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Transient - Contact Analysis in Ansys

  1. Jun 15, 2013 #1
    Hi all!

    I am trying to solve a transient contact analysis in Ansys 14.0

    The problem is a Bouncing Rectangle problem. That's the procedure I use:

    /Prep7

    k,1,-30,0,0
    k,2,30,0,0
    k,3,-30,30,0
    k,4,0,30,0
    Create->Areas->Arbitrary->Through Keypoints !Create the ground

    k,50,-20,30,0
    k,70,-20,45,0
    k,80,0,45,0
    Create->Areas->Arbitrary->Through Keypoints !Create the foundation

    k,500,-10,95,0
    k,600,0,95,0
    k,700,-10,105,0
    k,800,0,105,0
    Create->Areas->Arbitrary->Through Keypoints !Create the bouncing rectangle

    Element Type->
    Type1->Plane183 (Stress with thickness) rectangle
    Type2->Plane183 (Stress with thickness) foundation
    Type3->Plane183 (Stress with thickness) ground

    Real Constants

    Set1->Plane183 (Thickness=10)
    Set2->Plane183 (Thickness=10)
    Set3->Plane183 (Thickness=10)

    Add Materrial Properties
    Material 1 (rectangle)
    EX=4400 ksi
    Poisson Ratio=0.25
    Bilinear : Yield Stress=4, Tangent=220
    Material 2 (foundation)
    EX=5100 ksi
    Poisson Ratio=0.25
    Bilinear : Yield Stress=6, Tangent=255
    Material 3 (ground)
    EX=5500 ksi
    Poisson Ratio=0.25
    Bilinear : Yield Stress=8, Tangent=280

    Glue Areas (foundation & Ground)

    Meshing: Edge Length=2 for all

    Contact Pair (surface to surface): Using Contact Wizard: Target=Area of Foundation, Contact=Area of Rectangle

    Create Component: Based on Material Type : Rectangle

    Solution

    -Type=transient (No lumped mass approach)
    -Large Transiend Displacement
    -Automatic Stepping=off
    TIMINT,off
    -Time=0.0002
    -Time step size=0.0001
    -Rayleigh Damping:Stiffness Matrix Multiplies=0.0002
    -Component (Rectangle) Acceleration=386.4
    -Force Convergence=0.00001
    -Apply->Displacement->Nodes->Select all->All DOFs
    Solve
    -Delete->Displacement->Nodes->Select all->All DOFs
    -Apply->Displacement->Lines->(Fix foundation and Ground)
    -Timint,on
    -Time=3
    -Automatic time stepping=on
    -Initial time step size=0.02 with min 0.0002 and max 0.02
    -Reset force convergence tolerance
    -Save results for every time step
    Solve

    That's all I do

    The questions I have are:
    -Do I need to define any initial stiffness for the contact or I just should let the program calcualate it according to the material properties I am defining>
    -When I define global gravity for the whole system, the rectangle falls down w/o even getting in contact with the foundation!!!!
    -When I plot the displacement and velocity everything looks fine. However, in the animation I did the rectangle does not get in touch!!! in all the impacts that take place!!!So, the forces I get are wrong!!!Should I do anything extra to correct that!?
    -I want to solve also a problem that the contact and the target surfaces are in both surfaces (symmetric contact pair) because the material properties I use are not much different for the rectangle and the foundation! So, should I have the target rigid or I can just use flexible to flexible?
    -Sometimes, I have convergence problems. Should I change any of the contact default options to correct that? (ICONT, CNOF,close gap,exclude everything,gap and offset,penalty of augmented method, contact stiffness etc). I tried to change some of them but I didn't find any difference in the solution. And ansys doesn't provide any recommendations about all these...

    Thank you!!!!!
     
  2. jcsd
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