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!!!!!