Brookfield DV3T Rheometer - Manual (Page 44)

Brookfield Engineering Labs., Inc. Page 44 Manual No. M13-2100
Figure III-19 shows the Power Law equation for a typical set of data. A brief
definition of the equation will be shown if the i (information) button is pressed.
Figure III-19
Detailed information about Math Models is presented in Section VII.
III.12 Data Averaging
The DV3T Rheometer offers two techniques to average data, Live Averaging and Post Test Averaging.
Data averaging can be useful when measuring samples with entrained air or suspended particles that
case some variation in measurement results. Data averaging may not be useful when changes in
measurement results are caused by the rheological properties of the test sample such as thixotropy or
pseudoplasticity (shear thinning). Materials that exhibit thixotropy will show a steadily decreasing
measured viscosity over time. Materials that exhibit pseudoplasticity will show a changing viscosity
as the spindle speed changes.
TIP: When averaging data for a thixotropic material, begin the Averaging Duration after the
period of most significant change in measured viscosity. This will reduce the variability in
the averaged value.
TIP: When averaging data for a pseudoplastic material, do not average together (Test Averaging)
data collected at different speeds (or shear rates).
Live Averaging of data occurs during actual testing of a sample. Data can be collected as an average
of readings over a specific time interval; each data point saved in the file is an averaged value. This
averaging is defined in the Data Collection section of Configure Viscosity Test.
Single Point Averaging requires a definition of Averaging Duration, the amount of time for
which readings will be averaged. This time parameter will be applied at the end of the End
Condition. In this case a single data point will be collected which represents the average of all
data measured during the specified time period (Averaging Duration).