1、.vv: i* 1AUTHORS PERSONAL COFY . .:a71a15NATIONALADVISORYCOMMKITEEFOR AERONAUTICSTECHNICAL NOTE 2566A STUDY OF ELASTIC AND PLASTIC STRESS CONCENTRATIONFACTORS DUE TO NOTCHES AND FILLETS FIAT PLATES- -.By Herbert F. Hardrath and Lacblan OhmanLangley Aeronautical LalxmatoryLangley Field, Va.: Washingt
2、onDecember 1951.- .,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. .NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSTECHNICAL NOTE 2566A STUDY OF ELASTIC AND PIASTICSTRESSFACTORS DUE TOBy HerbertNOTCHES AND FILLETS IN FLAT PLATES.F. Hardrath and Lachl.
3、anOlman-: .Six large 2J+s-T3aluminum-alloy-sheet specimens containing variousnotches or fillets were tested in tension to ,a71INTRODUCTION*Themetlcal studies of stiess concentrations around discontlnuitiesin flat plates have been lAmlted because of .analytlcaldifficulties to .certain geometric shape
4、s (references I to 6) andj unt,ilrecently, to .-the realm of stresses in the elastic range. Experimental studies on _- ,-”“the subJect are scarce, such Investigationsbeing limited by availableloading and strain measuring equint (references7 to I-1). The presentinvestigationwas undertaken to obtain e
5、xperimentally Stress concentration -data in both the elastic and plastic ranges for sheet swctiti cont% a variety of notche= and fillets.A formula has been presented by Stowell (reference 12) for the .-stress concentration factor in the plastic range for a cticular hole in. -an infinite plate. -n th
6、e formula b written in a enerl=d f- “it ,.-;appesrs to be applicable to the mecn shaPes of ts investtgat?on -.:. . -. and to other configurations. . L.-. a71.,. .- -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 .-. . “- NACATN 2566 “ “-.$a71 a14E
7、XXERIMENTALPmcEDmE . b .Since the maximum stress in a panel containing a stress concentrtitiori joccurs at a point and the stress distribution around the point follows “. Za gradient, it is essential for reliable tiasurements that the ratioof notch dimensions to gage lehgth of the strain gages be as
8、 lszge as,.:.possible. Therefore, In order.to obtain a high ratio ad to be able to use strain gages of practical dimensions, the specimenswere made-_-48 by 142 inches. .:_- . -The specimens consisted of SIX 2kS-T3 dumlnum-alloy panels 1 Inchthick. Three panels, deslgned herein by M, contained notche
9、s; three, =designated by F, contained fillets. In each group of three there was . “-a panel designed to have a nominal stress concentrationfactor of 2, .-one of 4, and one ofand F2 F hence the specimens“aredesignated N2”,N4, iT6(Specimendimensions are shown in detail in figs. 1 - 011.shad a sins hol
10、e elongated in thetransverse direction, and three had singk holes at various positionsacross the width of the specimens. TIE spec-, IUS* Of 2W-T3 d.-=alloy, were inches wide, and the radius of a holes was l/2 inch.The stress-strain curve for the material is reproduced as figure 14.Comparisons of the
11、se data and predictions by forml.a (2) arepresented in figures 15 to 20. S“incethe strain measuring techniqpe .employed by Box gave inaccurate results for small strains, but improve,din accuracy for higher strains, the calculations were based on an eeri.-mental value of Kekstic obtained near the hig
12、h end of the elasticrange. The resulting predictions of laatic by formula (2) weewell with the eimental results obtained by Box. .-.I.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8. - .,.,=1.- . . .- -jam “m”2566 ,“- -,-+. . . -m .-REFERENms .-, -
13、:.1. Neuber, Heinz: Theory of Notch Stresses: lnciples for Exact Stres6.,Calculation. J. W. Edwards (Am Arbor, Mich.), 1946.,.- .,. -.-2. sJProc. Sot. erimental Stress lysis, vol. VIII, no. 2, 1951,pp. 99-110. .-10. Frocht,-M. M.: A Photoelastic Investigation of Stress Concentration Due to Small Fil
14、lets and Grooves in TensiELon. .,.“NACATN 2442, 1951.11. Coker, E. G.,and Filon, L. N. G.: A Treatise on Photoglasticity. .-Cambridge UnivPress, (London) 1931. ,-, -12. Stowell, Elbride Z.: StleSS.,- .-. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,
15、-,-.NACA m 2566.i1-15*+E151+;1=i!Lr:-IHEI.ist 321,. - .- lJ Tuokermon gage orelectromagnetic gageo SR-4 type A-1 gageI SR-4 type A-5 gage.Note Same gaging onappoelte elde. -. . .:I , II N2 I 6.750 IIN61 .4641-.w -.-. L- .- -.,. . . .-.:Figure 1.- Dlmeneione agd instrumentation of notched spmens.(All
16、 dimeneione are in inchee.). .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACA m 2%6.-a71a13a26a15 a15 a8a15a14.;-.-I40stress,Id200N2IFigure 3.-N4fN6Iti4m-IStrems-atialmcurves of MS-I!3 alumlnum alloy for eachapecinlen Imatad.- .-,Provided by
17、 IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.=12 NACAm 2566 - .:.Eladc airemCcimntmtbnfactw,Km .- . - - . . . .,. I6 r. .*-. : _. .(b) Apparent stress dlstributl.on.Figure 12.- Stra.indistribution and apperent stress distribution at thenet section of specim
18、en”E2. . . .9.a71.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. .NACA TN a66 “-”-StmlnStreq ksi.010rap “-.-/ %W24“.- . 0124 8 161DMnce *m edgooffillet,h,(a) Strain distribution.,6040200.ksla71.a71a15 a15 Dletance fram edge of fillet, In. -(b) App
19、arent stress distribution.Figure 12.- Strain distribution and apparent stress distribution,net section of specimen Fk. .- .-, ,4. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-19 . .StrafnKo0 20 40 1 60Averagenet-sedanstrese,Um,kslFigure . - Stres
20、s concentration factor for a flat”plate with semi- -”_.:“circular edge notches. , .-. ,. . stress40 Experiment (ref. 9)- Forma (2 ,32I-concentmtlonfactor, K. .t .-. “1:.-.“,.-.,n-o 20 40 60Avsrage net-ssction stress, crev,kslb Figure 16.- Stress concentrateIon factor for a flat plate with a sInglece
21、ntral hole elongated in the transverse direction.a71Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-22 HACA m 25662 - .- =I.O Experiment (ref 9) 0“. .- Formula (2) . -“stress camentmtion I () “factar, Ky - .“-:”:!o 20 40 -. -,.:A#eragenet-sectlan etr
22、ess, u, kelFire 17. - Stress concentration factor for.a flat plate with w .circulsx holes equally spaced in,ope cross gection. - stresscfmcentratlanftor, K432IIo Experiment (ref. 9)o Formula(2)o -,.m o1 )I I 1“-.?-. +i;. .- “.s*:.:.:-“-:;-o 20 40 60Avemge net-sectlan stress, Uaw kslJ . . !.-Fure 18.
23、- Stress coneentrationhole lcicated.factor for a flat plate with a cirmilar . - * from the edge. ,9_.1-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Klwl m 2566” 23. .0 Experhent (ref. 9)J2) Form.d2Stressconcentratbnfactor, KI,-.“. .“3E!EE“I. . -o
24、20 40 60StrSSS,Csv,kslAverage net-sectionplate with q circuJarfactor for a flatFigure 19. - Stress concentrationhole located from the edge.8.3 Io Experiment (ref. 9). Formu (2) 2Stressconcentrationfactor, KI.,-i 4=-, t-I-020 40 60Avemgenet-section streee, qv,ksiFigure 20.- Stress concentrationcentral,factor for a flat plate with a sf.ngle,circular hole.mcA-Iacg”-ls441. lm-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
