## General Mechanical

#### ANSYS Static Structural Analysis, Defining a Rigid Body and contacts

• mtcnonn
Subscriber

Hello,

I have a problem in ANSYS Static Structural Analysis when there are contacting surfaces. I explained the situaition below, could you please help me?

THE PROBLEM

I need to realize a static structural simulation where there are two contacting bodies as one of them is defined as rigid (brown body) and the other one is defined as deformable (yellow body) shown in the picture below.

• HuiLiu
Ansys Employee
For you yellow flexible body, it has displacement BC defined in the Y and Z directions but free in the X. The only support it gets in X is from the contact with the rigid body. When you apply a force in the X and the contact opens up, this can result in underconstrain problem in the X direction. One suggestion is to define displacement in the X to drive the yellow flexible body and read the reaction force from the BC. You can also try turn on weak spring and see if it helps to stabilize the model while it becomes under-constrained. nDo you have the model converge for a few steps or did it not converge at all from the beginning? If you have a few steps converged, you can take a look at those steps to see how the yellow part is deforming and what happened right before it stopped converge. Also check the solve.out file for warning messages and errors, which can give you more hints on diagnose the model.n
• peteroznewman
Subscriber
nI don't understand your problem.nIt seems like you have two bodies and you are separating them. In that case, there is nothing left to analyze except the acceleration of the yellow part, which you can do with a hand calculation of F = ma.n
• mtcnonn
Subscriber
Thanks for your kind responses, I overcome the problem by applying the right way of the force and by defining the cylinder part as filexible body whose BCs are fixed support instead of defining a rigid body. I used frictional contact (Augmented gauss points, stiffness factor of 0,1) between the conducting surfaces and when checked contact info there was no problem seems there as well. The analysis realized in a few iteration steps, like 5-6 on average and the results were satisifying the BCs like force and moment equilbrium. nHowever, there was a little corcern I have about the contact surfaces. When I accomplished results, I could see the contact surface area in both contact surfaces for some analyses. But among the other fork simulations, I encounter in the solution output file which is under alaysis section in the mechanical interface that there was no surface area information. (Surface areas are in touch when there is no force applied at the beginning). Could you tell me if you have any thoughts about this faulty?.Thanks ,Murat Cann