Dynamics and shear banding in stress-controlled start-up shear flow of a model aging soft materials: the role of inertia and thixotropy

We investigate the start-up dynamics under a stress-controlled flow field in aging soft materials, with the aid of an inelastic structural-kinetic model that exhibits non-monotonic steady-state shear stress–shear rate flow curve. In particular, we focus on the occurrence of both transient and steady-state shear banding in such systems. We find that even when the applied stress is greater than the minimum value of the stress associated with the non-monotonic flow curve, the system could eventually undergo structural arrest, resulting in a complete stoppage of flow. For further increase in stress, the system progressively shows transient shear banding as well as apparent steady-state shear banding. At sufficiently high shear stresses, the model shows an eventual homogeneous steady state. We delineate the effects of inertia and waiting time on the transient and apparent steady-state shear banding.