Automotive and Aerospace How Crash Simulations Succeed with Open-Source Software

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Open source software has numerous advantages over proprietary solutions. The workflow presented here shows how crash tests in the automotive and aerospace industry can now be carried out completely open source in four steps.

For a long time, it seemed impossible to perform crash tests with a complete open source workflow. However, since the explicit FEM solver Openradioss was released and Freecad is sufficiently mature, crash tests can now be performed with little barrier to entry. This makes it possible to develop your own designs and software solutions without being limited by proprietary software. Let's take a look below at the open source workflow for conducting crash tests in the automotive and aerospace industries, including Freecad, Prepomax, Openradioss and Paraview software, applied to a Euro NCAP crash test.

Step 1: Model CAD Geometry as Solids and Shells in FreeCAD

The CAD components of the EV platform are created in FreeCAD using a sketch-based modeling workflow. Shell geometries such as vehicle frames and wall elements were generated in the Part Workbench, while solid components like the wheel hub were created in the Part Design Workbench, utilizing a parameterizable workflow where features are generated from sketches. The final EV and wall geometries are all exported as STEP files.

Step 2: Prepare Crash Test Easily and with Full Control in Prepomax

The geometry of the EV platform, including the wall, is then imported as a STEP file into Prepomax. It is subsequently simplified using compounds. Finally, placeholder materials are assigned, meshed, and organized into shell and solid sections, utilizing "part as selection."

Reference points, boundary conditions, and general contact (Radioss_General, Hard Coupling) are defined. Initial velocities (through a Calculix keyword at the reference node) and gravity are set and updated after model changes. A dynamic time step and a fixed wall condition are applied, and the model is exported as a *Calculix .inp file for solving.

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Step 3: Calculating Crash Test Results with an Explicit Solver in Openradioss

The Calculix *.inp file is converted into a Radioss input deck using the standalone inp2rad program. In the Openradioss GUI, plastic materials with fracture behavior are defined in the 0000.rad file. The solver is executed with this input deck. Upon completion, animation data is automatically converted into VTK format, with plans for future versions to automate full integration of plastic and fracture behavior.

Step 4: 3D Visualization and Analysis of Crash Test Results in Paraview

The VTK stack generated by Openradioss is loaded into Paraview and visualized as an animation of individual frames. This allows for the creation of detailed animations of the behavior of the EV platform, including deformations, contacts, and material reactions.

Significance and Outlook

Open-source tools now enable crash tests in the automotive and aerospace industries without proprietary software. CAD geometries are:

• modeled in FreeCAD,
• prepared and meshed in Prepomax, and
• solved in Openradioss with material and contact definitions.
• The results are visualized in Paraview.

This workflow reduces entry barriers for academic research and allows students and researchers to conduct, analyze, and independently further develop crash tests.