flow. Considering a shear layer model, the necessary condition for perturbation growth and subsequent shear localization was derived. The localization analysis, in conjunction with experimental evidence, results in a new description for the rheology of semisolid materials, involving elasto-viscoplastic deformation at solid skeleton bonds, breaking of the bonds and subsequent granular deformation. Moreover, it was shown that the tendency to localization decreases with increasing liquid fraction at low and modest strain rates. It is shown that the rate sensitivity has a retarding effect on the shear localization. The constitutive model and the shear localization predicted by the presented model were fairly well correlated with the experimental results.