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Nonlinear analysis in ANSYS

  1. Jan 17, 2013 #1
    hi,

    I have some confusion for performing nonlinear analysis in ANSYS with NLGEOM.... I was following the tutorial, the APDL is given below

    /prep7 ! start preprocessor
    /title,NonLinear Analysis of Cantilever Beam
    k,1,0,0,0 ! define keypoints
    k,2,5,0,0 ! 5" beam (length)
    l,1,2 ! define line
    et,1,beam3 ! Beam
    r,1,0.03125,4.069e-5,0.125 ! area, izz, height of beam
    mp,ex,1,30.0e6 ! Young's Modulus
    mp,prxy,1,0.3 ! Poisson's ratio
    esize,0.1 ! element size of 0.1"
    lmesh,all ! mesh the line
    finish ! stop preprocessor
    /solu ! start solution phase
    antype,static ! static analysis
    nlgeom,on ! turn on non-linear geometry analysis
    autots,on ! auto time stepping
    nsubst,5,1000,1 ! Size of first substep=1/5 of the total load, max # substeps=1000, min # substeps=1
    outres,all,all ! save results of all iterations
    dk,1,all ! constrain all DOF on ground
    fk,2,mz,-100 ! applied moment
    solve
    /post1
    pldisp,1 ! display deformed mesh
    PRNSOL,U,X ! lists horizontal deflections

    the maximum displacement is 1.019

    now without NLGEOM option that is just omitting these lines from above apdl prog

    nlgeom,on ! turn on non-linear geometry analysis
    autots,on ! auto time stepping
    nsubst,5,1000,1 ! Size of first substep=1/5 of the total load, max # substeps=1000, min # substeps=1
    outres,all,all ! save results of all iterations

    maximum displacement is 1.024 , which should be less then the previous analysis with NLGEOM on

    I don't understand this... kindly guide me where I am wrong
     
  2. jcsd
  3. Oct 16, 2014 #2
    Hello,

    "Nlgeom,on" takes into account nonlinearities in your analysis, i.e. the stiffness matrix is re-evaluated for each substep. The structure is more rigid (come back to school), consequently the displacement is reduced compared with the case "Nlgeom,off".

    Rgds.
     
  4. Oct 27, 2014 #3
    hi ; my name is hossam
    i want to any thing about luders hands
    i have an exam tomorrow
    anybody respond to me quiqly
     
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