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Unformatted text preview: Chapter 8, Problem 3 A machined and fullfilleted AISI 4140 annealed steel bar carries a fluctuating axial loading, as shown in Figure P8.3. What is the value of endurance limit S e ? Given: b = 20 mm, D = 30 mm , r = 2 mm Assumptions: A reliability of 90% is used. Chapter 8, Solution 3 ' (1 ) e f r s t f S C C C C K S = e (a) We have 2 26 0.077, 1.154 r D d d = = = 2.5 t K = (Fig.C.3) Table B.4: 655 , 197 u B S MPa H = = ' 0.45 294.8 e u S S M = = Pa = Table 8.3: 0.89 r C = Fig.8.8: 0.8, 1 0.8(2.5 1) 2.2 f q K = = + − Table 8.2: 0.265 4.51(655) 0.809 b f u C AS − = = = Use 1 C = (axial loading) s 1 t C = Equation (a) is therefore 1 2.2 (0.809)(0.89)(1)(1)( )(294.8) 96.48 e S MPa = = Chapter 8, Problem 7 A cold drawn AISI 1020 annealed steel link is subjected to axial loading (that fluctuates from 0 to F ) by pins that go through holes (Figure P8.7). What is the maximum value of F with a factor of safety of n , according to the Goodman criterion? Given: R = 10 mm, r = 4 mm, t = 2.5 mm, n = 1 . 4 Assumption: A reliability of 99.99% is used. Chapter 8, Solution 7 Table B.3: ' 470 131 0.45 211.5 u B e u S MPa H S S MPa = = ∴ = = Tensile area through the hole: 2 2( ) 2(10 4)(2.5) 30 R r t mm − = − = and 2 2(30) 6 F F F A m a σ σ = = = = (a) We have C 0.70 r = (Table 8.3) 1 t C = C A 0.265 4.51(470) 0.88 b f u S − = = = C 1 s = (axial loading)...
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 Winter '10
 Kim

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