ABAQUS Volume II: I–Z - Manual (Page 30)

*IMPERFECTION
NSET
Set this parameter equal to the node set to which the geometric imperfection values are to be applied.
If this parameter is omitted, the imperfection will be applied to all nodes in the model.
Optional parameter if the FILE parameter is omitted:
SYSTEM
Set SYSTEM=R (default) to specify the imperfection as perturbation values of Cartesian
coordinates. Set SYSTEM=C to specify the imperfection as perturbation values of cylindrical
coordinates.
Set SYSTEM=S to specify the imperfection as perturbation values of spherical
coordinates. See Figure 9.3–1.
The SYSTEM parameter is entirely local to this option and should not be confused with the
*SYSTEM option. As the data lines are read, the imperfection values specified are transformed
to the global rectangular Cartesian coordinate system. This transformation requires that the object
be centered about the origin of the global coordinate system; i.e., the *SYSTEM option should
be off when specifying imperfections as perturbation values using either cylindrical or spherical
coordinates.
Data lines to define the imperfection as a linear superposition of mode shapes from the results
file:
First line:
1. Mode number.
2. Scaling factor for this mode.
Repeat this data line as often as necessary to define the imperfection as a linear combination of mode
shapes.
Data line to define the imperfection based on the solution of a static analysis from the results file:
First (and only) line:
1. Set to 1.
2. Scaling factor.
Data lines to define the imperfection if the FILE and INPUT parameters are omitted:
First line:
1. Node number.
2. Component of imperfection in the first coordinate direction.
3. Component of imperfection in the second coordinate direction.
4. Component of imperfection in the third coordinate direction.
Repeat this data line as often as necessary to define the imperfection.
9.3–2
ABAQUS Version 6.1 Module: ID:
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