Open Source Mechanics

More elements alone won't save a large deformation simulation.

These closed-die forging results show the combined effect of mesh density and time step size.

✓ Selective refinement near the flash captures the material flow accurately.

✗ A coarse mesh combined with an excessively large time step loses important deformation details and produces poor flash prediction.

✓ A balanced mesh together with controlled time stepping provides a stable and realistic solution.

In large deformation FEM, mesh adaptation and step size control are often as important as the constitutive model itself.

Good simulations require both spatial and temporal resolution.

#FEM #MetalForming #Forging #Remeshing #Simulation

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5 days ago | [YT] | 12

Open Source Mechanics

# FRICTION MATTERS

**Influence of Shear Friction on Material Flow and Forming Loads**

Same extrusion process.

* Same material
* Same mesh
* Same boundary conditions

Only the **shear friction factor (m)** was modified.

In metal forming simulations, friction is one of the most influential process parameters. Even relatively small changes can produce significant differences in:

• Forming loads
• Material flow
• Final geometry
• Die filling behavior

The figure compares three extrusion simulations using the same setup but different shear friction values.

Notice how both the load response and the deformation pattern evolve differently as friction increases.

**Shear Friction Model (m)**

* Frictionless
* m = 0.10
* m = 0.15

Solved with the WeldForm Explicit FEM Solver.

#FEM #MetalForming #CAE #Simulation #FiniteElement #Engineering #OpenSourceMechanics

1 week ago | [YT] | 11

Open Source Mechanics

Two important milestones in the development of the WeldForm implicit rigid-viscoplastic solver.

The first is the successful solution of a closed-die forging benchmark using the implicit formulation together with automatic remeshing. This type of problem combines large deformation, severe mesh distortion, nonlinear contact, and complex material flow, making it one of the most challenging classes of metal forming simulations. The simulation completed successfully while maintaining mesh quality through remeshing.

The second development is the validation of the shear friction implementation using the classical ring compression benchmark proposed by Ebrahimi and Najafizadeh (2004). The resulting deformation patterns show good agreement with the reference study, indicating that the current friction formulation can reproduce the expected material flow behavior under different friction conditions.

The friction factor was evaluated directly from the simulation results by measuring the evolution of the ring inner diameter using the overlay ruler tool available in the WeldForm postprocessor. This allows a direct comparison with the benchmark methodology commonly used in bulk metal forming friction studies.

These results represent another step toward a fully validated implicit metal forming solver capable of handling realistic forging processes involving large deformation, contact, friction, and remeshing.

Reference:

Ebrahimi, R., and Najafizadeh, A.,
"A New Method for Evaluation of Friction in Bulk Metal Forming",
Journal of Materials Processing Technology, 152(2), 136-143, 2004.

#FEM #MetalForming #Forging #ImplicitSolver #Remeshing #Friction #RingCompression #FiniteElementAnalysis #CAE #EngineeringSimulation #OpenSource #Cplusplus #SolverDevelopment

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2 weeks ago (edited) | [YT] | 12

Open Source Mechanics

Building a Metal Forming Benchmark Database: New 2D & 3D Explicit/Implicit Results

#FEM #GUI #CAE #ImplicitSolver #MetalForming #Forging #Remeshing #MMG #Simulation #NonlinearFEM #ComputationalMechanics #Engineering #Cplusplus #OpenSource #WeldFormGUI

A major milestone has been reached in the development of the implicit forming solver.

The first prototype of a rigid-viscoplastic implicit FEM solver using 3D tetrahedral MINI elements (Forge-style formulation) is now running together with automatic remeshing using MMG.

The combination of mixed velocity-pressure formulation, tetrahedral meshes, and continuous remeshing is showing very promising results for large deformation forging simulations, where mesh distortion is traditionally one of the biggest challenges.


Current work is focused on improving robustness, contact handling, remeshing transitions, and preparing a complete validation and benchmark suite for metal forming applications.

At the same time, I am expanding the benchmark section of OpenSource Mechanics with industrially relevant validation cases, including:

• Cylinder compression benchmarks
• Axisymmetric upsetting cases
• Large deformation forging examples
• Comparisons against commercial solutions such as Simufact and QForm
• Load-displacement curve validation
• Force prediction and deformation pattern comparisons

The goal is to build a transparent benchmark database showing not only final shapes, but also force evolution, convergence behavior, remeshing quality, and solver robustness under extreme deformation conditions.

The GUI is also receiving significant upgrades, including:

• Symmetry boundary conditions
• Clipping planes for model inspection
• Improved visualization tools
• Better model setup workflow
• Additional preprocessing and postprocessing capabilities

The long-term objective remains the same: creating a practical workflow for nonlinear FEM simulations focused on large deformation manufacturing processes such as forging, forming, and metal processing.

Exciting months ahead.
More benchmarks and validation results coming soon.

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3 weeks ago | [YT] | 15

Open Source Mechanics

20260528 - GUI & Solvers Update: Time Functions, Energy Visualization, and First OpenRadioss Python Exporter

#FEM #GUI #CAE #ImplicitSolver #ExplicitSolver #MetalForming #OpenSource #Cplusplus #OpenRadioss #Simulation #NonlinearFEM #SolverDev

This update adds time-dependent functions for boundary conditions and solver controls, together with improved energy computation, visualization tools, and the first working Python-based OpenRadioss exporter integrated directly into WeldForm GUI.

Boundary conditions can now be defined using functions of time directly from the GUI, allowing smoother and more realistic loading paths for forming simulations, displacement ramps, velocity-controlled problems, and solver parameter evolution.

Internal energy and external work calculations were also corrected and can now be visualized directly through integrated energy plots during postprocessing.

This update also introduces the first working Python OpenRadioss exporter running directly from the GUI workflow, moving WeldForm closer to a multi-solver CAE environment.

New:

- Added time-dependent amplitude functions for boundary conditions
- Added graphical editing of amplitude curves directly inside the GUI
- Added support for function-based solver parameter evolution
- Corrected internal energy computation
- Corrected external work calculation
- Added visualization of energy evolution curves
- Added the first Python-based OpenRadioss exporter integrated into the GUI workflow
- Improved postprocessing workflow for implicit and explicit simulations
- Improved handling of nonlinear loading histories

This enables:

- Smoother and more realistic load application
- Better control of nonlinear simulation workflows
- Improved validation of solver energy balance
- Clearer analysis of simulation stability and convergence behavior
- A first step toward integrated multi-solver workflows
- More robust workflows for large deformation simulations

Time-dependent loading is essential for many nonlinear FEM problems. With integrated function editors, energy visualization, and OpenRadioss export support, the workflow becomes closer to industrial CAE environments while remaining lightweight and open.

www.patreon.com/posts/gui-solvers-time-159480060?u…

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4 weeks ago (edited) | [YT] | 15

Open Source Mechanics

Version 0.0.8 is out.

This release expands Python scripting across the full model-building workflow. You can now create and
assemble an entire model from script, including model creation, STEP part import, extrusion-based
geometry generation, and load model workflow setup.

New in this update:

- Full scripting support for the load model workflow
- STEP geometry import from script
- Extrusion scripts
- Scripted model creation with automatic tree update
- Fixed scripted geometry visibility
- Scripts added to recent files
- Energy Plot dialog for the implicit solver
- Highlighted parts in the GUI
- Fixed element ID display
- Beginning of the new Model Checker
- Fixed remaining boundary condition symbols after closing a model
- Improved Radioss export with /ANALY and proper 2D /QUAD output


github.com/luchete80/WeldFormGUI/releases/tag/v0.0…


This pushes the GUI further toward a combined visual + scripted CAE workflow:
build interactively when needed, automate when reproducibility and parametric workflows matter.

#FEM #CAE #Python #Cplusplus #Automation #OpenSource #Radioss #SolverDev #GUI

1 month ago (edited) | [YT] | 11

Open Source Mechanics

GUI New Feature: Abaqus Export vis Python & Model Sets

The GUI now supports exporting models directly to Abaqus from simple Python scripts, exposing the full scripting capabilities behind the scene.

In addition, you can now define and manage sets within the GUI.

This enables:

Programmatic reproduction of any model
Full control over geometry, mesh, materials, boundary conditions, and sets
Automation and parametric workflows
Clean integration into custom simulation pipelines

Build your model visually. Extend it with Python.

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1 month ago | [YT] | 12

Open Source Mechanics

In the next few days, I’ll be uploading downloadable Windows binaries for my FEM GUI, including 3 built-in demos that showcase the complete workflow, from model loading to simulation and results visualization.

The release will include educational versions of both the explicit and implicit viscoplastic solvers, limited to 500 nodes, focused on large deformation workflows.

I’ll also be publishing a series of videos showing how these models can be created from scratch inside the GUI.

The goal of this release is simple: make the workflow easier to explore, test, and understand.

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1 month ago | [YT] | 19

Open Source Mechanics

0260422 - My FEM GUI Is Finally Becoming Usable

#FEM #GUI #CAE #Cplusplus #SolverDev #OpenSource


In the last two weeks, I focused on one thing: reducing friction between model and results.

This update moves my FEM solver from a developer tool toward something you can actually use.

What’s new:

Run directly from the model, without separate job setup
Built-in demo for faster testing and workflow exploration
Progress bars for both simulation run and results loading
Live job log with cleaner output and reduced visible lines
Load plots integrated with ImPlot
Explicit and implicit step definition from the GUI
Automatic input file generation from the model
Custom quad mesher integration instead of Gmsh
Improved visualization with nodes, vectors, and manual/auto color scaling
The goal of these changes is simple: make it possible to go from opening the GUI to running a simulation and visualizing results in seconds.

A demo binary is the next step. I am currently packaging and testing it.

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2 months ago (edited) | [YT] | 24

Open Source Mechanics

When More Contact Stiffness Makes Things Worse

I increased contact stiffness in my implicit FEM solver…
and penetration got worse.


What I Tested

**Case 1**
Velocity penalty = 5.0
Gap penalty = 0.01
→ Velocity dominated, poor convergence

**Case 2**
Velocity penalty = 5.0
Gap penalty = 0.05
→ Almost no change

**Case 3**
Velocity penalty = 0.1
Gap penalty = 1.0
→ Stable convergence, lower penetration

What Was Happening

The issue wasn’t just stiffness.

The velocity term was **masking** the gap enforcement.

Increasing the gap penalty didn’t help
because velocity forces still dominated.


Why It Works Now

Reducing velocity stiffness did two things:

* Improved conditioning
* Allowed gap enforcement to become effective

This not only fixed convergence,
but also allowed the solver to handle more complex matrices.


Takeaway

f one term dominates your formulation, the rest becomes ineffective.

Sometimes, reducing stiffness leads to better results.

2 months ago | [YT] | 6