user_manual:pre_processing

# 2. Pre-processing

The first step when building a simulation model is the creation of the geometry model, and its associated mathematical description: the mesh. These 2 steps form what is called the pre-processing.

There can be multiple ways to pre-process a model for a SesamX simulation. However, this page aims at exposing the efficient pre-processing workflow around which the SesamX solver is designed and interfaced. The main advantage of this workflow is that it is based on free software: FreeCad to handle the geometry creation, and Salome to handle the mesh creation.

Off course, you are free to adopt your own workflow. Do not hesitate to contact our support for help about setting up such a workflow.

This page does not discuss every detail about how to use the software mentioned. Instead it focuses on the big picture and how these software communicate in an efficient manner.

To create a geometry from scratch, we propose to use the FreeCad modeler. The full documentation can be found on the FreeCad website. It will teach you how to best use the many FreeCad features.

We advise you to split the geometry creation in 2 steps:

• First you should build the full geometry of the part that you would like to design.
• And then, from this complete geometry, you should build a simplified geometry more suitable to finite element modeling (removing small holes and so on).

Even though Salome proposes some geometry simplification tools, from our point of view, these tools are not as efficient as the FreeCad ones.

Once the geometry is created, you can export the simplified geometry to a step file and proceed to meshing.

To create the mesh, we propose to use Salome. The full documentation can be found on the Salome website.

The geometry module allows you to import the step file and organize the geometry (in order to gain more control on the meshing process and the mesh refinements). You can then use the mesh module to effectively build the mesh. We advise you to chose by default the NETGEN meshing algorithm: it provides a nice compromise between robust mesh generation and ease of use.

At this step, it is also important to generate the groups of nodes and elements that will be relevant later on when manipulating the SesamX model. For instance, you should prepare the groups for the load and the constraint cases definition (as explained in the related documentation here and here)

Once done with the mesh creation, you can export it to a med file. And finally you are ready to use the SesamX solver to create and manipulate your SesamX model.

To conclude, the following picture summarizes the proposed workflow.

• user_manual/pre_processing.txt