1、REPORT NO. 827CTS FOR THE. MINIMUM-WEIGHT DESIGN OF 24S-T ALUMINUhl-ALLOYCOMPRESSION PANELS WITH LONGITUDINAL Z-SECTION STIFFENERSBy EVAN H. SCHUETTISFLAT-.SUMMARYl?tw”gn char-k+are dembped jor .%$S-T aluminum-alloy flatcompresn”on panels with lonp”tudinal !Z+ection 8tij$eners.These charts make poss
2、ible the dem”gnof the ightest panek ofthis type for a un”derange of dem”gnrequhunent8. Eramplesof the u8e of the charts are giren and it is pm”ntedout on theba8is of these examples that, orer a wide range of detign condi-tions, i%e maintenance CJJbuckle-free the data were obtained from reference 2 a
3、ndfrom additional tests completed since publication of refer-ence 2. These charts make possibk the choice of thelightest pgels of this type to conform to a wide range ofdesign conditions. ti appendiy is presented in which theprocedure followed in preparing the charts from t the length ofpanel, or di
4、stance between supporting ribs; and the coefE-cient of end fixity. The most efficient (lightest) panel for agiven combination of these conditions is that panel whichwill develop the highest average stress for the particularDiscussion of charts .The charts include a wide range ofpanel proportions. Al
5、l the charts have been drawn for avalue of =0.4; it is shown in the appendix (figs. 7 ti 20),=0.3 and 0.5 wouId be in closeoJvever hat Curvw or bWagreement with the curves for from tlwstandpoint of aerodynamic smoothness, apprrcirhle bucklingprobably takes pItice at stresses somewhnt, Iower than tho
6、seindicated on the charts. It will be notod that for some ofthe lower vvdues of bJtand 6W/tWno buckling stress is shown.In these cases, there vvilI undoubledy be some buckling hut.presumably it will occur at a stress coincident with or onlyvery shghtly below the failure stress.It is pointed out that
7、 for =0.79 and 1.00 (figs. 4 mid 5),the curves for values of =25 and 30 have been obtainedentirely by extrapolation. These curves should thercforo Lwused with a certain clcgrce of caution. A few check test.smade since the preparation of the chwts, howcwr, indicatethat the curves will in no case be m
8、ore than G prrcent un-consermtive. In all the other curves, it is Mimwd thtit. nnyunconservatism that may be present is of much smallwmagnitude.Discussion of tests and test panels,-In order thtit the de-sign chats may be properly used, it is nccwsary to knowsomct.hing of the test panda and thr. test
9、. results on whichthe design charts arc basccl. The Mails of thwe tests nrcdescribed in reference 2; sonw of the pertinent- iuformat ionregarding the tests follows:TIM test panels consisted of six st.iflvnels and five buys.The panels were tested flat+ndcd and withou cdga support.,A ilxity coefficien
10、t of 3.75 was used in reducing the tvstdata for application to an rffw!tivc pin-rndrd hwgh. 1fwaverage compressive yield strength for tlw mntmkl of whichthe test panels were constructed was about 44 kai; the nlin-imum yield strength, about 41 ksi; and the mnximum yirldstrength, about 46.5 ksi. Tile.
11、 rive wvrc couubxaunk atdwere driven by the hTACA method of inserting n fht-hmulrivet from the stifhncr side of the hole, upsetting hc rivetshank into the countersunk cavity, and milling oil the Jro-truding portion of the upset shank. TIN rivets were Al W-T(AN442AD) and were of the sims and spncings
12、 indicwtwl bythe following table:t FRiet spncln IUrct dkvrwkrb 1# la.0.51.fa M MIZ ah 1. Oai+.63( :-10.9; , , i-ti-i-iI f I 1 1 I I I I I I I 1 I w. .W-H-rH-t-tl-t-tt-l-l-l-lI 1 I 1.HH-H-H+i+”w I-t+l+t +r I 1 I I I I I I I I It- -I“Stress for focal bucklingr- - -I I I II I I I 1 I I I I I I I, ! ! k
13、w-w-?-i-. 3.7kI I I 1 I I I i. * .25Ill II Itt 30 I II I 3k I 40dI “ -. - :I IIt I I I 1 I I I I I 1 I I I II I I t . .I I , # , ,0 I I Ill I I II II t t I I I t I I 1 I I I I ! 1 I I I I 1 t t I 1 I 1 I 1 I I I t“+li-ttt-l1 , , , , , , , , , , I , , I ,I I I I 1 I I I 1 I I I II I tI 1 I I 1 o30 !Z
14、 A +-p 25- FI I I .1 I I . - -30- II I I Ill 1111 Iltl II I iI 1 I I v II I I la I I ., , , , , , , ,. , r,J- .+tt+ -+%-+-+I IA-I I I I I I I I I I AA II I 1I1 1 !“. HHHHfi I I I I I I 1 I I I I I30 1 I I I i Ir Liiikkkl20LLLJ_LLI 1 I I I I I I I I I I I I tl!t;iiiiiii iiiiiii!t, ! ,!i iii I 1 I I I
15、 I t I I I 1 I 1 I t I I100I I I I 1 1 1 t r , 1 I , , , I I : I-1+-H-+-+ +-+-IFIOUBE5.Df.snobart for 24S-T Edumlnrrm+dloyJkt p8Ee18with j-lal (-aq-3;-*nd eamples havebeen worked out- by its use, however, to serve as a check onthe short method, so that that method can be used viithconfidence.Provide
16、d by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-560 REPORT NO. 827NATIONAL ADVISOR COMMllTEE FOR AEROiVAh2S Each of the three methods is given as a series of steps forreaching the final designs. In the method for obtaining theideaI design, the detailed comp
17、utations for the four values oftw/tincluded in figure 6 are given for = IOJ”20, and 30inches with P;=3.O kips per inch and c= 1. In the othertwo methods, the detailed computations are given only forL= 20 inches and tnr=0.79, again with P*=3.O kips per inchand c= 1; final results are given, however,
18、for the completeset of examples considered in the discussion of the firstrncthod. It is assumed in d cases that a skin thicknessof 0.064 inch is necessary in order to comply with otherdesign requirements. A value of bF/b,of 0.4 is used through-out. In arriving at the final these valuestherefore give
19、 an indication of the proportions needed in apractical design to meet the design requirements mostefficiently.Te resulting designs arc shown as the ideal ,7I -. 6- .-x“H-bfbttm“a-k, the original curve of column strengththerefore no longer applies and the point at which bucldingtakes place must be co
20、nnected with the line for local failureby means of a reduced curve. A typical curve, adjusted forthe effects of Iocal buckling, is shown in figure 14.The foregoing discumion shows that it is necessary toknow the stress at which buckling takes place. Data onbuckling stresses horn reference 2 plus add
21、itional data nowavailable are therefore plotted in figure 15 for =0.4. Be-cause the measured value of lit for the element (skin orstillener web) that CWinn sh?nqth Local- fdure Sfrenqfh . ;, rest it is assumed that neglecting thisfact will have no significant effeot because the total correctionis re
22、latively small.The method used in fairing curves through the test pointsin figure 15 is as follows:For the horizontal portions of the curves on the right-handside of figure 15, the skin is primariIy responsible for thebuckling; the ordinates for the curves in this region aredetermined by drawing ave
23、rage lines through the testpoints. As the value of tW/bwis reduced, however, theresponsibility for the buckling shifts to tic stiffeners andthere is a reduction in a.,. In the abrice of adequate testdata for low vahw of tW/bw,certain theoretical considera-tions are used for determining the values of
24、 a, in this region.It is possible to describe certain J.imiting conditions thatdetermine. curves between which the correct curves must lie.As the value of tm/brapproaches zero, with all other dimen-sion ratios held constant, the skin tends to become infinitelystifl by comparison with the stif7ene an
25、d the stiffener ap-proaches a condition of complete iixity at the edge where it isattached to the skin. This condition of complete fixity repre-sents the upper limit of buckling stress, The vaIue of k, thecoefficient in the fornnda for loca.I-buckling stress (reference4), when applied to, the stiffe
26、ner web may be taken for thiscondition as the geometric mean of the vaIue of k for theweb of a z-section cohmm with #w= 0.4 (about 3.77, seereference 4) and the value of k for a flat plate fixed at bothedges (about 6.98, see. ref ererice 5)._, This value of k is43.77X6.98, or 6.13. The upper dashed
27、curve in figure 15gives u., for k=5.13. The usc of the geometric moan 01values of k t.oobtain the critical stress for a phtte with differ-ent restraints along the two tmlowlcd cclgcs is discussed andjustified for practicaI use in refcrcmcc 5.When =$ it is a reasonable and probably conservativeassump
28、tion to consider the stiffrncr hingd at the edgewhere it ia attached to the skin. This hirgcd conditiorepresent the lower Iimit of buckling st rem The WAC ofk for the web of the stifhner may be taken for this conditionas the geometric mean of 3.77 for the simple Z-section andthe value for a flat plt
29、it+ hinged at both edges (4.00, scerefereac.e 5) or k=3.77)(4.00 = 3.88, The Joww dashedcurve in figure 15 gives UC,for k= 3.88. 1n kc preparationof the two dashed curves, the effcc%of reduction in the modu-lus of elasticity for strwme beyond the clast ic range wasdetermined from results of tests of
30、 248-T ahlminnm-nlloycohunna of Z-, chmnel, and H-section that develop localinstability.The solid curve on the left-hancl side of figmm 15 is drawnin to the remaining curves were then fnired in a manner consistentwith the curves already established.In a few cases (Iow bs/tswith high bW/ the avaiIabl
31、e test data were used as the scale guidefor fairing the curves in these cases.Correlation between design curves snd test data.Thetest data of reference 2 as we as the additional data madeavailable since the publication of reference 2 are plottedP,against the parameter in figures 17 to 20. Appropriat
32、eL/Iccurves taken from figur- 2 to 5 are aIso drawn in these fig-ures and good agreement between the fired design curva andthe test data for =0.4 exists throughout the range of the -data. In order to make it possible, if desired, to check thecorrdation on a larger-scale plot, the t=t data for - LmPr
33、ovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-572 REPORT NO. 82 7NATIONAL ADVISORY COAiMITTEE FOR AERONAUTICSTABLE 1VALUES OF AJts FOR FLAT PANELS WITH 21.iWCTION STIFFENERS. ;=0.3.g(l+g)+g=(,-;) (;+;+,) ,W ,*.1+ bslta: (dX1.+1: 4241+”+d:”lm.%: .s“ 4
34、448,48I L436 L 448 1.462 L 476 1.=!0L 448 1.481 1.444 L 467 L 4mL 402 L 416 L 427 L440 L 462L 269 1.4Ml L412 L 424 L 430L 276 L8$0 La L 410 L 421L362 1.372 LW6 L 390 L407L 673 L m 1.732 L 7E21.662 L 073 L m4 ;T#L 628 L 053 L 0731.OW 1.629 1.w 1:anL W LW3 L 081 L 654L 606 1.b#7 L 610 L 633L 647 L boa
35、 1.m L 612L L 561 L 872 L .KISL 614 L 634 L 656 :$6L 4a3 L 618 L mL484 L4 L 528 1:642262627282Q241L mL 840L 327L 816LY)612XL286L 276L268?%L246L.23QL7A2;: z12101.201L 192L 184L 177L lmL 164L 1691.162L 147L“126L126L 1181.887L 863L 840L 8281.816L203L226L287L !278L 270L2J32L 2661.249L 2411.236L2!ML 218L
36、20SL 109L 1911.1321.li6L lmL 164L 168L 102L 141L 121L 122L662L 621L 511i%L 430k%:%L8WL maL i?78L a68L aML840L 229L 814; g7L 265L 260k%L 230L 212L 197L184L aboL266L 262L 340L 8281.317L 307L WL2gL32QL 318L202L200L2QlL 2aaL 276L 26a1.%11.265L 242L222L 221L 2121.m1.ImL 180L182L 170L noL 167L 146LB3L 421
37、1.406L21ML 376L263L 251L MOL329L 3101.810L 821I!mL 2841.mL 270L%2L %1L239L220L 219L 211L 2L 196LIPSL 181L 175L162L 160L 140L 1325L 617JL W.L E%L 697L 574L062L623L 614L 497L 461L 400L 462L 439L mL 414L402L30bI. 886L678L 36bL 329L 224L 811L 26aL 287LL266L 267L 249LaL 21S1.loa1.624L%1.4s3 L 476 1.495L
38、416 L 424 L482 i 402L 436 L 462 1.460 L 4n7L 424 L 441 L 4Ca 1.474z39z4244464860L 404 L m L430 L 452L346 L 401 L 4Nl L 431LWd L 8S3 L m L 41X1.65a L 307 LW L896Lm1.363 L m L 380L220 L3W 1.362 L 354L 814 L 826 L 829 L a511.w L 316 L m L 239L m 1.W4 L S16 ;3.%L 242 L 2s L 2012220 L224 L 24t i 2a667076
39、L 621L 611L 44?21.4741.4%1.4481.428L 416L 4oaL 6?311.mL%NL mL2-YIL 341L882L WOL 3W2?EL266L 2ML 246L 237L 229L 221L204L 192L 177L :%1.b73L 6531.433L 614L 496L 47ki1.iG2L 4271.2061.m1:m3122332436L7Zb L 701L706 1.7201.084 L 716L284 L6!UL 646 L 674L 627 L 656L 010 L028L604 1.021L67O L IX16LM4 L62QL 037
40、L m2L613 1.mL 491 1.618L 4m L 4W2L 461 L 47236a7z4042243m6264M5360L 27S LX6 L206L %5 L 276 L!W1.266 L256 L 2741.247 L 246 L2ML2S9 L 247 L 263L 2m L 228 L 2281.206 L212 L 21.9L 191 1.m L 206L 247 .1.3433L322 L 2371.ml L a16*Provided by IHSNot for ResaleNo reproduction or networking permitted without
41、license from IHS-,-,-CHARTS FOR DESIGN OF 24S-T ALUMINUM-ALLOY COMPRESSION PANEIS WITH ZSECTION STIFFENERS 573TABLE l-ConcludedbF 0.3 Concluded.VALUES OF A4ft8FOR FLAT PMYELS WITH Z-SECTION STIFFENERS. =2782;ZH%Zm%43722s2ii%!Liak%2.mx 142x 1142060x 01L4WLO%L t?U1.m7L825L795L mL 7421.6s51.m6L694a.so?
42、: E1.222L 212L!M3L 196L ImL 180L 173L 167L 1611.lmL 144L 134LIML7?34 L 752 L 782 L811L6M L 724 L 732 a.mLa L647 Lm L 761L m L 072 1.boa L mL 624 L 049 L !374 L m1.m 1.027 L 232 1.m1.% L M7 L al L 0341.633 1.6s3 L 611 L 634L MS L bm 1.bQ2 1.014L 432 1.b64 1.mb ;. gL 617 L m L m ,L m 1.622 1.Ma L MaL
43、4s9 1.509 1.Ik2a L MB1.470 1.4e5 1.M4 L 334L464 1.482 1.ml ;g1.m L 471 1.4W .L 431 L448 L465 L 433L 411 1.428 L 444 L 401L m 1.4W L 423 L 441L 277 L 392 L 407 1.422L 202 L 876 1.al L KmL 348 L M2 L 3i6 L 2mL 33s 1.349 L m2 L 3i6L 3!X L 3M 1.349 ;%L 312 1.624 L 337L m L 314 1.226 1:23aL 447 L 462 L47
44、3 L 491L4.%1 L444 2.453 L 472L 414 L427 L441 L 4541.am L4U3 L 425 L433L286 L 398 L 410 L mL273 L2S3 1.S77 L40E1.WI Lam L384 1.396L 349 1.361 L 372 L3631.329 L6M L 281 L 2721.329 L 362 L35) L 2611.am L 232 L240 L 3EJIL 810 L 821 L W 1.3411.322 L 812 L 322 1.292L !W4 L304 1.313 1.32aL 237 1.m L20b 1.2
45、161.27% L 1.236 1.307L 266 L 276 1.382 L ti2L234 L 202 L 271 1.272L242 L 251 L2W L237L223 L 240 1.24a L2ML 224 1.281 L2W L M6L X6 L 222 L 223 LZZIL207 L 214 L 220 L 227L2J0 L X6 1.213 L !219L 192 L 139 1.m5 L m1.I1:4%1.482L 433L 432L 43$L 4231.4131.401L 301L2i K44L 48L402L 2871.673L6001.34aL 337H%L
46、207L maL!4KlLWL 27bLM6+2611.249L237L 227L 218L !239L XIILloaL 187L lSIL 174L 161L 149L1391.422L 416.:$1.873L 300L 249L 33-SL mL 318L2WL 300L 2921.28aL271L2701.%7L246k%L 216;!L 186L 180L 1691.L54L 144LamLLWL 481L464L446LL 419L4061.294L 382L 371i%i1.”242L2221.2261.309L 286L223L mL mlL230L 241L 222L224
47、L 217L mL 1.60L 173-LW7Lb84L502L 3421.6!23L2Q31.400L 474L 4841L 446L 4341.4221.4101.Wa1.wL 2801.261LM3L2Xl1.3161.304L !W21.281L271L 282L 264L 224L 217L 202L036L 612LLbL 540L520L blaL 497L 462L 403L433L 442L42JI1.4101.408L 3Q31.370LM2L 3461.331L 318L 303f$1.321L306L2Q7L 237L n71.2b3L 236L Y42L lW56#1
48、:020L 32!71.b72L m%L511L 4WL 4821.402L 4671.44bL 434L 413L 323L 877L3621.347L 234L 322L 310L!4WL2WL %71.248L 232813232EL 172 L 1% 1.la 1.1691.160 L 103 L 170 L 176L 149 L 134 L lb9 L 104 I I1:-m2032 1097 9.14 l13a!ao12 !4.034 2.037 i b77L MlL 6431.WL 617i%L 467L 446L427L40BL6%31.378L264L 3blL 33!2L2
49、27LXt2L.%1L262L033 2.maL926 L WL822 L 932L.%M L WILEL 662L 6441.6271.611: “L 466L430L 444:EL 401k%L 3blL327L8241.312L alL %1L alL20JL 2411.226L 690L 6771L346Lb%?LWlL680L582L 344LEML blzL497:.L4.ML 446L 425L 415;%iE;L 300L290L 268L 242L232L 7191.691L 205LM2L6KIL6W!2?%L b13L4W1.4S6L 473L 401L 449L42S;%?L 274L2b9L 246L333L3!UL 310L232L 476I. 2571.240L 741L
