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How to apply initial stress

Posted 30.08.2011, 11:02 GMT-4 MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Structural Mechanics Version 4.1, Version 4.2 2 Replies

Bruno Rango
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Hi!

I made a model of a string with initial stress using a truss element and I obtained exactly the same eigenfrequencys than manually using theorical formulas.
Now I want to make the model using a beam element, but I get totally different results. Moreover, changing the value of the initial stress, the eigenfrequency doesn`t vary, wich is no correct.

So, wich is the problem?

Thanks,

Bruno.
2 Replies Last Post 06.07.2012, 13:18 GMT-4
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Hello Bruno Rango

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Vadim Lebedev
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Posted: 1 decade ago 06.07.2012, 04:53 GMT-4
I have absolutely similar problem.
Is there any standard solution to define the pre-stress in the uni-/bimorph structures?

Somehow it is routine task, to look for the eigenfrequencies modified by the technology-induced
strain/stress variations.

I will be very thankfull for the advice from someone solved the problem.
At the moment I am using analytical formulas for simple bridges, but for mor complex geometries
it does not work of course.
I have absolutely similar problem. Is there any standard solution to define the pre-stress in the uni-/bimorph structures? Somehow it is routine task, to look for the eigenfrequencies modified by the technology-induced strain/stress variations. I will be very thankfull for the advice from someone solved the problem. At the moment I am using analytical formulas for simple bridges, but for mor complex geometries it does not work of course.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 06.07.2012, 13:18 GMT-4
Hi

"my way" is to apply a stationary solver case first and use that as intial conditions (with or without remeshing, all depends)

--
Good luck
Ivar
Hi "my way" is to apply a stationary solver case first and use that as intial conditions (with or without remeshing, all depends) -- Good luck Ivar

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