JOHNSON-COOK PARAMETER FIT¶
Fit the Johnson-Cook flow-stress constants A, B, n, C, m by sequential closed-form least squares. A, B, n come from the quasi-static effective-plastic hardening curve; C from optional higher-strain-rate curves; m from optional elevated-temperature curves.
When to use¶
Tagged: johnson-cook, material-calibration, curve-fitting, plasticity, strain-rate, thermal-softening, hardening, flow-stress.
Inputs¶
| Label | ID | Type | Default | Required | Description |
|---|---|---|---|---|---|
| Quasi-Static Hardening Curve | quasi_static_curve | vector | — | ✓ | Effective plastic strain (X) vs effective stress (Y) at the reference strain rate and room temperature. The only required input; A, B, n are fit from it. |
| Reference Strain Rate | reference_strain_rate | scalar | 1.0 | Quasi-static strain rate used to normalize rate_star (same units as strain_rates). | |
| Evaluation Plastic Strain | eval_plastic_strain | scalar | 0.1 | Plastic strain at which the rate and temperature ratios are evaluated for the C and m fits. | |
| Plastic Strain Threshold | plastic_strain_threshold | scalar | 1e-06 | Points at or below this plastic strain are excluded from the A,B,n log-fit. | |
| Room Temperature | room_temperature | scalar | 293.0 | Reference temperature for Tstar. | |
| Melt Temperature | melt_temperature | scalar | 0.0 | Melt temperature for Tstar. Leave <= room_temperature to skip the m fit. | |
| Strain-Rate Curves | rate_curves | vector | — | Optional CurveGroup of effective-plastic curves at higher strain rates, in the same order as strain_rates. Needed (with strain_rates) to fit C. | |
| Strain Rates | strain_rates | text | — | Comma-separated strain rates matching rate_curves in order. | |
| Temperature Curves | temperature_curves | vector | — | Optional CurveGroup of effective-plastic curves at elevated temperatures, in the same order as temperatures. Needed (with temperatures + melt_temperature) to fit m. | |
| Temperatures | temperatures | text | — | Comma-separated temperatures matching temperature_curves in order. |
Outputs¶
| Label | ID | Type | Description |
|---|---|---|---|
| A (Yield Stress) | a | scalar | |
| B (Hardening Coefficient) | b | scalar | |
| n (Hardening Exponent) | n | scalar | |
| C (Strain-Rate Coefficient) | c | scalar | |
| m (Thermal Softening Exponent) | m | scalar | |
| R2 (A,B,n fit) | r2_abn | scalar | |
| R2 (C fit) | r2_c | scalar | |
| R2 (m fit) | r2_m | scalar | |
| All JC Parameters | parameters | keyvalue | |
| Fit Summary (per bracket) | fit_summary | dataset |
Disciplines¶
- engineering.material.calibration
- engineering.material.characterization
- data.curve.transform
Runnable example¶
A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: /api/workflow/example?id=johnson_cook_parameter_fit
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