.. _auto_curves_get_triaxiality_at_failure:

*COMPUTES THE TRIAX AT THE TIME OF FAILURE*
===========================================

Computes the triaxiality value at the moment of element failure, given stress-tensor histories, eroded internal energy, and plastic strain curves. Supports multiple evaluation modes (erosion onset, peak triaxiality, or average between peak and erosion start) and can accept either raw stress tensors or pre-computed triaxiality curves as input.

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

Classification: **process**.

Tagged: ``element_deletion``, ``erosion``, ``failure``, ``gissmo``, ``material_failure``, ``plastic_strain``, ``stress_tensor``, ``triax_at_failure``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - STRESS TENSORS
     - stress_tensors
     - vector
     - —
     - 
     - Time-history stress tensor curves (σ_xx, σ_yy, σ_zz, σ_xy, σ_xz, σ_yz) for one or more elements, used to compute triaxiality internally; required when `triax_input` is set to `stress_tensors`.
   * - Part Eroded Internal Energy
     - part_eroded_internal_energy
     - vector
     - —
     - 
     - Part-level eroded internal energy curve (energy vs. time) used to detect the onset of element erosion/deletion; the time at which this curve first rises marks the failure instant.
   * - Plastic Strains
     - plastic_strains
     - vector
     - —
     - 
     - Equivalent plastic strain (PEEQ) time-history curves for the elements of interest; used alongside erosion energy to identify the failure point in strain space.
   * - Triax Input
     - triax_input
     - string
     - stress_tensors
     - 
     - Selects the source used to derive triaxiality: `stress_tensors` (default) computes triaxiality from the provided stress tensor curves, while `triaxiality` expects pre-computed triaxiality curves to be supplied directly.
   * - Triaxility Type
     - triax_type
     - string
     - time_when_erosion_starts
     - 
     - Defines which triaxiality value to extract: `time_when_erosion_starts` (default) reads triaxiality at the erosion onset time, `peak_triax` returns the maximum triaxiality over the history, and `avg_between_peak_triax_and_start_of_erosion` averages triaxiality between the peak and the erosion start.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curves_get_triaxiality_at_failure_output_1
     - curves_get_triaxiality_at_failure_output_1
     - scalar
     - Scalar triaxiality value at the identified failure point (dimensionless, ratio of hydrostatic to von Mises stress), computed according to the selected `triax_type` method.

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

- data.curve.pair
- engineering.material.calibration
- 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=curves_get_triaxiality_at_failure <https://www.d3view.com/api/workflow/example?id=curves_get_triaxiality_at_failure>`_

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