1、a c g ARRNo. 4E31 s3 /“ps 273126 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS ORIGINALLY ISSUED May 1944 as Advance Restricted Report 4E31 1 I TORSION TESTS OF STIFFENED CIRCULAR CYLINDERS By R. L. Moore and C. Wescoat Aluminum Company of America REPRODUCED BY NATIONAL TECHNICAL INFORMATION SERVICE U
2、. S. DEPARTMENT OF COMMERCE SPRINGFIELD. VA. 22161 WASHINGTON NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance research results to an authorized group requiring #em for the war effort. They were pre- viously held under a security status but are n
3、ow unclassified. Some of these reports were not tech- nically edited. All have been reproduced without change in order to expedite general distribution. w -89 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA ARR No. 4E31 c KATIOTJ4L ADVISOEY COMM
4、ITTEF: FOR AERONAUTICS ACJANCE RZST3ICTED REPORT BJ R. L. Mcore and C. Wesccat The design of curved ahest psnels to resist shear invol.ves a consideration of scvoiaal factors: tbe buck- lhg resiefacce of the aheet, thi. S-LY:SS at which buck- 1ii:g becones por!can=:-,5, ad tk-e ,c:erig?ki which may
5、be dcveleeit oot.n;l the h:xkl-ing l.ht5 ty tamion-field action. Altkoi,gh som exp?rimenfal as wall as theoret i- tal work has bsen time on tho back1:!1ig an2 tenslon-field ph33es of th-i.n probLm, neii-her of these types of action appsers to be very well unbrstood. sufficient bnportanse from the st
6、andpo-lnt ef aircraft design, it i.s belleved, to warrant fcrther experimental invetigation. This report presents the results of thc; first series of tsrsion test3 of stiffxxd circular cyl- ind.;.rs to be completed in connection wikh t,his study at kliminum Rmearch Laboratories. The problem is of In
7、 some respects the Rhear prcblem for curved sheet pan3ls is s!mila;- to that for flat panels. The buckling resistance dcpends not oly ipor, curvatme and the pro- por.tions of pariel but a180 “pon the restraint provided at the cdges The s-irrength which may be dewloped by- yond the buckiing limit dep
8、ends ujyn the capacity of the sheet 50 transmit shear by diagoml tension and the re- sistance of tho stiffener system te slrch tensile forces. The ou5.idcrness with whish t,ickling generally occurs in a curved sheet would appear to make thig action more de- terminate by expcrimcntal methods tnan is
9、the case in flat sheet where the effects of eccentrtcities of loading usual 1. y ob s cw e we 1.1 -de 1- i ne d 1) uc kl ing Thenome na . field action ia more compl?x for curved panels, however, in that the stiffeners are subjected to combined bending and twist as well as axial coinpression. Tens io
10、n- Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACA ARR No. 4E31 Several scl ut ims have been proposed. for tho problem of elaztic dwe-buckLin in curred sheet panels. The AT-5 Zandbocl; (refsrence 1) indicstes that this property my be d-ter-drr
11、eC by cmp1ti:ig the critical stress for a ilst panel of the srzme pyopcrtions and addirg a factor depc:ndirg .1pon curvatu-re. Thls so1.1.i.t ion is simi.lar in fora to that proposed by Wqpx? arid Bnllerstedt (refer- enci? 2). formula for the mabillty limit of infi.nite1.g long curved p1 atc, strips
12、; while Ebner (reference 4) i-ndicatss that tk: R Frcperty maj- be d.etermined by “ormulas s i.milar to those developed for c1xve:j. panels under compression. Schapitx (re ycrznce 5) concl.lr:s that the shear-buckling action of curved resistance of cylinders hav- ing ring stiffeners only, for which
13、tho buckling limit is also the ultimate stren +;b essential struc- tiiral detcilz. T3c: ring stiffxi-3.3 were made cf 112- by l/Z-inch 24s-T squzrc ba:-s, sl!:;ped cold tc ayyoximate eize in formirg roll-3. After fcra5.n4y, tho rins,.; were syliced an5 md:insC to obtain the re$-uired di:meter. Tka l
14、o?qiti.tdirial stiffeners wxc. fxmod of 0. CFA-inch 243-T shee.l;. Figure 1 shows the noainal dimensions. One of tbcse stiifmers wag meci at thc long!.i Iiiinal scam of all specimens in crder to prevc-rt the mv1.i:1s which might otherw!-g CICCIIY in a long thin lap jalnt I.?aving a largo nmb:;r of c
15、iocely spacod rivo-i;3. Th.3 er? bulk- head riw3 were mCe fron 3/-srlt nieeri cf curved sheet pnsls the d inemions mi. eprcimen number designa- tiom of which are sho-m in f?.gui*es 5 and 11. Al.1 sizes of panels were obtalnsd by varyiw tho stiffener sp?.c:ngs of four different cylinders. Specinenn 1
16、4, 15, 29, nnd 21, hcvlng the cloyest spsci.na of Rt iffmors, were th only ones teRted to failurc invclving t.ension-f ield act ion, PRO CEDIRE Method cf Loading 3 Ftgure 2 shows the lcnding fixtccre in which the torsior, tests were m3e. Thts equipmer.t consists of twci sjrailzr 8tructur-21 ateel fr
17、anics having a depth of 3 fcet 6 imiies at the center and an c“fective levzr am of 12 feet 1/8 inch. One Prme was bel-d against rotation bj anchxing it to the floor by means of bolts used in floor inserts; the other wm rotated by cieans cf IoadirG screws so arranged as to pall in opposite directions
18、 at the ends. Sphrically seatcd nuts were provided at bath end of both loadin6 screws to accom- modate the mcirement accompanyiw the expected angles Of twist. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 NACA ARR NO. 4E31 The forces at the cnds
19、of the mcvable frame were deterrrined b;r mxns cf an elurrinim alicy dynamometer. link kvjng a. m.parit;r cf !-JJP pc-ctis. This force, ap- plie3. In oyxm:te: G,imct ioria ct the en. Def1cct;ora were estimated by meum of a Cinl imimtor to the zorrest 0.0001 inch, ccrrespcnding to a +,orc,l-tion, otn
20、Crw183 SGm: transverso berdTw as :?ell iz3 torque rni5k-c .,TTC Seen rp,nlied, Fic,rc 3 shcv3 t1:e ?XY ; L“ 20 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-22 NACA ARR No, 4E31 where 1; z 0.75 for hinged edges For clJrved panels where K. buckling
21、fxtor for correepondlng flat sheet panel depending on ratio of a/b Reference 3 (Kromm) For infinitely long cirrred plate strips haviw3 hinged edges (central angle f 43) - -. when 2 /z 4.3 -L .I r (See reference 3 for other casse.) For the panel lsngths considered, values of To deter- minod by the ab
22、ove relation were multiplied by the ratio of the computed buckling stress for a ilat panel cf the same proportions to that for an infinitely long flat panel having the same short dimensicn, Ref:Lrence 4 (Ebner) For curved rancls - . * where T R T shear-buckllrg stross fw unsti ffened cylinder shear-
23、bxkling stress for corresponding flat panel Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-23 Referencs 5 (Schapitz) For coipl.ete Cuemion-f ield action after buckling - 7, T sin b: cos a, 0 =- Referxca G (Donnell) For wstiffenod circulw cylindors h
24、aving hirged ends where - L2t 5.2 D3 - -.- -I i - Et2 - To (1-p2)L2 2.8 + 2.E + 1.4 i Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-24 NACA ARR No. 4E31 1. Anon, : St.rengi;h of Aircraft Elements. Army-Navy- Civil Committee on Aircraft Design Crite
25、ria (RNC-5), 1942. 2. Wagner, E., and Ebllerstedt, W.: Tsnsion Fields in Originally Curved, Thin Sheets during Shearing Stresocs. WCA TI4 No. 774, 1935. 3. Kromm, A.: The Limit of Stability of 8 Cwved Plats Strip under Shoar and Axial stresses. NACA TM NO. ma, 1939. 4. Ebner, H.: Tho strength of She
26、ll Bodiee - Theory ana Practice. NACA TM Nc. 838, 1937. 5. Schapltz, E.: Tho Twisting of Thin-Walled, Stiffened Circul-ar Cyl.inders. NACA TM No, 878, 1938. 6. Donnell, L. H.: Stsbility of Thin-Walled Tubes under Torsion. NACA Rep. No. 479, 1933. 7. Lundqulst, E, E, : Strength Tests on Thin-Walled D
27、uralumin Cylinc?ers In Toroicn. NACA TN No. 427, 1932. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I Spctoiann No. NACA ARR NO. 4E31 Ratio of Mean Observed to ar-Buckling Stresses Dimensions of Panels, . in. ANC-3 Ref. 3 Ref. 6 I I ll.81 in. I P:
28、;b I 1.06 14 0.020 x 4.31 x 11.81 1.58 0.43 0.80 0.92 0.0eO x 13.50 I 11.81 0.020 x 9.00 Xll.l 5.90 in. I I 0.020 x 13-50 x 5.90 0.0195 x 8.81 x 5.90 0.0195 I 9.00 x 5.90 0.0205 x 9.00 I 5.90 0.0205 x 6.75 x 5.90 0.020 x 4.31 x 5.90 0.0205 x 2.06 x 5.90 1.39 1.60 1.71 1.84 1.99 2.31 2.02 1.12 1.24 1
29、.13 I - 1.30 l.W 1.25 1 1.27 0.71 1-50 I I 1 I I TJuEA “ORSIONtU STmTlIS OF 24s-T CYLINDERS HAVING BOTH RING AND LONGlTUDlNAL STIFFENERS Heen Dimeter - 30.08 in. Overall Length - 36 in. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA ARR lo. 4E3
30、1 Spoimn B. 26 s Dimensions of Panels, ne an in. Obnerved m-3 I bf. 3 ULUI SHBAR-BUCXLXNC SlRtSES FOR PANELS OF 24S-T CYLINDWS HAVING BOTH RlNG AND MNGIlUDIHAT, STI- Mean Diameter - 30.08 in Overall length - 36 in. I I M 15 1s n 21 eo 21 0.026 x 13.50 x 5-90 2 870 2 070 2600 2 570 e 210 0.0195 I 9.8
31、1 x 5.90 3 370 2 110 2 680 2 380 3900 3400 0.0206 I 2.06 x 5.90 13 900 6 890 19 500 9 300 8900 195 x 9.00 x 5.90 3 590 2 100 288G 3 I70 2 680 2 910 2 920 5400 5300 4 510 24a as50 a $8 I:! 205x 9.00 x5.90 0.0205 x 6.75 x 1-90 0.020 x 4.31 I 5.90 6 750 I I 10 000 22 500 33 000 8 500 12 000 19 000 9 50
32、0 14 000 18 500 10 000 14 000 20 000 29 000 2 110 1620 1 810 2s20 2 a10 !E I 4 2 770 510 19 x 13.50 X 11.81 l4 I 0.820 x 9000 4.31 x u.81 11*81 1 4 2 950 130 I I e 9 700 1 14 21 600 35 000 49 900 le 300 17 400 27 000 21 700 33 100 42 500 12 400 16 900 25 OM) 37 300 2 io0 3 400 1 loo 3 500 1 000 2 00
33、0 1 bo 5 100 2 900 Speoirnen NO 12 000 Or70 22 000 1.03 32 000 8500 1.20 26 000 - 13 000 - 24 000 - 33 500 9 500 2:OO 14 500 1.93 23 000 3.44 36 500 i:gi 15 000 14 16 20 21 Tor ue, it-qb 12 000 20 900 28 000 11 600 20 000 30 800 13 900 22 200 27 800 16 800 e2 200 30 200 4l 600 - 0.46 0.64 0.66 0.69
34、0.69 0.70 0.44 0.42 0.44 0.80 0.83 0.80 0.78 - 1 io0 2 loo 3 500 4 200 - - - - 2 800 6 600 17 500 iression in I hxim I aswed4 All aoaputed stresses baaed on Reference 5, aesuming complete tension-field aotion. t Based on average strains measured over 10-in. pge lengths near center of stiffeners. bse
35、d on average strains measured at centers o panels. Based on measured radial deflections. anpion in Sheet, 9 400 16 400 23 000 1: 38 25 600 15 500 23 800 30 700 11 500 16 000 23 100 33 400 1.28 1.34 1.39 0.87 0.93 1.01 0.84 1.01 1.09 0.82 0.91 0.99 1.09 Provided by IHSNot for ResaleNo reproduction or
36、 networking permitted without license from IHS-,-,- 0- Z -I 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA ARR NO. YE31 Fig. 2 h 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA ARR Woe YE31 Fig. 3 I I Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
