Gaps Panel - OptiStruct

Use the Gaps panel to create gap elements. When using the OptiStruct solver interface, it allows the creation of multiple node-element gap elements.

Location: 1D page

A gap element is an element created in a space between two nodes, or between a node and an element, of a model where contact may occur. Use a gap element when you want to impose a nonlinear constraint on a model; this constraint will limit the amount of movement possible during analysis. Gap elements have property pointers.

Gap elements are element config 70 and are displayed as a line between two nodes with GAP written at the centroid of the element.

Gaps can translate to CGAP or CGAPG elements in OptiStruct.

Create: Node-Node Subpanel

Option Action
from node Select the elements' starting node.
to node Select the elements' ending node.
orientation Choose between methods of orienting the element. Orientation is only necessary when the nodes are coincident.
default
Do not use an orientation. If necessary, use the global coordinate system.
node
Specify a node; the vector from the coincident nodes to this one is the orientation vector.
vector
Use the plane and vector selector to specify a vector along which to orient the element.
coordinates
Specify a point in space; the vector from the coincident nodes to this one is the orientation vector.
system
Orient the element based on a selected local coordinate system.
property = Select the property collector which the new elements should point.
elem type = Select an element type.

Create: Nodes-Elems Subpanel

Option Action
nodes Select the elements' starting node.
elems Select the elements that you want the nodes to connect to to via gap elements.
orientation Choose between methods of orienting the element. Orientation is only necessary when the nodes are coincident.
default
Do not use an orientation. If necessary, use the global coordinate system.
node
Specify a node; the vector from the coincident nodes to this one is the orientation vector.
vector
Use the plane and vector selector to specify a vector along which to orient the element.
coordinates
Specify a point in space; the vector from the coincident nodes to this one is the orientation vector.
system
Orient the element based on a selected local coordinate system.
property = Select the property collector which the new elements should point.
elem type = Select an element type.
search tol = Specify a value within which HyperLife Weld Certification will search for the projection of a selected node onto a selected element to create a node-elem gap.
face nodes If the elements you are creating the gaps to are 3D elements, use this selector to select the face to which you want the gaps created.
break angle = For 3D elements, this helps determine the extent of the face to which the gap projection occurs. Any feature on the face that exceeds this angle is treated as a boundary of that face for purposes of gap element projection.

Update Subpanel

Use the Update subpanel to alter the characteristics of existing gap elements.
Option Action
elems Select the gap elements that you wish to alter.
orient vector / no vector Choose between an orient vector collector, which defines the element orientation, or no vector (in which case the element is oriented by the from and to nodes).
property = Select the property collector which the new elements should point.
elem types = Select an appropriate element type.