Node

Node#

This method is used to construct a Node which stores information about coordinates and mass at a single point. The assignment of mass is optional. Each node has Model.ndm coordinates (position in space) and Model.ndf degrees of freedom (displacement and, in 2D/3D frame models, rotation).

Model.node(tag, coords[, mass])#
Parameters:
tag

integer tag identifying node

coords

tuple of Model.ndm float coordinates. Units of length. Coordinates may be retrieved with Model.nodeCoord() and updated with Model.setNodeCoord().

mass

tuple of Model.ndf lumped mass values per DOF (see Theory for units and interpretation)

Theory#

Nodes define discrete locations in a model. The number of coordinates is Model.ndm (number of dimensions); the number of degrees of freedom per node is Model.ndf (typically ndm for trusses, ndm + rotational DOFs for frames). See nodeDisp for the ordering of displacement components.

Mass. When the mass argument is provided, it is a tuple of ndf values: lumped mass (or rotational inertia) per degree of freedom, in the mass units of the chosen system (e.g. kg in SI, slug in fps). For a 2D model with ndf=3, the first two values are translational mass for u1 and u2; the third is rotational inertia for r3.

Examples#

The following example adds two nodes to a Model with ndm=2 and ndf=3. Node 3 is at coordinates (168.0, 0.0), node 4 at (168.0, 144.0). Node 4 is assigned lumped mass (10.0, 10.0, 0.0): 10.0 for translational DOFs 1 and 2, and 0.0 for rotational DOF 3.

model = xara.Model(ndm=2, ndf=3)
model.node(3, (168.0, 0.0))
model.node(4, (168.0, 144.0), mass=(10.0, 10.0, 0.0))

Code Developed by: fmk

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