GET BEST-FIT INITIAL SLOPE¶
Fits a linear regression to the initial (elastic) region of a curve — typically a stress-vs-strain curve — and returns the best-fit slope. The linear region is bounded by a minimum R² threshold and a maximum strain limit, whichever is reached first.
When to use¶
Classification: process.
Tagged: best_fit, curve_fitting, elastic_modulus, initial_slope, linear_regression, r2, stress_strain.
Inputs¶
| Label | ID | Type | Default | Required | Description |
|---|---|---|---|---|---|
| Curve | curve1 | vector | — | Input curve (x, y vector pair); typically a stress-vs-strain curve from a material coupon test — leave empty only if the curve is injected upstream in the workflow. | |
| R2 Error Limit | r2_limit | float | 0.975 | R² goodness-of-fit threshold (dimensionless, 0–1) below which the linear region is considered to have ended; default 0.975 is appropriate for most metallic stress-strain curves — lower this value to extend the fitted region. | |
| Max Strain | max_strain | float | 0.002 | Upper strain bound (engineering strain, dimensionless) beyond which the linear fit is not extended regardless of R²; default 0.002 (0.2 %) is a conventional elastic-limit cutoff for metals — increase for softer materials such as polymers. |
Outputs¶
| Label | ID | Type | Description |
|---|---|---|---|
| curve_lookup_best_fit_initial_slope_output_1 | curve_lookup_best_fit_initial_slope_output_1 | scalar | Best-fit initial slope scalar value extracted from the linear region of the input curve — for a stress-vs-strain input this equals the elastic (Young’s) modulus in the same stress units as the curve’s y-axis. |
Disciplines¶
- ai_ml.supervised.regression
- data.curve.transform
- engineering.material.characterization
Runnable example¶
A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: /api/workflow/example?id=curve_lookup_best_fit_initial_slope
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