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Stiffness in bending mode

Topics: MEMS, Structural Mechanics, 4.1

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Sankha Mukherjee

Sankha Mukherjee

January 30, 2013 9:43pm UTC

Stiffness in bending mode

Hello Everyone,

I have been COMSOL for quite sometime and have come across a problem that I can not solve very recently.

My objective is to find out the bending stiffness of a metallic nanoplate. What I have been doing is provide COMSOL with Young's modulus, Poissons ratio and density of the metal and got correct values of stiffness for longitudinal mode. However when I go for bending mode the numbers do not match with atomistic simulations. I think this can be solved by introducing anisotropic elastic constants of the metal (C11.C12,C44). Can anyone advise me as to how can I plugin these numbers in the solid mechanics module? Or if I were to plugin these values in the piezoelectric module what should I use for Coupling matrix, relative permittivity, loss factors?

Thanks

Sankha

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Ivar Kjelberg

Ivar Kjelberg

January 31, 2013 5:55am UTC in response to Sankha Mukherjee

Re: Stiffness in bending mode

Hi

first of all be aware that PZT and elastic material tensor notation for the matrices are different (by convention) so check carefully the order of the indexes.

you need to say more about your material, do you suspect it's anisotropic, in which structure (amorphe, crystalline ..., then you can decide which symmetry to use and enter the corresponding data, if you have them, or try to fit them from your measurements, but ass there are many variables, you would probably need also some torsion measurements to solve all anisotropic variables

Also, for such small models, be sure you have enough mesh elements also in the thickness, else your model might be wrong

--
Good luck
Ivar

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