1、k4T .:. . _INATIONAL ADVISORY COMMITTEE FOR AERONAUTICSORIGINALLYISSUED,.Februsry 1944asAdvance Reatrtcted.Report 4B03COMPRESSIVE STRENGTH OF FLAT PANEIS WITHZ-SECTICN STIFH!XWRSBy Carl A. Rossmen, LeLiI)s%resses fGr the sheet obtained in the in-vestq;atlon are presented in this report$ which isanex
2、tenslm of reference 1 and which supersedes thisreferei-me.width ofattachment flqewldtb OS outstanding flangespacins of 3tiffenerswidth of webthickness of stiffener c .t”. “- . -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.2.% thlclmess of sheetrA
3、 radius of bend between web and attachment flangerF radius of bend between web and outstanding flangeL lengthc end-fhity coefficient in Euler column formulaacr bucklhg stress of sheet%sx average stress in panel at maximum loadTEST SPI15XlSThe specbens used in the tests were constructed24S-T aluminum
4、 alloy with the raln in both sheet andstiffeners parallel-to the lontudinal aXiS of the stiff-.kmezs; . Longitudinal stress-strain curves representa-tive of the group of specimens for which the ratio%/tS was o-51 are presented ti fIgure 2. Inasmuch asthe investigation of which these tests are a part
5、 isstill in progress, a complete set of stress-strain curvesIs not yet avaSlable.The stiffeners for all panels were formed from sheetmaterial 0.064 inch thick. From the value = 0.064,the actual dimensions of any panel can be determined “from the dimension ratios subsequentlypresented h9rein.A lmowle
6、dge of the actual dimensions is not necessary,however, beoause the stresses that can be carried areestablishedby the relative dimensions of a panel.The stiffenerswere attaohed to the sheet withmachine-countersunk flush rivets driven by an NACA flush-riveting procedure. These rivets consisted of ordi
7、naryflat-head rivets inserted from the stiffener side of thejoint, the countersunkheads being formal in the drivingprocess, A flush-rivet milling tool of the t3e de-scribed in reference 2 was used to remove the portion of “the formed countersunk head that protruded above thesheet surface after drivi
8、ng. The rivets in each stiff- “drier were driven in a single operation on a Cincinnatipress brake as shown In figure 30 Machine-countersunk.ofs .-.-. .=. -. -. - -.”.-$fm.: 1:.:s(-. . : -4 -: .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.- . -_ -
9、 _ -_. . . - - L._ - . . . . . . . -t3rivets of this tyre have been found to be tighter thanthe conventional flush rivets. (See reference 3.) Anumber of tests were rsadeto obtain a comparisonbetweenconventional round-heaciries and this new type of rivetwhen it is auploed in tineconstruction of stiff
10、enedpanels. The results of these tests may be obtained fromreference 1. The conclusion was that the new type ofrivet is as strong as or stroner than conventionalround-head rivets used for -:, . . . r-.:a.-_.d” .2 _ ,“- . . . . - . - = “-. - .-4.RE8UIJ!SMD CONCLUSIONSBecause stresses are establishedb
11、y the relativerather tinanthe absolutd dhensions of the specimens,the results are Fresented in nondimensional form. .Figures 5 to 8 and tables I to IV present test data thathave been reduced to take into account the end flxltythat existed in the tests. The flxity coefficient forsimilar specimens tes
12、ted in the same testing machine hasbeen found to be about 3.75, and that value was used inthe reduction of the data. Two scales are given for theabscissas in figures 5 to 8 - one for a fixity coeffi-cient $ = 1, and the other for c!= 1.5.The data are adjusted to give stresses for panelsthat are suff
13、icientlywide to be conidered as havingan equal number of stiffeners and bays. This adjust-ment was made, in the calculat.onsof average stress atmsxlmm load, by subtracting from the total area and thetotal load the area and the load for one stiffener; theload In a stiffener was obtained by extrapolat
14、ion of theload-strain curve for the stiffener. The adjustmentwas in every case less than 4 percent of the stress.The sheet-buckling load was obtained from the load-strain curve for the sheet and was taken to correspondto the point at which the compressive strain on oneside of the sheet began to be r
15、educed with increasln$load. No correction for the number of stiffeners andbays was made in the calculation of buckling stressbecause the stress was assumed to be uniform untilbuckling occurred. The values of sheet-bucklngstressgiven in figures 5 to 8 are the averages of the valuesshown for correspon
16、ding oups of panels in tables I toIv. I.,-The important feature of tables I to IV and fig-ures 5 to 8 is the presentation of the actual dataSbe-cause these data enable the designer to study the effect .of various dimension ratios m the averae stresfiatmszlnnnnload and on the buckling stress for the
17、shet-stlffener combination.The following conclusions as to the effecc of eachdimension ratio on the average stress at maximum loadand on the buckling stress can be drawn from the data-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-5Ishown In the fig
18、ures and tables, if It is assumed In eachcase thatthe-other ratios are held constant. “The specirienahaving Z-sectionstiffenerswith/bl 6.2 develcped less compressive stress at maximumload than those with bF/bYl= 0.39 0.4, or 0.5. Littlechange Is noted In the average stresp for the values ofF/J above
19、 0.3. Changes in the ratio b have noapparent effect M the buckling stress of tlesheet.2. l%e average stress at maximum load and thebuckling stress of the sheet decrease with increasingvalues of the ratio b+#tS.3. The average stress at maximum load decroasbswith increasing values cf the ratio L/b-:lo
20、ver therane of values used. The tabulated tbatareveal no up-parent effectoithe ratio L/_q on the huclclingstressof the sheet over this rane.4. The averae stress at maximum load increaseswith increasln values of the ratio ti,ts. Althoughthe sheet-buckl:n stresses for panels with tyJ/ts= 1.00were high
21、er than fo corresponding groups of panels with = 0.51, the dt?fercnca is not large and there ap-pears to be n3 COYlS3tStilt trend over tile range ofvalues of tjy/t investigated.Gbw Changes in the ratio bF/: have little ap-parert efect on either the average stress at maximumload or tke bucklinc stres
22、s of the skeet.Some of the foregoing conclusions have been knownto aircraft desgers, but r:merical values havo notbeen Gvailabla to establtsh the optimm proportions ina Siven design nroble?n. Ehls series of tests wes madeto suiJplysome numenics.1deta.Langley wemrldl A9ronautlcalT,abaratory,National
23、AdvicJoryCommittee for Aeronautics,Langley Flold, Va. -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6REFERENCES1. RoHsman, Carl A., and Schuette, 13vanH.: Data onCompressive Strength of Flat Panels with Z-SectionStiffeners. IJACAR.13.,Sept. 1942.2
24、. Gottlieb, Robert, and Mandel, Herven W.: An Im-proved Flush-Rivst Hilllng Tool. NACA R.B.#o. lg,May lG43.3. Lundquist, Eugene l?.,and Gottlieb, Robert: A “Study of the Tightness and l?lushness of Machine-Countersunk Rivets for Aircraft. NACA R.B.,June 1942.Provided by IHSNot for ResaleNo reproduct
25、ion or networking permitted without license from IHS-,-,-NACAFig. 1See detail A,.,*1Detail A#rFFigure 1.- Cross section of Q test panel.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-=_ =- - “ “- u_ .:. - ,.= e. ,“ -6(7I I50 Sheet IStiffeners1/ , A
26、/ w4 A/ /. r r. 74C / / d/ / / / /30 / t I / / /20 t I i 1 ) A i iK)o -O.ooz+StrainFigure 2.- Representative compression stress-strain curves for test panelswith t#=O.5l.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-!-. -_:m+ -:-=-. - -wFigure 3.-
27、Gang riveting of stiffeners to skin with Cincinnati .15.922.6 17.717.116.9 26.323.721.1I- 30.3- 26.4 202i-f15.0F5.29.112.918.15.3J:19055577160015.211.2G18.616.513.7s190417.512.2a19.417.6U,8I0.20.35.810.214.420.0- 30.2-27.9-.- 25.I- 14.6160116.316.1.-24.221.619.712.4n24.720.815.2m24.022.213.6E24.922.
28、815.94.47.021.21549.07.67.06.9K703707-x7.67.87.2m7.57.88.2m7.27.27.07047.37037066.87.67.27087.88.77.27041:15.521.46.511.516.523.46.911.817.023.7*30.3 I32.50- 31.7- 26.6-4.98.411.916.6=8.812.518.2. . . . .17.2176e.-25I- 30.9- 31.2- 26.9 k5.710.214.522*O6.210.615.421.315.9160217.9-e-16.116.717.5-0.4-
29、32.3- 31.4- 27.05*49.413.518.60.50020.30.4O*5-.-.-.-K-.-.-46.$38.411a71416065.39.012.617.6mm.17.725.011.320.018.9160413.619.229.817.713.420,619.8voo13.26.110.615.223229.926.824.116.031.430.727.016.85.59.613.719.3 -123.221a918.413.6.M16,222.85.910.214.620.%6.210091s.421.6i25.624.322.615s725.023.822.6
30、160425.524.423.01.605“3030.731O27.517.4G30.327.517.55.39.613.518.85.81000140320.17.211.217.925.26.5110516.022.316.716.816.9-._ . .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA!% 35tcJ 30Fig. 575e.20.2 n -ALo- “IO“Q()30 920,0100“10oo 10 20 301
31、 I I 1 I IIs . ., _,v ,- -0-c10 10 20 30*forc=lI I I I I I I.,a- -o 10 20 301 I 1 I I I 1 Io 10 20 30 400 10 20 30 400 10 for c= 1.5 m bimo 021 .3.4$ .5Figure 5.- Strenqth of test panels with Z-section2530Stiffeners, lW/t =0.51 (bJtw=ll.4, rw =3,rF/tw=4).Provided by IHSNot for ResaleNo reproduction
32、or networking permitted without license from IHS-,-,-NACATable IITABU II.- TEST DATA FOR PANELSWITH tw/tg = 0.63bSq. = 35 75nbF16.524.3m12.417.824.6 T29.? 35.5- 32.o- 29.4- 17.7 w L:7.98.022.719,215.6-1:19.226.333*132.424.714.4+7.1 18.012.4 16.617.8 15.826.3 -7.5 15.513.4 16.418.8 -e-26.0 -27.425.02
33、0.613.sG25.020.41s.50.3 -8.0 I-1 33.8 6.911.917.124.2_ZE-10.515.521.s22.114.0II-32.420.0 - 26.1275 - 15.119.816.411.3 I0.4122.720.91 a7.5 129.7 32.5 I6.9 16.912.2 16.117.2 16.8 28.026.223.0 8.17.3X_m0.5 A!J18.1123.5 I- 17.26.6 29.6 31.211.4 - 27.316.5 - 23.522,8 - 16.97.1 - 30.712.3 - 29.917.6 - 27.
34、924.2 - 17*9- 30.71;:; - 31.418.1 - 28.125.4- 18.5- 30.41:; - 29.119.3 - 27.627.0 - 18.0EIEE:0.20.30.40.5+5.4 7.49.4 6.913.8 8.119.0 7.65.8 -10.2 7.214.s 7.620.4 7.66.2 8.410.8 7.515.3 8.021.4 7.929.917.316.913*120.619.618.613.83021.221.018.814.121.020.218*O6.8 16.312.0 17.816.9 16.6.23.8 -:;23.216.
35、2II7.2 16.1 26.212.7 15.8 24.0i8.1 15.4 22.35.0 - 17.1 -L6.5 6.411.4 8.316.5 -226 70Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fig. 6!5E.sE30203 w0G Q,010 Z030 0 10 20 30.kfor c= I6+ (1 0w- -m,.0 10 20 302530.Figure 6.- Strength of test pane Is
36、with Z-sctionstiffeners, tw/t =0.63 (bA/tw=10.9, rA/t3, rF/tw=4).Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Table IIITABLE III.- TEST DATA FOR.PANELS WITH. = 1NACAts = 0.79$202530?6.60.2 11.616.723.07.00.3 12.517.925.37.40.4 13.218.725.80.5 1:18
37、.926.6- 34.1-31*G- 27.7-16.9- 34.5-34.4- 26.9-16.527.4 35.7-34.6-29.7- 16.8- 34.831.6 33.726.1 27.7-17.621.319.816.16.2 18.7 26.910.8 18.8 24.115.5 17.5 21.521.5 - 16.35.6- 9.814.119.67.47.98.48.39.68.78.89.6-16.5 -1105 20.516.5 18.922.7 -28.727.223.416.25.910.214.620.722.921.717.412.76.912.117.324.
38、516.919*O18.729.627.223.216.46.210.815.221.79.79.18.68.78.29.38.08.424.723.1 I20.414.2- 124.222.31:18.024.!517.6180818.7-29.728.523.116.4.6*611.316.322.5 J19.413.30.20.30.4L0.528.424.322.815.9 T8.8 21.37.9 18.79.2 16.68.7 13.37.112.518.024.9J:18.726.0- 32.8-29.7-25.7- 16.228.3 37.0- 32.6- 28.2- 17.6
39、- 35.2- 33.3-29.3- 17.1- 33.2- 33.8- 27.9- 17.76.711.716.823.417.218.2-6.110.615.221.26.511.316.222.66.812.017.223.86.911.817.024.0J:17.924.828.928.224.416.929.227.823.317.028.527.4.23.517.223.622.219*313.8-9.48.69.210.17.99.18.2-17.6-.-24.422.619.513.41:20.327.47.513.218.725.814.418.6-.-18.5-17.4-7
40、.913.919,827.57*5130318.826.78.8-7.98.223.622.919.914.2r 7.212.618.025.47.613.519.126.58.114.020.127.88.014.120.228.6- 32.0- 27.7- 23.6-17.36.811.916.62!4.170712.818.125.419.220.125.322.720.217*36.310.915.721.89*O8*68.88.920.817.816.313.70.2 -6*611.716.523.28.98.58.57.922.922.319.214.428.4 33.8-32.0
41、-28.5- 18.619.119.519.127.826.623.617.60.3-18.620.118.4-27.626.822.617.2- 32.5- 31.7- 28.2- 17.5J:19.326.57.613.619.527.47.112.517.825.17.212.717.825.49.09*O8.88.923.621.619.714.00.40.58.18.88.88.122.520.918.914.8- 31.2- 30.2- 26.5-17.117.9- 26.925.023.716.5-Provided by IHSNot for ResaleNo reproduct
42、ion or networking permitted without license from IHS-,-,-NACA.-Fig. 7J?&A. 35 50.- .-75Lsc) .- -0pQd u- -nc*,d *. .- -!?!L?itZo3020250- - m. 30,lo0 I I t 1 1 t I002030I I I I I I I Io 10 20 30kfix C“lo 10 20 301111 I I I I I 111111111Olo 20 30 40%+V?o 10 20 30 400 10 20 30 40-kfor c= 1.5 0 aza75 a71
43、3: :figure 7- strength of test pane is with Z- wet ionstiffaw-s, t /t =0.79 (bA/tw =9.8, rA/tw =3, rF/tw=4).Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TABLE IV.- TEST DATA FOR PANEIS WITHro = 1-J$ = 35mti75 Qo.QbF LEEIa- 33.8- 30.4- 26.7- 16.8-
44、36.3- 32.8- 26.8- 17.6- 36.7- 33.7- 27.3- 17.533.0 36.132.2 34.1- 28.0- 17.20.2-0.30.40.50.20.30.40.527.626.922.316.07.212.718.125.31:!18924.86.812.117.124.0J:17.725.419.519.720.66.310.915.621.68.39.29.09.18.67.7:22.219.917.413.718.318.418.630.227.823.218.51:16.423.224.023.218.314.6- 207.913.719.626
45、.47 a71412.9M.825.818.818.017.5-31.629.124.116.77.012.317.524.69.78.48.38.925.923.820.114.38.314.220.428.58.013.819*527.120.019.017.632*O28.223.216.57.212.918.325.59.08.58.79.226.124.720.214.8-.-6.7210516.825.48.98.99.18.9.- 21.s18.818.013.77.412.919.126.1i.813.919.326.931.626.822.917.333.531.727.318.135.431.828.716.435.333.125.316.87.212.818.224.720.919.626.924.621.216.7- .- 7.413.018.526.019.219.418.629.627.124.317.27.112.01?,424.49.28.28.39.224.222.420.714.7-.-258.113.820.027.1
