Brookfield DV2+Pro Viscometer Uživatelský manuál stáhnout pdf (Strana 60)

Brookeld Engineering Labs., Inc. Page 60 Manual No. M03-165-F0612

V1.3.3 The Bingham Model

τ=

+ hD (

=shearstress,

=yieldstress,h =plasticviscosity,and D =shearrate)

What does it tell you?

TheBinghammodelindicatesaproduct’syieldstress,

, which is the amount of shear stress

requiredtoinitiateow.Italsoprovidestheplasticviscosity,

h, which is the viscosity after a

product yields.

Figure V1-16

When should you use it?

This model should be used with non-Newtonian materials that have a yield stress and then behave

inaNewtonianfashiononcetheybegintoow.Asaresult,theshearstress-shearrateplotforms

astraightlineafteryielding.(Productsthathaveayieldstressonlybegintoowafteracertain

amount of shear stress is applied. They are also called “viscoplastic”. Their shear stress vs. shear

rate graphs intersect the y-axis at a point greater than 0.)

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Brookfield DV2+Pro Viscometer Uživatelský manuál Strana 60