Chapter6-Lecture 9

# Chapter6-Lecture 9 - 13 Griffith Crack Model 2 1 2 ≈ ρ...

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Chapter 6 Mechanical Behavior Issues to address… Tensile test: What information can be obtained? Elastic behavior Plastic behavior

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Gage length (2inch) Tensile Test
Stress versus Strain 0 A P = σ 0 0 0 l l l l l = - = ε Engineering stress Engineering strain

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Elastic and Plastic Deformation ε σ E = Figures 6-4 Hooke’s law
1. Modulus of elasticity (Young’s modulus), E 2. Yield strength, Y.S. 3. Tensile strength, T.S. 4. Ductility, 100x ε failure 5. Toughness Figure 6-6 Tensile Test

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True Stress and Strain Hardening n T T K ε σ= Figures 6-7 and 8 Actual T A P = σ
Figure 6-9 Toughness

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z x ε ν - = Figure 6-11 Poisson’s Ratio
s s A P = τ o z y = = α γ tan = G ( 29 ν + = 1 2 G E Figure 6-12 Shear stress Shear strain Shear modulus

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Example A 10-mm-diameter metal rod (E=70GPa; ν=0.33; Y.S.=145MPa) is subjected to a 6kN tensile load. Calculate the resulting rod diameter. What about 6kN compressive load?
Ceramics and Glasses Figure 6-13 280MPa 2,100MPa Alumina (Al 2 O 3 )

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Ceramics and Glasses Figure 6-14 (flexual strength)

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Unformatted text preview: 13 Griffith Crack Model 2 / 1 2 ≈ ρ σ c m Figure 6-15 Example A defect-free glass fiber (100 μm diameter) breaks under a tensile load of 40N. After subsequent handing (defective fiber), a similar fiber breaks under a tensile load of 0.15 N. Assuming the second fiber broke due to an atomically sharp surface crack, calculate the length of that crack. Polymers (Plastics) Figure 6-16 Practice A 20-mm-diameter steel bar is used as a structure member in an engineering design. (E=200GPa; Y.S.=600MPa) The unstressed length of the bar is 1m. The structure load on the bar is 90kN in tension. What will be the length of the bar under the tension? What is the maximum tensile load that can be permitted without producing extensive plastic deformation of the bar?...
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Chapter6-Lecture 9 - 13 Griffith Crack Model 2 1 2 ≈ ρ...

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