Hi Friends,
Actually, I want to state a little bit more on the meshing issue of my
current study using Solid226. The problem I have is the Ansys program
simply crashes when I try to solve. I searched online and somebody says the
14.5 versions are not really stable. But I think it might be the problem
with the meshing. I wonder whether Daniel or anyone else has come into this
problem before.
Thanks.
On Mon, Nov 4, 2013 at 11:54 AM, Youmin Wang wrote:
> Hi Daniel,
>
>
> Thank you for you kind help!
>
> After investigations done so far, I recognized that Trans126 element might
> not be a good choice to be used in my tilting mirror applications. Though
> the Ansys help manual indicated something as below:
>
> [image: Inline image 1]
>
> As you can see, the above figure is using Trans126 elements, though I
> think it is a simplified model. I heard that Trans126 is good for
> attraction, while difficult to perform the leaving electrodes. Beyond that.
> I think my micromirror has more complicated geometry than the parallel
> plates, I don't know this parallel-plate simplification would be a good
> choice for it.
>
> As for now, I am considering to proceed with the Solid226 option, which is
> exactly what you have suggested. I am trying to mesh the air gap between
> the movable mirror and the fixed electrodes using Solid226 elements, while
> leaving the other parts using Solid45. The electroelastic and structural
> elements are joined through nodal connectivity at the interface between
> them. I am still working on this direction right now, when the geometry
> becomes more complicated, seems it get more difficult to converge, I have
> many small parts to trim, such as the meshing and boundary conditions...
>
> Another option seems to be multi-field solver, which up-to-now I have not
> acquired too much reference materials and did not dive in too deep yet.
>
> Again, thank you very much for your help and suggestions! I am really
> grateful to you. If you could provide more insight, that would be really
> great.
>
>
> On Fri, Nov 1, 2013 at 11:22 AM, Daniel Shaw wrote:
>
>> Hi Youmin:
>>
>>
>>
>> To perform an electrostatic-structural simulation using Mechanical APDL
>> (aka “classic ANSYS”), you can use either the 22x coupled-field elements,
>> the multi-field solver (MFS), or the electro-mechanical transducer element
>> (TRANS126). You could also use the reduced order electrostatic-structural
>> element (ROM144). The 22x elements and the MFS use a sequential coupling
>> approach. TRANS126 and ROM144 use a matrix coupling approach.
>>
>>
>>
>> If possible, I recommend using TRANS126. It is the simplest and most
>> robust approach. With the 22x elements and the MFS, you might have
>> meshing
>> issues at pull-down. ROM144 can be complicated to implement. If fringing
>> effects are significant, TRANS126 might be difficult to accurately
>> implement. In that case, you need to use one of the other methods.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Daniel Shaw
>>
>> ANSYS, Inc.
>>
>>
>>
>> On Wed, Oct 30, 2013 at 9:50 PM, Youmin Wang > >wrote:
>>
>> > Dear Friends,
>> >
>> > I am starting to use Ansys for the modeling of MEMS micromirror
>> > static/dynamic analysis. There have been many previous work in this
>> field,
>> > but according to my observations, 3 key technologies were basically used
>> > for MEMS electromechanical coupling, which are 1. using Coupled Field
>> > Element (SOLID226); 2. Multi-field solver; and 3. Trans126.
>> >
>> > Seems for method #1 I have to use air to enclose the whole device if
>> fringe
>> > electric field needs to be considered, but in "Gyimesi, Miklos, Ilya
>> > Avdeev, and Dale Ostergaard. "Finite-element simulation of
>> > micro-electromechanical systems (MEMS) by strongly coupled
>> > electromechanical transducers." Magnetics, IEEE Transactions on 40.2
>> > (2004): 557-560." it says in large deformation bending electrode
>> problem,
>> > Trans126 might not be suitable.
>> >
>> > Do you guys have any previous experience on this selection issue?
>> Besides,
>> > seems Trans126 also requires the pre-stress definition, which I am still
>> > struggling to find out where to apply...
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>> _______________________________________________
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>
>