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Documentation

Tutorial: Underrun protection device – Static stress analysis

In the following you find a step-by-step instruction for a static stress analysis of an underrun protection device. Note that the complete analysis is static, dynamic effects are neglected.

Import tutorial case into workbench

Step-by-step

Import tutorial project

  • To start this tutorial, you have to import the tutorial project into your ‘Dashboard’ via the link above.

The CAD model

  • Once the workbench is open you will be in the ‘Geometries’ tab.
  • The CAD model named “Underrun Protection” is displayed in the viewer, as shown below.
  • You can interact with the CAD model as in a normal desktop application.
CAD model loaded to SimScale
CAD model displayed in the viewer.

Create a Static Analysis

  • With the geometry selected, click on ‘Create Simulation’.
  • In our case we are interested in running a static stress analysis, so select the Static analysis option and press ‘Create Simulation’.
  • A new tree will be automatically generated in the left panel with all the parameters and settings that are necessary to completely specify such an analysis.
  • All parts that are completed are highlighted with a green check. Parts that need to be specified have a red circle. A blue circle indicates an optional setting that does not need to be filled out.
Static analysis SimScale
Selecting the analysis type.

 Create a mesh

  • As Finite Element analyses are carried out on discretized domains, we have to generate a Mesh for our CAD model.
  • Therefore as the next step select the Mesh option.
  • First order elements are used here.
  • Note that the results generated with First order elements might not be as accurate as with Second order elements. But choosing a Second order mesh will lead to longer computing times so is avoided here.
  • The mesh fineness will be coarse. As a rule of thumb, one should make sure that the resulting mesh does have more than one volume layer across the cross section of the model.
  • To start the meshing operation, hit the ‘Generate‘ button, highlighted in the figure below.
SimScale generating a tet-dominant mesh.
Generating a tet-dominant mesh.
  • The resulting mesh is shown in figure below.
  • There is also a Meshing log available which provides quantitative information about the mesh.
Tet-dominant mesh generated on SimScale's online platform.
Generated Mesh.

Material selection and assignment

  • Next, assign a material to the solid. Click on ‘+’ next to ‘Materials’.
  • In the pop-up window, select ‘Steel’ and click on ‘Apply’. This loads the standard properties for steel.
  • Then, assign the material to the domain and save.
Assigning a new material in SimScale's online platform.
Adding a new material.
Assigning a material to the domain on SimScale
Assigning the material to the domain.

Boundary conditions

Now, we come to define the boundary conditions.

  • To create a boundary condition, click on the ‘+’ option next to ‘Boundary conditions’ and select the required boundary condition from drop down menu, as shown in the figure below.
Creating a boundary condition on the SimScale online platform.
Creating a new boundary condition.
  • We will start by constraining the displacement of the fixation holes.
  • For this, create a ‘Fixed Value‘ boundary condition from the drop down menu.
  • Set the displacement to zero in all directions.
  • Next, assign this boundary condition to the fixation holes.
  • Click on the blue checkmark to save this boundary condition.
Fixed value boundary condition on SimScale.
Fixed value boundary condition.
  • The second boundary condition is the actual pressure load that acts on the shield of the underrun protection.
  • Choose a ‘Pressure‘ boundary condition from the drop down menu.
  • Enter a pressure value of 25 bar or 2.5*10e6 Pa.
  • Assign the boundary condition to ‘face82@solid1‘, as shown in figure below.
Pressure boundary condition on SimScale's online FEM platform.
Pressure boundary condition.
  • Numerics and Simulation Control are already indicated as complete via the green checks. This means that reasonable default values are already chosen for them.

Start a simulation run

  • The last thing to do is to create a run.
  • It is done by clicking on the ‘+’ symbol next to ‘Simulation Runs’.
  • Give a name to the run and click on ‘Start’.
SimScale creating a new simulation run.
Creating a new simulation run.

 Post-Processing

  • Once the simulation is finished, select ‘Solution Fields’ to post-process the results on the platform. Results can also be downloaded and post-processed locally (e.g. with ParaView).
  • In the post-processing environment, select “Results” and then “von Mises stress”.
Analyzing von Mises stress on SimScale
von Mises stress distribution.
  • Similarly the displacement field can be visualized as shown below
Displacement in Static analysis made on SimScale
Displacement field.
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