*Imperfection: scale factors
*Imperfection: scale factors
(OP)
Hi,
how to define scale factors of various modes in *imperfection? the scale factor is base on what?
please advise
how to define scale factors of various modes in *imperfection? the scale factor is base on what?
please advise





RE: *Imperfection: scale factors
*IMPERFECTION
1,0.1
Then I am scaling mode 1 by a factor of 0.1, or 10%. The eigenvalue buckling modes are normalised to give a maximum deflection of 1 unit.
Regards
Martin Stokes CEng MIMechE
RE: *Imperfection: scale factors
so I can choose any scala factor (10%, 15%, 20%)? But how do I know what scala factor value is the one i am 'looking for'?
If I have negative eigenvalues, should I ignored them, and 'call' only the positive eigenvalues from the *buckle analysis to *imperfection?
please advise.
RE: *Imperfection: scale factors
As for which buckling modes to use, it's down to your judgement and experience to decide which ones are the most physically significant. If possible, try and find a hand calc that will give you the approximate load, or even better, do some actual experiments if you can.
Regards
Martin Stokes CEng MIMechE
RE: *Imperfection: scale factors
I got the eigenvalue from *buckle, I carry on with the load-displacement analysis, by using *Static, *Dsload. I apply *Imperfection on the model, but nothing happen.
The results (displacement) with and without the *imperfection are the same. Part of my input file as follow, was that anything wrong? please advise.
** BOUNDARY CONDITIONS
**
** Name: BCL Type: Displacement/Rotation
*Boundary
_PickedSet162, 1, 1
_PickedSet162, 2, 2
_PickedSet162, 3, 3
_PickedSet162, 5, 5
_PickedSet162, 6, 6
** Name: BCR Type: Displacement/Rotation
*Boundary
_PickedSet163, 1, 1
_PickedSet163, 2, 2
_PickedSet163, 5, 5
_PickedSet163, 6, 6
** ----------------------------------------------------------------
**
*IMPERFECTION, STEP=1, FILE=ipb
1, 0.001
** STEP: load
**
*Step, name=load, nlgeom=YES
*Static
1., 1., 1e-05, 1.
**
** Name: Load-1 Type: Pressure
*Dsload
_PickedSurf181, P, 1.
**
** OUTPUT REQUESTS
*Restart, write, frequency=0
** FIELD OUTPUT: F-Output-1
*Output, field, variable=PRESELECT
** HISTORY OUTPUT: H-Output-1
*Output, history, variable=PRESELECT
*NODEOUTPUT, NSET=SUPPORT
RF,
*NODEOUTPUT, NSET=RESULT
U,
*End Step
RE: *Imperfection: scale factors
Try using values more like 0.1 (10%), 0.2 (20%) etc...
Regards
Martin Stokes CEng MIMechE