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ANSYS command problem re element death/element table postprocessing

  1. Oct 19, 2008 #1
    I am a new to ANSYS command-language mode. I am having trouble animating the procedure described below. The procedure is meant to model melting over time through element death (based on example from U. Alberta at www.mece.ualberta.ca/tutorials/ansys/AT/BirthDeath/BirthDeath.html).

    My problem is that I can't get the elements that exceed 600 C (my melting criterion) to disappear SEQUENTIALLY from the animation. Instead, I can only get those elements that exceed 600 C in EITHER the first or last step to disappear. The temperature contours evolve during the animation, but the melted/disappeared elements stay the same. I have tried writing a loop to make a new element table for each substep in which melted elements disappear, but this has not worked.

    I would very much appreciate help with this...The postprocessing part of the code should appear in bold blue italics.



    finish
    /clear

    /title, Transient melting by element death (conduction)
    /prep7 ! Enter the preprocessor

    ! define geometry

    BLC4,0,0,20,15 ! Create rectangle
    BLC4,0,0,10,4 ! Create smaller rectangle (magma)
    ASBA,1,2 ! Boolean Subtraction (subtracts area 2 (small) from area 1 (big))


    ET,1,Plane55 ! Element type

    MP,Dens,1,2262e9 ! Define density
    mp,c,1,0.001604 ! Define specific heat
    mp,kxx,1,0.001 ! Define heat transfer coefficient

    ! Mesh size
    SMRT,6
    CM,_Y,AREA
    ASEL, , , , 3
    CM,_Y1,AREA
    CHKMSH,'AREA'
    CMSEL,S,_Y

    AMESH,_Y1 ! Mesh area

    ! Refine mesh
    CMDEL,_Y
    CMDEL,_Y1
    CMDEL,_Y2

    FLST,5,6,2,ORDE,4
    FITEM,5,6
    FITEM,5,22
    FITEM,5,-25
    FITEM,5,44
    CM,_Y,ELEM
    ESEL, , , ,P51X
    CM,_Y1,ELEM
    CMSEL,S,_Y
    CMDEL,_Y


    EREF,_Y1, , ,3,0,1,1
    CMDEL,_Y1


    finish
    /solu ! Enter solution phase

    antype,4 ! Transient analysis
    nropt,full ! Newton Raphson - full

    SOLCONTROL,ON,0

    TUNIF,200,
    TREF,200,

    OUTPR,ALL,ALL,

    OUTRES,ALL,ALL

    time,3.1536e13 ! Time at end of analysis
    AUTOTS,0
    DELTIM,315360e6, , ,1 ! Time step
    AUTOTS,0
    KBC,1

    TSRES,ERASE

    TIME,31536000000000
    AUTOTS,0
    NSUBST,100, , ,1 ! Number of substeps,100
    KBC,1


    lumpm,0 ! Lumped mass off

    neqit,100 ! Max no. of iterations
    autots,off ! Auto time search off
    lnsrch,on ! Line search on
    kbc,1 ! Load applied in steps, not ramped

    IC,all,temp,200 ! Initial conditions, temp = 200

    PRED,-1
    FLST,2,628,1,ORDE,2
    FITEM,2,1
    FITEM,2,-628
    IC,P51X,TEMP,200,
    FLST,2,2,4,ORDE,2
    FITEM,2,6
    FITEM,2,-7
    /GO

    DL,P51X, ,TEMP,1200,1 ! BC
    FLST,2,2,4,ORDE,2
    FITEM,2,2
    FITEM,2,-3
    /GO

    DL,P51X, ,TEMP,200,1
    SAVE
    SAVE
    SAVE
    /STAT,SOLU
    SOLVE

    TIME,31536000000000
    AUTOTS,-1
    DELTIM,315360000000, , ,1
    KBC,1

    TSRES,ERASE

    TIME,31536000000000
    AUTOTS,-1
    NSUBST,100, , ,1
    KBC,1

    TSRES,ERASE
    /STAT,SOLU

    solve
    finish

    /post1

    set, first
    etable,melty,temp, ! Create an element table
    esel,s,etab,melty,600 ! Select all elements from table ! above 600
    finish

    /solu ! Re-enter solution phase
    antype,,rest ! Restart analysis
    ekill,all ! Kill all selected elements
    esel,all ! Re-select all elements

    finish

    /post1 ! Re-enter postprocessor
    set,first ! Read in last subset of data
    esel,s,live ! Select all live elements
    plnsol,temp ! Plot the temp contour of the live elements

    !/CONT,1,10,200,100,1200
    !PLNS,TEMP,
    !/REPLOT

    *DO, i,1,10,1
    set,i
    etable,delete
    etable,melty,temp, ! Create an element table
    esel,s,etab,melty,600 ! Select all elements from table ! above 600
    finish

    /solu ! Re-enter solution phase
    antype,,rest ! Restart analysis
    ekill,all ! Kill all selected elements
    esel,all ! Re-select all elements

    finish

    /post1 ! Re-enter postprocessor
    set,i ! Read in last subset of data
    esel,s,live ! Select all live elements
    plnsol,temp
    /CONT,1,10,200,100,1200
    PLNS,TEMP,
    /replot

    *ENDDO

    ANTIME,100,0.5, ,0,2,0,0.31536E+14
     
  2. jcsd
  3. Oct 20, 2008 #2
    Re: ANSYS animation problem (melting/element death/loop)

    I'm a new user and realized my initial post wasn't very clear...I worked on the problem some more by incorporating some advice and think I'm on the right track, but still have a couple of problems. I would really appreciate any help. The code (below) now includes a loop for checking whether elements meet the melting/death criterion at each substep.

    Although I have a SOLUTION, I still can't ANIMATE the element death/melting. Also, when I change parameters like the initial T or BC T, I get error messages saying that no elements have been selected. I also get errors when I try to change the time range of the calculation (I want total time to be ~1e13 for example). Here's the code:

    /title, Convection Example
    /prep7 ! Enter the preprocessor

    ! define geometry

    k,1,0,0 ! Define keypoints
    k,2,0.03,0
    k,3,0.03,0.03
    k,4,0,0.03
    a,1,2,3,4 ! Connect the keypoints to form area


    ! mesh 2D areas

    ET,1,Plane55 ! Element type

    MP,Dens,1,2262e9 ! Define density
    mp,c,1,0.001604 ! Define specific heat
    mp,kxx,1,1.8 ! Define heat transfer coefficient

    esize,0.0025 ! Mesh size
    amesh,all ! Mesh area

    finish


    /solu ! Enter solution phase

    antype,4 ! Transient analysis

    tot_time = 1e6
    t_steps = 10
    time_inc = tot_time/t_steps

    time,1e6 ! Time at end of analysis

    nropt,full ! Newton Raphson - full
    lumpm,0 ! Lumped mass off
    nsubst,10 ! Number of substeps, 20
    neqit,10 ! Max no. of iterations
    autots,off ! Auto time search off
    lnsrch,on ! Line search on


    TUNIF,200,
    IC,all,temp,200 ! Initial conditions, temp = 200

    *do, i,1 ,10, 1
    /solu
    time=i*time_inc
    nsub, 1
    outres,all,all ! Output data for all substeps

    !... any stuff about boundary conditions ...

    ! fixed temp BC's
    nsel,s,ext ! Node select all exterior nodes
    sf,all,conv,10,1200
    NSEL,ALL ! Reselect all nodes
    kbc,1 ! Load applied in steps, not ramped
    /gst,off ! Turn off graphical convergence monitor

    solve
    finish

    /post1
    set, last
    etable,melty,temp, ! Create an element table
    esel,s,etab,melty,200 ! Select all elements from table above 200
    finish
    /solu ! Re-enter solution phase
    antype,,rest ! Restart analysis
    ekill,all ! Kill all selected elements
    esel,all

    !*enddo

    /post1 ! Re-enter postprocessor
    set,last ! Read in last subset of data
    esel,s,live ! Select all live elements
    plnsol,temp ! Plot the temp contour of the live elements
    /seg,delete
    /seg,multi,anm1,.1
    /CONT,1,10,200,100,1200

    !PLNS,TEMP,
    /REPLOT

    *enddo
    /post1
    /seg,off
    ANTIME,20,0.5, ,0,2,200,1200
     
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