Internal Surfaces- Perforation

[haseeb99b]

I am working on bullet impact on ceramics. Materials are ABQ_JHB_siliconCarbide and Gold. I also performed this on the Aluminum and Steel (Tech. Brief) and used this procedure in that model and it worked perfectly.

*Surface, type=ELEMENT, name=SPlate
,
Set-Plate, INTERIOR
....
*Contact Inclusions
.....
This is not working when I apply the SiC and Gold properties to Plate and Bullet. Please guide me over here if somebody has worked on that. Thankyou !!

 

[Mcakir]

Dear Haseeb;
Do you still need help on your issue?

 

[haseeb99b]

Dear Mcakir,

Yes, I am stuck on this issue and tried different things but in vain. I'd be grateful if you could guide me regarding this issue.

 

[Mcakir]

Dear Haseeb;
Please check the following steps;

Check units and quantities you already have used in your model (Very crucial)
Create a Element Based Set in the Assembly module. While doing this select all elements probably will be in contact during your analysis.
Name this set as "erodeset"
After completing all necessary arrangements Create a Job and Write Input file.
Go to that input file, open a text editing software.
Just Before the *End Assembly line
Add the following lines

---
*Surface,type=element,name=surfa
,
erodeset,interior
---
At this stage you are defining an extra surface composed of the surfaces defined by erodeset elements.

And add these lines just after *Bulk Viscocity data
---
*contact, op=NEW
*contact inclusions
surfa,
*contact controls assignment, nodal erosion=no
---

Save your input file. Then delete the one in your Job module. then recall it again in the module. run and hope to enjoy the results.

 

[ShadowWarrior]

I have a question regarding Nodal Erosion. Is it better to erase failed nodes or not?

 

[Mcakir]

Dear ShadowWarrior;
It depends on the problem you are coping with. But I can directly say that If the inertial forces are important even the elements failed in a zone you will still need the MASS containing those elements. If you erease the nodes, then you will lose some information carried on these elements. Such as, consider a high speed impact problem. Even some materials are deleted, their mass information is transfered to the associated nodes. If you delete those nodes you will be neglecting considerable amount of kinetic energy.
You decide

 

[ShadowWarrior]

@Mcakir, Hmmm, decisions decisions. Are there at least any advantages of nodal erosion?

 

[Mcakir]

Nodal erosion can reduce computation time a little but as far as I know not much. Other than this I have no experience.
Abaqus Documents discuss as below in detail:
You can control whether contact nodes remain in the contact domain after all the surrounding faces and edges have eroded due to element failure. By default, these nodes remain in the contact domain and act as free-floating point masses that can experience contact with faces that are still part of the contact domain. You can specify that nodes of element-based surfaces should erode (i.e., be removed from the contact domain) once all contact faces and contact edges to which they are attached have eroded. Nodes that you include in the contact domain only with node-based surfaces are never removed from the contact domain.

Computational cost can increase as a result of free-flying nodes if nodal erosion is not specified, particularly for analyses conducted in parallel. The increased computational cost is related to the likelihood of free-flying nodes moving far away from the elements that remain active, which stretches the volume of the contact domain and thereby tends to increase contact search costs as well as the cost of communication between processors in parallel analysis. However, contact involving free-flying nodes can contribute significant momentum transfer in some cases, which will not be accounted for if nodal erosion is specified

 

[ShadowWarrior]

@Mcakir, thanks for the detailed answer. I think I will keep the eroded nodes from now on.