Question

5. A small leaf spring b=10mm wide by L=125mm long by tam thick is simply supported at its ends and subjected to a center load P that varies continuously from 0 to 20 N. Using the modified Goodman criterion, determine the value of t, given t, given a fatigue strength Ocr = 740M Pa, ultimate tensile strength, ou = 1500M Pa, and safety factor of n=2.5. KL/ 27 L/2 -

Answer 1

Sailun criven In het 4277 b= lomm = 0.olom La 125 mm - Oolasm ou = 1500 MPa = 1500 x 100 la Oty : 7нома : нохо° Ра n = 2.5 Pe Oto 20n bere Bending stress will be developed in the beam and we know that so, o=MxY here, Mmax & PL I= bt & Y = 1 - 2 12 - 3 PL ab tz 3 For my n man Pmax 1 = LX 203,0-), 3 x ROXO-12T Oolo xt 2 6+2 375 Omar =

Similarly I min = 3x min L . 3x0x 0.125 2x0.Ulo xt2 - bez lomino Mean Stress (cm) O max +Omin- om= 2 +0 S5 to m = 187.5 +2 Variable Stress (JV) o max-omin - 313-0 - 2 bus 187.5 According to modified Goodman criteria - Om + xhep Ows of in here ke = 1 therefore, 187.5 { x1500x106 t'x 740X10 t2 = 9.4594x167 It = 9.7258104com 1875 07 t = 0.9725mm