Viscous Heating During Shear: Check the Energy-Dissipation Scale

Identify the Deformation and Model

TA Instruments notes that work associated with viscous deformation produces heat, which can cause local temperature rise if it is not removed. A thermal balance is separate from a nominal temperature setting. Primary reference: viscous heating.

Review a Hypothetical Comparison

In a hypothetical uniform, steady, purely dissipative simple-shear region, stress 100 Pa and shear rate 10 per second give power density τγ̇ = 1,000 W/m³. If that region occupies 0.001 m³, its dissipative power is 1 W. These invented values do not determine temperature rise without thermal capacity, heat removal and time.

Keep the Evidence with the Decision

Retain the actual stress and rate histories, spatial assumptions and sample-temperature evidence. Compare the energy timescale with the test duration and identify where cooling or conduction occurs. Separate instrument-set temperature from temperature measured at the material location relevant to the interpretation. Ask whether a trend changes when the thermal history is controlled.

In viscoelastic transients, total stress work can include stored energy as well as dissipation; the simple steady example must not be applied blindly to every oscillatory signal. No HM vessel load, temperature excursion or material damage is inferred. The useful decision is whether a thermal-condition check is missing before assigning a changing rheology curve solely to structure or rate dependence.

Could dissipated mechanical energy change the sample temperature during the reported test?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Primary reference: viscous heating
• Reference from hmpharmamachines.com