NASA NACA-TN-1553-1948 Compressive strength of 24S-T aluminum-alloy flat panels with longitudinal formed hat-section stiffeners having four ratios of stiffener thickness to skin th.pdf

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1、b 7 APR 1948 NATIONAL ADVISORY COMMITTEEFOR AERONAUTICS .a71a15a14TECHNICAL NOTENo. 1553COMPRESSIVE STRENGTH OF 24S-T ALUMINUM-ALLOY FLAT PANELS-WIIH LONGITUDINAL FORMED. HAT-SECTION STIFFENERS HAVINGFOUR RATIOS OF STIFFENER THICKVRS+ TO SKIN THICSS.By William A. Hickman and Norris F. DowLangley Mem

2、orial Aeronautical LakratoryLangley Field, Va.WashingtonMarch 1948? IiANGL:;gM no attempthas yet been made to prepare desn charts from these data.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACAEmno. 15532.“SYMBOIS.Synibolsfor dinmnsicms,of panel

3、 cross sections e.re.shown infigure 1. In addition, the following synibolsare used:Pi compressive load per inch d panel width, Hps per inch% cross-sectionalarea per inch of pamel width, expressed as anequivalent or average thickness, inchesL length of panel, inchesc coefficient ofcr local-bucklingzf

4、 average stressend fixity in Euler column formulastress of skin or stiffener, ksiat failure, ksiTEST SPECIMENSA typical cross section of the test panels is shown in figure 1.Both the skin and the stiffenerswere made of 24s-T aluminun+alloy sheetwith the grain of the material parallel to the longitud

5、inal axis of thepanels. The with-grain compressive yield strength of the skin materialranged between 42.2 ksi emd 47.9 ksi with en average of 4s.8 ksi andthat of the stiffenermaterial before forming varied between hl.9 ksiand 46.2 ksi with an average of 44.3 ksi.For the tests reported herein, the no

6、minal thicknesses of the skinmateriel were 0.102 inch, 0.064 inch, 0.040 inch, and 0.032 inch and thenaminal stiffener thickness was 0.040 inch. The nominal ratios of thestiffener thickness to the skin thickness tU/tS were therefore constentjthe values being 0.39, 0.63, 1.00, and 1.25, respectively.

7、 With thesedimensions known, numerical values for all other cross-sectionaldimen-sions can be found by means of the proper dimension ratios. Thestiffenerswere formed from flat sheet to an inside radius of 0.125 inch()twfor allbends z 3 . For panels having = 0.39, 0.63, 1.00,.and 1.25, the wdths-of t

8、he attachment flange bA were 0.85 inch,0.75 inch, 0.65 inch, and 0.55 inch, respectively. The rivet lines onthe stiffeners were on the longitudinal center lines of the attachmentflemges. s-.The NACA flushrivetingmethod (methodE of reference 5) wasemployed in the construction of the test specimens. T

9、he rivet holeswere countersunk on the skin side of the panel to a depth of three-fourths -.of the skin thickness, the countersink having an included angle of CIOO.Ordinary flat-head A17W aluminum-alloy rivets were insertedfrom theProvided by IHSNot for ResaleNo reproduction or networking permitted w

10、ithout license from IHS-,-,-. .liM2AmI?o* 1553 3-.the solid-line parts of the curves were draw tough the experimental test points. -The following conclusionsmay be drawnverious dimension ratios on the strength of-.regarding the effect of thethe test panels. It isProvided by IHSNot for ResaleNo repro

11、duction or networking permitted without license from IHS-,-,-IwmATN I?o. 1553 5* .assumed that as each dimension ratio is changed all others remain constant. .These conolusbns can only be considered to apply within the range of“.panels tested.1. PiAt very low values of (long psnels that fail by colu

12、mmmbending), the stress developed by the panels increases with an increasein bW/tW because an increase in the height of tQe stiffeners providesincreased column strength. For high values of L+ (short panelsthat fall by locel buckling), however, the stress generally decreasesas btv increasesbecause an

13、 increase in the height of the stiffenersdecreaaes the local-buckling strength.2. At very high values of i%(short panels that fail by localbuckling), en increase in the ratio /tw tends to decrease the stressdeveloped by the psmels because an increase in the width of the stiffenerstends to decrease t

14、he local-buckling strength.Pi3. Icraft. NACA RB, June 1942.6. Schu . v 60IllJr;/ IIIw Ill50 w! 751,9,80+0.2+!, , 1, , t, , 1, , 1, ,. t, , 0, , 1, , 1, ., 1, ,-2% Si -=xS=”Figure 3.-Compressive strength of flat panels wifh hat-section sWfeners.+=0.39; =0.6.“.-Provided by IHSNot for ResaleNo reproduc

15、tion or networking permitted without license from IHS-,-,-12.NACA TN No. 1553TABLB2T2ST D.4TAFOR PUT PAML2 WITHRAT-s2CTIOllsTIPFEMBR!JWT12 tw - 0.39 , % _ 0.13minal pro.ort.lon giveninpsr.ntlw. =40.b I .59 1 z.uy I I - I - I -.1 I .102,-.I .-1 I . 9 I .82 I i7.% I I +.6 I 7.0 I 173I .12Z.Provided by

16、 IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN NO. 1553. ,. .40.,.,1.,.a.nb,b.bu,.,.,.,.,1,., = HI:If1, , , , ., 1, 1,. 1 Figure 5.- Compreshez%s .strength of fht panek with hot-section stiffeners.*=0.39; +NACA TN No. 1553TASIXbTEST DATA POR FIAT PANE=

17、 WITPIEAWS20TIOH STIFPEH2RSwIZN = 0.39 ,2 - 1.2.min.l prop.rti.nmare glv.n in renthl.-.-.,“w%-=Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.NACA TN No. 1553. .40r30L20 :u,#wts-.4 1,0+02+ 1, , 1, , 1, . . . 1, , 1, , 1, .,!“40r1- 1E3020II1/ !l/If5

18、0+02+r t,J,l.,b 1, 1, 1, lEaEL lb, 1, !, 1, ,.175J,l, 1, , 1, , 1, , 1, , 1, , Is, , , ,1,-22 SiFigure 6.-Compressive sirength of flat ponelsw/fh hot-sectbn stiffm.+=0.39, 3=L2.s w.-. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-,18 ),-,;: Tm?.w5

19、T2dTMTA ?OR FIAT PAU2L2WITHEAT-.3WCTIOllSTIN2RS WXNACA TN No. 1553“7,. . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN No. 155319-.“-.t ,ml J;b- 91w-25 35-.2 1, ,0 1,. ,s 1 1o, 1, , I,mss 1, ,s 1, , 1, , t, , 1, 1.1-Q2-iSa,.,. ,L,l, ,E, ,1

20、,30 :-Itt1111MIIElrml.:75IL, ,. .*CqZzE *i1: g: .55511.411.:%19:7lo.k(1.935) 10.9%i :2 i:! g(2.115) :! %! %:27.511.8 g,:1?10:9 ,4816.5 17(2.423) 11.6$; 21.6 .14921.6 .0291?: 21.314:6 .05517.6 .030“”.-. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-

21、,-NACA TN No. 1553.2?.q , ksiL/_ _.-Figure /1- Compressive strength of floi panels with hat-section stiffeners.+0; + =0.6.s.*Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-28.NACA TN No. 1553TASL2 10T2ST DATA F02 i+LATPS KLflIHAT SEOTIOR STX?FSN2XSW

22、IT2 =1.oo, b=oo8.4 :; :f jg (2.199;o 17.33.039 I .981J I 50.2 I 30 3. I 8X12?% . I.“;. .-. -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN No. 1553.30 -J I! lltlllillrl!llll!l I! lllllrlllitllltlll Istlrltlllllltrll, 1,1Figure /2.Compressiveq ksimstrength of fld punels with, hut-seciim stiffeners.-.-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-