Stress decomposition in LAOS of dense colloidal suspensions

We present a method for stress decomposition to understand the rich interactions present in the large amplitude oscillatory shear (LAOS) of shear-thickening suspensions. This method is rooted in experiments, does not rely on a preexisting rheological model, and is free of any a priori symmetry arguments. The decomposition allows us to extract the hydrodynamic, contact, and Brownian contributions to map out how these stresses evolve over an oscillation cycle. Access to the time evolution of each stress component provides us with valuable insights into the microscopic details governing the system rheology such as the identification of the time scale for buildup and relaxation of the force chains governing suspension thickening, as well as various asymmetries characterizing the microstructure. While we have chosen to demonstrate this technique on colloidal suspensions, its generality should allow us to utilize it to investigate the LAOS response of other systems ranging from colloidal gels to polymer melts.