Ellipsoidal Surface to Segment Contact (TYPE15)

TYPE15 interface between surfaces made up of 4-node or 3-node segments and hyper-ellipsoids is a penalty contact interface without damping.

It applies to TYPE14 interface, especially when the mesh is coarser than the ellipsoid size. Remember that in such a case, TYPE14 interface is able to compute low quality contact forces even if it fails to find contact.


Figure 1. No Contact is Detected

Interface stiffness is a nonlinear increasing function of penetration, computed in order to avoid penetrations up to half the ellipsoid:

K = K 0 [ D e p t h D e p t h − P e n e t r a t i o n ] 2

Where,
K 0
Input stiffness factor


Figure 2. Penetration is Detected

A Kinematic Time Step is computed so that the element does not cross the line Lt within one time step.

A friction coefficient m is input.

Interface takes into account sliding/rolling effects.

Coulomb Friction condition is expressed as:

F t ≤ m F n for each penetrated element