Magnetorheological Fluids: Qualitative comparison between a mixture model in the Extended Irreversible Thermodynamics framework and an Herschel–Bulkley experimental elastoviscoplastic model

A well-known mixture approach treats magnetorheological materials as mixtures composed of a fluid continuum and an equivalent solid continuum. In the framework of extended irreversible thermodynamics, this obtains a complete physical-mathematical model characterized by interesting evolutionary constitutive equations which, in the pre-yield region, show the co-presence of elastic, viscoelastic, and viscoplastic behaviors. Due to its high computational complexity, it is necessary to find a qualitatively corresponding model that, under the same conditions, provides easy-to-implement evolutionary constitutive equations. In this paper, the authors verify the correspondence of the simple shear flow and thinning behavior of the Herschel–Bulkley plastic component (predominant in the pre-yielding region) from a known experimental model with a reduced computation load with elastoviscoplastic generalization under the framework of generalized standard materials.