Yield stress, heterogeneities and activated processes in soft glassy materials*
نویسندگان
چکیده
The rheological behaviour of soft glassy materials results essentially from the interplay between shearing forces and an intrinsic slow dynamics. This competition can be described by a microscopic theory, which can be viewed as a nonequilibrium schematic mode-coupling theory. This statistical mechanics approach to rheology results in a series of detailed theoretical predictions, some of which are yet to be experimentally verified. We present new, preliminary, results about the description of yield stress, flow heterogeneities and activated processes within this theoretical framework.
منابع مشابه
Analogy between glass rheology and crystal plasticity: yielding at high strain rate.
An abrupt increase of the yield stress at sufficiently high strain rate, seen in glassy as well as crystalline structures, signifies a transition from classical thermal fluctuation to stress activated processes. For crystals this behavior has been recently explained using transition-state-theory with a stress-dependent activation barrier for dislocation glide. An equivalent approach, developed ...
متن کاملInternal dynamics and activated processes in soft-glassy materials.
Plastic rearrangements play a crucial role in the characterization of soft-glassy materials, such as emulsions and foams. Based on numerical simulations of soft-glassy systems, we study the dynamics of plastic rearrangements at the hydrodynamic scales where thermal fluctuations can be neglected. Plastic rearrangements require an energy input, which can be either provided by external sources, or...
متن کاملHow polymers lose memory with age.
Uniquely in the world of materials, polymers deformed at high temperature and subsequently quenched at low temperature, memorize the temperature at which they have been processed. Polymers can even memorize multiple temperatures. This temperature memory is reflected by a maximum of residual stress restored at the temperature of initial processing. It has been speculated that this capability cou...
متن کاملAgeing and Rheology in Soft Materials
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 ...
متن کاملShear banding and yield stress in soft glassy materials.
Shear localization is a generic feature of flows in yield stress fluids and soft glassy materials but is incompletely understood. In the classical picture of yield stress fluids, shear banding happens because of a stress heterogeneity. Using recent developments in magnetic resonance imaging velocimetry, we show here for a colloidal gel that even in a homogeneous stress situation shear banding o...
متن کامل