Learning Forum

[ashishkumar.gupta]

Can someone tell me what type of Force (also in  Cartesiuan/Cylcindrical coordinate system) I should apply on bore surface of Inner Race so that it produces Hertzian region of correct magnitude when solved analytically? 

If if give even 0.01 mm of radial disp., it influnces the magnitude of von-mises stress?

Is this how solver of Ansys works where Forces do not have that much inlfuence compared to disp.?

Thank you

[dlooman]

No, just the opposite.  An applied displacement usually produces a very large stress.  In a cylindrical body an applied radially displacement will produce a large hoop stress proportional to displacement/radius and the elastic modulus.  If you apply the radial displacement at the inner radius, some of it may be lost at the outer radius.  An examination of the contact status may offer an explanation.

[ashishkumar.gupta]

Ok. Thanks for the clarification. 

But what I have in my B.Cs are:

1. Forces from the shaft on the bore surface of IR in Newtons
2. RPM of the shaft causing the IR to rotate ( given as circumferential disp. in Cylindrical Coordinate System here)
3. Fixed Support of the OR
4. 3 FSI (IR, OR and ball)

So now, I DO NOT want to give radial disp. but keep it free. I just want to give Radial forces. Any hints what can be done here please?

[dlooman]

Sometimes an easy way to move geometry is with thermal expansion.  You could specify an elevated temperature on the inner race to move it radially.

[ashishkumar.gupta]

But I am not at all interested in the temperature/Thermal stuffs. Moreover, I do not know any Thermal parameters.

Why is it not possible to create the right stress with radial force being applied?

[dlooman]

In a cylindrical body a radial force is carried by hoop (dylindrical) stress so might not give you the radial displacement you expect.

[ashishkumar.gupta]

Why is that so? What are the other mechanical Alternatives? like can u explain the process so I know what to apply to create Hertz contact stress in Ball bearing with radial force.