Calculator Inputs
Formula Used
τeff = k × P
Gi = τeff,i / γi
Gfit = Σ(γiτi) / Σ(γi2)
This calculator assumes your pressure reading can be treated as effective shear stress after applying the conversion factor k. Set k = 1 when the measured pressure already equals the effective shear stress in your test setup.
How to Use This Calculator
- Enter the material name for easier reporting.
- Select the pressure unit that matches your test data.
- Choose whether strain is entered as percent or decimal.
- Set the stress conversion factor. Use 1 for direct equivalence.
- Input one or more pressure and strain pairs.
- Select the result unit you want for shear modulus.
- Press the calculate button to show results above the form.
- Use the CSV or PDF buttons to export the analysis.
Example Data Table
| Point | Pressure (MPa) | Strain (%) | Effective Stress (MPa) | Estimated Modulus (GPa) |
|---|---|---|---|---|
| 1 | 0.40 | 0.05 | 0.40 | 0.80 |
| 2 | 0.80 | 0.10 | 0.80 | 0.80 |
| 3 | 1.20 | 0.15 | 1.20 | 0.80 |
| 4 | 1.60 | 0.20 | 1.60 | 0.80 |
This sample represents a near-linear response with an approximate fitted shear modulus of 0.80 GPa.
FAQs
1) What does this calculator estimate?
It estimates shear modulus from pressure and strain data after converting pressure into effective shear stress with a user-defined factor.
2) Why is there a stress conversion factor?
Some experiments record pressure that must be translated into effective shear stress. The factor lets you represent calibration, geometry, or sensor scaling.
3) When should I use k = 1?
Use k = 1 when the measured pressure already equals the effective shear stress acting in the material model or test interpretation.
4) Why does the calculator show a fitted modulus and an average?
The fitted modulus comes from all points together. The average simply summarizes individual point estimates. Comparing both helps judge consistency.
5) What does R² tell me here?
R² indicates how well a straight line explains the converted stress-strain trend. Values closer to 1 suggest stronger linear behavior.
6) Can I use only one data point?
Yes. One point produces a direct modulus estimate. Multiple points are better because they reveal noise, spread, and possible nonlinearity.
7) Which unit should I choose for output?
Choose the unit that best fits your reporting style. GPa is convenient for stiff solids, while MPa may suit softer materials.
8) Why might my results vary between points?
Variations can come from measurement noise, nonlinear response, poor calibration, strain reading errors, or an incorrect pressure-to-stress conversion factor.