Contact Surface Definitions

 

Contact surface definitions are used to associate parts of the model which may come into contact and are defined in FEMGEN using the following command:

PROPERTY BOUNDARY GENERAL constr_name part1 flip part2 [1] [$\mu$]

Where:

constr_name 		 = constraint type (see table 5.1). 
part1 		 = the slave segment
flip 		 = surface flip indicator
		 = 1: do not flip segments
		 = 2: flip segments
part2 		 = the master segment
$\mu$ = static and dynamic friction coefficients

constr_name Meaning

SLID**** Type 1 (Sliding)

TIED**** Type 2 (Tied)

SIMF**** Type 3 (Sliding,Impact,Friction)

SELF**** Type 4 (Self Contact)

NIMP**** Type 5 (Discrete Nodes Impact Surface)

NTIE**** Type 6 (Discrete Nodes Tied To Surface)

SHEL**** Type 7 (Shell Edge Tied To Shell Surface)

SPOT**** Type 8 (Nodes Spot Welded To Surface)

TIEF**** Type 9 (Tiebreak Interface)

Notes:

1.

All surface normals in a contact surface for shell elements must point in the direction in which contact is anticipated. For three-dimensional elements, and the edges of plate elements, the interface program determines the correct contact face/edge identifier automatically.

2.

The flip indicator may be used to reverse the direction of contact segment normals for shell elements. This is useful where self contact is to be modelled via two sets of type 5 contact conditions with opposing segment directions instead of via a single type 4 contact condition.

3.

The static and dynamic friction coefficients are set to the same value, and the exponential decay coefficient to zero

4.

The small penetration flag is set to 1.

5.

The command 'LABEL MESH CONST [constr_name] ' can be used to display contact segment definitions.