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Simulation Question: As I refine the mesh, max displacement decreases but stress increases

Question asked by Ronan Timmins on Aug 21, 2014
Latest reply on Aug 23, 2014 by Pablo Jorge

I have been running a study on a trailer coupling ball.

 

For the first run i used the default mesh density (not a draft quality mesh) ;

Results:    Deformation is as expected.

                   Max stress (node) = 729 N/mm^2

                   Max stress (element) = 582 N/mm^2

                   Max displacement = 1.605 mm

 

So I set a mesh control to refine the mesh in the area of interest. I increased the mesh density in that area until the difference between Node and Element stress values were within 10%.

 

Results:

1. Displacement

ball fea displacement.JPG

2. Node stress

ball fea Nodal Stress.JPG

3. Element stress

ball fea element Stress.JPG

 

Can anybody explain how stress has increased if displacement decreased? This trend was seen gradually in the results as I refined the mesh.

Also, the max stress calculated is roughly 40% higher than the fatigue limit, But the component has passed a 2 million cycle physical test at this loading.

 

Any help would be greatly appreciated.

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