Tutorial-01: Stress analysis of a connecting rod

In this tutorial we will conduct a structural analysis of a connecting rod. Doing this, we like to show you how to set up a simulation run and produce results in a very short period of time.

Stress field of the connecting rod under pressure load.

Stress field of the connecting rod under pressure load.

Step-by-step

1) Getting started

  • The tutorial project “Tutorial-01: Connecting rod stress analysis” has been imported and is open in your SimScale Workbench.

2) Mesh Generation

  • Once the Workbench is open you will be in the Mesh creator tab.
  • The CAD model CAD-connecting-rod_v1 loads in the viewer
The CAD model displayed in the web browser

The CAD model displayed in the web browser

  • To create a new mesh from this CAD model, click the New Mesh button
  • Automatically, a new mesh called CAD-connecting-rod_v1 mesh is created and a default mesh operation called Operation 1 (you may rename it to a useful name)
  • First we need to choose the meshing type which basically defines the algorithm that will be used to create the mesh
  • For this static stress analysis, we will use the Tet-dominant mesh operation
  • It only needs a few settings to be defined: We keep Element sizing as Automatic and set the Mesh fineness to 2 - Coarse, Element order to First order and Number of computing cores to 4
Choose the type of mesh operation and its settings

Choose the type of mesh operation and its settings

  • That’s all for the mesh operation. Let’s start it by clicking the Start button on the top of the page
After the meshing process was started the progress can be observed in the Job Status panel

After the meshing process was started the progress can be observed in the Job Status panel

  • The Job Status box in the lower left will show the progress of the operation
  • Queued means that the SimScale platform is preparing a computer to carry out the operation
  • Computing means that the mesh operation is currently carried out
  • After the first seconds of computing, there will appear a Meshing Log tree item below our mesh operation in the tree
  • This is the direct command line output of the meshing framework, that in the beginning might be a bit cryptic but can be very useful if a meshing operation fails
The meshing log providing details of the mesh operation execution.

The meshing log providing details of the mesh operation execution.

  • Once the mesh operation is finished, the Job status box will show the green Finished box
  • The mesh immediately appears in the viewer and we can see the small elements that have been created
  • The advantage of running the mesh operation remotely is that you do not have to wait until the mesh is finished. You can simply move on and already work on the simulation setup since your local computer is not used at all for computing
The completed, tetrahedral, first order mesh.

The completed, tetrahedral, first order mesh.

  • This was all it takes to create an automatic, tetrahedral mesh on SimScale. You can also see the created elements of the mesh from inside at some cutout. To do so, apply a Mesh Clip filter by clicking on the Filter dropdown menu on top right and selecting Mesh Clip.
  • Next you will see a cutting plane which you can adjust under Mesh Clip parameters. For example, in this case give Normal (y) a value of -1 in order to clip the mesh from the middle of the geometry. Click Preview button to see the cutting plane. The black arrow shows the direction of clipping. Figure below elaborate the steps.
Mesh clipping

Mesh Clip filter

  • Click the Apply button to see the clipped mesh. Figure below shows the clipped mesh.
Clipped mesh

Clipped mesh

  • To get back to the standard mesh view, choose Filter and click on Clear Filter
  • Now let’s move on to the actual simulation setup.

3) Simulation Setup

Now after we have created the mesh, let’s define the actual simulation.

  • First switch to the Simulation Designer tab next to the Mesh Creator tab
  • Click on New button
  • Give it a meaningful name
Give the simulation a meaningful name.

Give the simulation a meaningful name.

  • The first thing to do in any simulation setup on SimScale is to choose the actual analysis type that we want to carry out.
  • In our case, we are interested in running a static stress analysis, so we choose Solid mechanics and then Static
  • We are not taking nonlinearities into account, so we keep this setting as false
Choose the analysis type for your simulation.

Choose the analysis type for your simulation.

  • To confirm this analysis type, hit the blue Save button
  • Immediately the analysis template is loaded and the tree on the left is expanded
  • We can see different icons, that indicate different tasks
  • The red circle indicates that this item is missing something - a definition, or a choice
  • The green check means that this item is already completed - however you might want to check on the default values since they might not be suitable for your simulation
  • The blue circle indicates an optional settings that does not need to be filled out
  • Now we simply work our way from top to bottom of the simulation tree to complete the simulation setup
The simulation designer tree with all items necessary to complete the simulation setup.

The simulation designer tree with all items necessary to complete the simulation setup.

  • The first item is the Domain which defines the actual model or mesh on which you want to run this simulation
  • We choose the mesh connecting-rod-v1-mesh we just created and hit the blue Save button
  • Immediately, the chosen mesh is loaded in the viewer
The mesh that has been assigned to our simulation.

The mesh that has been assigned to our simulation.

  • The Domain tree item is then expanded with the items Geometry Primitives, Topological Entity Sets, Contacts and Mesh
  • However in this tutorial we won’t need any of them, so we simply go on to the next tree item
  • Under Model we don’t change anything and move on
The global model properties, that we leave as they are.

The global model properties, that we leave as they are.

  • The next relevant tree item is Materials where we click on the New button to add a new material
  • We will use Steel as the material for connecting rod.
  • Click on Import from material library button located just below the Simulation Designer tab
  • A Material Library window will pop up, select Steel from the library and click on Save
Steel as material selected from the material library.

Steel as material selected from the material library.

  • Complete the material definition by assigning this material to the volume of the conneting rod
  • This is done by assigning via left-click the solids for this material directly from the viewer
  • Save the settings and the material icon in the tree with get the green check mark
Steel as material defined and assigned to the existing volume.

Steel as material defined and assigned to the existing volume.

  • The next tree item Boundary conditions is the place where we can define constraints as well as loads acting on the connecting rod.
  • For our simulation, we’ll only assign two boundary conditions: A pressure load at the lower end and a fixed support at the top end of the connecting rod.
  • Depending on the analysis type we chose, there would be even more boundary conditions available
  • We will start with the pressure boundary condition
  • So we click on the Load under Boundary conditions and then click on New
The boundary condition dialogue.

The boundary condition dialogue.

  • Automatically, a new boundary condition called ‘boundary condition 1’ is created
  • First we’ll give it the meaningful name pressure-load which indicates the type of load
  • Next we’ll choose the type Pressure since we don’t want to deal with any directions - simply a normal pressure load is sufficient for this tutorial
Pressure load boundary condition.

Pressure load boundary condition.

  • Next we actually define the value. We chose 20e6 Pa which is around 200 bar
  • To complete the boundary condition setup, we have to choose on which faces this boundary condition shall be assigned to
  • So we select the two of the inner faces at the lower end of the connecting rod. Their color turns immediately blue, indicating that they have been assigned to the current boundary condition.
  • Clicking on the Save button completes the pressure boundary condition which is indicated by the green check in the tree item of the boundary condition.
Pressure load boundary condition completely defined.

Pressure load boundary condition completely defined.

  • The setup for a boundary condition is always the same: Give it a name, choose a type, choose the values and then assign it to a set of faces.
  • So the second boundary condition we will define a fixed constraint at the top of the connecting rod.
  • We add a displacement boundary condition by clicking on Constraint and then New, give it a meaningful name (e.g. fixed-constraint), choose Fixed support as the type, which sets all displacement values to zero and prescribes that these faces are not allowed to move
  • Finally click on Save button to save the settings.
The fixed constraint at the top of the connecting rod.

The fixed constraint at the top of the connecting rod.

  • The tree item Numerics allows us the control the solving mechanism in detail, where we also won't change anything in this tutorial.
  • The next important tree item is Simulation Control which allows to steer the overall simulation settings. However in our case, we will leave everything as it is
Settings for the simulation control tree item.

Settings for the simulation control tree item.

  • The last step to start this simulation is to create a Simulation Run from it, which basically means that we generate a snapshot of all simulation settings that will be saved and available for later review
  • So we switch to the Simulation Run tree item, and first check the simulation via Check simulation which should be successful, if we haven't made any mistakes
  • Next, we hit the New button and give the run a meaningful name for later review
  • And to start the run, we hit the Start button which will start the simulation run
  • The Job status box in the lower left again provides updates about the job status like we saw in the meshing operation
Hit Start to create and directly start the new run.

Hit Start to create and directly start the new run.

  • Also, as we saw in the mesh operation setup, a Solver log is provided after a few seconds which shows the exact output of the actual solver run
  • The simulation run should take a few minutes to be carried out
The completed simulation run.

The completed simulation run.

  • Once the simulation run is Finished we can move on to the Post-processor tab to visualize the simulation results

4) Post-Processing

  • Next we will visualize the results of the simulation we just completed, so we switch to the tab Post-Processor next to the Simulation Designer tab.
  • We click on the Solution fields tree item on the left under the name of the run we just ran (in our case, it is called 200-bar-load-case to indicate which thermal loads we have assigned)
  • Immediately after the click, the post-processing environment is loaded
  • First, we want to see the von Mises stress field so we click on the Select field dropdown-menu on top of the post-processing window and choose vonMises_stress
  • Immediately, the von Mises stress field solution field is loaded as a color-coding of the result
  • In case you want to see the color scale which defaults to the min-max-value range you can toggle its visibility with the small scale icon in the viewer bar
The von Mises stress field color map.

The von Mises stress field color map.

  • Lastly we can also visualize other physical quantities of the results, for example the displacement field across the rod by again switching the field on top of the viewer
Displacement result field color coding.

Displacement result field color coding.

  • We can use further post-processing filters to generate a warped visualization of the connecting rod according to the computed displacement field
  • A click on the Add Filter button provides a list of all available filters
List of available post-processing filters.

List of available post-processing filters.

  • We choose the Warp by vector filter which allows to warp the results by the displacement field.
  • The Scale Factor in the warp by vector filter settings allows to exaggerate the displacement to get an understanding of the displacement field.
Warped visualization next to the original results.

Warped visualization next to the original results.

  • You can select the field for the solution field (200bar-load-case) as Solid color in order to differentiate between deformed and undeformed geometry.
  • Congratulations! You just completed a complete static stress simulation using the SimScale platform!