Shear induced normal stress differences in aqueous foams

A finite simple shear deformation of an elastic solid induces unequal normal stresses. This nonlinear phenomenon, known as the Poynting effect, is governed by a universal relation between shear strain and first normal stresses difference, valid for non-dissipative elastic materials. We provide the first experimental evidence that an analog of the Poynting effect exists in aqueous foams where besides the elastic stress, there are significant viscous or plastic stresses. These results are interpreted in the framework of a constitutive model, derived from a physical description of foam rheology

Rhéologie non linéaire des mousses aqueuses

PARIS-EST Marne-la-Vallee-BU (774682101) / SudocSudocFranceF

Shear induced normal stress differences in aqueous foams

International audienc

Constitutive equation to describe the nonlinear elastic response of aqueous foams and concentrated emulsions

International audienceWe present a constitutive equation that describes the nonlinear elastic response of aqueous foams and concentrated emulsions that undergo affine deformations. We derive it from the expression for interfacial energy of strained aqueous foam or concentrated emulsions using the formalism of large deformation continuum mechanics. By linearizing the strain energy potential, we obtain a constitutive equation of Mooney–Rivlin form. The predicted nonlinear elastic response is compared to that in previous models and numerical simulations. Furthermore, we discuss the approximations used, particularly those regarding the nonaffine character of deformation in real foams and concentrated emulsions

Rhéologie non linéaire des mousses aqueuses

PARIS-EST Marne-la-Vallee-BU (774682101) / SudocSudocFranceF