We study theoretically the role of ageing in the rheology of soft materials. We define several generalized rheological response functions suited to ageing samples (in which time translation invariance is lost). These are then used to study ageing effects within a simple scalar model (the “soft glassy rheology” or SGR model) whose constitutive equations relate shear stress to shear strain among ...

Consideration of sludge rheology is very important for a proper solids transport and to obtain the necessary settler capacity. Although a true yield stress does not exist, large apparent viscosities at low shear rates inhibit an efficient sludge transport. Research indicates that the dimensionless ratio of gravity to viscous forces is an important operational parameter towards settler capacity....

We investigate the use of two distinct and complementary approaches to measuring the viscometric properties of low viscosity complex fluids at high shear rates up to 80,000 s−1. Firstly we adapt commercial controlled-stress and controlled-rate rheometers to access elevated shear rates by using parallel plate fixtures with very small gap settings (down to 30 μm). The resulting apparent viscositi...

We study the nonlinear rheology of a glass-forming binary mixture under the reversal of shear flow using molecular dynamics simulations and a schematic model of the mode-coupling theory of the glass transition (MCT). Memory effects lead to a history-dependent response, as exemplified by the vanishing of a stress-overshoot phenomenon in the stress-strain curves of the sheared liquid, and a chang...

background: the study of rheological properties of blood has special interest since it is a circulating fluid exposed to shear rates during its life time. this work aims to investigate the influence of whole body gamma irradiation on the rheological properties of rat’s blood. the applied shear rate was from 12 to 375 s-1. low shear viscosity (up to 100 s-1) depends mainly on the erythrocytes ag...

Loosening is recognized as one of the primary sources of total hip replacement (THR) failure. In this study the influence of the bone surface texture on loosening of the cement/bone interface was studied. Model cemented hip replacements were prepared and subjected to cyclic loads that induced pure shear fatigue of the cement/bone interface. The femoral canals were textured with the use of speci...

When the shear stress measured in Large Amplitude Oscillatory Shear (LAOS) deformation is represented as a two-dimensional Lissajous-Bowditch curve, the corresponding trajectory can appear to self-intersect and form secondary loops. This self-intersection is a general consequence of a strongly nonlinear material response to the imposed oscillatory forcing and can be observed for various materia...

An understanding of sludge rheology during anaerobic digestion can improve digester performance, particularly with regards to mixing. However, the “black box” nature of digesters limits the knowledge on sludge flow behaviour, once it enters the digester. A study on the flow properties (i.e. apparent viscosity and yield stress) as well as the yielding and restructuring behaviour of primary, seco...

Transforming growth factor-β1 (TGF-β1) is thought to drive fibrogenesis in numerous organ systems. However, we recently established that ectopic expression of TGF-β1 abrogates collagen accumulation via canonical SMAD signaling mechanisms in a shear-induced model of kidney fibrosis. We herein delineate the temporal control of endogenous TGF-β1 signaling that generates sustained synchronous fluct...

The shear rate and corresponding shear stress have impacts on arterial thrombus formation. In particular, the effects of increasing concentration of platelets at the vessel wall and activation of platelets at this site increase the growth and stability of the thrombi which may result in a fatal narrowing of the arterial lumen. The efficacy of many antithrombotic agents is shear dependent as wel...