Freecad tutorial pdf3/29/2024 ![]() Let's start by specifying which faces are fixed into the ground and can therefore not move. In the Material drop-down list, choose the Concrete-generic material, and press the OK button. A task panel will open to allow us to choose a material.Select the analysis object, and press the New Material button. This is important because depending on the material strength, our object will react differently to forces applied to it. We can now define the material to be applied to our mesh.After pressing the OK button and a few seconds of calculation, our FEM mesh is now ready:.For now, we can leave the default value of 1000: ![]() ![]() ![]() The main setting to edit is the Max Size which defines the maximum size (in millimeters) of each piece of the mesh. Here you can define the meshing parameters to be used to produce the FEM mesh. A new analysis will be created and a settings panels opened.We are now ready to start a FEM analysis.Switch to the Part Workbench, select the two objects, and press the Union button. Therefore, we need to join our two objects (the wall and the slab). The FEM Workbench can currently only calculate deformations on a single object.Now move the roof slab down so it rests on top of the wall: Edit the Rectangle object that we used as a base of the roof slab, and change its Placement->Position->X value from 3.18m to 3.00m.Instead, we will assume that the roof slab is placed directly on top of the wall. They are very different objects from the rest of the house so we will simplify our calculation by not including them. Also hide the metal beams on the roof.Hide the window, the door and the ground slab.Delete or hide the page object, the section planes and the dimensions, leaving only our model.Load the house model we modeled earlier.This involves, basically, discarding the objects that we don't want to include in the calculation, such as the door and window, and joining all the remaining objects into one. However, some changes have to be made to make the model suitable for FEM calculations. We will start with the house we modeled in the BIM modeling chapter. Detailed instructions to install these two components are provided in the FreeCAD documentation. Another piece of software, called NetGen, which is responsible for generating the subdivision mesh, is also required. However, currently only CalculiX is fully implemented. As there are several interesting open source FEM simulation applications available, the FEM Workbench allows you to choose between them. The simulation itself is done by another piece of software, that is used by FreeCAD to obtain the results. There are a number of steps: Preparing the geometry, setting its material, performing the meshing, division into smaller parts, like we did in the Preparing objects for 3D printing chapter, and finally calculating the simulation. Obtaining such simulation is done in FreeCAD with the FEM Workbench. This has several uses in the engineering and electromagnetism fields, but we will focus on one use that is already well developed in FreeCAD, which is simulating deformations in objects which are submitted to forces and weights. It is a vast mathematical subject, but in FreeCAD we can think of it as a way to calculate propagations inside a 3D object, by cutting it into small pieces, and analyzing the impact of each small piece on its neighbours.
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