Issue in creating "Contact" in MotionSolve

Altair Forum User

Dear Sir/Madam'

  I have been trying to do a motion analysis required for a problem statement which is required in AOC-2019 contest. While I have tried a lot but every time I am facing 1 issue repeatedly in creating 'Contact' by '3D Rigid to Rigid Contact'. Every time I try to create the contact between two gears, while solving it says 'ERROR: Contact graphics undefined for contact force [id=301001]!'.

 I have defined the bodies and selected their graphics also but it still shows the error. The image of the selections can be seen in the attachment. Kindly help me to solve the issue.

 

Regards

Pritish Shubham

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi Pritish, 

 

To help you in debugging this, can you provide some more information: 

 

1. From the error message you post, it looks like MotionSolve is not able to determine the geometry intended for contact calculations in Force_Contact/301001. I assume you are able to successfully export the model from MotionView before starting the simulation?  
2. In the XML model that is exported from MotionView, can you ensure that in <Force_Contact> id = 301001, the following two attributes are defined correctly i.e. pointing to the right graphics statement:

 <span style='color:#0000ff;'>i_graphics_id</span> 

 <span style='color:#0000ff;'>j_graphics_id</span>

Finally, are you able to share the model for us to take a look?

 

Thanks, 

Tanuj

 

Altair Forum User

Altair Forum User said:

Hi Pritish, 

 

To help you in debugging this, can you provide some more information: 

 

1. From the error message you post, it looks like MotionSolve is not able to determine the geometry intended for contact calculations in Force_Contact/301001. I assume you are able to successfully export the model from MotionView before starting the simulation?  
2. In the XML model that is exported from MotionView, can you ensure that in <Force_Contact> id = 301001, the following two attributes are defined correctly i.e. pointing to the right graphics statement:

  <span style='color:#0000ff;'>i_graphics_id</span> 

  <span style='color:#0000ff;'>j_graphics_id</span>

Finally, are you able to share the model for us to take a look?

 

Thanks, 

Tanuj

 

 

 

Dear Tanuj

  Thanks for replying to my query. I had tried checking the .xml file and I can see the force_contact had 'i and j' well defined. The image and the .XML file can be seen in the attachment. 

 

Regarding the model sharing option, I really wish to share it, but I am afraid I am not allowed to do so. Its a problem from AOC-2019 contest, so I don't know whether I can share the problem here. But I will try to discuss it with the concerning person and seek permission for it, if possible before sharing the model here. 

 

Regards

<?xml version="1.0" encoding="UTF-8"?>

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Altair Forum User

Altair Forum User said:

Hi Pritish, 

 

To help you in debugging this, can you provide some more information: 

 

1. From the error message you post, it looks like MotionSolve is not able to determine the geometry intended for contact calculations in Force_Contact/301001. I assume you are able to successfully export the model from MotionView before starting the simulation?  
2. In the XML model that is exported from MotionView, can you ensure that in <Force_Contact> id = 301001, the following two attributes are defined correctly i.e. pointing to the right graphics statement:

  <span style='color:#0000ff;'>i_graphics_id</span> 

  <span style='color:#0000ff;'>j_graphics_id</span>

Finally, are you able to share the model for us to take a look?

 

Thanks, 

Tanuj

 

 

 

 Dear Tanuj

  I had simplified the model and attaching with this message. Kindly look into the problem and guide me what necessary steps I need to do to correct the contact error.

 

Regards

 

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asajd_20372

For simple spur gears it is often much simpler to just use a Coupler... it can run very efficiently because contact detection is not required.

See attached ZIP file containing a model where coupler is used instead of contacts.

 

Sincerely,

Tony S.

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Altair Forum User

Altair Forum User said:

For simple spur gears it is often much simpler to just use a Coupler... it can run very efficiently because contact detection is not required.

See attached ZIP file containing a model where coupler is used instead of contacts.

 

Sincerely,

Tony S.

 

 Dear Tony

   Thanks a lot for guiding me to resolve my problem. I was trying to solve this issue for last 10 days but I was unable to do it. Your help really means a lot to me. 

 

Regards

Pritish Shubham

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Altair Forum User

Altair Forum User said:

For simple spur gears it is often much simpler to just use a Coupler... it can run very efficiently because contact detection is not required.

See attached ZIP file containing a model where coupler is used instead of contacts.

 

Sincerely,

Tony S.

Dear Tony S. 

  Can you please help me to create Contact in between these two gears, if I need to find the velocity ratio?  With coupler method we need to know their velocity ratios, and then we can see their animation. But I am trying to learn to find the velocity of big gear with the know velocity of the smaller gear. I think, for that, Contact may help to find the velocity. Can you please advice me for this too?

 

Regards

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Praful

Hello Pritish -

I am the Program Manager for MotionView and I would be interested to look into your problem. You can share this model if possible via email to me. (my address is mentioned below).

Please be assured that the files you share will remain confidential.

Alternatively, in case the model still cannot be shared, I have another recommendation in order to circumvent this problem.

You may replace the graphics that are being used (I believe those are CADGraphics) by using File Graphics (H3d format) instead. You may use the 'Import CAD/FE using Hypermesh option available under Tools menu. You might want to use the 2nd radio option there (Import CAD or Finite Element model only) to import as graphics and not create bodies. Once imported, you would have to manually resolve the bodies of each graphics to existing bodies.

 

You can then delete the original CADGraphics and make sure that the new set of graphics are selected in the Contact panel.

 

Regards

Praful

ppraf@altair.com

Altair Forum User said:

 

 

Dear Tanuj

  Thanks for replying to my query. I had tried checking the .xml file and I can see the force_contact had 'i and j' well defined. The image and the .XML file can be seen in the attachment. 

 

Regarding the model sharing option, I really wish to share it, but I am afraid I am not allowed to do so. Its a problem from AOC-2019 contest, so I don't know whether I can share the problem here. But I will try to discuss it with the concerning person and seek permission for it, if possible before sharing the model here. 

 

Regards

<?xml version="1.0" encoding="UTF-8"?>

 

Unable to find an attachment - read this blog

Altair Forum User

Altair Forum User said:

 

 

 Dear Tanuj

  I had simplified the model and attaching with this message. Kindly look into the problem and guide me what necessary steps I need to do to correct the contact error.

 

Regards

 

 

Thanks Pritish. As Praful mentioned in the last comment, please share the MotionView model for this simplified model with him or on this forum so we can investigate the root cause of the issue you are seeing. 

 

For now, based on the XML that you shared, the root cause seems to be a missing Graphics model element for both your gear geometries in the MotionSolve XML file. If you look for a <Post_Graphic> with ID = '90000000' or '90000001' in the 'Spur_Gear.xml' that you shared, you will not find these. 

I am attaching a modified MotionSolve model for you to get you started with your analysis. Please note that you may have to tune the model to get the results that you wish to achieve. 

The model attached here contains the mesh information necessary to run this model. 

 

Hope this helps. 

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Altair Forum User

Hi Tanuj

  I checked the file and realized the issue after getting .xml file from you. So I tied creating finer surface mesh through HyperMesh which can define the model geometry better and then exported to MotionSolve. This created the required graphics for the model and I was able to create the 'Contact'. Thanks a lot for all your advises and giving me your precious time due to which I was able to solve my problem.

 

Regards

 

 

Altair Forum User said:

 

Thanks Pritish. As Praful mentioned in the last comment, please share the MotionView model for this simplified model with him or on this forum so we can investigate the root cause of the issue you are seeing. 

 

For now, based on the XML that you shared, the root cause seems to be a missing Graphics model element for both your gear geometries in the MotionSolve XML file. If you look for a <Post_Graphic> with ID = '90000000' or '90000001' in the 'Spur_Gear.xml' that you shared, you will not find these. 

I am attaching a modified MotionSolve model for you to get you started with your analysis. Please note that you may have to tune the model to get the results that you wish to achieve. 

The model attached here contains the mesh information necessary to run this model. 

 

Hope this helps. 

 

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