.. _auto_curve_failurepoint_min_derivative:

*COMPUTE THE POINT AT WHICH THE Y-VALUE DROPS TO ZERO OR STARTS TO DECLINE AT THE END OF THE CURVE. USEFUL FOR MATERIAL FAILURE ETC*
====================================================================================================================================

Detects the failure point on a curve by finding the location of the steepest negative slope (minimum derivative), optionally confirming that the Y-value sustains below a threshold ratio after that point. Primarily used for material stress-strain or force-displacement curves to extract failure onset (e.g., necking, fracture).

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

Classification: **process**.

Tagged: ``curve_analysis``, ``failure_point``, ``fracture``, ``material_failure``, ``min_derivative``, ``necking``, ``stress_strain``, ``transformation``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve From Which The Failure Point Is To Be Extracted
     - curvefromwhichthefailurepointistobeextracted
     - vector
     - —
     - 
     - Input curve (e.g., force-displacement or stress-strain) from which the failure point is to be detected; typically a vector of X/Y pairs.
   * - Ratio
     - ratio
     - scalar
     - 0.01
     - 
     - Fractional threshold relative to (YMAX − YMIN) used to identify where the Y-value has effectively dropped; default is 0.01 (1%), leave at default for most material curves.
   * - Ensure Sustained Failure
     - ensuresustainability
     - string
     - no
     - 
     - Set to 'yes' to require that the curve continues to conform to the ratio threshold after the steepest-descent point, confirming sustained failure; default 'no' returns the minimum-derivative point unconditionally.
   * - Return Point Just Prior To The Failure Point
     - returnpreviouspointtominderivative
     - string
     - no
     - 
     - Set to 'yes' to return the data point immediately preceding the detected failure point (e.g., the last stable point before fracture); default 'no' returns the failure point itself.
   * - Return Type
     - return_type
     - string
     - count
     - 
     - Selects whether to return the X-coordinate ('xval', e.g., strain at failure) or Y-coordinate ('yval', e.g., stress at failure) of the detected failure point.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curve_failurepoint_min_derivative_output_1
     - curve_failurepoint_min_derivative_output_1
     - scalar
     - Scalar value of either the X- or Y-coordinate (as selected by Return Type) of the detected failure point on the input curve.

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

- data.curve.transform
- engineering.material.characterization
- engineering.material.failure

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

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

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_failurepoint_min_derivative</code>. Schema hash: <code>3affab0534a7</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
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