*IMPERFECTION
NSET
Setthis 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 m odel.
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 specifiedare transformed
to the global rectangular Cartesiancoordinate system. This transformationrequires 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 cy lindrical or spherical
coordinates.
Data lines to define the imperfection as a linear superpositionof 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 theimperfection based on the solution of a static analysis from the results file:
First (and only) line:
1. Se t to 1.
2. Scaling factor.
Data lines to define the imperfection if the FILE and INPUT parametersare omitted:
First line:
1. Node num ber.
2. Componentof imperfection in the first coordinate direction.
3. Componentof imperfection in the second coordinate direction.
4. Componentof imperfection in the third coordinate direction.
Repeat this data line as often as necessary to define the imperfection.
9.3–2
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