.. _auto_dataset_creep_coefficients_optimizer:

*DATASET CREEP COEFFICIENTS OPTIMIZER*
======================================

Fits the three-parameter creep law ε = A · σⁿ · tᵐ to experimental creep data by optimizing coefficients A, n, and m via Nelder–Mead minimization on the sum-of-squared errors. Use this worker to calibrate creep material parameters from coupon test data for downstream material card authoring.

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

Tagged: ``creep``, ``creep_coefficients``, ``creep_law``, ``curve_fitting``, ``material_calibration``, ``nelder_mead``, ``optimization``, ``parameter_fitting``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Dataset
     - dataset
     - dataset
     - —
     - ✓
     - Tabular dataset containing at least one column of test stress values (scalar per row) and one column of creep strain curves (time–strain curve objects); each row represents a separate creep test.
   * - stress_column_name
     - stress_column_name
     - text
     - —
     - 
     - Name of the dataset column holding the applied stress values (e.g. 'stress_MPa'); leave blank only if the column can be auto-detected, otherwise required.
   * - strain_column_name
     - strain_column_name
     - text
     - —
     - 
     - Name of the dataset column holding the time–strain creep curves (curve type); must reference a column containing (time, strain) pairs for each stress level.
   * - Time Unit
     - time_unit
     - text
     - —
     - 
     - Time unit of the creep curves: 'hour', 'second', or 'msec'; defaults to 'second' — set explicitly to match your test data to ensure correct internal time-axis scaling.
   * - Initial Value for Parameter A
     - initial_A
     - text
     - —
     - 
     - Initial guess for the pre-exponential creep coefficient A (must be > 0); defaults to 0.1 — adjust if convergence is poor for your material system.
   * - Initial Value for Parameter n
     - initial_n
     - text
     - —
     - 
     - Initial guess for the stress exponent n (must be > 0); defaults to 2 — typical range 1–10 for polymers and metals.
   * - Initial Value for Parameter m
     - initial_m
     - text
     - —
     - 
     - Initial guess for the time exponent m (must be < 0 for primary creep); defaults to −1 — adjust toward 0 for near-steady-state creep data.

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - Output Dataset
     - dataset
     - dataset
     - Augmented input dataset with additional columns: 'log_slopes' (log-space derivative curve), 'log_sr' (log strain-rate curve), and scalar columns for the optimal A, n, m values applied per row.

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

- ai_ml.supervised.regression
- design_exploration.optimization
- engineering.material.calibration
- 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=dataset_creep_coefficients_optimizer <https://www.d3view.com/api/workflow/example?id=dataset_creep_coefficients_optimizer>`_

.. raw:: html

   <hr style="margin-top:2em">
   <p style="font-size:11px;color:#888">
   Auto-generated from <code>platform</code> schema. Worker id: <code>dataset_creep_coefficients_optimizer</code>. Schema hash: <code>961e2f5df8d2</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>