9.3 Interface Behavior

This section details the syntax of material data input for interface elements. The models set a linear or nonlinear relation between tractions, i.e., stresses, and relative displacements across the interface. The tractions are a normal traction t_n and shear tractions t_s t_t . The relative displacements are a normal relative displacement $\Delta$u_n and a shear relative displacement $\Delta$u_t .

To simulate interface behavior, models for linear and nonlinear elasticity [§9.3.1], discrete cracking [§9.3.2.1], crack dilatancy [§9.3.2.2], bond-slip [§9.3.3], friction [§9.3.4], combined cracking-shearing-crushing [§9.3.5] and a general user-supplied model [§9.3.6] are available for the various elements as indicated in Table 9.1.

Table 9.1: MATERIAL MODELS FOR STRUCTURAL INTERFACES

Type	Linear elasticity	Nonlin. elasticity	Discrete cracking	Crack dilatancy	Bond-slip	Friction	Crack-shear-crush	User-supplied
N4IF	yes	yes	yes	yes	yes	yes	yes	yes
N6IF	yes	yes	yes	no	yes	yes	yes	yes
L8IF	yes	yes	yes	yes	yes	yes	yes	yes
CL12I	yes	yes	yes	yes	yes	yes	yes	yes
CL20I	yes	yes	yes	yes	yes	yes	yes	yes
L16IF	yes	yes	no	no	no	yes	no	no
L20IF	yes	yes	no	no	no	yes	no	no
CL24I	yes	yes	no	no	no	yes	no	no
CL32I	yes	yes	no	no	no	yes	no	no
CL18I	yes	yes	no	no	no	no	no	no
T18IF	yes	yes	yes	no	yes	yes	yes	yes
Q24IF	yes	yes	yes	no	yes	yes	yes	yes
CT36I	yes	yes	yes	no	yes	yes	yes	yes
CQ48I	yes	yes	yes	no	yes	yes	yes	yes

The constitutive models for nonlinear interface behavior from the various sections (columns 2-8 in Table 9.1) cannot be combined in one element.