Bearing Analysis
Altair Employee Hey!
I am trying to perform a structural and transient analysis on a Roller Element Bearing model. I am able to perform simple static analysis but I would like to utilize Hyperworks to simulate the following conditions:
Inner race to be rotating with a constant velocity and a fixed radial load is applied. Outer race is fixed. The balls should also be rotating.
I wish to know:
1. How I can give a constant velocity to the inner race of the bearing while also allowing the balls to rotate? Which card am I supposed to use?
2. What kind of contact constraint should I apply. Right now I am working with slide contact only.
3. Is quasi static analysis adviced or implicit non linear?
There is one video but in a different solver which does what I have been trying to do. I wish to do it in Hyperworks. Here is the link:
Also please suggest whether optistruct's non linear can be used or whether I should switch over to a different solver module!
Cheers
Answers
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Hi,
You can run a Non-linear transient analysis and you need slide contact.
You can apply constant velocity using TABLED1 and TLOAD# card when doing a nonlinear transient analysis. Use the below link for an example of how to do NL Transient.
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Hey!
Thank you for the help. Will this allow the balls to rotate independently as well? Since slide condition involves no friciton, the balls would simply slide. Would Motion Solve help me in performing such an analysis where the motion of multiple bodies is required?
Please let me know!
Regards0 -
Yes, you can also use MotioView and MotionSolve but if you are interested in Structural analysis, this may not help as MS doesn't support flexible to flexible contacts as of now. .
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Hey Prakash!
I referred to your method and tried the analysis but the analysis stops due to Fatal Error. It says that there is a gap between the contact surfaces. Also, the displacement obtained in the result is very large and erroneous. I have attached the model. Could you please let me know where I am going wrong with respect to the applied loadcollectors as well as the geometry?
I have kept the contact as sliding and have initialised the required control cards.
Thank you!0 -
Hi,
I see a lot of distortion in the elements and I think this is because of the material.
Do you have more material data?
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Hey!
The following material properties are being used:
E=207GPA
u=0.3
density=7860kgpm^3Damping Coefficient: 0.02
Should I input structural stiffness as well? Is the analysis method and setup that I have done correct for the analysis that I am trying to do?
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Hi @Sp108
I tried different iterations and somehow the ball bearings got crushed.
I will check this with experts and will get back to you soon.
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Apart from that what is the objective of the analysis?
If you are interested in the only motion of the ball bearing, I suggest you use MotionSolve with Analytical contacts instead of Mesh-based contacts which are faster.
Please refer to this tutorial: MV-1012: Analytical Contact Simulation Using MotionView and MotionSolve
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Hi Prakash!
My main objectives regarding the bearing simulation are as follows:
1. Simulate varying compliance vibration of a defect free bearing. Here, I am applying a radial load of 40N to the inner race rotating at 1200 rpm. (Currently using Non-Linear Quasi static)
2. Transient analysis using time varying load. (Will this be done using Non-Linear Transient Analysis due to Contact non linearity?)
I was able to reduce the errors by changing the contact clearance value to 0 and allowing OVERLAP since there were penetrating elements. I also updated the material properties by setting the Damping Coefficient to 0.02. The values of displacement and stress reduced. Although I was not able to see the inner race rotate in the analysis.
How can I get incremental load results from NLOUT? I am only able to get the initial and final results.
Currently I am interested in the stress results. I will try MotionSolve as well. Does Optistruct show rotation animation or does it just show the deformations and stress values?
Please let me know! I greatly appreciate your assistance!
Regards
PFA: Attached updated Model.
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Altair Forum User said:
My main objectives regarding the bearing simulation are as follows:
1. Simulate varying compliance vibration of a defect free bearing. Here, I am applying a radial load of 40N to the inner race rotating at 1200 rpm. (Currently using Non-Linear Quasi static)
2. Transient analysis using time varying load. (Will this be done using Non-Linear Transient Analysis due to Contact non linearity?)
I was able to reduce the errors by changing the contact clearance value to 0 and allowing OVERLAP since there were penetrating elements. I also updated the material properties by setting the Damping Coefficient to 0.02. The values of displacement and stress reduced. Although I was not able to see the inner race rotate in the analysis.
How can I get incremental load results from NLOUT? I am only able to get the initial and final results.
Currently I am interested in the stress results. I will try MotionSolve as well. Does Optistruct show rotation animation or does it just show the deformations and stress values?
Please let me know! I greatly appreciate your assistance!
Regards
PFA: Attached updated Model.Hi,
I will check the updated model.
HyperView will show animation along with results. In the previous model, I see the ball bearings were stuck to the outer ring. I am able to rectify that but there are convergence issues (element crushing)
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Hey Prakash!
Yes I believe there are convergence issues and I think that causes the solution to end abruptly stating 'Fatal Error'. I am having an issue with the mapped mesh. I generated the mapped mesh by created a face mesh and then performing a line drag of the 2D mesh. In the solution, I can observe a discontinuity in the stress and displacement distribution as well as the inner race breaking at the place where the face mesh was created. How can I rectify that?
Please let me know!
Regards
PFA: Images of the mesh error<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
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Hi,
You can equivalence nodes. Goto Edges panel (Shift+F3) and equivalence.
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Hey Prakash!
I did the equivalence step but I get an error.
It states that error occurs when SPCD is applied to two GRIDs equivalenced with use of PERBC, CONNECT or MPIN cards. I have attached the same. Please let me know!
Regards
<?xml version="1.0" encoding="UTF-8"?>
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Altair Forum User said:
Hi,
You can equivalence nodes. Goto Edges panel (Shift+F3) and equivalence.
Hey Prakash!
I was able to rectify this error.
Regarding the transient analysis, I wanted to know if there is any tutorial available for time varying loading.
Regards
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Altair Forum User said:
Regarding the transient analysis, I wanted to know if there is any tutorial available for time varying loading.
Hi @Sp108
Did you check this model file which uses time-varying load?
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Altair Forum User said:
Hey!
Yes I found the model in one of the other forum questions where you had mentioned it. I am looking into the same.
Thank you!!0 -
If you still face any, please share the updated file with us through FTP link in my signature.
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Hey Prakash!
I used the NL_DTRANS to input stepped load for my bearing analysis for transient analysis. I did not use velocity in this case as I wanted to do a test run. I am unable to obtain convergence for the same and encounter fatal error. I utilized NLADAPT to obtain convergence yet I still am not able to get the same. By removing the contact constraint, the solution converges but without any displacement or stress results.
Please give me your opinion about the same.
Regards
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OK, I will check and update you soon.
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Hey Prakash!
I carried out the simulation on a model with lesser elements as the earlier one was taking a lot of time. The result I got does show the motion of the inner race and balls although at a higher scale of deformation, it shows that the race and balls are getting deformed. I have shared the files via FTP.
Also, I wanted to know how I can input time dependent loads on different nodes which are triggered separately, ie, 4 forces on 4 different nodes that get triggered at separate time intervals. How can I develop a response curve from the same?
Please let me know!
Regards
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Hey Prakash!
I wanted to know how I can input time dependent loads on different nodes which are triggered separately, ie, 4 forces on 4 different nodes that get triggered at separate time intervals. How can I develop a response curve from the same? I have sent the model via FTP. Please verify the same!
Regards
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Altair Forum User said:
Hey Prakash!
I wanted to know how I can input time dependent loads on different nodes which are triggered separately, ie, 4 forces on 4 different nodes that get triggered at separate time intervals. How can I develop a response curve from the same? I have sent the model via FTP. Please verify the same!
Regards
HI,
You can use TLOAD# to provide different loads and use DLAOD to combine all TLOADs
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Altair Forum User said:
HI,
You can use TLOAD# to provide different loads and use DLAOD to combine all TLOADs
Hey!
I made use of the method you mentioned here but I am still not able to simulate an impact scenario here and generate a acceleration-time response curve. I get an output but the force applied increases and becomes constant instead of being an impulse. Any tutorial about the same that I can refer to?
I wish to perform the following:
1. Impact simulation on the outer race on 4 nodes:
Load steps for one impact
Step Load, (N) Time step, (s)
1 (Bearing Entry) 31.5 T1 3.4975 9 10-3
2 (Bearing in motion) 21.5 T2 9.4925 9 10-3
3 (Bearing exit) 34.5 T3 1.049 9 10-2
4 (Bearing on race) 31.5 T4 1.399 9 10-2I wish to use the above values to simulate the impact analysis on 4 nodes in straight line on the outer race.
2. Generate acceleration response curve using Hypergraph
I have attached the time response curve (image: 12) and the simulation file. Please let me know what I should rectify in the model to achieve the response curve similar to image:13.
Regards<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
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Hi @Sp108 If I understood correctly, beyond 4th step the curve is a straight line, is that correct?
Is it possible to share the model file?
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I did this analysis in Radioss,
If you are familiar with radioss then i can help you out.
1. Mesh the model with good quality elements
2. Create material
3. Create solid prop (P_14solid)
4. Assign it to individual components
5. Create contact surface
6. Create contact (TYPE 24)
7. Define curves (one for angular rotation and one for radial load)
8. Define boundary conditions( OR fix, Inner ring rotating, use RBody for the same and assign radial load curve and angular rotation to master node).
if you face any issue in above points revert with the same.
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Altair Forum User said:
<?xml version="1.0" encoding="UTF-8"?>
I did this analysis in Radioss,
If you are familiar with radioss then i can help you out.
1. Mesh the model with good quality elements
2. Create material
3. Create solid prop (P_14solid)
4. Assign it to individual components
5. Create contact surface
6. Create contact (TYPE 24)
7. Define curves (one for angular rotation and one for radial load)
8. Define boundary conditions( OR fix, Inner ring rotating, use RBody for the same and assign radial load curve and angular rotation to master node).
Agree,
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Altair Forum User said:
Hey!
I made use of the method you mentioned here but I am still not able to simulate an impact scenario here and generate a acceleration-time response curve. I get an output but the force applied increases and becomes constant instead of being an impulse. Any tutorial about the same that I can refer to?
I wish to perform the following:
1. Impact simulation on the outer race on 4 nodes:
Load steps for one impact
Step Load, (N) Time step, (s)
1 (Bearing Entry) 31.5 T1 3.4975 9 10-3
2 (Bearing in motion) 21.5 T2 9.4925 9 10-3
3 (Bearing exit) 34.5 T3 1.049 9 10-2
4 (Bearing on race) 31.5 T4 1.399 9 10-2I wish to use the above values to simulate the impact analysis on 4 nodes in straight line on the outer race.
2. Generate acceleration response curve using Hypergraph
I have attached the time response curve (image: 12) and the simulation file. Please let me know what I should rectify in the model to achieve the response curve similar to image:13.
Regards<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
Hey Prakash
Can you advice me on how I can rectify this?
Also, I did the entire simulation again and had a few doubts. Please assist me in clarifying the same:
1. For applying a velocity can RFORCE card be utilized?
2. For using RBE3 connectors, which DOFs are needed to e constrained in the given case? You had sent a model where the RBE3 connectors are used to connect the inner nodes of the inner race to the center. Should only the inner nodes be selected or all the nodes? Will it make any difference?0 -
HI,
The acceleration values are scaled. Please check the units.
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Hi @Sp108,
Are you triggering the 4 loads with in 0.015 seconds and your inner race takes 5 sec to attain 1200 rm.
By the time you have triggered all loads you race is only at 6 rpm.
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