.. _auto_curve_ersatz_hardening:

*ERSATZ HARDENING CURVE GENERATOR*
==================================

Generates a synthetic true stress–true strain hardening curve from basic tensile test parameters using the ERSATZ method (Hollomon+Linear or Log-Quadratic models). Use this worker to produce MAT_24-ready plasticity curves when only engineering yield stress, UTS, necking strain, and elongation-at-break are available, without requiring full coupon test data.

When to use
-----------

Classification: **process**.

Tagged: ``curve_generation``, ``elongation``, ``ersatz``, ``hardening_curve``, ``hollomon``, ``mat_24``, ``material_characterization``, ``necking``.

Inputs
------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20 20 20

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Material Name
     - material_name
     - scalar
     - —
     - 
     - Optional label for the material; used to annotate the output curve and any downstream reports — leave blank if no name is needed.
   * - Eng Yield Stress
     - eng_yield_stress
     - scalar
     - 210
     - 
     - Engineering yield stress in MPa (default 210 MPa); defines the onset of plastic flow and anchors the start of the hardening curve.
   * - Eng Ultimate Stress
     - eng_ultimate_stress
     - scalar
     - 0.12
     - 
     - Engineering strain at UTS / ultimate engineering stress (default 0.12); serves as the second anchor point for the Hollomon fit — confirm whether the field stores stress (MPa) or strain (dimensionless) for your dataset.
   * - Necking Strain
     - necking_strain
     - scalar
     - 0.3
     - 
     - True or engineering strain at the onset of necking / diffuse instability (default 0.30, dimensionless); marks where the Hollomon power-law is evaluated up to before clamping or extrapolation.
   * - Elongation at Break
     - elongationat_break
     - scalar
     - 0.4
     - 
     - Engineering strain at fracture / elongation at break (default 0.40, dimensionless); used as the failure-strain anchor when Failure Stress is non-zero.
   * - Failure Stress
     - failure_stress
     - scalar
     - 0
     - 
     - Engineering failure stress (MPa) at the elongation-at-break point (default 0 = disabled); when non-zero the curve is fit through yield, UTS, and this failure point using the selected hardening model, bypassing the standard 2-parameter Hollomon clamping.
   * - Hardening Model
     - hardening_model
     - select
     - hollomon_linear
     - 
     - Hardening model selector (default 'hollomon_linear'): 'hollomon_linear' preserves yield exactly and fits the failure point with possible minor UTS drift; 'log_quadratic' fits all three anchors exactly but may decrease beyond the failure strain and is unsuitable for long-strain extrapolation.

Outputs
-------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20

   * - Label
     - ID
     - Type
     - Description
   * - curve_ersatz_hardening_output_1
     - curve_ersatz_hardening_output_1
     - vector
     - True stress–true strain hardening curve (vector of [strain, stress] pairs, stress in MPa) suitable for direct use as a MAT_24 plasticity curve in LS-DYNA.

Disciplines
-----------

- ai_ml.surrogate
- data.curve.transform
- engineering.material.calibration
- engineering.material.characterization
- engineering.material.library

Runnable example
----------------

A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=curve_ersatz_hardening <https://www.d3view.com/api/workflow/example?id=curve_ersatz_hardening>`_

.. raw:: html

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_ersatz_hardening</code>. Schema hash: <code>eb6bcbf28c0a</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>