FEM Shear of a Composite Block

Introduction
In this tutorial we analyze the shear deformation of a composite block consisting of a stiff core embedded in a soft matrix. It demonstrates the use of BooleanFragments and CompoundFilter to create solids for the block and the matrix from two concentric cubes. This work-flow ensures that separate MeshRegions, Materials and Boundary Conditions can be defined for the block and the surrounding matrix. The CalculiX results clearly show the effect of the stiff core on the response of the composite block.

Geometry
First we create two concentric cubes, one size 10mm and the other size 5mm. This is done in the workbench "Part". By default the cube is placed at the origin [0, 0, 0], so the smaller cube needs to be scaled down and shifted by changing the settings in the Data tab of the property panel. To make the core visible, the Transparency of the outer block is set to 50 in the View tab of the property panel. The result is shown below.



Mesh and Mesh Regions
From workbench FEM we create an Analysis container. This will contain all definitions required for the CalculiX analysis and its results. Note that this Analysis container needs to be activated (right-click and select "Activate analysis") whenever re-loading the file or after switching back from other analyses. To start the meshing process, highlight the CompoundFilter in the Object Tree and activate the meshing dialog "Mesh > FEM mesh from shape by Gmsh". Leave the dialog by clicking OK.

A Mesh object is now created in the Object Tree. Highlight this object and create a Mesh Region object via "Mesh > FEM mesh region". Open the dialog box for this Mesh Region by double clicking and tick the radio box for Solid. Next click the "Add Reference" button and select the Cube_Matrix object in the Graphical Window. This should add a reference to "Box:Solid1" in the object list of the Mesh Region. Finally specify the maximum element size for this region (5mm in the current analysis). Leave the dialog by clicking OK.



Next make the Cube_Matrix object invisible by highlighting it and pressing the space bar. In a similar way make the Cube_Core visible. Now create a new Mesh object as above and select the Cube_Core object in the Graphical Window. This time the reference list should show "Box001:Solid1", as below. This time we chose a maximum element size of 1mm



Fixed Nodes
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