6_ch 08 Mechanical Design budynas_SM_ch08

6_ch 08 Mechanical Design budynas_SM_ch08 - δ = pt = t N...

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Chapter 8 209 8-15 (a) A d = 0 . 7854(0 . 75) 2 = 0 . 442 in 2 A tube = 0 . 7854(1 . 125 2 0 . 75 2 ) = 0 . 552 in 2 k b = A d E grip = 0 . 442(30)(10 6 ) 13 = 1 . 02(10 6 ) lbf/in Ans. k m = A tube E 13 = 0 . 552(30)(10 6 ) 13 = 1 . 27(10 6 ) lbf/in Ans. C = 1 . 02 1 . 02 + 1 . 27 = 0 . 445 Ans. (b) δ = 1 16 · 1 3 = 1 48 = 0 . 020 83 in | δ b |= ± | P | l AE ² b = (13 0 . 020 83) 0 . 442(30)(10 6 ) | P |= 9 . 79(10 7 ) | P | in | δ m |= ± | P | l AE ² m = | P | (13) 0 . 552(30)(10 6 ) = 7 . 85(10 7 ) | P | in | δ b |+| δ m |= δ = 0 . 020 83 9 . 79(10 7 ) | P |+ 7 . 85(10 7 ) | P |= 0 . 020 83 F i =| P |= 0 . 020 83 9 . 79(10 7 ) + 7 . 85(10 7 ) = 11 810 lbf Ans . (c) At opening load P 0 9 . 79(10 7 ) P 0 = 0 . 020 83 P 0 = 0 . 020 83 9 . 79(10 7 ) = 21 280 lbf Ans . As a check use F i = (1 C ) P 0 P 0 = F i 1 C = 11 810 1 0 . 445 = 21 280 lbf 8-16 The movement is known at one location when the nut is free to turn
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Unformatted text preview: δ = pt = t / N Letting N t represent the turn of the nut from snug tight, N t = θ/ 360 ◦ and δ = N t / N . The elongation of the bolt δ b is δ b = F i k b The advance of the nut along the bolt is the algebraic sum of | δ b | and | δ m | Original bolt Nut advance A A ± ± m ± b Equilibrium Grip...
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This note was uploaded on 12/13/2011 for the course EML 3013 taught by Professor Shingley during the Fall '11 term at UNF.

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