General Mechanical

General Mechanical

XFEM 3D model terminates with error

    • theodoreyang
      Subscriber

      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
      Ansys Employee

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

    • theodoreyang
      Subscriber

      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


       


       

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