Analysis to determine residual stresses in a brazed joint

[jrrudd7]

I am trying to simulate a brazed component and need to evalute the residual stress levels in my design. I am brazing a sapphire window to Titanium, SS, and Nickel. I need to understand the residual compressive stresses in the sapphire. I have set up a thermal-mechanical simulation and have three ideas on how to accomplish this:

1) Do the thermal anlysis and get the expansion at braze temperature, then apply a contact condition while they are expanded, then run the temp back to room temperature...sounds ideal, but I do not know how to resolve the contact only at the high temp after it is expanded. I am going to plya around with using STRM real constant which allows you to resolve the contact in a specific load step, but the thermal analysis is not considered a load step from what I can tell...any suggestions on how to do this approach?

2) Use TBND which specs a critical bonding temp used primarily for weld simulations...I could set this variable, and when it is expanded, it should change the contact to bonded for contacts that are in a "closed" state. My problem hear is, even with a .005" gap and a 1mm pinball radius, the contact condiiton is "near" and not "closed" as required ot change the state to bonded...again anyone have any ideas.

Thanks in advance, any comments or suggestions are appreciated.

Jeff