pa9_Nov10_09

pa9_Nov10_09 - σ 2/3 vs ρ P I chart(from the W Chapter of...

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AERO3700 PA 9 Three problems below PI Quiz – 45 minutes Tuesday, Nov 10 Purpose: Familiarization and review of Performance Indices using notes and course pack (pg 75- 105). Callister is needed for B and C. A. A cantilever beam which is cylindrical in cross-section is subjected to a force F at the free end. Derive the PI for a light strong beam. Recall σ = Flr/I where L, r, and I are respectively the length, radius and moment of inertia of the beam. The deflection at the free end is δ where δ = FL 3 /3EI and E is the modulus of elasticity. (You may ignore the issue of a safety factor N. ) (Ans: P I = σ 2/3 / ρ) B. Using Appendics B.1 and B.4 in Callister, and the
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Unformatted text preview: σ 2/3 vs ρ P I chart (from the W Chapter of Callister) in your notes locate Ti, Al and steel. Pick Ti-6Al- 4V, 2024T351 and 4340 Oil quenched and tempered, and calculate the P I for each. (Recall g/cm 3 = Mg/m 3 for density.) (Ans: Ti about 24 MPa m 3 /Mg, Al about 17 MPa m 3 /Mg,and 4340 about 17 MPa m 3 /Mg). Note where they sit on the materials chart. C . Using Appendix C in Callister, rank the three choices from B using the P I for strength against relative cost σ 2/3 /CR ρ . Use midrange values for CR if necessary. (Ans: Ti about .24 MPa m 3 \$ / \$ Mg, Al about 1.5 MPa m 3 \$ / \$Mg,and 4340 about 6 MPa m 3 \$ / \$ Mg.)...
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This note was uploaded on 11/13/2011 for the course CIVE 2*** taught by Professor - during the Spring '11 term at Carleton CA.

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