Learning Forum

[theodoreyang]

Hello,

My 3D XFEM model offen terminates with the following error message:

 *** FATAL ***                           CP =     204.958   TIME= 11:22:19

 Unable to check if element 14776 is cracked since it is not a composite element. 

I checked this element in the post-processing. This element is not adjacent to the crack front.

For 2D model, it always works well, but for 3D model, it can only solve very little substeps and stop with errors.

[David Weed]

Hi Theodre, would you be able to post your APDL code? Thanks

[theodoreyang]

Hi DavidW,

Here is the APDL code. Thanks.

 

/prep7

/com *** Geometry 

length = 10.0           ! model centered at (0,0,0)

width = 10.0            ! geometry for each block

thickness = 10.0

 

xnum = 15    ! quantity of element on x

ynum = 15    ! quantity of element on y

znum = 20     ! quantity of element on z

 

et,1,185    ! element type

 

/com *** Material Properties *********************************

mp,ex,1,   2000.0    

mp,nuxy,1, 0.3

mp,alpx,1, 52e-6

 

/com *** Model ***** centered at (0,0,0)**********************

/com *** Corner made by 7 small blocks

BLOCK, 0, length, 0, width, 0, -thickness/4    ! x1,x2,y1,y2,z1,z2 

BLOCK, 0, -length, 0, width, 0, -thickness/4    

BLOCK, 0, -length, 0, -width, 0, -thickness/4   

BLOCK, 0, length, 0, -width, 0, -thickness/4    

BLOCK, 0, length, 0, width, 0, thickness   

BLOCK, 0, -length, 0, width, 0, thickness

BLOCK, 0, length, 0, -width, 0, thickness  

vglue,all

 

/com ***mesh

type,1

mat,1

 

x_size = length/xnum

y_size = width/ynum

z_size = thickness/znum

 

lesize, 7, x_size   ! element size on x

lesize, 8, y_size   ! element size on y

lesize, 9, z_size   ! element size on z

 

lesize, 97, x_size   ! element size on x

lesize, 92, y_size   ! element size on y

lesize, 85, z_size   ! element size on z

vmesh,all

 

/com *************************************************************

/com

/com                    INITIAL CRACK DATA

/com

/com *************************************************************

 

/com ***define crack position

 

x0 = 0

y0 = 0

z0 = z_size/2

 

xc = x_size/2

yc = y_size/2

zc = z_size/2

 

/com ***define enrichment identification***********************

 

esel,s,cent,x,-length*1,length*0.5

esel,r,cent,y,-width*1,width*0.5

esel,r,cent,z,-thickness/4,thickness/4

 

cm,testcmp_1,elem                    ! name the element set for xfenrich

allsel

xfenrich,ENRICH_1,testcmp_1     ! define the method: phantom node (default) or SIF

 

 

/com ***loop for crack level set identification***********************

 

esel,s,cent,x,x0-x_size*1,xc+x_size*0.499

esel,r,cent,y,y0-y_size*1,yc+y_size*0.499

esel,r,cent,z,z0,zc+z_size*0.499

 

cm, cenelem, elem    ! name the element set for vertical crack elements

nelem = 1000

iel = 0

Phi = 0.0

Psi = 0.0

*do, i, 1, nelem, 1

 iel = elnext(iel)

 *if, iel, ne, 0, then

  *do, j, 1, 8, 1

    nd = nelem(iel,j)

    Phi = nz(nd) - zc

    xfdata, ENRICH_1, LSM, iel, nd, Phi   

  *enddo

 *endif

*enddo

 

 

cm, crktipelem, elem

allsel,all

 

/com ******** Boundary conditions *********************

 

nsel,s,loc,x,0

nsel,r,loc,y,0,-width

nsel,r,loc,z,0,thickness

d,all,all,0

 

nsel,s,loc,x,0,-length

nsel,r,loc,y,0

nsel,r,loc,z,0,thickness

d,all,all,0

 

nsel,s,loc,x,0,-length

nsel,r,loc,y,0,-width

nsel,r,loc,z,0

d,all,all,0

 

nsel,s,loc,x,-length-x_size/2,-length+x_size/2

dsym,symm,x,0

 

nsel,s,loc,y,-width-y_size/2,-width+y_size/2

dsym,symm,y,0

 

allsel

 

/com ******** Temperature load *********************

 

Tref,150

BF,ALL,TEMP,25

 

/SOLU

 

autots,on

 

time, 1.0                  ! --- time

 

deltim,0.05,0.05,0.05

 

outres,all,all

 

tb,cgcr,1,,,STTMAX  ! crack growth criterion, max circon stress

tbdata,1,3

tb,cgcr,1,,,RLIN    ! rigid linear law

tbdata,1,0.04,,,0.05

 

CINT, NEW,1

CINT, CXFE,crktipelem

CINT, TYPE,STTMAX

CINT, RSWEEP,181,-60,60

CINT, NORM, 0, 3

 

CGROW,NEW,1

CGROW,CID,1

CGROW,METHOD,XFEM

CGROW,FCOPTION,MTAB,1

 

SOLVE                         

Save

 

/POST1  

SET,LAST