REG NACA-TR-1117-1953 A Study of Elastic and Plastic Stress Concentration Factors Due to Notches and Fillets in Flat Plates.pdf

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1、REPORT 1117A STUDY OF ELASTIC AND PLASTIC STRESS CONCENTRATION FACTORS DUE TONOTCHES AND FILLETS IN FLAT PLATES 1By HEEBIIBTF. HAEDBATHandLACHLAN OHMANSUMMARYSix large 2L-53 alunvkuwhy-dwet 8pecimm3 cOntain-i variommtch.txwfltk% weretestedin temionto determinetheirstTes8concentration fact0r8 in both

2、 the elmtic and plmticranges.The elaalti sW38 concentration factors were fownd to beslightly higher than. tlwse cakulakd by Neuber8 method andtho8e obtained photd.a.sttiy Tocht. lh.e rtxu.h 8howedfurther that tlw 8tre38concentration factor deeream a8 straimat the discontinuity enter the piMiz range.

3、A generakation of L!3towtis rd.ationfor tb pbtti 8tre38concentration factor at a circular Me in an in$nit# plute mappkxi to tk 8pecim.ei 8h5pk t.ed and gave good agTWIW%tWiJ?hL?.9tT three, designated by F, contained Mets.In each group of three there was a panel designed to have anominal stress conce

4、ntration factor of 2, one of 4, and one of6; hence the specimens are designated N2, N4, N6 and F2,F4, and F6. (Specimen dimensions are shown in detail infigs. 1 and 2.)The panels were cut from sheets 54 inches wide. Excessmaterial from the region near the notches or fiIlets was usedto make standard

5、tensile coupons, four for each panel.Standard tensile tests run on these coupons yielded stmss-strain curves. Each of the shww-stmin curves as presentedin iignre 3 is an average of the four curves obtained from thefour coupons for each panel.Four types of strain gages were used in the investigation.

6、On panels N2 and F2 Tuckerman optical strain gages with aX-fich gage lth were moted on tie face at the edge ofthe panel at the critical points which are defined as.the pointson each panel where the maaimum stress concentrationsoccur. In a notched specimen the maximum stress occursat the center of th

7、e base of the notch. Photo elastic studiesof filleted specimens (ref. 6) indicate that the maximumstress occurs at a point about 10 around the fillet from thetangent between the iillet and the straight side of the reducedpart of the panel. Straim3 at the critical points of panelsN4, N6, F4, and F6 w

8、ere measured with fie-inch-gage-lengthelectromagnetic extensometers mounted on the edges of thepanels at the critical points. (See figs. 1 and 2.)Baldwin SR4 type A5 strain gages were applied atintervals across the width of each panel at the net section todetermine the strain distribution at that se

9、ction (figs. 1and 2). In a no.tohed panel the net section is dd0) .15fFremm S.-EfastfoatrwaamcentmtkdrfnotomforSlfetedsw.lmanni5)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-13LASTIC AND PLASTIC STRESS CONCENTRATION FACPORS DUE TO NOTCHES AND FILL

10、ETS IN FLAT PLATRS 217PLA13TfC8TBE3SCONCENTRAON FACTORS AND A SUGGESTED FORMULA IIigurea 6 and 7 show the experimentally determined stressconcentration factom plotted against average net-sectionstress. The stress concentration factors start to decrease asthe load on a panel exceeds a value suilicien

11、t to cause plasticyielding at the critical point.Stowell (ref. 12) presented a relation to be used in calcu-lating the stress concentration factor in the plastic rangefor a circular hole in an infidite plate subjected to tension.This relation states that at any one instant in the loading- a-+ :,.-SY

12、:+r“ w20 40 fin.“Awoge net-section stress, St-ksiFmcms 19.-Stms3 concentrationfaotorfora t platnwith a chuhr hdo khstad wfrom the E&e.3 I Ik O Expsrinmt(ref.9)s FwrmJo (2)z o 0& o5F!: . .0 20 40 60rherq-e m+ectbn stress, S, Waux 20.-Shcss czmomtraffon faotor foraflatPI.WwSthasfn mntrol,drdor 1100.3.

13、 Ling, Chih-Bing: Stressm in a Notched Strip Under Tension,Jour. Appl. Me&., vol. 14, no. 4, Dee. 1947, pp. A-276-&MO.4. Ling, Chih-Bing:On the StreeSMin a Plate Containing TNO Cir-0* Holes. Jour. Appl. Physics, vol. 19, no. 1, Jan, 194S,pp. 77-82.5. HoMand, 1% C: J.: On the Stresses in the Neighbor

14、hood of a&cular Hole in a Strip Under Tension. Phil, Trans. Roy. SOO,(London), sm. A, vol. 229, Jan. 6, 1930.6. Tirnosherdm, S.: Theory of Ekrgtioity. First cd., MoGrrnv-HillBook Co., Irm., 1934.7. Tirnoehenko, S.: Strength of Materiala, Part 11-AdvanoedTheory and Problems. Second cd., D. Van Nostra

15、nd Co., Ino.,1941.8. Grif3th, George E.: erimental Investigation of the Effoote of910.11.12.Plastio Flow in a Tension Pahel With a Ciroular Holo. NA(YATN 1705, 1948.Box, William A.: The Effect of Pla.stio Strains on Strc.qef.2cmcen-titora. Proc. Soo. Experimental Stress Analysisj vol. VIII, no,2, 19

16、61, pp. 99-110.Frooht, M. M.: A Photoelastio Investigation of Stroee Conoentr&tions Due to Small Fillets and Grooves in Tension. NA(YATN 2442, 1951.(%ker, E. G., and Filon, L. N. G.: A Tmatfse on Photo-Elasticity.Cambridge Univ. Press (London), 1931.Stmve Elbridge Z.: stress and Strain Concentration m+a CirouhmHole in an InRnite Plate. NACA TN 2073, 1950,.-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-