Welcome to ThermoNTFA’s documentation!

Thermo-Plastic Nonuniform Transformation Field Analysis

In engineering applications, surface modifications of materials can greatly influence the lifetime of parts and structures. For instance, laser melt injection (LMI) of ceramic particles into a metallic substrate can greatly improve abrasive resistance. The LMI process is challenging to model due to the rapid temperature changes, which induce high mechanical stresses. Ultimately, this leads to plastification and residual eigenstresses in particles and matrix. These depend on the process parameters. In order to predict these stresses, we propose a major extension of the Nonuniform Transformation Field Analysis that enables the method to cope with strongly varying thermo-elastic material parameters over a large temperature range (here: 300 to 1300K). The newly proposed θ-NTFA method combines the NTFA with a Galerkin projection to solve for the self-equilibrated fields needed to gain the NTFA system matrices. For that, we exploit our recent thermo-elastic reduced order model [1] and extend it to allow for arbitrary polarization strains. An efficient implementation anda rigorous separation of the derivation of the reduced order model is proposed. The new θ-NTFA is then validated for various thermo-mechanical loadings and in thermo-mechanical two-scale simulations.

[1] S. Sharba, J. Herb, F. Fritzen, Reduced order homogenization of thermoelastic materials with strong temperature dependence and comparison to a machine-learned model, Archive of Applied Mechanics 93 (7) (2023) 2855–2876. doi: 10.1007/s00419-023-02411-6

Features

• The ThermoNTFA acts as a reduced order model (ROM) and approximates the effective behavior of composite materials that consist of thermoelastic and thermoplastic constituents.

• The material parameters of all constituents are allowed to depend strongly on the temperature.

• This temperature-dependence is reflected in the ROM that is based on interpolated space-saving tabular data at arbitrarily many temperature points.

• Possible application: Eigenstress Analysis of Laser Dispersed Materials

Contents:

• Workflow
  • Offline phase: Training of the thermo-mechanical NTFA
  • Online phase: Application of the thermo-mechanical NTFA in simulations on the macroscale
• Installation
  • Using the PIP package
  • From this repository
  • Requirements
• ThermoNTFA Documentation
  • TabularInterpolation
  • ThermoMechNTFA
• Examples
  • Thermo-mechanical NTFA - results of the CMAME article
  • Material parameters
  • Truncate NTFA modes
  • Thermo-mechanical NTFA - Generate input files
• Citation
• Changelog
  • [1.0.0]

© Copyright 2024

• Felix Fritzen (fritzen@simtech.uni-stuttgart.de),

• Julius Herb (julius.herb@mib.uni-stuttgart.de),

• Shadi Sharba (shadi.sharba@isc.fraunhofer.de)

University of Stuttgart, Institute of Applied Mechanics, Chair for Data Analytics in Engineering

Funding acknowledgment

The IGF-Project no.: 21.079 N / DVS-No.: 06.3341 of the “Forschungsvereinigung Schweißen und verwandte Verfahren e.V.” of the German Welding Society (DVS), Aachener Str. 172, 40223 Düsseldorf, Germany, was funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK) via the German Federation of Industrial Research Associations (AiF) in accordance with the policy to support the Industrial Collective Research (IGF) on the orders of the German Bundestag.

Felix Fritzen is funded by the German Research Foundation (DFG) – 390740016 (EXC-2075); 406068690 (FR2702/8-1); 517847245 (FR2702/10-1).