Help!!! Fastest way to define contacts?!!

Sebastian Yang

Hello,

 

I have a model with multiple components that consists of a outer case and several internal components, 

 

I want to define type 7 symmetric contact for all of them because I think there is a possibility that each one of them comes into contact with each other, 

but right now I have to define a lot of contacts for each pair of components, for instance, green´s nodes with blue's elements, green´s nodes with orange´s elements, etc. This is really time consuming.

Is there a way to define type 7 for all possible combination of components? An option where you insert a bunch of components and the program would define type 7 contact for you?

 

(I have seen something similar in this tutorial, on step 9.2 it defines a single type 7 contact which includes 8 components, which seems insane to me https://2021.help.altair.com/2021.2/hwsolvers/rad/topics/solvers/rad/front_impact_bumper_hm_r.htm#ariaid-title11)

Michael Herve_21439

Hello @Sebastian Yang ,

 

is there any specific reason why you want to define a separate type7 contact for each pair of contact? For explicit analysis, the best practices today is rather to define one single contact per sub-assembly, with all components of the same sub-assembly being slave and master of the interface.

From a pure performance point of view, having a unique contact instead of multiple contacts is also better.

One of the main (not to say the only) reason to create a contact per pair is if you need to extract contact forces for each pair of component. If you do not need to output these contact forces, then you can go with the single contact. If you need some contact forces, then you can use /INTER/SUB. If that can help, there is a macro in Community that can help for populating these /INTER/SUB cards:

https://community.altair.com/community/en/creating-sub-contacts-for-radioss-general-contacts?id=kb_article&sysparm_article=KB0122363

 

Hope that helps,

Michael

Michael Herve_21439

Hello @Sebastian Yang ,

 

is there any specific reason why you want to define a separate type7 contact for each pair of contact? For explicit analysis, the best practices today is rather to define one single contact per sub-assembly, with all components of the same sub-assembly being slave and master of the interface.

From a pure performance point of view, having a unique contact instead of multiple contacts is also better.

One of the main (not to say the only) reason to create a contact per pair is if you need to extract contact forces for each pair of component. If you do not need to output these contact forces, then you can go with the single contact. If you need some contact forces, then you can use /INTER/SUB. If that can help, there is a macro in Community that can help for populating these /INTER/SUB cards:

https://community.altair.com/community/en/creating-sub-contacts-for-radioss-general-contacts?id=kb_article&sysparm_article=KB0122363

 

Hope that helps,

Michael

Polyvios Romanidis

Hi Sebastian,

You can define a self contact with /INTER/TYPE7 including all parts.  To do that you can define the GRNOD by changing entities to components and select all our parts (Figure 1) and do the same with SURF definition (Figure 2).

For the different formulations available in /INTER/TYPE7, you should start with the recommended values shown in Figure 3.

Polyvios

Sebastian Yang

Michael Herve_21439 said:

Hello @Sebastian Yang ,

 

is there any specific reason why you want to define a separate type7 contact for each pair of contact? For explicit analysis, the best practices today is rather to define one single contact per sub-assembly, with all components of the same sub-assembly being slave and master of the interface.

From a pure performance point of view, having a unique contact instead of multiple contacts is also better.

One of the main (not to say the only) reason to create a contact per pair is if you need to extract contact forces for each pair of component. If you do not need to output these contact forces, then you can go with the single contact. If you need some contact forces, then you can use /INTER/SUB. If that can help, there is a macro in Community that can help for populating these /INTER/SUB cards:

https://community.altair.com/community/en/creating-sub-contacts-for-radioss-general-contacts?id=kb_article&sysparm_article=KB0122363

 

Hope that helps,

Michael

hi Michael,

 

No, there is no specific reason for me to define a separate type 7 contact, I am new to Radioss and I did not know that it´s preferable to define one single contact per sub-assembly!

Thanks for the insights.

 

I have another question! 

It is a standard practice to define a global type 11 contact for possible interactions between the edges of the components? Thanks!

Sebastian Yang

Polyvios Romanidis said:

Hi Sebastian,

You can define a self contact with /INTER/TYPE7 including all parts.  To do that you can define the GRNOD by changing entities to components and select all our parts (Figure 1) and do the same with SURF definition (Figure 2).

For the different formulations available in /INTER/TYPE7, you should start with the recommended values shown in Figure 3.

Polyvios

Hi Polyvios,

 

Glad to see you again!  Thanks for the explanation!

Michael Herve_21439

Sebastian Yang said:

hi Michael,

 

No, there is no specific reason for me to define a separate type 7 contact, I am new to Radioss and I did not know that it´s preferable to define one single contact per sub-assembly!

Thanks for the insights.

 

I have another question! 

It is a standard practice to define a global type 11 contact for possible interactions between the edges of the components? Thanks!

Hello again @Sebastian Yang ,

 

yes this is remmoended. By the way instead of creating type 7 and type 11, you can create a type19 contact instead, which is nothing but the combination of type 11 and symetrical type7.

Also, depending on your typer of parts, you may also have a look at type 24 and/or 25. If you are not familiar wiith these contacts, please feel free to follow either one of our Radioss virtual led training, or our Radioss e-learning.

 

Best Regards,

Michael Herve

Polyvios Romanidis

Sebastian Yang said:

Hi Polyvios,

 

Glad to see you again!  Thanks for the explanation!

Hi Sebastian,

You should see them as attachments!  I upload them here anyway!

Polyvios

 

Sebastian Yang

Michael Herve_21439 said:

Hello again @Sebastian Yang ,

 

yes this is remmoended. By the way instead of creating type 7 and type 11, you can create a type19 contact instead, which is nothing but the combination of type 11 and symetrical type7.

Also, depending on your typer of parts, you may also have a look at type 24 and/or 25. If you are not familiar wiith these contacts, please feel free to follow either one of our Radioss virtual led training, or our Radioss e-learning.

 

Best Regards,

Michael Herve

Understood, thank you very much!

Sebastian Yang

Polyvios Romanidis said:

Hi Sebastian,

You should see them as attachments!  I upload them here anyway!

Polyvios

 

Yes I see them now, thank you!