9.1. Nodes

This section describes various tasks related to the direct generation of nodes. Topics include:

You can use any of the methods described in the following table to define nodes.

Table 9.1: Defining Nodes

DefineCommand
individual nodes in the active coordinate system (1) N
a node at an existing keypoint NKPT

  1. If using Mechanical APDL interactively, you can define a working plane snap increment and use picking (N, P) to generate nodes graphically. (For more information on the working plane, see Using Working Planes.)

Once you have created an initial pattern of nodes, you can generate additional nodes using the methods described in the following table.

Table 9.2: Generating Additional Nodes from Existing Nodes

Generate nodesCommand
generate a line of nodes between two existing nodes FILL
generate additional nodes from a pattern of nodes NGEN
generate a set of nodes from a pattern of nodes NSCALE
generate a quadratic line of nodes from three nodes QUAD
generate a reflected set of nodes NSYM
transfer a pattern of nodes to another coordinate system TRANSFER
define a node at the center of a curvature of an arc of nodes (1) CENTER

  1. If a local cylindrical coordinate system is defined (CS) at the center of curvature, you can use the FILL command to generate additional nodes on the arc. If a radius of curvature is given, the center of curvature is automatically calculated to be along the perpendicular bisector of the NODE1-NODE2 line in the plane of NODE1, NODE2, and NODE3.

You can use any of the methods described in the following table to maintain nodes.

Table 9.3: Maintaining Nodes

MaintenanceCommand
list nodes NLIST
display nodes (1) NPLOT
delete nodes (2) NDELE

  1. Node numbers will also be displayed in EPLOT displays for nodes attached to elements, if you have issued the proper /PNUM command.

  2. Deleting a node also deletes any boundary conditions (such as displacements, forces, etc.) as well as any coupling or constraint equations containing the deleted node.

You can move a node by overwriting it with the N command (or any other node-generating command) or by using one of the methods in the following table.

Table 9.4: Moving Nodes

MoveCommand
modify one or all of the coordinates defining a node NMODIF
move a node to an intersection of coordinate system surfaces MOVE

Use the NDIST command to calculate the distance between two nodes.

You can use any of the methods described in the following table to rotate a node's coordinate system. The nodal coordinate system is parallel to the global Cartesian coordinate system by default. See Nodal Coordinate Systems for more information.

Table 9.5: Rotating a Node's Coordinate System

Rotate a Nodal Coordinate SystemCommand
into the active coordinate system NROTAT
by direction cosines NANG
by anglesN, NMODIF

 

9.1.1. Reading and Writing Text Files That Contain Nodal Data

You can read a text file containing nodal data. This ability could be useful if you are importing ASCII nodal data from another mesh generator, a CAD/CAM program, or another Mechanical APDL session. You can also write such an ASCII file for export to another program (which must be able to read this Mechanical APDL file) or to another Mechanical APDL session. You will not normally need to read or write nodal data in a standard Mechanical APDL model-generation session. If you do need to read or write nodal data you can use any of the methods described in the following table.

Table 9.6: Reading and Writing Files Containing Nodal Data

Read and writeCommand
specify a range of nodes to be read from a node file NRRANG
read nodes from a file NREAD
write nodes to a file NWRITE