Meshing help!

[gregthomas]

I have the following model that I want to mesh. I have a rectangular silicon membrane with a thin film of piezoelectric material on the front and the back. I'm having a lot of trouble meshing the two piezoelectric thin films. Everything I've tried gives me lots of warnings about bad mesh elements. Can anyone suggestion what type/size/shape of elements to use? Thanks!!

/prep7

! Material properties for PZT-4
!
mp,DENS,1,7700 ! Density, kg/m**3

tb,DPER,1 ! Relative permittivity at constant strain
tbdata,1,729,635,729

tb,ANEL,1 ! Anisotropic elastic stiffness, N/m^2
tbdata,1,13.9E10,7.43E10,7.78E10 ! c11,c13,c12
tbdata,7,11.5E10,7.43E10 ! c33,c13
tbdata,12,13.9E10 ! c11
tbdata,16,2.56E10 ! c44
tbdata,19,2.56E10 ! c44
tbdata,21,3.06E10 ! c66

tb,PIEZ,1 ! Piezoelectric stress coefficients, C/m^2
tbdata,2,-5.2 ! e31
tbdata,5,15.1 ! e33
tbdata,8,-5.2 ! e31
tbdata,10,12.7 ! e15
tbdata,15,12.7 ! e15


mp,dens,2,2330
mp,ex,2,1.65E+011
mp,nuxy,2,0.22

!
! Define a piezoelectric membrane
!
H = 1e-6 ! Transducer size, m
block,0,1000*H,0,800*H,0,0.5*H ! Define volume
block,0,1000*H,0,800*H,0.5*H,10.5*H
block,0,1000*H,0,800*H,10.5*H,11*H


et,1,SOLID226,1001 ! 3-D coupled-field brick, piezo option
mat,1 $ type,1 ! Set element attributes
vmesh,1 ! Generate nodes and elements
vmesh,3
et,2,SOLID185
mat,2 $ type,2
vmesh,2



Greg

 

[cbrn]

Hi,
this has been adressed many times: it's due to huge difference between principal dimensions of the thin layer (investigate about what "aspect ratio" means). The best solution, whenever possible, has been recognized being the use of shell elements instead of solid elements.

Regards

 

[meshparts]

A more effective way is the use of multi layer elements, like SOLSH190 or SHELL99.

Regards,
Alex