# Transient - Contact Analysis in Ansys

1. Jun 15, 2013

### dimikallio

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)

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!!!!!