The following example illustrates a postbuckling analysis
of a structure with an imperfection defined by a linear superposition of the
buckling eigenmodes and involves two analysis runs with the same model
definition.
The initial analysis run performs an eigenvalue
buckling analysis with
Abaqus/Standard
to establish the probable collapse modes and writes them to the results
file.
HEADING
Initial analysis run to write the buckling modes to the results file
NODE
Data lines to define initial “perfect” geometry
…
**
STEP
BUCKLE
Data lines to define the number of buckling eigenmodes
CLOAD and/or DLOAD and/or DSLOAD and/or TEMPERATURE
Data lines to specify the reference load,
NODE FILE, GLOBAL=YES, LAST MODE=n
U
END STEP
The second analysis run introduces the imperfection and
performs a postbuckling analysis employing the modified Riks method in
Abaqus/Standard.
HEADING
Second analysis run to define the imperfection and perform the postbuckling analysis
NODE
Data lines to define initial “perfect” geometry
…
IMPERFECTION, FILE=results_file, STEP=step
Data lines specifying the mode number and its associated scale factor
…
**
STEP, NLGEOM
STATIC, RIKS
Data line to define incrementation and stopping criteria
CLOAD and/or DLOAD and/or DSLOAD and/or TEMPERATURE
Data lines to specify reference loading,
END STEP
An alternative second analysis run introduces the
imperfection and performs a postbuckling analysis with
Abaqus/Explicit.
HEADING
Second analysis run to define the imperfection and perform the postbuckling analysis
NODE
Data lines to define initial “perfect” geometry
…
IMPERFECTION, FILE=results_file, STEP=step
Data lines specifying the mode number and its associated scale factor
…
**
STEP
DYNAMIC, EXPLICIT
Data line to define the time period of the step.
CLOAD and/or DLOAD and/or DSLOAD and/or TEMPERATURE
END STEP