.. _auto_curve_yield_using_stm:

*CURVE YIELD STRAIN USING STM METHOD*
=====================================

Computes yield strain and yield stress from a stress-strain curve using the STM (Secant-Tangent-Mean) method, as defined in Dr. Maximilian Benz's PhD dissertation. The yield point is identified where the arithmetic mean of the secant and tangent modulus ratios exceeds a user-defined threshold.

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

Classification: **process**.

Tagged: ``benz``, ``material_characterization``, ``secant_modulus``, ``stm``, ``stress_strain``, ``tangent_modulus``, ``yield_strain``, ``yield_stress``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve In
     - curve_in
     - vector
     - —
     - 
     - Input stress-strain curve (X = strain, Y = stress) to be analysed; must cover the elastic-to-plastic transition region.
   * - Threshold
     - th
     - scalar
     - 1.2
     - 
     - Threshold value for the arithmetic mean of the secant-to-tangent modulus ratio; the first point where this ratio exceeds the threshold is taken as the yield point (dimensionless; default 1.2).
   * - Smooth Derivatives
     - smooth
     - scalar
     - yes
     - 
     - Whether to apply smoothing to the derivative (tangent modulus) before computing the STM ratio; set to 'yes' (default) to reduce noise sensitivity, 'no' to use raw derivatives.
   * - Offset curve so the initial point is at origin of 0,0
     - offset
     - scalar
     - no
     - 
     - Whether to shift the curve so that its initial point coincides with the origin (0, 0) before processing; set to 'yes' if the raw data has a non-zero start offset, 'no' (default) to use the curve as-is.
   * - Average Over
     - average_over
     - scalar
     - 0.0
     - 
     - Window half-width (in strain units) over which the modulus is averaged around the detected threshold point; leave at 0.0 (default) to use a single-point detection without windowed averaging.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - Yield Stats
     - yield_stats
     - keyvalue
     - Key-value map containing the computed yield results, including yield strain, yield stress, and associated STM modulus values at the detected yield point.

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

- 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_yield_using_stm <https://www.d3view.com/api/workflow/example?id=curve_yield_using_stm>`_

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_yield_using_stm</code>. Schema hash: <code>7efd10da89f3</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
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