Analysis of plane Couette shear test of granular media in a Cosserat continuum approach

• The deformation of granular sample in a plane Couette shear test is categorized into three stages.
• A governing equation with analytical solution is obtained for the initial response.
• A governing equation is derived for the fully developed shear band. Solution is presented.
• A governing equation is derived for the fully developed shear band. Solution is presented.

Cosserat continuum models have proven to be able to capture microstructural effects in granular materials. This paper studies the modality for determining the microstructural effects related to Cosserat model parameters. The plane Couette shear test is considered with a particular hypoplastic Cosserat continuum model, which consists of two undetermined parameters. The development of the sample deformation in a plane Couette shear test is categorized into three stages. An analytical solution is presented for the initial response, which characterizes the sample response to small strain shear. Numerical results are presented for shear tests at finite strain, which demonstrate the development of a localized zone within the sample. Finally, governing equation is derived and solution is obtained for the steady flow state in a fully developed shear band. These results provide a method for estimating the micro-deformation-related strength parameters in the Cosserat continuum model.