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It's EALIVE! It's Alive!

To be able to EKILL and EALIVE elements is a neat trick. It allows for a dormant element that springs to life. The reactivated elements have zero strain so some people use it to simply clear it of any unwanted stresses. I have more frequently use it to turn on and off contacts.

Here's a simple example problem: A block is fixed at the bottom, the top cylinder is pushed by hand downwards until it touches the block. Because of adhesive, the two are now 'bonded' together. In the second step, the hand lets go of the cylinder, the spring which is attached to ground at the top pulls on the cylinder creating stress on both parts.

Just push down to cure glue and let go!

There are a few steps needed to get this to work.

Firstly create a snippet of the bonded contact so it could be identified later. The code is simply:
mycid = cid
mytid = tid

Secondly, create two more snippets in the Analysis tree. Snippet #1 will EKILL the contacts for the first time step. Specifying the Step Number is critical here.

Snippet #2 will EALIVE the contact elements at Step Number 2.  

Finally, there are other odds-and-ends setup similar to other nonlinear analysis. For example Large Deflection - ON, large Pinball Radius, and deactivating the 'hold down' Displacement on the second time step. Additional details can be found in the archived v18 file. Download button is on the top right.

There are other great examples of this on the web. Here are a few:
PADT's example has contacts that controls penetration.
Simutech's example is cool in e-killing elements above a certain stress level while still in /SOLU

Update: Ansys V19 has Contact EKILL and EALIVE options native in Workbench. Snippets are no longer necessary.


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