POST-BUCKLING CUT-OFF OF CURVED STIFFENED PANELS (COMPOSITE SKIN & STRINGER)

[StressMan2506]

Fellow Stress Engineers:

Do any of you have any references to post-buckling cut-off as applied to the above structural form? I've taken a look at the manual for the software we're using, but, as expected, it doesn't really enlighten me. I need to use engineering judgement on a low concession RF, so I need a handle on the theory.

Thanks in anticipation.

Louis

 

[rb1957]

does "composite" mean plastic or combined skin/stringer panels ? if plastic, i think you'll have to develop your own, depending on the layup and processing.

by "post-buckling" do you mean diagonal tension ? if DT then i don't think there's a cut-off, failure is defined by several scenarios; possibly the best reference is the cert analysis that'll show the MS for B/P design and that'll show how touchy the design is.

Quando Omni Flunkus Moritati

 

[StressMan2506]

Thanks, rb1957. "Composite" here means "plastic" skin & stringer.

A note in one of our output files suggests that the "post-buckling cut-off" parameter is a limit applied to the loading to prevent debonding of stringer from skin. It appears in "incomplete diagonal tension" analysis and is derived from 1.50 & 1.25 limits on local buckling loads in compression & shear respectively. In my case I get "post-buckling cut-off" parameter = 1.4 and "post-buckling cut-off" RF = 0.97. I feel that it is very likely that engineering judgement will see me through, but I need more theory to do it...

Louis

 

[rb1957]

aren't they making up that theory as they go ?

Quando Omni Flunkus Moritati

 

[StressMan2506]

They could be, but I'm seeking an independent source to get a handle on what the concept means and how my concession case would affect it...

 

[rb1957]

GL!

Quando Omni Flunkus Moritati