[ANSYS] Composites. Problems using shell181 at postproc and tsai-hill criterion

Hi all,

I've modeled a composite sandwitch with ANSYS with a pressure. The element chosen was SHELL181.
I want to know the Stresses in the x, y and xy directions; the displacements and the deformations only in a few points so as to compare with the Navier and Rayleigh-Ritz solutions made following Reddy's book.

1.-The first problem is that I don't know how to ask ANSYS to list the displacements and deformations.

2.-The second one is that I know how to ask ANSYS to list all the elements in a layer,

[code]ESEL,S,LAYER,,1,12,1
ETABLE,TABLE_Sx,S,X
ETABLE,TABLE_Sy,S,Y
ETABLE,TABLE_Txy,S,XY
ESEL,ALL[\code]

but I don't know how to ask only for 'the element in the center of the layer and the four corners' (in fact I have no idea of how many nodes I need to compare)

3.-The last one is about verifying the stress in the plies by the Tsai-Hill criterion. I must do that but I've only found the Tsai-Wu criterion in the ANSYS help. I've tried to apply it, but when I go (in the workbench) to 'General Postproc->Failure Criteria->Criteria Check', ANSYS says:  "The input failure criteria for    2 materials generated errors, warnings, and/or notes"

Thank you in advance,

Ferraz
Engineering Student

The code developed:

[code]/TITLE, MCL PROJECTII
/PREP7

SMRT,OFF
ANTYPE,STATIC
ET,1,SHELL181                ! 4 NODE LAYERED SHELL
OUTRES,ALL,ALL     ! ALL SOLUTION ITEMS
KEYOPT,1,3,2                 ! FULL INTEGRATION
KEYOPT,1,8,2                 ! WRITE LAYER RESULTS
SECTYPE,1,SHELL
SECDATA,1.83E-3,2,90  ! LAYER 1: 1.83E-3 THK, THETA 90
SECDATA,1.83E-3,2,90
SECDATA,1.83E-3,1,0
SECDATA,1.83E-3,1,0
SECDATA,1.83E-3,2,45
SECDATA,1.83E-3,2,-45
SECDATA,1.83E-3,2,-45
SECDATA,1.83E-3,2,45
SECDATA,1.83E-3,1,0
SECDATA,1.83E-3,1,0
SECDATA,1.83E-3,2,90
SECDATA,1.83E-3,2,90

 ! ORTHOTROPIC MATERIAL PROPERTIES FOR BOTH MATERIALS

 !Material 1   
MP,EX,1,60e9
MP,EY,1,24.8e9  
MP,EZ,1,10e9   ! EZ ASSUMED LOWER
MP,GXY,1,12e9
MP,GYZ,1,12e9
MP,GXZ,1,12e9  ! ASSUMPTION GYZ=GXZ
MP,PRXY,1,0.23
MP,PRYZ,1,0.23!INVENTAT            
MP,PRXZ,1,0.23!INVENTAT

 !Material 3
MP,EX,2,209e9
MP,EY,2,19e9  
MP,EZ,2,5e9   ! EZ ASSUMED LOWER
MP,GXY,2,6.4e9
MP,GYZ,2,6.4e9
MP,GXZ,2,6.4e9  ! ASSUMPTION GYZ=GXZ
MP,PRXY,2,0.21
MP,PRYZ,2,0.21!INVENTAT            
MP,PRXZ,2,0.21!INVENTAT

 ! SPECIFY GEOMETRY PARAMETERS
ndiv=30   !NUMBER OF DIVISIONS
a=1.5
b=1.5
r=0.75
k=0.75
s1=0.3
s2=0.4
ht=0.022  !TOTAL THICKNESS

 ! CORNER KEYPOINTS OF QUADRANT (AREA) 
K,1,-a/2,-b/2,0  !D
K,2,a/2,-b/2,0  !C
K,3,a/2,b/2,0  !B
K,4,-a/2,b/2,0  !A
A,1,2,3,4

 ! MESHING
ESIZE,,ndiv                    ! 30X30 MESH USING QUARTER SYMMETRY (ndiv)
AMESH,1

 ! APPLY B.C.    
NSEL,S,LOC,X,a/2              ! SELECT NODES             
D,ALL,UX,,,,,UY,UZ,ROTX,ROTZ
NSEL,S,LOC,X,-a/2                           
D,ALL,UX,,,,,UY,UZ,ROTX,ROTZ
NSEL,S,LOC,Y,b/2
D,ALL,UX,,,,,UY,UZ,ROTY,ROTZ
NSEL,S,LOC,Y,-b/2
D,ALL,UX,,,,,UY,UZ,ROTY,ROTZ
NSEL,ALL

 !SURFACE LOAD GRADIENT
SFGRAD,PRES,0,Y,0,-7500/1.5
NSEL,S,LOC,Y,-s2
*DO,i,1,(s1+s2)/(b/ndiv),1
NSEL,A,LOC,Y,-s2+i*(b/ndiv)
*ENDDO
SF,ALL,PRES,7500
NSEL,ALL

FINISH

/SOLU
SOLVE
FINISH

/POST1
!Failure criteria
FC,1,S,XTEN,0.82e9    !Mat1, Stresses, allowable tensile stress in the x direction
FC,1,S,YTEN,0.045e9
FC,1,S,ZTEN,1e15   !If you do not want the failure stress to be checked in a particular direction, specify a large number in that direction
FC,1,S,XCMP,-1e15
FC,1,S,YCMP,-1e15
FC,1,S,ZCMP,-1e15
FC,1,S,XY,0.045e9
FC,1,S,YZ,1e15
FC,1,S,XZ,1e15

FC,2,S,XTEN,1.28e9
FC,2,S,YTEN,0.06e9
FC,2,S,ZTEN,1e15
FC,2,S,XCMP,-1e15
FC,2,S,YCMP,-1e15
FC,2,S,ZCMP,-1e15
FC,2,S,XY,0.105e9
FC,2,S,YZ,1e15
FC,2,S,XZ,1e15

LAYPLOT,1,1,12     !Element 1, from layer 1 to layer 12 (all of them)
ESEL,S,LAYER,,1,12,1
ETABLE,TABLE_Sx,S,X
ETABLE,TABLE_Sy,S,Y
ETABLE,TABLE_Txy,S,XY
ESEL,ALL
FINISH[/code]