Rheology and rheometry a short introduction

Rheology and rheometry –

a short introduction

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Introduction to Rheology

The term rheology was proposed by E.C. Bingham and M.

Reiner in 1929 for an interdisciplinary field of

material sciences

It derives of the Greek terms for flow ῥεῖ (rhei) and λόγος

(logos) for word (science)

The genesis of rheology

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Rheology is the science of the deformation and flow

of matter under controlled testing conditions!

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M. Reiner also proposed the ancient

aphorism panta rhei* (everything flows) as

the motto of the Society of Rheology.


http://www.rheology.org/sor

The Society of Rheology was officially formed

on December 9, 1929.


*Heraclitius (Simplicius)

http://www.rheology.org/sor

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A fundamental principle in rheology

Panta rhei! But does really everything flow?

Well, it depends!

How long do you want to wait?

Deborah* Number = Time of Relaxation

Time of Observation


*after prophetess Deborah, Judges 5:5

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Everything flows!

Example 1: The visco-elastic behavior of Silly Putty


Bouncing ball Gravity acting over time

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Images taken from wikipedia

Everything flows!

Example 2: The glass windows of the Cathedral of Chartres in France

1200 2011

Gravity


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Sir Isaac Newton

1642 - 1727

“The resistance which arises from the lack of

slipperiness of the parts of the liquid, other

things being

equal, is proportional to the velocity with

which the parts

of the liquid are separated from one another.”

Philosophiae Naturalis Principia Mathematica 1687

Definition of basic rheological parameters

Viscosity and viscous flow

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Robert Hooke

1635 - 1703

“The power of any spring is in the

same proportion with the tension

thereof.”

True Theory of Elasticity 1678

Viscoelasticity


Image taken from wikipedia

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(Spring)


Viscoelasticity

Rotation and Oscillation Rotation and Oscillation

Elasticity

Real Systems

(Dashpot)

Viscosity

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Thank you for your attention

Any questions ?

Rheology and rheometry a short introduction

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