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NX NASTRAN - Pre-Stress a Beam With Other Beam Stress Results
- Thread starter RPereira
- Start date
Hi RPereira,
What solution are you using? Sol101, Sol601, etc..
What is your objective of analysis?
I think probably a restart analysis might help, to continue your analysis to the second stage of what you are planning to achieve. Hope this help.
Kind regards,
Tuw
What solution are you using? Sol101, Sol601, etc..
What is your objective of analysis?
I think probably a restart analysis might help, to continue your analysis to the second stage of what you are planning to achieve. Hope this help.
Kind regards,
Tuw
- Thread starter
- #3
Hello Tuw, thank you very much for your reply and I am sorry for my late reply.
I am using NLSTATIC 106 (to solve large displacements & rotations).
I want to simulate the following:
1. Bend a beam (CBEAM)
2. Use that pre-stressed beam in a new structure composed with those beams.
I want to say: all the beams in the structure have that shape because they were bended previously (therefore a pre-stressed structure).
Thank you,
RPereira
I am using NLSTATIC 106 (to solve large displacements & rotations).
I want to simulate the following:
1. Bend a beam (CBEAM)
2. Use that pre-stressed beam in a new structure composed with those beams.
I want to say: all the beams in the structure have that shape because they were bended previously (therefore a pre-stressed structure).
Thank you,
RPereira
Hi RPereira,
Interesting. I believe restart is the solution. Below is a restart I did using Sol101, not so relevant to your case Sol106. But you may take a look.
Interesting. I believe restart is the solution. Below is a restart I did using Sol101, not so relevant to your case Sol106. But you may take a look.
- Thread starter
- #5
Hello Tuw,
Thank you for creating the Restart instructional video.
I always thought about Restart only for continuing previous solutions and I did not ever thought about it as a initial input for a new solution. Thank you for your suggestion! I have read some of the info at the Documentation and in fact it is not a user friendly operation...
Regarding my case, I will have a truss with several beams. My intention is to 3D model all them with the pre-stress shape. Then make a complete assembly stress analysis were I say to all the beams that they have already stress incorporated within them.
Take an umbrella for example. When is open it forms a stiff structure. I can 3D model all the beams that compose the umbrella with the final deformed shape. But if I want to make a wind gust aerodynamic analysis, it is VERY important to previously instruct the solver that structure is already stiff/pre-stressed. To accomplish this I just could: a) 3D model one straight beam; b) make a stress analysis with a load; c) take that deformed shape result; d) 3D model the open umbrella with the all the beams with that deformed shape; e) go to NX NASTRAN and tell it that all the beams in the umbrella have that shape because they have internally 'these' stresses from the deformed straight beam.
Do you think that a Restart is the only way to go?
Thank you for creating the Restart instructional video.
I always thought about Restart only for continuing previous solutions and I did not ever thought about it as a initial input for a new solution. Thank you for your suggestion! I have read some of the info at the Documentation and in fact it is not a user friendly operation...
Regarding my case, I will have a truss with several beams. My intention is to 3D model all them with the pre-stress shape. Then make a complete assembly stress analysis were I say to all the beams that they have already stress incorporated within them.
Take an umbrella for example. When is open it forms a stiff structure. I can 3D model all the beams that compose the umbrella with the final deformed shape. But if I want to make a wind gust aerodynamic analysis, it is VERY important to previously instruct the solver that structure is already stiff/pre-stressed. To accomplish this I just could: a) 3D model one straight beam; b) make a stress analysis with a load; c) take that deformed shape result; d) 3D model the open umbrella with the all the beams with that deformed shape; e) go to NX NASTRAN and tell it that all the beams in the umbrella have that shape because they have internally 'these' stresses from the deformed straight beam.
Do you think that a Restart is the only way to go?
Hi RPereira,
I am not sure what you are trying to do, but on page 1.7 below, it has something about pre-stress concrete.
If this is appropriate to your situation, probably you can resolve by using Preload force definition on 3D mesh model.
I am not sure what you are trying to do, but on page 1.7 below, it has something about pre-stress concrete.
If this is appropriate to your situation, probably you can resolve by using Preload force definition on 3D mesh model.
- Thread starter
- #7
Hi Tuw,
Thank you for that link, thats one application for a pre-stress structure.
You're thinking right. The beams in my umbrella example are prestressed beams.
When we open the umbrella the final shape will be a prestress structure and therefore it can accept much more external loads.
If I simply 3D model the open umbrella and want to make a stress analysis without applying any pre-load in those simply curved 3D model beams, the structure will not be the same stiff structure as with a pre-load/prestressed beams.
After 3D model the open final shape of the umbrella, is there any way to instruct NX NASTRAN that all the beams (that are curved) have a pre-load/prestress (where this pre-load was found with a previous stress analysis with just one single umbrella beam) ?
Thank you for that link, thats one application for a pre-stress structure.
You're thinking right. The beams in my umbrella example are prestressed beams.
When we open the umbrella the final shape will be a prestress structure and therefore it can accept much more external loads.
If I simply 3D model the open umbrella and want to make a stress analysis without applying any pre-load in those simply curved 3D model beams, the structure will not be the same stiff structure as with a pre-load/prestressed beams.
After 3D model the open final shape of the umbrella, is there any way to instruct NX NASTRAN that all the beams (that are curved) have a pre-load/prestress (where this pre-load was found with a previous stress analysis with just one single umbrella beam) ?
Hi RPereira,
There might be simpler way to do it. For example, if your prestress beam only consist of compressive load, then the Bolt Pre-load definition might be sufficient. For your information, Bolt Pre-load can be applied on 3D elements.
If this is not your case, probably restart is required. If so, I hope you can illustrate your case clearly by not using the umbrella, but your actual case. This is because I do not want to make wrong assumptions.
There might be simpler way to do it. For example, if your prestress beam only consist of compressive load, then the Bolt Pre-load definition might be sufficient. For your information, Bolt Pre-load can be applied on 3D elements.
If this is not your case, probably restart is required. If so, I hope you can illustrate your case clearly by not using the umbrella, but your actual case. This is because I do not want to make wrong assumptions.
- Thread starter
- #9
No worries about Tuw.
My case is not so different from the umbrella and I know about the Bolt Pre-Load capabilities.
Probably the restart could be the way to go...however is not user friendly and I will need to apply it to hundreds of beams...
Please, check this another approach (if is possible to solve this, it will be possible to solve my real case):
Once again, thank you very much for being so patience with me.
All the Best!
Ricardo
My case is not so different from the umbrella and I know about the Bolt Pre-Load capabilities.
Probably the restart could be the way to go...however is not user friendly and I will need to apply it to hundreds of beams...
Please, check this another approach (if is possible to solve this, it will be possible to solve my real case):
Once again, thank you very much for being so patience with me.
All the Best!
Ricardo
- Thread starter
- #10
Hi RPereira,
At 1:10 of this video, it shows an animation of 2 subsequent process.
1. Pressing
2. Rolling
I suspect the solver involved for this simulation result is NX Nastran Advanced Nonlinear (Sol601106). Do you have this solver? Things would be much easier..
I think your simulation requires subsequent process too. From your sketch, stage 1 to stage 2 is conducted using Enforced Displacement Constraint. But you didnt mentioned what kind of loading condition for stage 3?
At 1:10 of this video, it shows an animation of 2 subsequent process.
1. Pressing
2. Rolling
I suspect the solver involved for this simulation result is NX Nastran Advanced Nonlinear (Sol601106). Do you have this solver? Things would be much easier..
I think your simulation requires subsequent process too. From your sketch, stage 1 to stage 2 is conducted using Enforced Displacement Constraint. But you didnt mentioned what kind of loading condition for stage 3?
Hi RPereira,
I have been trying to work on something.
Hope this helps.
I have been trying to work on something.
Hope this helps.
- Thread starter
- #13
Hi Tuw,
Very nice video and great simulations at 0:53 and 1.1 !
I think the other simulations can be accomplished using the NX NASTRAN Tutorials and CAST.
I have access to SOL601/106.
At stage 3 there are no applied loads except for the internal pre-stresses gather from stage 1.
(Put the results from stage 1 into stage 3 is what I am pursuing).
I am using NX 8.0 so I am unable to open your files...
Hi RPereira,
If you have the Advanced Nonlinear Solver available, you should probably always choose that solver for modeling complex nonlinear problems. This is because Sol106, from Nastran Solver is not a strong selling point of Nastran Solver. Sol601 is from Adina Structural Solver, which handle nonlinear problems much better. You may consider your simulation model as boundary nonlinear, in other words boundary changes with time.
Can you try to import the .dat and .op2 files instead of reading .sim directly? The .dat file can be read into all version of NX because it is a set of standard Nastran keywords. The .op2 files are the simulation result file, you can import the op2 files to see the result at post processing navigator.
If you have the Advanced Nonlinear Solver available, you should probably always choose that solver for modeling complex nonlinear problems. This is because Sol106, from Nastran Solver is not a strong selling point of Nastran Solver. Sol601 is from Adina Structural Solver, which handle nonlinear problems much better. You may consider your simulation model as boundary nonlinear, in other words boundary changes with time.
Can you try to import the .dat and .op2 files instead of reading .sim directly? The .dat file can be read into all version of NX because it is a set of standard Nastran keywords. The .op2 files are the simulation result file, you can import the op2 files to see the result at post processing navigator.
- Thread starter
- #15
- Thread starter
- #17
Hi RPereira,
Judging from the word doc that i attached previously, we need to add the additional keyword to specify which subcase and loop to restart from. My guess you are seeing no difference between direct applying subcase 1 and subcase 2 is because the loading condition (force load) and constraint (enforced disp) does not affect each other and can be applied independently. In my case, when restarting from subcase 1, the enforced displacement still holding the center portion of the beam, restrict/prohibit any displacement on that node, while the subsequent force load is applied.
I think the enforced displacement needs to be removed at 1 point of time for subsequent analysis. For example, you can use the pressing and rolling animation shown previously. Initially, a contact is defined to deform the beam. Next, the contact is then removed, before continuing to the next stage. You will need Sol601106 for this.
Judging from the word doc that i attached previously, we need to add the additional keyword to specify which subcase and loop to restart from. My guess you are seeing no difference between direct applying subcase 1 and subcase 2 is because the loading condition (force load) and constraint (enforced disp) does not affect each other and can be applied independently. In my case, when restarting from subcase 1, the enforced displacement still holding the center portion of the beam, restrict/prohibit any displacement on that node, while the subsequent force load is applied.
I think the enforced displacement needs to be removed at 1 point of time for subsequent analysis. For example, you can use the pressing and rolling animation shown previously. Initially, a contact is defined to deform the beam. Next, the contact is then removed, before continuing to the next stage. You will need Sol601106 for this.
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