Question

2. The cold drawn AISI 1040 steel bar with 25-mm width and 10-mm thick has a 6- mm diameter thru hole in the center of the plate. The plate is subjected to a completely reversed axial load that fluctuates from 12kN to 28kN. Use notch sensitivity of 0.83. (40 points) a. Estimate the fatigue factor of safety based on yielding criteria. b. Estimate the fatigue factor of safety based on Goodman and Morrow criteria.

11th Edition data must be used

Answer 1

Given, Finan =28kx) Finiy =12kN Sut ¿ 590MPS Sy 490MPa 2 Check for yielding Fmare mark A Q8X103 IO (25-6) = 147.4 nimms 2 2 147.4m pa Factor of safety by sy Imax 490 27 1474 3.32 b) Goodman criteria sel 0.5 Sat ( equations 6.10) endurance limit 2 0.5x 590 = 295M Pa Surfuce conditation modefications factor ka - asub (eq -6.18) a 23.04 6 -0.217 /

-0.017 Kaz 3.06 (590) = 0.26 size factor, kb = 1 Cancal load) equaten-6-20 lachy fectoi Kc =0.85' (arcal load) eq - 6-255 endurance limual critical Costus, Se = kako ke sel 6:19) 0.76x) x0.85 x 295 z 190.6 MPa Given, q 20.83 Yo = 9a5 = 0.24 from figure A-15 1 for diw = 0.24 SKUs concentrale Fulton ke 2.44 we know, ks = Itecky-1) 1+0.83(2.46-1) 2 a.20 Finan - Fimin amplehude component, Jaz kg z 2A 28000 - 12000 11 d. 2x 2x10x (25-6) = 92.63MPa

med range camponens, om 2 Foran & Famis kg 2A 290007 12000 2.2 x dx cox (05-6) 231.6 MPa hoodman nitona ý oa -it Se om Sur 2 231.6 - 90.63 + 590 uf 190.6 0.8785 nf ng 21:14 1:14 ng 2 Factor of safety Morrow criteres oat 11 of se of a true fracture stress 6-44) of equ See +345 Ce 2 590 +345 3 935 mpa 92.63 231.6 0.486 +0.248 0.734 N it hf 190.6 935

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