Identify whether the intended rheology experiment imposes stress or deformation before interpreting the remaining recorded response.
Identify the Deformation and Model
TA Instruments distinguishes rotational designs that apply torque and observe motion from designs imposing deformation and measuring sample torque. The controlled input and measured response must be named in the actual test. Primary reference: imposed motion and torque.
Review a Hypothetical Comparison
Imagine one fictional experiment requests oscillatory stress amplitude 100 Pa and measures the resulting strain. A second requests strain amplitude 0.01 and measures resulting stress. The two requested amplitudes do not define equivalent tests without a compatible material-response relation. Neither experiment guarantees the unknown output merely by selecting the input label.
Keep the Evidence with the Decision
Retain the achieved input trace as well as the command, actual control mode and response channel. Distinguish strain from strain rate, even when one rotational instrument can impose several modes. Ask how the measured torque and geometry become stress, or how the observed displacement becomes deformation. Mark feedback and instrument limits as part of the method evidence.
A product family name does not establish which variable was controlled during a specific measurement. Nor does a nominal command prove the achieved input matched it throughout a transient. The invented requests supply no HM controller, sample property or permitted test range. Their purpose is a controlled-input record that stops a response change from being interpreted as though both sides of the experiment had been imposed independently.
Does the test impose force response or deformation history while measuring the other?
This blank worksheet is for your own project. It contains no H M machine trial result.
| Review field | Reference or result | Responsible person |
|---|---|---|
| Requested versus achieved input | To complete | To complete |
| Stress/strain/rate control identity | To complete | To complete |
| Measured response and geometry conversion | To complete | To complete |
| Time trace and method boundaries | To complete | To complete |
Customer Questions
Is strain 0.01 also a specified stress?
No. The stress response must be established.
Are strain and strain rate the same controlled quantity?
No. They have different time definitions.
Does a command prove the achieved waveform?
No. Retain actual input evidence.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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