Variable-Order Springpot Model Tuning via Cross-Entropy Method

SpringpotTune: Variable-Order Springpot Model Tuning via Cross-Entropy Method is a Matlab package designed to fit variable-order springpot models (fractional rheological elements) using the Cross-Entropy (CE) method for global optimization. With simple adaptations, the SpringpotFit framework can be extended to optimize other variable-order fractional models in rheology and time-dependent systems, offering a versatile and robust approach to parameter identification.

SpringpotTune uses as optimization tool the package CEopt - Cross-Entropy Optimizer, which can be downloaded at https://ceopt.org.

Overview
Features
Usage
Documentation
Reproducibility
Authors
Citing FracTune
License
Institutional support
Funding

Overview

SpringpotTune was developed to fit variable-order springpot models for rheological systems by addressing nonconvex optimization problems using the Cross-Entropy (CE) method. The underlying results are reported in the following publication:

J. G. Telles Ribeiro and A. Cunha Jr, Advanced creep modeling of polypropylene: A variable-order fractional calculus approach, 2024 (under review)

Preprint available here.

Features

Implements the Cross-Entropy method for fitting variable-order springpot models
Transparent “gray-box” optimizer offering intuitive control over key parameters
Robust and scalable for moderately complex fitting problems in rheological systems
Demonstrated versatility and effectiveness through case studies of variable-order fractional models

Usage

To get started with SpringpotTune, follow these steps:

Clone the repository:

git clone https://github.com/americocunhajr/SpringpotTune.git

Navigate to the code directory:
```
cd SpringpotTune/SpringpotTune-1.0
```
To calibrate the Springpot model, execute the main file corresponding to your case:
```
Main_ModelCalibration_VOSpringpot
```

This package includes the following files:

CEopt.m – Cross-entropy solver
Main_ModelCalibration_VOSpringpot.m – Model calibration for the variable-order springpot
PlotSemilogx2.m – Auxiliary function to plot two temporal curves from given datasets in semilogx scale

Documentation

The routines in SpringpotTune are well-commented to explain their functionality. Each routine includes a description of its purpose, inputs, and outputs.

Reproducibility

Simulations done with SpringpotFit are fully reproducible, as can be seen on this CodeOcean capsule.

Authors

José Geraldo Telles Ribeiro
Americo Cunha Jr

Citing SpringpotTune

We ask the code users to cite the following manuscript in any publications reporting work done with our code:

J. G. Telles Ribeiro and A. Cunha Jr, Advanced creep modeling of polypropylene: A variable-order fractional calculus approach, 2024 (under review)

@article{TellesRibeiro2024SpringpotTune,
   author  = {J. G. {Telles Ribeiro} and A. {Cunha~Jr}},
   title   = "{Advanced creep modeling of polypropylene: A variable-order fractional calculus approach}",
   journal = {Under Review},
   year    = {2024},
   volume  = {~},
   pages   = {~},
   doi    = {~},
}

License

SpringpotTune is released under the MIT license. See the LICENSE file for details. All new contributions must be made under the MIT license.