Session 1: Non-linear FEA of a Suspension Assembly

Homework Submission

Submitting all three homework assignments will entitle you to a certificate of participation

Homework 1 - Deadline: 25th of June (12:00 pm)

Submission Form

Introduction

The purpose of the ATV design competitions is to test the endurance of All Terrain Vehicles(ATV). An ATV is subjected to steep climbs and drops in ATV Design Competitions, hence making the suspension system a central design decision. The suspension system is responsible to absorb the shocks, for example during an impact from a drop.

In this tutorial, we implement a methodology to analyse the suspension undergoing different deformations. The stresses due to this deformation allow us to calculate the maximal allowable drop heights.

The loading conditions and constraints on a generic ATV suspension is shown here:

The non-linear regime of steel helps us estimate the yield point as 500 MPa.

Handout Project:

Mesh Generation

Navigate to your geometry and click on New Mesh.

Please select a Tet-dominant mesh and change the Mesh Fineness to 4-Fine.

The mesh may now be visualized in the viewer.

Once the mesh is ready, we may assign the Topological entity sets A new toplogical entity set is assigned as follows:

1. Navigate to topological entity sets in the Navigator
2. Select the face entity from the viewer.
3. Click on New from selection
4. Name your entity set as you deem suitable and Create.

Please follow the above steps and this image to create the upper_master_bonded entity.

Please follow the above steps and this image to create the lower_master_bonded entity.

Please follow the above steps and this image to create the upper_slave_bonded entity.

Please follow the above steps and this image to create the lower_slave_bonded entity.

Please follow the above steps and this image to create the cylinder_master_physical entity.

Please follow the above steps and this image to create the cylinder_slave_physical entity.

Please follow the above steps and this image to create the displacement entity.

Please follow the above steps and this image to create the fixation entity.

Simulation Setup

Please navigate into the Simulation Designer in the workflow and click on New to create a new Simulation setup.

The Analysis Type is to be set as Solid Mechanics > Static analysis (advanced).

The domain is now selected as the mesh you created in the Mesh creator. Please select the mesh you just created, as the domain for your FEA calculations.

The contacts are now to be defined. Please select Contacts and create a New contact.

The upper_bonded contact is created as follows:

Make sure to decrease the tolerance to 0.001

The lower_bonded contact is created as follows:

Make sure to decrease the tolerance to 0.001

The contact between the Upper and lower cylinders of the suspension set as a friction-less physical contact. Please navigate to Physical contacts in the Navigator, select Physical Contacts and create a New physical contact.

Select the type as Frictionless Physical Contact and increase the Penalty coefficient to 1000000000000(10e+12). Please select the Master entity face on the ground and Add selection from viewer.

Please select Materials in the Navigator and click on New.

Import steel from the material library and assign it to the upper and lower cylinders.

We now proceed to add material to the spring of the suspension. To add a new material, please right click on Materials in the Navigator and click on Add Solid material.

Import steel from the material library.

Since we intend to study whether the drop would plastify the suspension, please set Material behaviour to Plastic.

The plastic behaviour of the material is defined with a .CSV file containing the stress and strain data. The prepared CSV file for Non-linear steel data can be downloaded from here. Please download it to your local system and click on Upload file.

Next, please assign the material to the spring.

We now proceed to add constraint boundary conditions. Please click on Constraints and click on New.

The displacement constraint is modeled as follows:

To add a new constraint, please right click on Constraints in the Navigator and Add Constraint boundary condition.

The fixation constraint is modeled as follows:

Please navigate to Numerics and select the solver MUMPS.

Under Simulation Control, please set the Number of Computing cores to 16 and the Number of cores used for computation to 4. Increase the Maximum Runtime to 14400. Change the Write Control Definition to All computed timesteps.

For an effective analysis of the results, it is imperative to monitor the solution fields with Result Control Items. The Volume calculation is done as follows.

The Area calculation for reaction force calculation is done as follows.

Please Create a new run by navigating to Simulation Runs in the Navigator and clicking on New.

Post-Processing

Please navigate to the Post-Processor in the workflow.

Quantitative analysis:
The Von Mises Stresses in the spring subjected to a deformation of 3 cm:

The Von Mises Stresses in the spring subjected to a deformation of 5 cm:

Quantitative Analysis:

To visualize your result in the viewer, select it in the Navigator and click on Solution Fields in Run 1 under suspensionSystemSim .

To add another copy of simulation results to the viewer, please right click on Solution Fields in Run 1 under suspensionSystemSim and Add selection to viewer.

Warp by Vector:

This filter enables the user to dynamically visualize the displacement in each element in the suspension. It can be added for the as follows:

To add the filter to the Suspension subjected to 5 cm deformation, click on Run 1 and Add Filter.

Select the Warp By Vector Filter.

Switch the Field to von Mises Stress[Point data].

Transform filter:

The transform filter is a useful tool to qualitatively analyse two different results simultaneously. It may be added as follows:

To visualize your result for the Suspension subjected to 3 cm deformation in the viewer, hover over (DO NOT left click) it under Solution Fields in Run 1 under suspensionSystemSim3cm. Now, right click here on it and Add selection to viewer.

Click on Run 1 and change the Opacity to 0.3. Now, click on Add Filter.

Select the Transform filter.

Translate as follows:

Change the Opacity to 0.3.

Rescale the von Mises Stress to a maximum value of 300 MPa.

PDF Version of the Workshop: Non-linear FEA analysis of a Suspension Assembly

2 Likes

Hello, I was completing the first exercise until I came up to the part in which I have to ‘Add Contact Constraint Condition’. However, the Physical Contacts option does not appear. Have I done a stage incorrectly or has there been an update to the software that means I don’t need to use this option?

Thanks for the help in advance.

Hi @jdixonf1,

Click on “Analysis Type” in the left hand menu and then in the center window change the Nonlinear option to “true”. Once you save, the physical Contacts should show up in the left menu tree.

Good Luck,
Christopher

1 Like

Hello again,

Thanks for the help on my previous difficulty. However, since then I have had a few more difficulties with the course, specifically the guide, the problems are as follows:

1. For the stage in which you are told to create the upper_bonded and lower_bonded contacts, it doesn’t actually state how to create the lower_bonded contact, instead it skips to the Physical Contacts step.

2. For the Physical Contacts step, the type it states does not exist, when it states select the Master entity face on the ground there is no such face.

3. For the Result Control Items, the figures which are meant to show the stages of creating the first Volume calculation completely skip that and instead show how to create the Result Control Item 2.

This isn’t a complaint, instead it’s me wishing for a solution to these problems as I would like to complete the course and add it to the other SimScale courses which I’m currently completing.

Hi @jdixonf1,