FEM tutorial/de

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Thema
Tutorial
Finite Element Analysis
Niveau
Beginner
Zeit zum Abschluss
10 minutes + Solver time
Autor
Drei
FreeCAD version
0.16.6700 or above
Beispieldatei(en)

Contents 1 Tutorial 2 Introduction 3 Requirements 4 Procedure 4.1 Modeling 4.2 Creating the Analysis 4.2.1 Netgen 4.2.2 GMSH 4.3 Constraints and Forces 4.4 Final preparations 4.5 Running the Solver 4.5.1 Standard Procedure 4.5.2 Quick Procedure 4.6 Analyzing Results

Introduction

This tutorial is meant to introduce the reader to the basic workflow of the FEM Workbench, as well as most of the tools that are available to perform a static analysis.

Requirements

FreeCAD version 0.16.6700 or above
Netgen and/or GMSH is installed on the system
In the case of GMSH, install Macro GMSH from the AddonManager, developed by psicofil
Calculix is installed on the system
The reader has the basic knowledge to use the Part and PartDesign Workbenches

Procedure

Modeling

In this example a Cube is used as the study object, but models created in the Part or PartDesign Workbenches can be used instead.

Create a new document
Activate the Part Workbench
Create a Cube
Change its Dimensions to the following:
1. Height: 1.000 mm
2. Length: 8.000 mm
3. Width: 1.000 mm

Now we have a model with which to work with.

Creating the Analysis

Netgen

Select the model
Click New mechanical analysis from the menu to create an analysis from the object that was selected
In the meshing dialog, click OK

You can also drag and drop a mesh to a Mechanical Analysis that does not have a mesh within the Tree View.

GMSH

The usage of psicofil's macro is recommended, and is used for this example.

Activate the macro
Select the object you wish to use, in this case our Cube
Check the box Create Mechanical Analysis from mesh
Click OK

We have now meshed our object and are ready to add constraints and forces.

Constraints and Forces

Hide the mesh from the Tree View.
Show the original model
Select Create FEM fixed constraint
Select the back face of the Cube (face on the YZ axis) and click OK
Select Create FEM force constraint
Select the front face of the Cube (the face parallel to the back face) and set the Area load value to 9000000.00
Set the Direction to -Z by selecting one of the face edges parallel to that direction.
Click OK

We now have established the restrictions and forces for our static study.

Final preparations

Select Mechanical material... and choose Calculix as the material
Click OK

Running the Solver

Standard Procedure

Select the solver object contained in the Mechanical Analysis
Select Start calculation from the menu
Select Write Calculix Input File
Select Run Calculix
Click Close

Quick Procedure

Select the solver object contained in the Mechanical Analysis
Click on Quick Analysis.

Analyzing Results

From the Object Tree, select the Results object
Select Show result
Choose among the different Result types to view the results
The slider at the bottom can be used to alter the mesh visualization. This allows us to visualize the deformation experienced by the object, keep in mind that this is an approximation.
To remove the results select Purge results

Comparison to previous example file

If you select the Z displacement result type, you can see that the obtained value is almost identical to the test example provided by FreeCAD. Differences may occur due to the quality of the mesh and the number of nodes it possesses.

We are now finished with the basic workflow for the FEM Module.

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FEM