Learning Forum

[fa-ri]

Dear All,

I am modeling a four-legged structure in ANSYS. The four legs are positioned at the following coordinates at the bottom:
(-a,-b,0), (-a,b,0), (a,-b,0), (a,b,0)

The four legs are connected at the top to a plate of a/b. like a chair without back.

My goal is to investigate the deformation of the top plate when the legs are pushed inward. In the model, the two legs on the left side are displaced by 20 mm in x direction, while the two legs on the right side are displaced by 2 mm in -x direction. In other words, all four legs move toward the center of the structure.

I would like to apply these displacements as displacement-controlled boundary conditions in ANSYS and study the resulting bending/curvature of the top plate.

The main difficulty I am having is defining the supports and boundary conditions of the system.

I do not want to simply set at the four contact locations, because when the legs move inward, I expect them to rotate slightly (if im wrong physically please advise me). As a result, part of the bottom surface of a leg may lose contact with the ground (lift-off). Therefore, I believe the vertical displacement at the leg-ground interface should not be directly constrained Uz=0, and the contact should be allowed to open and close.

I have modeled the leg-ground interfaces using Frictionless Contact (i have modeled the ground), but I am not sure its the correct way of modeling this problem.

Could you please advise me on how and where the supports and boundary conditions should be defined for this problem?

So far, the only direction that I guess can be constrained is the y direction. The Uz direction should remain free because the top plate needs to be able to bend, and the Ux direction is the direction in which I want to impose the prescribed displacement.

Thank you for your guidance.

[soupadhy]

Hi,

If you are not interested in contact modelling, then the base plate can be supressed. Apply a remote displacement boundary condition at each of the leg, while applying a displacement in a particular load step, keep the other legs fixed. Apply displacement for each leg in a separate load step instead of applying them simultaneously.