follower force

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Can someone help me to simulate a beam subjected to non-conservative follower force , I have found a video on youtube about a beam subjected to a follower force but it was not clear , he started the explanation after he had created a beam with options like (RBE2...) , here you the video on youtube
I tried many times to create that beam like the video but I was not abe. for example , when he applied the force, the beam already contains nodes and that cross on its top  !

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you should start from the CAD geometry or try to draw the geometry in HM, first of all.

Once you have the geometry, you can start building the 3D mesh (using tetramesh or solidmap, depending on the complexity).

The 'x' that you see is a rigid element (RBE2 in OptiStruct), that can be created in 1D>rigids

once you have the mesh, amterials, and properties, you create a load collector, and going in forces you

For the follower force, you will create a force otf type FORCE1 and select 2 nodes on your mesh as reference for the direction.

So once you enable PARAM,FFLOWER,YES, your force will follow these 2 nodes.

This is all covered in the documentation unbder the tutoria for OptiStruct

OS-T: 1510 Follower Loads, Nonlinear Adaptive Criteria, and Nonlinear Intermediate Results

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2 hours ago, Adriano A. Koga said:

thank you so much for your response .  the only thing which confused me in this tutrial is the mesh and  how to select nodes , I just want to get to know how to create that beam  . since I am totoally beginner at this software I was not able to make that beam with meshing .

You should start from the CAD geometry or try to draw the geometry in HM, first of all.

Once you have the geometry, you can start building the 3D mesh (using tetramesh or solidmap, depending on the complexity).

The 'x' that you see is a rigid element (RBE2 in OptiStruct), that can be created in 1D>rigids

once you have the mesh, amterials, and properties, you create a load collector, and going in forces you

For the follower force, you will create a force otf type FORCE1 and select 2 nodes on your mesh as reference for the direction.

So once you enable PARAM,FFLOWER,YES, your force will follow these 2 nodes.

This is all covered in the documentation unbder the tutoria for OptiStruct

OS-T: 1510 Follower Loads, Nonlinear Adaptive Criteria, and Nonlinear Intermediate Results

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Can you walk me through the steps of making that beam with mesh !!

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3 hours ago, Adriano A. Koga said:

you should start from the CAD geometry or try to draw the geometry in HM, first of all.

Once you have the geometry, you can start building the 3D mesh (using tetramesh or solidmap, depending on the complexity).

The 'x' that you see is a rigid element (RBE2 in OptiStruct), that can be created in 1D>rigids

once you have the mesh, amterials, and properties, you create a load collector, and going in forces you

For the follower force, you will create a force otf type FORCE1 and select 2 nodes on your mesh as reference for the direction.

So once you enable PARAM,FFLOWER,YES, your force will follow these 2 nodes.

This is all covered in the documentation unbder the tutoria for OptiStruct

OS-T: 1510 Follower Loads, Nonlinear Adaptive Criteria, and Nonlinear Intermediate Results

Would please help me create that beam with RBE2 option and how to  exactly mesh it, I really want a tutorial to follow it  .  through the document you  mentioned  I was able to create NLPARM ,NLOUT, Follower YEs , but  I was not able to create such a beam with RBE2 and mesh , I specifically want a straight beam under a follower force ( cylindrical section or rectangular section ,  I wil try with both  . honestly I am going to write an article in the field of robotics and compare this simulation to the theory of flexible robots ,  I will write your name  in my article in the second or third position .
I am waiting for your answer adriano . it would a great help  , you know  it has been such a long time when I have started with follower force , going through solidworks , anysys..etc  and finally Hypermesh optistuct proved the right software to do it .

thank you so much in advance adriano .
waiting for you answer

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please, take a look at this video at youtube..it is very similar.

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38 minutes ago, Adriano A. Koga said:

please, take a look at this video at youtube..it is very similar.

I will go through it , thank you

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On 6/4/2020 at 11:27 PM, selman djeffal said:

I will go through it , thank you

On 6/4/2020 at 10:49 PM, Adriano A. Koga said:

please, take a look at this video at youtube..it is very similar.

wow , it really worked out dear.  you do not know how I am thankful. Now I have to do the same thing on a cylindrical beam ( circle section). is it the same thing !!  how can  I create nodes like this video with a cylindrical beam !!

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Hi,

you should take the basic HM training class, as it can help you a lot to improve your skills.

Probably your local Altair support provide some videos or trainings, or even in Altair University website.

For performing exactly the same thing with a cylindrical beam, you just need to create a cylinder from the beginning.

For creating a cylinder in HM, you need first the center point of one side of the cylinder, and another point to define the axis of it.

Start creating the nodes from the 'nodes' panel, giving the coordinates.

Having the nodes, go to the 'solids' panel, select 'Full Cylinder' and then select the bottom center node, and the other node to give the axial direction.

Type the radius and Height and there you go. You will have the cylinder ready to be meshed and perform your analysis.

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32 minutes ago, Adriano A. Koga said:

Hi,

you should take the basic HM training class, as it can help you a lot to improve your skills.

Probably your local Altair support provide some videos or trainings, or even in Altair University website.

For performing exactly the same thing with a cylindrical beam, you just need to create a cylinder from the beginning.

For creating a cylinder in HM, you need first the center point of one side of the cylinder, and another point to define the axis of it.

Start creating the nodes from the 'nodes' panel, giving the coordinates.

Having the nodes, go to the 'solids' panel, select 'Full Cylinder' and then select the bottom center node, and the other node to give the axial direction.

Type the radius and Height and there you go. You will have the cylinder ready to be meshed and perform your analysis.

Thank you so so much , I made it. I will try to apply a follower force on it now. I know how to do it based on the help you provided me with the last time. I will try it now

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everything worked properly but when I applied follower force , No error found but the beam does not show any affect and results were 0

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Here youare the beam file with everything defined but it does not bend or move or show any affect by the applied force !!

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1 hour ago, selman djeffal said:

Thank you so so much , I made it. I will try to apply a follower force on it now. I know how to do it based on the help you provided me with the last time. I will try it now

2 hours ago, Adriano A. Koga said:

Hi,

you should take the basic HM training class, as it can help you a lot to improve your skills.

Probably your local Altair support provide some videos or trainings, or even in Altair University website.

For performing exactly the same thing with a cylindrical beam, you just need to create a cylinder from the beginning.

For creating a cylinder in HM, you need first the center point of one side of the cylinder, and another point to define the axis of it.

Start creating the nodes from the 'nodes' panel, giving the coordinates.

Having the nodes, go to the 'solids' panel, select 'Full Cylinder' and then select the bottom center node, and the other node to give the axial direction.

Type the radius and Height and there you go. You will have the cylinder ready to be meshed and perform your analysis.

would please hav a look on the whole file , it works properly but the beal does not bend or show any sign of displacement  !!

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follower_model.femHi again,

your model does not perform as expected because you have applied both forces and constraints(SPC) in free temp nodes (the ones that you've used for creating the geometry).

The temp nodes were not attached to your mesh, thus they do not transmit anything to your structure.

In order to connect them, i've created a couple rigid elements (1d>>Rigids>>RBE2) in both ends.

I attached the model with RBE2's, but it is not converging for your loading.

I don't know what you're trying to accomplish here, but i would review these loads. Also depending on your targets, NL material could also be considered.

Please take a look also at Altair free e-books at Altair University. They might help with some modelling tips.

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11 minutes ago, Adriano A. Koga said:

follower_model.femHi again,

your model does not perform as expected because you have applied both forces and constraints(SPC) in free temp nodes (the ones that you've used for creating the geometry).

The temp nodes were not attached to your mesh, thus they do not transmit anything to your structure.

In order to connect them, i've created a couple rigid elements (1d>>Rigids>>RBE2) in both ends.

I attached the model with RBE2's, but it is not converging for your loading.

I don't know what you're trying to accomplish here, but i would review these loads. Also depending on your targets, NL material could also be considered.

Please take a look also at Altair free e-books at Altair University. They might help with some modelling tips.

I would like to simulate a column subjected to a follower force which means the force keeps moving as the beam bends ( force normal to the beam along the bending of the beam)

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15 minutes ago, Adriano A. Koga said:

follower_model.femHi again,

your model does not perform as expected because you have applied both forces and constraints(SPC) in free temp nodes (the ones that you've used for creating the geometry).

The temp nodes were not attached to your mesh, thus they do not transmit anything to your structure.

In order to connect them, i've created a couple rigid elements (1d>>Rigids>>RBE2) in both ends.

I attached the model with RBE2's, but it is not converging for your loading.

I don't know what you're trying to accomplish here, but i would review these loads. Also depending on your targets, NL material could also be considered.

Please take a look also at Altair free e-books at Altair University. They might help with some modelling tips.

wow than you so much , it is working , would you please  show me what you have done to make it work  !!

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How did you attach (RBE2's )  can you show me through pictures , I mean the steps you performed to create RBE2  and the exact changing you did to make it work !!

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26 minutes ago, Adriano A. Koga said:

follower_model.femHi again,

your model does not perform as expected because you have applied both forces and constraints(SPC) in free temp nodes (the ones that you've used for creating the geometry).

The temp nodes were not attached to your mesh, thus they do not transmit anything to your structure.

In order to connect them, i've created a couple rigid elements (1d>>Rigids>>RBE2) in both ends.

I attached the model with RBE2's, but it is not converging for your loading.

I don't know what you're trying to accomplish here, but i would review these loads. Also depending on your targets, NL material could also be considered.

Please take a look also at Altair free e-books at Altair University. They might help with some modelling tips.

would you please show me how did you create RBE2 and that spider-like on both sides of the beam . explain to me through pictures as you did before. I am very thankful.

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You should watch this video

I recommend you to go through the trainings at Altair University as they cover the basics of HM pretty well.

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20 minutes ago, Adriano Koga said:

You should watch this video

I recommend you to go through the trainings at Altair University as they cover the basics of HM pretty well.

God bless you , I managed to create it . I can not really learn hypermesh , I just use it for a specific reason , the only thing which concerns me is the follower force . none of the existing software allow you to apply a follower force except ' hypermesh' , this is why I am trying to use it. thank you so so much .
You seem an expert in this software, I wish you can squeeze me in and figure out how to apply a follower force on a cylindrical beam. it has been 2 years since I started workin on this issue . it is a part of my thesis of doctorate . I will write you in my thesis . you really opened doors to me through your comments . thank you so much .
I have already simulate a continuum robot with matlab and I am trying to compare results with another software. its backbone is a cylindircal beam .....

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have you tried linear buckling as a initial guess of buckling load?

this shoud be your first approach, probably.

good luck in your thesis.

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7 minutes ago, Adriano A. Koga said:

have you tried linear buckling as a initial guess of buckling load?

this shoud be your first approach, probably.

good luck in your thesis.

Buckling has nothing to do with non-conservative follower force. I have delibertately chosen this type of force because the continuum robot I am working on is assimulated into a circular beam with disks and cables  and the force actuatted on the cables is similar to a follow'er force, it keeps moving as the backone of the robot bends . actually , the force must be applied on one of the three cables but I just want to start with a beam . by the way can I draw this robot and mesh it in hypermesh!!! . it seems awfully coomplicated to me to do so . the blue beam is the backbone of he robot , circular shapes are the disks and three cables pass through holes in the disks.

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you should probably work with a mixed 1D/2D model in HM/OptiStruct for that. Shell elements for the disks and beam elements for the cables.

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2 hours ago, Adriano A. Koga said:

you should probably work with a mixed 1D/2D model in HM/OptiStruct for that. Shell elements for the disks and beam elements for the cables.

Can you please recommend any tutorial on how to do that  and what do  you think if I create that robot on solidworks then import it to hypermesh  !!

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the same video i've shared before for rigids shows how to create beam elements.

you should find something in Altair University or their youtube channel.

for your model, having only the disks geometry modelled into the CAD is enough, including the points for attaching the beams.

In HM you will create first the 2D mesh, using the fixed points as reference.

I'm attaching a very basic video as well, but again, go after some training material in Altair University.

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