Probe Follower pressure

Alphald

can anyone help me to simulate a probe follower pressure

I created two cylinders and the small one is probe. I want to create a suction in the probe like suction tube.

 

1 、is it right to create pressure with "nodes on face" ?  I select the top nodes (the small circle in probe) I want.

2、how to create a follower pressure like "B" ? I set LGDISP and FLLWER by "Follower force in Altair OptiStruct - YouTube"  and don't work.

Jason_Craanen

This setup should work fine. Verify your PARAM > FLLWER = 1

Jason_Craanen

Jason Craanen_20442 said:

This setup should work fine. Verify your PARAM > FLLWER = 1

 

And be aware of the message in the .out file that follower force is turned on by default when using large displacement. Set it =0 if you want to see the difference.

Alphald

Jason Craanen_20442 said:

This setup should work fine. Verify your PARAM > FLLWER = 1

Thank you so much! That's the result I want

But when I run non linear with my model, I got this

*** ERROR # 4965 ***
Maximum number of time increment cutbacks reached,
analysis aborted.

Jason_Craanen

Alphald said:

Thank you so much! That's the result I want

But when I run non linear with my model, I got this

*** ERROR # 4965 ***
Maximum number of time increment cutbacks reached,
analysis aborted.

You seem to have rigid body motion as you don't have any constraint in thy X-Z plane.

You can monitor your non-converged increments with the NLMON card.

Jason_Craanen

Jason Craanen_20442 said:

You seem to have rigid body motion as you don't have any constraint in thy X-Z plane.

You can monitor your non-converged increments with the NLMON card.

The displacement error tolerance is too high which is a clue to the rigid body motion as well

Alphald

Jason Craanen_20442 said:

You seem to have rigid body motion as you don't have any constraint in thy X-Z plane.

You can monitor your non-converged increments with the NLMON card.

Thank you.

I don't set the dof1 and dof3 because I want the translational motion of X-Z.

I set all dof in constraint and it work.

As a result of displacement

linear non-dof1,3: 0.05

linear all dof:0.044

non-linear(follower force): 0.048

I can't get the results as yours: 0.22 - 0.84

and the shape is more like the right side (nofollower)

Jason_Craanen

Alphald said:

Thank you.

I don't set the dof1 and dof3 because I want the translational motion of X-Z.

I set all dof in constraint and it work.

As a result of displacement

linear non-dof1,3: 0.05

linear all dof:0.044

non-linear(follower force): 0.048

I can't get the results as yours: 0.22 - 0.84

and the shape is more like the right side (nofollower)

You can't have rigid body motion in a nl static analysis. You could possibly try inertial relief?

Alphald

Jason Craanen_20442 said:

You can't have rigid body motion in a nl static analysis. You could possibly try inertial relief?

Thank you. It seems like more difficult.

I try to simulate the suction of the skin. I don‘t want the whole model to move. But I think the mesh in the surface should move a little to the centre at x-z when suctioning.

Maybe I'll try to do some changes for constraint to remove rigid body motion.

 

Another question: Is there a way to see the process of suction and suction-stop.

something like time-displacement graph.

I had try to make a curve  pressure (2s on and 2s off)

But I only got the final results.(2s max 2s 0)

Jason_Craanen

Alphald said:

Thank you. It seems like more difficult.

I try to simulate the suction of the skin. I don‘t want the whole model to move. But I think the mesh in the surface should move a little to the centre at x-z when suctioning.

Maybe I'll try to do some changes for constraint to remove rigid body motion.

 

Another question: Is there a way to see the process of suction and suction-stop.

something like time-displacement graph.

I had try to make a curve  pressure (2s on and 2s off)

But I only got the final results.(2s max 2s 0)

Yes, now you are getting into the transient analysis. 

Please take a look at some tutorials on it. Here is a good place to start.