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ANSYS. Composite problems using shell181 at postproc and tsai-hill criterion

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Topic starter
(@rossella)
New Member
Joined: 13 years ago

Hi all,

Ive 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 Reddys book.

1.-The first problem is that I dont 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 dont 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 Ive only found the Tsai-Wu criterion in the ANSYS help. Ive 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]

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