Re: residual stress application in ansys (amar atre)
Sjoerd Haasl
2002-06-26
Hi Amar,
I have previously modeled the residual stress in a thermal actuator by
applying a temperature to it. In my case the residual stress caused a
shrinkage, so I applied a negative temperature. The temperature difference
I applied on the part under stress was such that it would cause the same
stress as the residual stress if held constrained.
In formulas:
sigma = E * epsilon
epsilon = dT * TCE
So: dT = sigma / (E*TCE)
where epsilon is the relative expansion, TCE the coefficient of linear
thermal expansion, E Young's modulus, sigma the residual stress and dT is
the temperature difference I applied.
I have no idea if this reasoning is correct, and have not had the
simulations confirmed by experiments, but it gave me an idea of what to
expect. I leave it open to the MEMS community to correct me.
And then there is of course still the problem of thermal insulation if you
have residual stress in only certain parts of your actuator.
Good luck,
Sjoerd Haasl
Royal Institute of Technology
Department of Signals, Sensors and Systems
Microsystem Technology
Stockholm, Sweden
> ----- Original Message -----
> Message: 10
> Date: Mon, 24 Jun 2002 14:54:27 -0700 (PDT)
> From: amar atre
> To: mems-talk@memsnet.org
> Subject: [mems-talk] residual stress application in ansys
> Reply-To: mems-talk@memsnet.org
>
> HI
>
> I am modeling a thermal actuator in ANSYS. i am trying to model the
> residual stress in the actuator to get some initial deflection. but dont
> have any idea how to proceed. This question was asked before but i
> didnt find a reply for it.
>
> Can anyone help me
>
> Thanks
>
> Amar
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