Simulating Disbond and Core Crush in Honeycomb Panel

[sperry2565]

Hello all!

Please forgive my ignorance as I am fairly new to Patran/Nastran the other person working in my group isn't exactly sure where to start to even accomplish this. If more information is needed, please let me know. Any and all help would be greated appreciated.

What I am trying to accomplish is to simulate a disbond in a metallic honeycomb core panel in Patran. I tried a disassociate but that is a no go, it does not select any of the nodes or elements. The core is a solid element while the facesheet panels on either side are quads. Is there a quick and easy way to simulate a disbond in one or multiple locations of this panel?

Also, since we're on the subject of honeycomb core panels, would anyone have any idea how to simulate a core crush situation? I think I need to go into the properties and for the z-direction set it to a really low number to ensure an ineffective core flatwise. Any I on the right path for this?

Thank you!

 

[nlgyro]

Quoting:

> Is there a quick and easy way to simulate a disbond in one or multiple locations of this panel?

Dis-connect the nodes b/w the core and the face-sheets. Note sure what you previously meant by "I tried a disassociate but that is a no go, it does not select any of the nodes or elements"

> Also, since we're on the subject of honeycomb core panels, would anyone have any idea how to simulate a core crush situation?

The simplest, is to do a hand-calc, comparing the core-compression strength against the sigma-Z stress from the solid elements, and derive a Margin of safety (MS)

 

[sperry2565]

Sorry, I assumed I could disconnect the nodes by disassociating them but I guess there is nothing to disassociate. How do I disconnect them without deleting?

So, our core is still in the beginning phases of allowables, which is why I think they wanted to model the behavior on our model.

 

[nlgyro]

What you could do is:

Transform--->Element---> Translate , select the 2D shells elements of the face-sheet, and put <0,0,0> for the direction vector. Make sure to check the "delete original element" radio button, then hit apply. You'll have duplicate nodes created at the interface of the shell & solids. Now all you have to do is just to merge the ones where you need a continuous structure, the remaining un-merged nodes would be the dis-bond b/w the core and the face-sheets.