Rheology

The rheology is part of the Mécanique which studies the plasticity, the elasticity, the Viscosité and the Fluidité characteristic of the deformable bodies. Of the Greek reo (to run) and logos (study). One could also define rheology as the study of the liquid flows as of the deformations which accompany them.

That can concern:

  • pasty liquids: manufacture of the Glass, agribusiness industry;
  • working of the parts: injection or Polymeric extrusion of the S and Metals, Rolling, Geophysical Forging…
  • in : the landslides, the flow of the Lava and the magma, convection in the terrestrial coat,
  • in Geomechanical: deformation of the foundations,
  • in Agronomy: the behavior of the fruit and vegetables under a constraint of crushing.
  • in Medicine: the behavior of blood and the Homeostasis

Bond between elasticity, solid viscosity, characters and liquid, plasticity

One with the practice to associate liquid and viscous (a thick oil is a viscous liquid) as solid and elastic (a spring is an elastic solid).

In fact, when one tries to deform a material, some of the properties listed above appear at short times, others at long times.

the characters liquid and solid are properties at long times :

  • if the material, after being itself deformed, resists finally, it is a solid;
  • if on the contrary the material ends up running out, it is a liquid.

On the contrary, the characters rubber band and viscous (or behaviors intermediate, viscoelastic) appear at short times :

  • if the deformation of material follows the force or the pressures applied, then the material is elastic;
  • if it is the derivative of the deformation compared to the time (rate of deformation) which follows the force or the constraints, then the material is viscous.

plasticity appears with the strong constraints

Characters liquid and solid, viscous and elastic are detectable for low pressures applied. If a strong constraint is applied, a material which seemed solid can be put to run out. It reveals a plastic character then . One speaks about solid plastic . The plasticity is thus characterized by a threshold of constraint (called threshold of plasticity ) beyond whose the material runs out.

By practice, one speaks about solid plastic when the threshold of plasticity is rather raised, and of fluid with threshold when the threshold of plasticity is rather low. There is however no basic difference between these two concepts.

See too

Related articles

  • Mechanical of the continuous mediums

  • Mechanical of the fluids
  • Rheology of the complex solids
  • Flows
  • Viscoanalyseur

External bonds

  • ''' CADFLOW ''' - Software of rheological simulation and Engineering for Plasturgie
  • Rheology and formulation
  • Viscosities of various liquids according to the temperature

Among the scientific magazines which treat rheology:

  • '' Journal off Rheology ''
  • '' Journal off Non-Newtonian Fluid Mechanics ''
  • '' Rheologica Acta ''
  • '' Applied Rheology ''
  • '' Korea-Australia Rheology Newspaper ''

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