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Accelerometer simulations

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Hi,
I am simulating a simple comb drive structure for an accelerometer design. I am having problems trying to interpret the results that I got.
After running the simulation, the results from the 3D plot group shows the deformation figures for the design seem to be not in scale with the dimensions of the design. I mean, the deformation plot that I get is not conforming with the order of the dimensions of the design. The max displacement is about 4pm but the deformation figure shows a very exaggerated situation.
Can anyone help me understand why this happens?
Also, it would be great if someone can tell me how to use functions like intop() to calculate the mass of certain domains so that I can verify it with my analytical result.
regards,
Vadiraj

6 Replies Last Post 2011年6月15日 GMT-4 11:55
Jeff Hiller COMSOL Employee

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Posted: 1 decade ago 2011年6月6日 GMT-4 16:10
Yes, deformation plots are automatically scaled to present deformations that are visible with the naked eye. You can control that "scale factor" through the Deformation node in the Model Builder.
Yes, deformation plots are automatically scaled to present deformations that are visible with the naked eye. You can control that "scale factor" through the Deformation node in the Model Builder.

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Posted: 1 decade ago 2011年6月7日 GMT-4 10:38
Thanks Hiller for your reply.
Thanks Hiller for your reply.

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Posted: 1 decade ago 2011年6月8日 GMT-4 10:33
Hi again,
I have a question about simulating a frequency analysis for my accelerometer. I have a laterally driven accelerometer design with a thickness of 2um. Hence it suffers less from squeeze film damping in the direction it is being driven.
I would like to study the effect of this damping on the quality factor of my device.
The only way to do this is a frequency simulation. I am unable to obtain these plots.
Can you tell me how to consider the squeeze film damping effects in order to obtain the frequency response ?

regards,
Vadiraj
Hi again, I have a question about simulating a frequency analysis for my accelerometer. I have a laterally driven accelerometer design with a thickness of 2um. Hence it suffers less from squeeze film damping in the direction it is being driven. I would like to study the effect of this damping on the quality factor of my device. The only way to do this is a frequency simulation. I am unable to obtain these plots. Can you tell me how to consider the squeeze film damping effects in order to obtain the frequency response ? regards, Vadiraj

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Posted: 1 decade ago 2011年6月8日 GMT-4 10:33
Hi again,
I have a question about simulating a frequency analysis for my accelerometer. I have a laterally driven accelerometer design with a thickness of 2um. Hence it suffers less from squeeze film damping in the direction it is being driven.
I would like to study the effect of this damping on the quality factor of my device.
The only way to do this is a frequency simulation. I am unable to obtain these plots.
Can you tell me how to consider the squeeze film damping effects in order to obtain the frequency response ?

regards,
Vadiraj
Hi again, I have a question about simulating a frequency analysis for my accelerometer. I have a laterally driven accelerometer design with a thickness of 2um. Hence it suffers less from squeeze film damping in the direction it is being driven. I would like to study the effect of this damping on the quality factor of my device. The only way to do this is a frequency simulation. I am unable to obtain these plots. Can you tell me how to consider the squeeze film damping effects in order to obtain the frequency response ? regards, Vadiraj

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年6月9日 GMT-4 02:29
Hi

have you considered the squeezed film example in he model library ? (do not forget to update your model library regularly, new models come each week ;)

--
Good luck
Ivar
Hi have you considered the squeezed film example in he model library ? (do not forget to update your model library regularly, new models come each week ;) -- Good luck Ivar

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Posted: 1 decade ago 2011年6月15日 GMT-4 11:55
Hi again,
Well, until now i was simulating the accelerometer with just solid mechanics physics. I was trying to obtain the frequency response which somewhat gives me an idea of my Q factor. Now realizing that my Q factor is too high for a reliable accelerometer, I decided to damp my structure using the fluid-damping shell physics by appropriately setting the fluid properties.
the problem is that with both these physics settings, i am unable to obtain both the frequency response and time domain response. i am not aware of how to apply symmetry setting for my design. it is just a simple comb drive structure with the central proof mass which is sensitive to acceleration in one direction. the mass is attached to a simple folded spring structure on both sides. So, my design has symmetry along the proof mass.
my errors are mainly related to the memory issues. I tried almost all the solutions which are talked about in the forum but nothing seems to be doing the trick. Can anyone tell me how can i use symmetry to solve my prob?

regards,
Vadiraj
Hi again, Well, until now i was simulating the accelerometer with just solid mechanics physics. I was trying to obtain the frequency response which somewhat gives me an idea of my Q factor. Now realizing that my Q factor is too high for a reliable accelerometer, I decided to damp my structure using the fluid-damping shell physics by appropriately setting the fluid properties. the problem is that with both these physics settings, i am unable to obtain both the frequency response and time domain response. i am not aware of how to apply symmetry setting for my design. it is just a simple comb drive structure with the central proof mass which is sensitive to acceleration in one direction. the mass is attached to a simple folded spring structure on both sides. So, my design has symmetry along the proof mass. my errors are mainly related to the memory issues. I tried almost all the solutions which are talked about in the forum but nothing seems to be doing the trick. Can anyone tell me how can i use symmetry to solve my prob? regards, Vadiraj

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