Cannot convergence?

Brian_20847

Hi experts,

I want to do a structural analysis of the screw shaft. I tried to do small sliding, finite sliding, and continuous sliding, but it could not still converge.

Can you help me fix this bug?

Thanks

Johan Dahlberg_20306

Hi Brian
You have some severe penetration in your model which will make your model hard to converge. Overlap can be modelled and need to resolved prior to rotation.

Here is and interference fit model:

OS-V: 0280 Axisymmetric Elements - Interference Fit Between Two Cylinders (altair.com)

 

And here is a case of large sliding

OS-E: 0160 Nonlinear Static Analysis of Snap Fit Assembly Using Continuous Sliding (altair.com)

Be careful with meshing, it is good to coarsen the mesh out to reduce model size!

For initial set-up, you can also consider to just model 1-2 threads!

/Johan

Brian_20847

Johan Dahlberg_20306 said:

Hi Brian
You have some severe penetration in your model which will make your model hard to converge. Overlap can be modelled and need to resolved prior to rotation.

Here is and interference fit model:

OS-V: 0280 Axisymmetric Elements - Interference Fit Between Two Cylinders (altair.com)

 

And here is a case of large sliding

OS-E: 0160 Nonlinear Static Analysis of Snap Fit Assembly Using Continuous Sliding (altair.com)

Be careful with meshing, it is good to coarsen the mesh out to reduce model size!

For initial set-up, you can also consider to just model 1-2 threads!

/Johan

Hi @Johan Dahlberg,

How to reduce the penetration because the model has many nodes so we cannot use translate or move nodes? Maybe I can use scale for the screw shaft or not?

Thanks

 

Johan Dahlberg_20306

Brian_20847 said:

Hi @Johan Dahlberg,

How to reduce the penetration because the model has many nodes so we cannot use translate or move nodes? Maybe I can use scale for the screw shaft or not?

Thanks

 

Hi Brian
yes downscaling and then apply radial displacment of bolt could be one option.
I would have started with a interference fit (overlap) subcase to resolve the initial state.

Anyway, you need to define two subacases:

subcase 1, Interference fit 

subcase 2, continuation from first subcase, and then apply rotation only

/Johan

Brian_20847

Hi @Johan Dahlberg,

I tried to do this but the results seem not good.

Can you check it for me?

Please find the attachment to see my model

Thanks