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Displacement is too large...

  1. Mar 13, 2016 #1
    1. The problem statement, all variables and given/known data
    hi,i am using pipe289 to simulate a marine riser in ansys,
    the length of marine riser:1000m
    the outside diameter of marine riser:0.5334m
    the thickness of marine riser:0.0254
    the velocity of current:1m/s
    the wave peroid:8s
    the wave height:6.5m
    boudary conditions: ux/uy on node 1 and ux/uy/uz on node 2, a force(5e6) was applied on node 1
    2. Relevant equations
    N/A

    3. The attempt at a solution
    after i set the boudary conditions and ocean loads, the displacement is very large(1000m),i have tried to change the variables, i found the velocity of current has a big difference to the result, Can someone help ? Much appreciated thanks!

    Mod note: The following is contained in the attached file.
    Code (Text):

    /FILENAME,RISER,1
    /TITLE,RISER

    DWATER=1000
    H_WAVE=6.5
    T_WAVE=8
    V_SURFACE=1
    V_MIDDLE=0.5
    V_BOTTOM=0
    RISMAT=1
    MATWAT=2
    FLUWAT=3

    OD=0.5334
    TW=0.0254

    T_TOP=5e6

    /PREP7
    ET,1,PIPE289
    KEYOPT,1,1,0
    KEYOPT,1,4,2
    KEYOPT,1,6,1
    KEYOPT,1,7,0
    KEYOPT,1,8,0
    KEYOPT,1,9,2
    KEYOPT,1,11,3  
    KEYOPT,1,12,1  
    KEYOPT,1,15,0

    MP,EX,1,2.1E11
    MP,PRXY,1,0.3
    MP,DENS,1,7850
    MP,DENS,2,1030
    MP,DENS,3,1200


    SECTYPE,SECPIPE,PIPE,,riser
    SECDATA,OD,TW,16,0,3,FLUWAT,0,0
    OCTYPE,BASIC
    ocdata,DWATER,MATWAT,0,1,1,1,0
    octable,,,0.5,0.5,,2,2
    octype,curr
    octable,0,V_SURFACE
    octable,-500,V_MIDDLE
    octable,-DWATER,0.0
    octype,wave
    ocdata,2
    octable,H_WAVE,T_WAVE,58
    CSYS,0
    K,1,0,0,0
    K,2,0,0,-DWATER
    LSTR,1,2
    LSEL,S,LINE,,1
    LATT,1,1,1
    LESIZE,ALL,1,,,,,,
    LMESH,ALL
    ALLSEL
    SAVE
    FINISH

    /SOLU
    ANTYPE,0
    NSEL,S,LOC,Z,-DWATER
    D,ALL,UX
    D,ALL,UY
    D,ALL,UZ
    D,ALL,ROTZ
    ALLSEL
    NSEL,S,LOC,Z,0
    D,ALL,UX
    D,ALL,UY
    ALLSEL
    NSEL,S,LOC,Z,0
    F,ALL,FZ,F_TOP
    ALLSEL
    ACEL,0,0,9.8

    TIME,1
    SOLVE
    SAVE
    FINISH

    /POST1
    SET,LAST
    PLDISP,O
     
     

    Attached Files:

    Last edited by a moderator: Mar 13, 2016
  2. jcsd
  3. Mar 14, 2016 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Is there a sketch showing this riser and how it is restrained and loaded? Trying to decipher a data file is less than ideal.
     
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