.. _auto_curves_yield_using_stm:

*COMPUTE YIELD VALUES USING STM METHOD*
=======================================

Computes yield strain and yield stress from stress-strain curves using the STM method (Secant, Tangent, and Arithmetic Mean of modulus ratios) as defined in Dr. Maximilian Benz's PhD dissertation. The yield point is identified where the arithmetic mean of the secant and tangent moduli exceeds a user-defined threshold. Use this worker to extract yield properties from single or multiple rate-dependent stress-strain curves.

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

Classification: **process**.

Tagged: ``benz``, ``material_characterization``, ``quasi_static``, ``rate_dependent``, ``secant_modulus``, ``stm``, ``stress_strain``, ``tangent_modulus``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve In
     - curve_in
     - vector
     - —
     - 
     - One or more stress-strain curves (x = strain, y = stress) to be analysed; accepts multiple vector curves simultaneously.
   * - Threshold
     - th
     - scalar
     - 1.2
     - 
     - Dimensionless threshold for the arithmetic mean of the secant-to-tangent modulus ratio; the point where this ratio first exceeds the threshold is taken as the yield point (default 1.2).
   * - Smooth Derivatives
     - smooth
     - scalar
     - yes
     - 
     - Whether to apply smoothing to the computed derivatives before threshold detection; set to 'yes' (default) to reduce noise-driven false positives, 'no' to use raw derivatives.
   * - Offset curve so the initial point is at origin of 0,0
     - offset
     - scalar
     - no
     - 
     - Whether to translate the curve so that its first data point sits at the origin (0, 0) before processing; use 'yes' when raw data has a non-zero initial offset, default is 'no'.
   * - Use QS yield strain to find modulus at higher rates
     - use_qs_strain
     - scalar
     - no
     - 
     - Whether to anchor the yield-strain search to the quasi-static yield strain when computing moduli at higher strain rates; set to 'yes' for rate-dependent series sharing a common QS baseline, default is 'no'.
   * - Average Over
     - average_over
     - scalar
     - 0.0
     - 
     - Strain window (same units as the curve x-axis) centred on the detected threshold point over which the modulus is averaged; set to 0.0 (default) to use the exact threshold point with no windowed averaging.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - Yield Stats
     - yield_stats
     - dataset
     - Dataset containing per-curve yield results including yield strain, yield stress, and computed secant/tangent modulus values at the detected yield point.

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

- data.curve.transform
- data.statistics
- 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=curves_yield_using_stm <https://www.d3view.com/api/workflow/example?id=curves_yield_using_stm>`_

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curves_yield_using_stm</code>. Schema hash: <code>4afb5d46956d</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
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