WeldFormFEM
WeldFormFEM is the main finite element solver line for large deformation mechanics. It currently follows two complementary methods: an explicit line for fast large-deformation simulations and an implicit line for quasi-static forming problems.
Current focus
- Large strain elastoplasticity
- CPU/GPU solver consistency
- Reduced integration and locking control
- Contact algorithms for forming and compression
- Remeshing workflows for distorted meshes
Explicit method
The explicit method is based on reduced integration and is intended for large-deformation problems where robust time-marching and low per-step cost are important.
Its 2D remeshing workflow follows the remeshing strategy described in Paulo Martins' metal forming work.
For 3D simulations, the remeshing workflow is based on MMG.
The GitHub link below points to a reduced public version of this explicit solver line.
Implicit method
The implicit branch is currently being used for quasi-static large-deformation forming benchmarks, including upsetting/compression and extrusion-style validation cases where contact stability, pressure behavior, and mesh robustness are critical.
For slow forging workflows, the implicit formulation is usually the most common choice. In this project, that line is the main path for quasi-static metal forming studies.
In the upsetting/compression benchmark, the 2D formulation uses a mixed U-P approach with selective reduced integration, following the Paulo Martins scheme used in metal forming simulations.
Reference related to the general implicit rigid-viscoplastic formulation
Nielsen and Martins, Metal Forming: Formability, Simulation, Tool Design.
For the 3D model, the implementation does not rely on hexahedra as described in Martins' book. Instead, it follows the MINI element methodology with bubble enrichment for mixed formulations.
References related to the 3D MINI element methodology
Arnold, Brezzi and Fortin, A stable finite element for the Stokes equation.
Andrea Cioncolini and Daniele Boffi, The MINI mixed finite element for the Stokes problem: An experimental investigation.
The implicit version used for slow forging workflows is also available as a binary in the WeldFormGUI repository.
Implicit solver feature matrix
This is a simple status matrix for the current 2D and 3D implicit solver capabilities. It will be expanded as more workflows are consolidated.
| Feature | 2D | 3D | Notes |
|---|---|---|---|
| Contact | Working | Working | Used in current upsetting/compression and forming validation workflows. |
| Automatic penalty | Working | Working | Used to improve contact robustness in both 2D and 3D quasi-static workflows. |
| Remeshing | Working | Working | In 2D it is currently homogeneous only, with no refinement; 3D remeshing is available in the current workflow. |
| Thermal coupling | - | Working | Integrated in the current 3D implicit branch. |
| Quad mapping after large strain | Known limitation | - | Quad remapping in 2D is known to have limitations after strong distortion. |
| Plastic-strain-based remeshing | In progress | Working | 2D refinement driven by plastic strain is under active development; the 3D workflow is already working. |
Project links
GitHub repository - reduced public version of the explicit solver line.