Looking for the Royal Aeronautic Society Data Sheets from the 1940s.

[tomsing]

I'm on a bit of a scavenger hunt. I've got a chart of shear buckling coefficients vs aspect ratio for unstiffened rectangular flat panels with different boundary conditions (all sides simply supported, all sides clamped, long sides SS/short sides C, and long C/short SS). One of my colleagues said he tried using some curve fits published in another reference, and noticed a significant difference for the long SS/short C case.

The chart is dated from the 1950s, and references NACA TNs that individually address the all SS and all C cases, Timoshenko's Theory of Elasticity that addresses both of those and long C/short SS, and also the Royal Aeronautics Society Data Sheets for Stressed Skin Structures, which I assume must cover the long SS/short C case, because none of the others do.

All the references I can actually find for long SS/short C case agree pretty well with each other, and disagree with my chart. Some quick FEMs to spot check things also line up with those references. So I'm pretty confident that my chart is in error, but I'd like to find the RAeS document to see if maybe I'm interpreting a boundary condition incorrectly or something.

I believe the number of the Data Sheet I'm looking for is 02.03.01. The RAeS Data Sheets were replaced by ESDU, and ESDU 71005, Buckling of Flat Plates in Shear, noted that it supersedes 02.03.01. (And ESDU 71005 lines up with all the other references, and doesn't match my chart.)

Hoping one of you might have a copy. Appreciate any help you can provide!

 

[tomsing]

Ran out of space in the post...

My search for the Data Sheets has turned up nothing online. The US National Forest Service library had a physical copy, and their librarian took a look and said it was incomplete, didn't include 02.03.01, nor was there anything else that looked like flat plate shear bucking. Johns Hopkins's library website says they have a physical copy on off-site storage, and I've reached out to them, as well. (Both of those I found through World Cat.) The only other library that I'm aware of with a copy is the UK National Archives, also in off-site storage. I kind of suspect that the doc might be loose leaf and poorly organized, and tough for someone without an engineering background to identify.

I've also asked all the local structures graybeards and British folks. Some have had a handful of articles from the Data Sheets, but none have had what I'm looking for.

(Fwiw, the difference between my chart and the rest of the world isn't like a smoothed curve vs the true cusped behavior that you'd get as you transition between buckled shapes. It's a significant difference between smoothed curves.)

 

[rb1957]

didn't these get "flipped" into ESDU ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[tomsing]

Yes. That's how I come to think that the article in the Data Sheets is 02.03.01, because ESDU 71005 notes that it supersedes that. But ESDU 71005 doesn't match my chart, it matches all the other sources.

It's possible the Data Sheets had an error that was corrected in the transition, or maybe before. Not sure about revision history. It's also possible that my chart pulled in the wrong thing. I'm wondering if it's a case of a mislabeled boundary condition....

At an aspect ratio of 0 (infinitely long), the long SS/short C curve meets the all sides SS, which is what I'd expect as the clamped edge becomes negligible, and at an aspect ratio of 1 (square), the long SS/short C curve meets up with the long C/short SS, which it would have to.

The curve on my chart is showing higher buckling coefficients than what it should be, so maybe it's actually for one long side clamped? But then I wouldn't expect it to meet with all sides SS at AR=0 or long C/short SS at AR=1. So I don't think that's the case.

 

[SWComposites]

can you post a copy of the Data Sheet in question?

 

[tomsing]

You mean the chart I'm looking at, with the apparent error? I'd prefer not to. Got company markings on it.

 

[SWComposites]

ok, understand. I've looked at a lot of buckling equations and plots in the past. Have access to some proprietary buckling curves to compare to. What is your company?

If a FEM is agreeing well with ESDU curves, then I would suspect there is an error in your chart or interpreting your chart.

 

[tomsing]

Oh, I'm sure it's an error in my chart. I'm just trying to figure out how to explain it so I can make a case to update it.

 

[WKTaylor]

Contact Royal Aeronautical Society office in Washington DC...

https://www.aerosociety.com/get-involved/branches-divisions/washington-dc/

Washington DC
The Royal Aeronautical Society, Capital Branch was formally inaugurated on 17 December 2003, a momentous date in the annals of aviation, as it was the centenary of manned flight by the Wright brothers. The aims of the Washington DC branch are to stimulate advances in aviation safety and technology by providing a forum to improve still further the technical, political and social interchange between the US and UK aerospace communities.

Contact Details:
Chair: Terry McVenes
Vice-Chair: Shawn Bullard
Secretary: Bill Strandberg
Treasurer: Benjamin Ivers
Membership: Shelly Simi
Email: WashingtonDC@aerosociety.com

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[rb1957]

but why bother ? ok, there's some data out there that we don't have the "providence" for, and we suspect that it isn't good ... so ignore it. no ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[tomsing]

I was ready to go with an updated chart. But my boss is concerned that we need a good story to tell on this one.

Thank you, Wil! I'll reach out to them.

 

[Stress_Eng]

Is the buckling equation of the same form as given in your other references? Just wondering, if the equation is in a different format, are the curves compensating in some way, making them different?

 

[tomsing]

Depending on the source, the coefficient is sometimes presented with the π^2/12(1-nu^2) factor built in, without that factor built in, sometimes presented as sqrt(k). I'm accounting for that, and the curve in my chart matches where it should be at aspect ratios of 0 (infinitely long) and 1 (square), and goes off in the middle, so I'm reasonably confythats not the issue. Good suggestion, though.

 

[verymadmac]

RAeS has the National Aerospace Library in the UK,

https://www.aerosociety.com/news-expertise/national-aerospace-library/library-catalogue/

library search function

https://raes.soutron.net/Portal/Default/en-GB/Search/SimpleSearch

 

[LiftDivergence]

You might try having a look through the Cranfield Aerade:

"The Aerade Reports Archive incorporates more than ten thousand, historically significant, digitised reports from: The Aeronautical Research Council (ARC) - the principal agency in Great Britain with a major output of reports on matters aeronautical, which existed from 1909-1979, and published reports until 1980 and the National Advisory Committee for Aeronautics (NACA) - chartered in 1915 and operational from 1917-1958."

https://reports.aerade.cranfield.ac.uk/

I just searched for "shear buckling of plates" and a bunch of stuff came up. Not sure it will have what you are looking for, but it is a good resource.

Keep em' Flying
//Fight Corrosion!

 

[rb1957]

I went on Cranfield (thx for the link), search for "buckling", sort by published date, 2nd entry ...

is that it ?


"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[SAITAETGrad]

https://www.reddit.com/r/engineerin.../?utm_source=share&utm_medium=web2x&context=3

 

[sdm919]

Sorry I just saw this. I have a copy of Data Sheet 02.03.01. I can confirm that nu is built into the buckling coefficient, with an assumed value of 0.3.

I did a quick comparison using the equations from Galambos as a baseline (Guide to Stability Design Criteria for Metal Structures, Fifth Edition, Theodore V. Galambos, John Wiley & Sons, 1998, pages 140-142).

The cases all sides simple, all sides fixed, and long fixed/short simple agree fairly well. The case long simple/short clamped agree at at b/a=0 (long plate) and b/a=1 (square plate), but in between the Data Sheet curve is noticeably lower. For example, at b/a=0.6, Galambos gives 7.69 while the Data Sheet is about 6.75.

Without more study, I can't say which is “right”, but I would say this: When you look back at the original references you often find that they are based on approximate numerical solutions of differential equations. And because the numerical computations were tedious (1930s-50s), they only computed a few discrete points. Design curves were made by fairing a smooth curve through the computed points. Taking that into account it is entirely possible that modern FEM computations with a well built and executed FEM will give results that are at least as “accurate” as design curves found in the original references.

 

[tomsing]

Interesting! Is there any chance you could send me a copy? I was able to find a copy at Johns Hopkins, and that agreed with other sources. Perhaps yours is an earlier revision? I don't recall seeing a date or anything on what I was looking at, maybe I should take a closer look.

 

[sdm919]

My copy of the Data Sheet says "Third Issue June 1963"

The most recent reference referred to by the data sheet is:
Shear Buckling of Rectangular Plates with Mixed Boundary Conditions
I. T. Cook and K. C. Rockey
The Aeronautical Quarterly
Volume XIV, November 1963, Part 4
pages 349-356

I have a copy of this paper too. In it, they assume a buckled shape in the form of a double Fourier series, then determine the coefficients of that series using energy minimization. They said convergence was slow, and they used up tp 48 terms. They computed both symmetric and anti-symmetric modes, whereas I guess the earlier researchers only did symmetric. When I plot Cook & Rockey's data against the Data Sheet curve in question, it's not exact, but seems to agree pretty well. So this could be the original source for that particular curve.

Attached is the table of results data from the Cook & Rockey paper (see Table II). Note that the buckling coefficients in this paper DO NOT include Poisson's Ratio. They compare their results to Iguchi, who's paper was in German, but he only considered symmetric terms. They say that some of Iguchi's results appear to be incorrect.