How do I apply a radial displacement to an element to compress another element

- July 4, 2024 at 9:55 am
  
  Zacarías Conde Teruel
  Subscriber
  
  Good afternoon everyone,
  
  I'm trying to simulate a displacement of a radial band to compress radially a semisphere. This band is modeled with an internal radius equal to the external radius of the eye but it has really a lesser radius so the idea is to model the pressure that the band apply to the sphere as a result of trying to recover its real radius.
  I have created a cylindrical coordinate system and I have modeled firstly as a displacement of the internal surface of the band that is in contact with the external surface of the sphere but it doesn't get a result. Secondly, I have calculated the pressure it apply as p = E * (R - r )/ r where E is the young modulus of the band and R y r are the external radius of the sphere and the real radius of the band (that it wants to recover). The problem in this second analysys is that it gets a excessive displacement compressing the sphere in a irreal manner.
- July 10, 2024 at 11:52 pm
  mjmiddle
  Ansys Employee
  A radial displacementy should work by setting the x value of a displacement that uses a cylindrical coordinate system, as long as rotation does not occur around the cylindrical Y axis. But it seems by the shape, you would really want a spherical direction for displacement, and Mechanical doesn’t allow you to create a spherical coordinate system.
  You seem to be describing a press fit model. We don’t handle these by prescribing a fixed radial displacement. We model press-fit two ways:
  1. Model the geometry in the dimensions before assembly. When the bodies are placed together, there will be an interfence and you will use a contact. The analysis will deform both bodies into touching status, and in so doing, it computes the press-fit stress and strain. The interference should be within the first layer thickness of the volume elements at the contact.
  2. Model geometry as touching, and specify an offset distance in the contact Details that would be the interference distance of the assembled bodies before press-fit occurs. The analysis will deform the geometry and compute stress/strain just like method 1.