Low stresses but enormous displacements

Altair Forum User

Hi,

I am currently trying to Simulate a Wheelhub for a Formula Student Car in Altair Hyperworks. But the Problem is that my Analysis shows Stresses of around 140 MPa which is totally acceptable for Aluminum but the Displacement has a Value of 1-4 Kilometers. 

The Wheelhub is constrained with Rigid-Elements on the Surfaces for the Bearings. These are Connected to Constraints allowing movement in the Moment-Directions and on one Bearing in the Y-Direction. The Rigids have no dof.

When I locked all dof´s on the constraints and allowed the movements in the Rigid-Elements, the Displacement became realistic. But the Results should be the same in both Cases or am I getting this wrong? 

Or is there any other Reason why the Displacement reaches these High-Values?

Rahul Rajan_21763

Hi,

Could you share some screenshot of your model with loads & boundary condition for more information?

 

Regards

Rahul R

Altair Forum User

Hi LuHuck,

 

Please share the .out file.

 

Check if there are any free nodes and also check the unit consistency in your model.

Altair Forum User

Hi,

attached you find the .out file of the last Analysis Run.

Unable to find an attachment - read this blog

Altair Forum User

Hi LuHuck,

 

In your out file I can see the warning message saying that compliance is too large or negative.

 

Check your boundary conditions. Large compliance means, your model 'flys away'.

 

One cause can be no stiffness, another as stated missing contact definitions, another can be missing links in rigids or wrong BCs.