Gap Element Library

This section provides a reference to the gap elements available in Abaqus/Standard.

This page discusses:

 

See Also
Gap Contact Elements
*GAP

Element Types

Stress/Displacement Elements

GAPUNI

Unidirectional gap between two nodes

GAPCYL

Cylindrical gap between two nodes

GAPSPHER

Spherical gap between two nodes

Active Degrees of Freedom

1, 2, 3

Additional Solution Variables

Three additional variables relating to the contact and friction forces.

Coupled Temperature-Displacement Element

GAPUNIT

Unidirectional gap and thermal interactions between two nodes

Active Degrees of Freedom

1, 2, 3, 11

Additional Solution Variables

Three additional variables relating to the contact and friction forces.

Heat Transfer Element

DGAP

Thermal interactions between two nodes

Active Degrees of Freedom

11

Additional Solution Variables

None.

Nodal Coordinates Required

For DGAP elements, and for GAPUNI and GAPUNIT if you specify the contact direction n, the nodal coordinates are not used in the contact calculations; however, it is useful to define the coordinates of the two nodes for plotting purposes.

GAPCYL and GAPSPHER: X, Y, Z

Element Property Definition

You can specify the initial clearance, the contact direction (normal to the interface), and the contact area.

For GAPUNI, GAPUNIT, and DGAP elements, a negative clearance indicates an initial overclosure.

For GAPCYL and GAPSPHER elements, specify the maximum separation as a positive number or the minimum separation as a negative number.

Element-Based Loading

None.

Element Output

S11

Pressure transmitted between the surfaces. The pressure is defined as the force divided by the user-specified area.

S12

First frictional shear stress normal to the gap direction.

S13

Second frictional shear stress normal to the gap direction.

E11

Current opening h of the gap element.

E12

Relative displacement (“slip”) in the first direction orthogonal to the contact direction.

E13

Relative displacement (“slip”) in the second direction orthogonal to the contact direction.

Available for elements with temperature degrees of freedom.

HFL1

Heat flux across the interface in the contact direction.

The increments of shear slip are the relative displacement increments projected onto the two local directions that are orthogonal to the contact direction.

In two-dimensional or axisymmetric models when the contact direction is along the first axis (X or r), the active slip direction is E13 and the active shear stress is S13. In any other two-dimensional or axisymmetric case, the active slip direction is E12 and the active shear stress is S12.

Nodes Associated with the Element

Two nodes: the ends of the gap.