Quadratic Surface Contact (/INTER/LAGMUL/TYPE16 & /INTER/LAGMUL/TYPE17)

Interface TYPE16 allows defining contact conditions between a group of nodes (secondary) and a curve surface of quadratic elements (main part), as shown in Figure 1 for a symmetric contact. The main part may be made of 16-node thick shells or 20-node bricks. The Lagrange Multiplier method is used to apply the contact conditions; therefore, no gap is necessary to be applied. Some applications of this interface are sliding contacts without gaps as in gear box modeling.

Figure 1. Interface TYPE16 - Node to Quadratic Surface Contact
Interface TYPE17 allows modeling contact between two quadratic surfaces using the Lagrange Multiplier method. It is a generalized form of interface TYPE16 in which the contact on the two quadratic surfaces are directly resolved. The contact is supposed to be sliding or tied.

Figure 2. Interface TYPE17 - Quadratic Surface to Quadratic Surface Contact
As defined above, both interfaces do not model friction effects. Contact is either considered as tied or without friction (pure sliding).
Note: When using interfaces with the Lagrange Multiplier method, it is not recommended to symmetrize the contact.

Tied Interface (/INTER/TYPE10)

This interface is similar to interface TYPE7, except for the stiffness which remains constant during the contact.

Moreover, after impact a secondary node becomes tied to the main surface with or without rebound (flag Itied).


During impact, a mass-less spring with constant stiffness is added in order to push the secondary node back. Moreover, as the secondary node is tied, a second massless spring is used to maintain the secondary node close to its impact point. Depending on whether or not rebound is allowed, these two springs are maintained when the secondary node is no longer penetrated.

Figure 3. Interface TYPE10