Brookfield R/S Coaxial Cylinder Rheometer - Manual (Page 72)

Brookfi eld Engineering Labs., Inc. Page 72 Manual No. M08-219-B1211
D.4.1 Stress Constant:
τ
prom.
All standard vanes supplied for the Soft Solids Tester have a height (H) to diameter (D) ratio of 2:1. A
stress constant is required for each vane to convert torque in Newton meters to shear stress in Pascals.
This constant is calculated as follows:
___ τ
prom
_ 10 -4
πD
3 D
H 1
3
-1 ( )
+
_ _
The constants for the standard vanes are as follows:
Vane Diameter (mm) Height (mm)
τ
prom.
V3-10-5 5 10 109.206
V3-20-10 10 20 13.651
V3-20-20 20 20 2.986
V3-30-15 15 30 4.045
V3-40-20 20 40 1.706
V3-40-40 40 40 0.373
V3-50-25 25 50 0.874
V3-60-8 8 60 7.941
V3-60-15 15 60 2.178
V3-60-30 30 60 0.506
V3-80-40 40 80 0.213
V3-80-70 70 80 0.063
These are pre-loaded in the Rheo 3000 software. If you do not have these vanes available in Block
Editor or on your instrument, then please load them using Meas-Editor for software driven setups, or
see Section VI.6.4: Utilities
→ Measuring Systems for stand-alone setups.
D.4.2 Strain/Rate Constant: K-Gamma
The constant K-Gamma converts the rotational rate or position into shear rate/strain values. Its value
is dependent upon the ratio of container-to-vane diameter. The vanes pre-loaded into the Rheo 3000
software (e.g. V40-20-3 to 1) assume a ratio of 3:1. If you use vane/container combinations that don’t
match this, you will need to set up a new measuring system in Meas-Editor or see Section VI.6.4: Utilities
→ Measuring Systems. You can calculate out the required value using this equation:
K
_
1 − b
2
___
_
gamma
0.2094
D.4 Vane Constants For The Soft Solids Tester