INTER204 Element Description

INTER204 is a 3D 16-node quadratic interface element. When used with 3D quadratic structural elements (SOLID186, and SOLID187), INTER204 simulates an interface between two surfaces and the subsequent delamination process, where the separation is represented by an increasing displacement between nodes, within the interface element itself. The nodes are initially coincident.

INTER204 is defined by 16 nodes having three degrees of freedom at each node: translations in the nodal x, y, and z directions.

See Cohesive Zone Material Model and INTER204 in the Mechanical APDL Theory Reference for more details about this element.

Also see Crack-Initiation and -Growth Simulation, Interface Delamination, and Fatigue Crack-Growth in the Fracture Analysis Guide for more details about the interface failure/delamination capability.

Figure 204.1: INTER204 Geometry

INTER204 Input Data

The element geometry, node locations, connectivity, and the nodal coordinate system are shown in Figure 204.1: INTER204 Geometry. The element geometry is defined by 16 nodes, which form bottom and top surfaces of the element. The bottom surface is defined by nodes, I, J, K, L, Q, R, S, T; and the top surface is defined by nodes, M, N, O, P, U, V, W, X. The element may be degenerated to a wedge (prism) element, by setting nodes K=L=S and O=P=W, as shown in Figure 204.2: INTER204 3D 16-Node Degenerated Quadratic Interface.

Figure 204.2: INTER204 3D 16-Node Degenerated Quadratic Interface

For the degenerated element, 3 integration points are used for numerical integration. The degenerated element can be used in conjunction with 10-node solid tetrahedral elements (SOLID187). Dropping any or some of the midside nodes, Q, R, S, T, U, V, W, X is not permitted.

Temperatures may be input as element body loads at the nodes. The node I temperature T(I), defaults to TUNIF. If all other temperatures are unspecified, they default to T(I). For any other input pattern, unspecified temperatures default to TUNIF.

The next table summarizes the element input. See Element Input in the Element Reference for a general description of element input.

INTER204 Output Data

The solution output associated with the element is in two forms:

The output directions for element items are parallel to the local element coordinate system based on the element midplane as illustrated in Figure 204.3: INTER204 Stress Output. See Cohesive Zone Material in the Mechanical APDL Theory Reference for details.

A general description of solution output is given in Solution Output. See the Basic Analysis Guide for ways to review results.

Figure 204.3: INTER204 Stress Output

The Element Output Definitions table uses the following notation:

A colon (:) in the Name column indicates that the item can be accessed by the Component Name method (ETABLE, ESOL). The O column indicates the availability of the items in the file jobname.out. The R column indicates the availability of the items in the results file.

In either the O or R columns, “Y” indicates that the item is always available, a letter or number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.

INTER204 Assumptions and Restrictions

INTER204 Product Restrictions

There are no product-specific restrictions for this element.