Learning Forum

[ashishkumar.gupta]

Hello, I am seeing weird/maybe interesting stuff. I might be missing on the basics. So I have a part of ball bearing with Symmetry B.C. OR - fixed and IR - Rotating and force applied on its bottom surface.

1. STATIC STRUCTURAL - With Frictionless surface, I am getting an error (maybe rigid body condtion/unconstrained) but when changed to NO Separation, I can see the deformation...like I can see the animation how the ball is moving/deforming.

2. I have been doing the same thing in Transient Structural, But I do not see any motion, the deformation/stress is constant throughout the 10 s. 

 

My target is too get nice Hertzian contact region between Ball and Race as the IR rotates around the bearing axis with the surfaces in contact being frictionless allowing for Separation and Sliding.

 

This will then be taken ahead to perform FSI (Mech-fluent-System Coupling). So i guess, I might have to use Transient solution, as the parameters (pressure, viscosity) might not be be steady. Please help me out with some tips. Thank you!!!

 

 

 

In addition, I have tried the revolute joint as suggested below. that also not working. Symmetry B.C. are applied.

 

 

 

 

 

[Lydia]

Hi Ashish,

First of all, you can do both steady state and transient FSI analysis. The choice will be made according to whether you problem is time dependent or not. 

Now:

• Frictionless and non-separation contacts are non-linear contacts which very often create complexities in the model. Frictionless allows surfaces to slide relative to each other without any resistance and in No Separation surfaces can slide but cannot separate. Review this course for more insight on how to use contacts in Ansys Contact Mechanics | Ansys Innovation Courses
• In Transient Analysis it is very important to select the correct timestep. If your timestep is not small enough it is possible you will miss some transient phenomena.
• When viewing your results make sure you have the required scaling of the deformation
• As for the difference in result animations between static and transient structural analyses, it's because these two types of analyses model different types of behavior. A static analysis assumes that loads are applied slowly and that the system's response does not depend on time, whereas a transient analysis accounts for the effects of time and dynamic loading. Therefore, the animation of a transient analysis will show how the structure responds over time to dynamic loads, which can include time-varying forces, impacts, or other time-dependent effects. This can result in different deformation patterns, stress distributions, and other responses that change over the duration of the analysis

Transient Structural Analysis (ansys.com)

Static Structural Analysis (ansys.com)

 

[ashishkumar.gupta]

 

Hello Lydia, 

I want to do Transient Structural and I want to use cyclic symmetry (but cpcyc,all,,1,,40     allsel,all ) does not work. I have used Normal Symmetry now (but I am not sure it is right or wrong).

I have applied radial load (500 N in +Y dir.) on bottom surface on IR and outer surface of OR is FIXED support. The contact is Frictional (0.1 around). I gave the IR to rotate around Z direction (+1000 RPM)

I made it bit less complicated now….

 

 

The ball has to rotate around their own axis in Z direction as the IR rotates and OR is fixed.

I am not able to come up with the correct B.C./Solver setup. Could you please help me out here?

Thank you!!

 

[ashishkumar.gupta]

Hello Lydia, The Cylic Symmetry works. But the B.C. does not. Could you please help me out here. Thank you!!