.. _auto_curve_truetoengstress:

*TRUE TO ENG*
=============

Converts a true stress–strain curve to its engineering (nominal) equivalent using the standard inverse relationships, with optional Poisson's ratio correction and tension/compression mode selection. When post-necking failure modelling is enabled, the converted engineering curve is truncated at its peak (necking point) and extended to a user-specified failure point via a concave-down power-law decay.

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

Classification: **process**.

Tagged: ``compression``, ``curve_transform``, ``engineering_stress``, ``failure_model``, ``mat_24``, ``necking``, ``poissons_ratio``, ``post_necking``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - True Stress Vs Strain Curve
     - truestressstraincurve
     - vector
     - —
     - 
     - True stress vs. true strain curve to be converted (dimensionless strain, stress in consistent units); supplied as an (x, y) vector pair — leave empty only if chaining from an upstream curve output.
   * - Poisson's Ratio
     - poissons_ratio
     - scalar
     - 0.0
     - 
     - Poisson's ratio of the material (dimensionless, e.g. 0.3 for steel); used to correct the lateral strain contribution during conversion — default 0.0 omits the correction.
   * - Tension/Compression Flag
     - tension_compression_flag
     - text
     - tension
     - 
     - Indicates whether the input curve represents a tension ('tension') or compression ('compression') test; controls the sign convention applied during the true-to-engineering conversion — default is 'tension'.
   * - Model Post-Necking Failure
     - model_failure
     - select
     - no
     - 
     - Set to 'Yes' to truncate the converted engineering curve at its peak stress (necking onset) and append a concave-down power-law decay to the failure point; default 'No' returns the converted curve unmodified.
   * - Failure Strain (eng)
     - failure_strain
     - scalar
     - 0
     - 
     - Engineering strain at failure (dimensionless); must exceed the necking strain — only used when Model Post-Necking Failure is 'Yes', default 0.0.
   * - Failure Stress (eng)
     - failure_stress
     - scalar
     - 0
     - 
     - Engineering stress at failure (same units as the input curve); defines the terminal stress value of the appended power-law tail — only used when Model Post-Necking Failure is 'Yes', default 0.0.
   * - Post-Necking Exponent (n)
     - post_necking_exponent
     - scalar
     - 2
     - 
     - Power n in sigma(t) = sigma_u - (sigma_u - sigma_f) * t^n with t = (eps - eps_u) / (eps_f - eps_u). n = 2 (default) gives a zero-slope, concave-down decay that matches typical ductile metals; higher n keeps the curve flatter near necking.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curve_truetoengstress_output_1
     - curve_truetoengstress_output_1
     - vector
     - Converted engineering stress vs. engineering strain curve (same stress units as the input); includes the optional post-necking failure tail when Model Post-Necking Failure is 'Yes'.

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_truetoengstress <https://www.d3view.com/api/workflow/example?id=curve_truetoengstress>`_

.. raw:: html

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_truetoengstress</code>. Schema hash: <code>7426ea59910e</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>