ESSOLV and INITIAL STRESS

[Abatt]

Hello, everybody!!!
I'm modeling a simple 3D electrostatic actuated MEMS structure with Solid 122 (electric field), Shell 93 (mechanical structure) and ESSOLV macros. But I don't know, how can I apply an initial stress to the structure.
Who has experience with coupled electrostatic-structural analysis??? Could you help me???
Thanks!

 

[Stringmaker]

I have no experience with any sort of electromechanical analysis, but there is a MEM's example in the Ansys Documentation. Checkout Tutorials: Chapter 6 MEM's Tutorial

I hope this helps you out in some way.

-Brian

 

[Abatt]

Thanks for your answer!
But I have already read this Tutorials. There are no information about initial stress. And it's thermal actuated structure. Please, somebody, help me!!!

 

[Stringmaker]

Here is a link which contains a coupled thermal-stress analysis tutorial:

http://www.mece.ualberta.ca/tutorials/ansys/AT/Coupled/Coupled.html

Although this is relatively simple the procedure will remain the same for other analyses of this type. Maybe this will be of more help...

 

[Abatt]

Thanks, Stringmaker!
I'll try to do it... I hope it can help me. But some time ago I tried to do it with TREF and TUNIF comands. It didn't work. Maybe, I made some mistake...
On the other hand, Ansys has ISTRESS comand which works with ESSOLV macros. Could you look at this comand in Ansys "help". Perhaps, you have more experience and you will get it.
Thanks!

 

[jiligeo]

Dear Abat,
I have also no experience with any sort of electromechanical analysis, but I define initial stress on model using iswrite and isfile commands.

iswrite,on
isfile,read,,,,0

regards
Jalil

 

[Abatt]

Dear Jalil,
but how you apply this initial stress on a model? With ISTRESS comand? It works only with certain elements.

Regards
Abat

 

[jiligeo]

Dear Abatt,
it is trure that we can use only certain elements. I use solid 95 in my model.contact and target elements (if you have in your model) must be unselected before using the istress.

esel,u,type, ,2 ! contact elemet
esel,u,type, ,3 ! target element

regards
Jalil