913_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

913_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

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Problem 11.9-28 A solid round bar of aluminum having diameter d (see figure) is compressed by an axial force P ± 60 kN. The bar has pinned supports and is made of alloy 6061-T6. (a) If the diameter , what is the maximum allowable length of the bar? (b) If the length , what is the minimum required diameter ? ( Hint: Convert the given data to USCS units, determine the required quantities, and the convert back to SI units.) d min L ± 0.6 m L max d ± 30 mm SECTION 11.9 Aluminum Columns 907 Solution 11.9-28 Aluminum bar Alloy 6061-T6 Pinned supports (a) F IND L max IF d ± 30 mm ± 1.181 in. Assume L/r is less than 66: Eq. (11-85 a ): Solve For L/r : L max ± (62.54) r ± 18.47 in. ± 469 mm ; L r ± 62.54 L r 6 66 ok or 12.32 ± 20.2 ² 0.126 ( L / r ) s allow ± 20.2 ² 0.126 ( L / r ) ksi s allow ± P A ± 13.49 k 1.095 in. 2 ± 12.32 ksi r ± A I A ± d 4 ± 0.2953 in. A ± p d 2 4 ± 1.095 in. 2 I ± p d 4 64 ( K ± 1). P ± 60 kN ± 13.49 k (b) F IND d min IF L ± 0.6 m ± 23.62 in. Assume L/r is greater than 66: Eq. (11-85 b ): L / r ± 94.48/ d ± 94.48/1.317 ± 72 7 66 ok d min ± 1.317 in. ± 33.4 mm ; d 4 ± 3.007 in. 4 or 17.18 d 2 ± 51,000 (94.48/
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Unformatted text preview: d ) 2 s allow ± 51,000 ksi ( L / r ) 2 s allow ± P A ± 13.48 k p d 2 /4 ± 17.18 d 2 (ksi) A ± p d 2 4 r ± d 4 L r ± 23.62 in. d /4 ± 94.48 in. d Wood Columns When solving the problems for wood columns, assume that the columns are constructed of sawn lumber (c ± 0.8 and K cE ± 0.3) and have pinned-end conditions. Also, buckling may occur about either principal axis of the cross section. Problem 11.9-29 A wood post of rectangular cross section (see figure) is constructed of structural grade, Douglas fir lumber ( ). The net cross-sectional dimensions of the post are (see Appendix F). Determine the allowable axial load P allow for each of the following lengths: L ± 5.0 ft, and 10.0 ft. Probs. 11.9-29 through 11.9-32 b ± 3.5 in. F c ± 2,000 psi, E ± 1,800,00 psi 4 in. * 6 in. h b 11Ch11.qxd 9/27/08 2:27 PM Page 907...
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This note was uploaded on 12/22/2011 for the course MEEG 310 taught by Professor Staff during the Fall '11 term at University of Delaware.

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