MATLAB–OpenFAST Coupled Framework for TMD Optimization (v3.5)

This repository provides a MATLAB-based optimization framework coupled with OpenFAST v3.5 for the design and optimization of a Tuned Mass Damper (TMD) applied to a floating offshore wind turbine.

The framework uses time-domain simulations in OpenFAST and optimizes the TMD parameters using Particle Swarm Optimization (PSO).

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⚙️ Software Requirements

• OpenFAST v3.5.0
• MATLAB R202x or later
• Global Optimization Toolbox (for particleswarm and ga)
• Windows OS (tested configuration)

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🎯 Objective

The goal is to optimize two TMD parameters:

• Damping ratio (ξ)
• Stiffness (k)

Objective function:

Minimization of the standard deviation of the platform pitch motion obtained from OpenFAST simulations.

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🔁 How the Code Works

The coupling between MATLAB and OpenFAST follows a sequential automation process:

1. Optimization starts (MATLAB PSO)

MATLAB generates candidate TMD parameters:

• damping ratio (ξ)
• stiffness (k)

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2. Input file modification

For each candidate solution:

• Structural Control input file is updated
• ServoDyn input file is updated
• Main OpenFAST .fst file is updated

This ensures that each simulation uses the current TMD design.

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3. OpenFAST execution

The modified model is executed using:

• OpenFAST v3.5 solver
• Time-domain simulation of floating wind turbine dynamics

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4. Output extraction

After simulation:

• .out file is read into MATLAB
• Platform pitch response is extracted

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5. Objective function evaluation

The performance metric is computed as:

• Standard deviation of platform pitch motion

This value represents the vibration level of the system.

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6. Optimization update

The PSO algorithm updates the TMD parameters and repeats the process until convergence.

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🧠 Optimization Method

• Particle Swarm Optimization (PSO) via MATLAB particleswarm

Optional:

• Genetic Algorithm (ga)

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📁 Main Files

• main_optimization.m → Main PSO/GA optimization script
• compute_objective_function.m → Objective function linked to OpenFAST
• modify_strucCtrl_input_file.m → Updates TMD parameters in structural control file
• modify_servodyn_input_file.m → Updates ServoDyn input file
• modify_openfast_input_file.m → Updates OpenFAST .fst file
• runFAST_optimization_riad.m → Runs OpenFAST simulation

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⚠️ Important Notes

User-defined paths

Before running the code, the user must define local paths:

coupling.path_of_openfast_exe
coupling.path_of_openfast_filename
coupling.path_of_servodyn_input_file
coupling.path_of_strucCtrl_input_file

📊 Outputs

The optimization returns:

Optimal damping ratio (ξ)
Optimal stiffness (k)
Objective function value (Standard deviation of platform pitch)

📚 Reference

If you use this work, please cite:

Riad El Hamoud, Philip Alkhoury, Abdul-Hamid Soubra, Mourad Aït-Ahmed,
Bidirectional Vibration and Fatigue Mitigation of a Barge-Type Floating Offshore Wind Turbine Using an Omnidirectional Tuned Mass Damper,
Applied Ocean Research, Volume 171, 2026, 105066
https://doi.org/10.1016/j.apor.2026.105066

📌 Disclaimer

This repository is intended for academic and research use only.
No guarantee is provided for compatibility with future OpenFAST versions.

2026.105066

📚 BibTeX
@article{elhamoud2026tmd,
  title={Bidirectional Vibration and Fatigue Mitigation of a Barge-Type Floating Offshore Wind Turbine Using an Omnidirectional Tuned Mass Damper},
  author={El Hamoud, Riad and Alkhoury, Philip and Soubra, Abdul-Hamid and Aït-Ahmed, Mourad},
  journal={Applied Ocean Research},
  volume={171},
  pages={105066},
  year={2026},
  doi={10.1016/j.apor.2026.105066}
}