Only compressive stress is negative by convention

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Unformatted text preview: OF,ELASTICITY,(E) SHEAR,MODULUS,(G) POISSON'S,RATIO,( ν ) GPa GPa ALUMINUM,ALLOYS 70:79 26:30 0.33 2014:T6 73 28 0.33 6061:T6 70 26 0.33 7075:T6 72 27 0.33 CONCRETE,(COMPRESSION) 17:31 0.1:0.2 GLASS 48:83 19:35 0.17:0.27 PLASTICS NYLON 2.1:3.4 0.4 POLYETHYLENE 0.7:1.4 0.4 RUBBER 0.0007:0.004 0.0002:0.001 0.45:0.50 CORK 0 STEEL 190:210 75:80 0.27:0.3 TUNGSTEN 340:380 140:160 0.2 1/17/13 M. Mello/Georgia Tech Aerospace 9 MATERIAL( ALUMINUM(ALLOYS 20145T6 60615T6 70755T6 BRASS BRONZE CAST(IRON((TENSION) CAST(IRON((COMPRESSION) CONCRETE((COMPRESSION) COPPER(AND(COPPER(ALOYS GLASS PLATE(GLASS GLASS(FIBERS MAGNESIUM(ALLOYS MONEL((67%(Ni,(30%(Cu) NICKEL PLASTICS NYLON POLYETHYLENE YIELD(STRESS MPa 355500 410 270 480 70(5(550 82(5(690 120(5(290 80(5(280 170(51100 ULTIMATE(STRESS MPa 1005550 480 310 550 200(5(620 200(5(830 69(5(480 340(5(1400 (10(5(70( 230(5(830 30(5(1000 70 7000(5(20000 140(5340 450(51200 100(5(620 310(5(760 55(5(760 40(5(80 7(5(28 50(5(280 20(5(200 ROCK RUBBER STEEL HIGH5STRENGTH MACHINE SPRING STAINLESS TOOL STEEL,(STRUCTURAL ASTM(5(A36 ASTM(5(A572 ASTM(5(A514 1/17/13 MATERIAL (YIELD) PROPERTIES 1(5(7 (7(5(20 340(5(1000 340(5700 400(5(1600 280(5(700 520 200(5(700 250 340 700 550(5(1200 550(5(860 700(5(1900 400(5(1000 900 340(5(830 400 500 830 M. Mello/Georgia Tech Aerospace 10 Example 2- 7 (post mortem) thermal strain mechanical strain CHECK OUT PHYSICAL IMPLICATONS OF THIS RESULT. . . E = 205GPa ↵ = 17 ⇥ 10 6 [C ] T = 100[C ] = + 1 1 T = E ↵( T ) T = 348.5 MPa RepresentaOve properOes of Stainless steel This is high! ²་  Yield stress of stainless steel is in this range (depends upon specific grade) ²་  A 100 C° temperature increase would YIELD the constrained steel beam. ²་  A similar calculaOon for concrete demonstrates the need for expansion joints in bridge design. T 1/17/13 = E ↵( T ) (2- 18) M. Mello/Georgia Tech Aerospace 11 Example 2- 8: SLEEVE AND BOLT ASEMBLY SUBJECTED TO TEMPERATURE CHANGE Displacement of steel sleeve: GIVEN: ²་  Steel sleeve (circular tube) of length (L) around bolt fised between washers at each end with “snug” nut. ²་  αs = coefficient of thermal expansion (CTE) of sleeve ²་  αb = coefficient of thermal expansion (CTE) of bolt ²་  αs > αb PROBLEM STATEMENT: ²་  Assembly undergoes uniform temperature increase ΔT ²་  CALCULATE thermal stresses (σs) and (σb) developed in the sleeve and bolt, respecOvely. ²་  CALCULATE overall length increase (δ) of the assembly SOLUTION STRATEGY: ①  Apply some basic mechanical intuiOon before analysis ²་  AS TEMP INCREASES...
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This note was uploaded on 09/19/2013 for the course CEE 3001 taught by Professor Zhu during the Spring '09 term at Georgia Institute of Technology.

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