Dear everyone:

I am using the finite element analysis to calculate the quality factor
of quart resonating beam accerometer. But I've got a puzzle: how to take
piezoelectricity and electrodes into account.  The thermal conductivity
of gold is larger than that of quartz. so,the piezoelectricity and
thermal conduct of the electrodes will affect the temperature gradient
in the beam.

I used the ansys as the FEA tools to do this job. The beam is
quartz,and solid226 is used to mesh the beam. The electrodes deposited
on the beam is about 3000 A, which is beyond the the thickness of the
beam. If i use the 3-D solid to model the electrodes, the elements are
so large that the computer can't resolve it. I haved tried to use
plane223 to model the electrodes,but i don't know how to deal the link
between electrodes and the surface of the beam.

Is there anyone who has tactics to solve the problem. I am looking
forward to your answer. thanks a lot in advance. my english is poor,
and i don't know whether i have described the problem clearly.

                                                        sincerely yours,
                                                        jianfa zhou


ps. the error code of ansys hint

 *** ERROR ***                           CP =      53.719   TIME= 14:46:01
 There are elements with negative electric charge and current conduction
 reaction solutions for the VOLT degree of freedom in the model.  This
 analysis is not valid.

ps.brief codes of ansys

/prep7
....
et,1,226,1011
et,2,223,110,
mp
.......  !define meterial properties

!creat models
block,.....!model the beam
k,,...
a,.....  !model the electrodes
aovl,....!overlap the electrodes and the surface of the beam

!mesh the models
type,1
mat,1
......!mesh the beam
......

type,2
mat,2
.......!mesh the electrodes
.......

!apply boundary conditions
.........!clamped-clamped beam
.........!apply voltage conditions

fini

!solve the problems
.....

......