structure liner create command

Syntax

structure liner create keyword

Primary keywords:

by-line    by-nodeids    by-ray    by-zone-face

Create a liner consisting of a collection of beam finite elements. The four main keywords articulate four creation techniques: (1) create a collection of elements that lie between a begin point and an end point (by-line); (2) create a single element from two existing nodes (by-nodeids); (3) create a collection of elements that lie along a ray (by-ray); and (4) create a collection of elements from a set of zone faces (by-zone-face).

The elements of the liner will be assigned the group name Liner N where N is the ID number of the liner. And the beginning and ending nodes will be assigned the group name Liner Begin and Liner End. See the group, group-begin, and group-end keywords to customize these assignments.

by-line v1 v2 [liner2dcreateblock]

Create a collection of elements that lie along a straight line between the locations v1 and v2. New nodes associated with the elements will also be created (see the id keyword). The nodal connectivity of each new element will be ordered such that the direction from v1 to v2 corresponds with the direction from the begin point to the end point. If there are objects (zones in FLAC3D) in these locations, the element will be attached to the objects at its nodes according to the Single Sided Liner-Grid Interaction section. If no attachment to objects is desired, then the links may be deleted with the command structure link delete after creating and positioning the element.

by-nodeids i1 i2 [liner2dcreateblock]

Specify the ID numbers (i1, i2) of two nodes that will define the element. These nodes must already exist and can be created with the structure node create command. Ordering of the nodes defines the limer element coordinate system as follows. The positive \(x\)-direction lies along the line from i1 to i2, and the \(y\)-direction is found by projecting the global \(y\)- or \(x\)-directions onto the element cross-section. The \(y\)-direction can also be modified with the property direction-y.

The new element will not be attached to any objects (zones in FLAC2D); if you wish to attach it to objects, then after creating it, position its nodes with the structure node initialize position command (which will create links and set appropriate attachment conditions for all nodes that are moved into an object.

by-ray v1 v2 f [liner2dcreateblock]

Create a collection of elements that lie along a straight line starting at v1, proceeding in the direction specified by v2, for a distance given by f. New nodes associated with the element will also be created (see the id keyword). The nodal connectivity of each new element will be ordered such that the direction from v1 corresponds with the direction from the begin point to the end point. If there are target objects (zones in FLAC2D) in these locations, the element will be attached to the objects at its nodes according to the Single Sided Liner-Grid Interaction section. If no attachment to objects is desired, then the links may be deleted with the command structure link delete after creating and positioning the element.

by-zone-face [liner2dcreateblock] <range>

create new elements that are attached to the set of 2-noded edges. By default, only surface faces will be considered, and the internal keyword can be used to select internal faces. New nodes associated with each element will also be created. The nodes of each element will be ordered counter-clockwise with respect to the outside of the zone faces, thereby making each element \(y\) axis point outward from the zone face. The orientation of the \(y\) axis can be reversed with the reverse keyword. Note that after creating the elements with this command, the zones may be deleted and the elements may be positioned by moving their nodes with the structure node initialize position command.

structure liner create Keyword Block

The following keywords may be optionally provided on element creation performed using any of the major keywords:

distinct

Eliminate sharing of nodes among created elements. Every element will create a new set of nodes, even if they are at the same location in space and elements share the same ID number. This option is most commonly used with a later structure node join command to create links connecting nodes at the same location in order to apply custom inter-element behavior.

embedded

Specify that this liner is two-sided. If the embedded keyword is used, then the internal keyword is implied, even if not explicitly given.

group s1 <slot s2 >

Assign the created elements to group s1. The group is assigned to the slot named s2 if supplied; it is assigned to the slot named Default if not. Use of the group logic is described in Groups.

id i

Specify the ID (this is the collection ID) that will be assigned to all new elements created by this command. If this value is not given, then the next available ID will be used. The ID controls potential joining of the element nodes to an existing element, as follows. At each potential new node location, a new node is created unless all of the following conditions are fulfilled: 1) the ID is given; 2) an existing node is found “near” the potential new node location; and 3) the found node is part of an element of the same type with ID equal to i.

internal

This keyword only applies if the by-zone-face option was used. Specifies that all internal and surface faces in the range will have elements created on them. Normally only surface faces are considered.

maximum-length f

Break the element into segments no greater than length f. The segments setting, if provided, is overridden as needed by this setting.

reverse

Specifies that the orientation of the element will be reversed from the default, so that only the element \(y\) axis points in the other direction.

Note

reversing the \(y\)-direction will change the sign of the shear forces and moments in the beam elements. The magnitude will remain the same.

segments i

Break the element into i equal segments, creating new nodes as needed. The default value is 1, indicating that only one element will be created.

separate keyword

Select a group of internal faces, and separate them into surfaces as with the zone separate command. A liner will be created between the two surfaces. This keyword implies both embedded and internal. The following keywords are available:

origin v

The point v is used to determine which side of the faces selected will be considered side 1, and which will be side 2. The vector from v to the face centroid is compared with the normal to the face. The side pointing toward v will be side 1, and the side pointing away from v will be side 2. If the origin keyword is not specified, it is assumed to be (0,0).

clear-attach

If specified, causes any attach conditions on the boundary to be cleared. By default, an existing attach condition causes an error.