A Convex Route to Thermomechanics: Learning Internal Energy and Dissipation

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Hauptverfasser: Holthusen, Hagen, Steinmann, Paul, Kuhl, Ellen
Format: Preprint
Veröffentlicht: 2026
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author Holthusen, Hagen
Steinmann, Paul
Kuhl, Ellen
author_facet Holthusen, Hagen
Steinmann, Paul
Kuhl, Ellen
contents We present a physics-based neural network framework for the discovery of constitutive models in fully coupled thermomechanics. In contrast to classical formulations based on the Helmholtz energy, we adopt the internal energy and a dissipation potential as primary constitutive functions, expressed in terms of deformation and entropy. This choice avoids the need to enforce mixed convexity--concavity conditions and facilitates a consistent incorporation of thermodynamic principles. In this contribution, we focus on materials without preferred directions or internal variables. While the formulation is posed in terms of entropy, the temperature is treated as the independent observable, and the entropy is inferred internally through the constitutive relation, enabling thermodynamically consistent modeling without requiring entropy data. Thermodynamic admissibility of the networks is guaranteed by construction. The internal energy and dissipation potential are represented by input convex neural networks, ensuring convexity and compliance with the second law. Objectivity, material symmetry, and normalization are embedded directly into the architecture through invariant-based representations and zero-anchored formulations. We demonstrate the performance of the proposed framework on synthetic and experimental datasets, including purely thermal problems and fully coupled thermomechanical responses of soft tissues and filled rubbers. The results show that the learned models accurately capture the underlying constitutive behavior. All code, data, and trained models are made publicly available via https://doi.org/10.5281/zenodo.19248596.
format Preprint
id arxiv_https___arxiv_org_abs_2603_28707
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Convex Route to Thermomechanics: Learning Internal Energy and Dissipation
Holthusen, Hagen
Steinmann, Paul
Kuhl, Ellen
Computational Engineering, Finance, and Science
Artificial Intelligence
65, 74
I.6; J.2
We present a physics-based neural network framework for the discovery of constitutive models in fully coupled thermomechanics. In contrast to classical formulations based on the Helmholtz energy, we adopt the internal energy and a dissipation potential as primary constitutive functions, expressed in terms of deformation and entropy. This choice avoids the need to enforce mixed convexity--concavity conditions and facilitates a consistent incorporation of thermodynamic principles. In this contribution, we focus on materials without preferred directions or internal variables. While the formulation is posed in terms of entropy, the temperature is treated as the independent observable, and the entropy is inferred internally through the constitutive relation, enabling thermodynamically consistent modeling without requiring entropy data. Thermodynamic admissibility of the networks is guaranteed by construction. The internal energy and dissipation potential are represented by input convex neural networks, ensuring convexity and compliance with the second law. Objectivity, material symmetry, and normalization are embedded directly into the architecture through invariant-based representations and zero-anchored formulations. We demonstrate the performance of the proposed framework on synthetic and experimental datasets, including purely thermal problems and fully coupled thermomechanical responses of soft tissues and filled rubbers. The results show that the learned models accurately capture the underlying constitutive behavior. All code, data, and trained models are made publicly available via https://doi.org/10.5281/zenodo.19248596.
title A Convex Route to Thermomechanics: Learning Internal Energy and Dissipation
topic Computational Engineering, Finance, and Science
Artificial Intelligence
65, 74
I.6; J.2
url https://arxiv.org/abs/2603.28707