2009+9-2 - Introduction to Solid Mechanics-Vm211...

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1 SJTU Introduction to Solid Mechanics-Vm211 Chapter 9 Mechanical Properties of Materials Chapter 9 Mechanical Properties of Materials SJTU Introduction to Solid Mechanics-Vm211 CHAPTER OBJECTIVES ± Show relationship of stress and strain using experimental methods to determine stress- strain diagram of a specific material SJTU Introduction to Solid Mechanics-Vm211 CHAPTER OBJECTIVES ± Discuss the behavior described in the diagram for commonly used engineering materials ± Discuss the mechanical properties and other test related to the development of mechanics of materials SJTU Introduction to Solid Mechanics-Vm211 1. Tension and Compression Test 2. Stress-Strain Diagram 3. Stress-Strain Behavior of Ductile and Brittle Materials 4. Hooke s Law 5. Strain Energy 6. Poission sRatio 7. Shear Stress-Strain Diagram Chapter Outline SJTU Introduction to Solid Mechanics-Vm211 EXAMPLE 9.1 Tension test for a steel alloy results in the stress-strain diagram below. Calculate the modulus of elasticity and the yield strength based on a 0.2%. SJTU Introduction to Solid Mechanics-Vm211 Modulus of elasticity Calculate the slope of initial straight-line portion of the graph. Use magnified curve and scale shown in light blue, line extends from O to A , with coordinates (0.0016 , 345 MPa) E = 345 MPa 0.0016 = 215 GPa EXAMPLE 9.1 (Solution)
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SJTU Introduction to Solid Mechanics-Vm211 Yield strength At 0.2% strain, extrapolate line (dashed) parallel to OA till it intersects stress-strain curve at A’ σ YS = 469 MPa EXAMPLE 9.1 (Solution) SJTU Introduction to Solid Mechanics-Vm211 Ultimate stress Defined at peak of graph, point B , σ u = 745.2 MPa EXAMPLE 9.1 (Solution) SJTU Introduction to Solid Mechanics-Vm211 Fracture stress When specimen strained to maximum of ε f = 0.23, fractures occur at C. Thus, σ f = 621 MPa EXAMPLE 9.1 (Solution) SJTU Introduction to Solid Mechanics-Vm211 ± When body subjected to axial tensile force, it elongates and contracts laterally ± Similarly, it will contract and its sides expand laterally when subjected to an axial compressive force POISSON’S RATIO SJTU Introduction to Solid Mechanics-Vm211 ± Strains of the bar are: POISSON’S RATIO ε long = δ L ε lat = δ r SJTU Introduction to Solid Mechanics-Vm211 POISSON’S RATIO Poisson’s ratio, ν = ε lat ε long ± Early 1800s, S.D. Poisson realized that within elastic
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This note was uploaded on 08/09/2011 for the course EE 211 taught by Professor Liuxila during the Summer '09 term at Shanghai Jiao Tong University.

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2009+9-2 - Introduction to Solid Mechanics-Vm211...

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