Finite Element models 4 Nonlinear Intrinsic Aeroelastics in JAX

FENIAX is an aeroelastic toolbox written in Python using JAX. It acts as a post-processor of commercial software such as MSC Nastran.

• Arbitrary FE models built for linear aeroelastic analysis are enhanced with geometric nonlinear effects, flight dynamics and linearized state-space solutions about nonlinear equilibrium.
• Nonlinear solutions run very fast, at or close to real time.
• Algorithmic differentiation (AD) of the response is available via JAX. The code is carefully crafted to perform all computations on tensor data structures and via algorithms available for AD, much like Machine Learning models are built.
• The code can be run on modern hardware architectures such as GPUs.

Warning

The software is in beta, and while it has been thoroughly tested, new features keep being added and it is likely features for your analysis might be missing. Get in touch if you encounter problems.

Getting started

If you just want to start running the code, navigate to the Getting started

Examples

The most relevant examples in the code base are shown here, these and more can be found in the folder /examples They are also part of a large test suite that is integrated into the development using CI/CD.

Tip

Navigate to the code of the various examples, including the simulation input settings and postprocessing of the simulation --exactly as it was used for the articles backing the software. See examples

Nonlinear structural static results

Success

• Validated with MSC Nastran nonlinear solution (sol 400)
• AD differentiation of the response verified against finite-differences

Notebook

Note

Take a liner FE model of arbitrary complexity from your favourite FE solver, and turn it into a fully geometrically nonlinear model. You just need a condensation step into the main load paths and the resulting linear stiffness and mass matrices.

Wing free dynamics

Success

• Validated with MSC Nastran nonlinear solution (sol 400)
• Runs over x100 faster than Nastran
• AD differentiation of the response verified against finite-differences

Notebook

Free flying structure

This example first appeared in the work of Juan Carlos Simo (see Bio) , a pioneer in the field of computational structural mechanics and the

Notebook

2D dynamics

3D dynamics

Industrial Aircraft model

Success

• Linear response validated with MSC Nastran linear aeroelastic solution (sol 146)
• Nonlinear response in our solvers takes similar times to the linear Nastran solution!!

Theoretical background

Code base

License

Please see the project license for further details.