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Lab #1 Report due TODAY Individual Data Processing and Individual Write Up Lab #1 Report is due TODAY by midnight Answer Multiple Choice Questions ONLINE TODAY by midnight Answer Student Survey ONLINE TODAY by midnight Submit the Lab Report #1 in the drawer labeled “MECE204 - Strength Lab” under Mech. Engg. Mail Folders
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Tensile Testing: Objectives
Learn elastic and plastic behavior of metallic materials in monotonic tension Learn the use of Tinius Olsen 120 kips UTS and clip-on extensometer Conduct tensile testing experiment on 1018 steel and 2024 aluminum alloy Determine quantitatively elastic and tensile mechanical properties Determine qualitatively the material’s failure mode Become familiar with ASTM E-8 Standard Submit a professional lab report with abstract, data, graphs, and discussion Answer multiple-choice questions and student survey ONLINE using MyCourses
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Tensile Properties Quantitative determination of
Elastic Modulus, E Proportional Limit, PL 0.2% Offset Yield Strength, Y Tensile Strength, TS % Elongation to Failure, %f Modulus of Toughness, Atotal Qualitative study of Failure
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Stress and Strain (b) Cross-Section at B (a) Tension-Test Specimen
F B r (b) Cross-Section at B Figure 1.1 Tension-test Specimen (a) Axially Loaded and (b) Cross-Section at B
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Engineering Stress-Strain Curve
Non-uniform Plastic Deformation Uniform Plastic Deformation Elastic Deformation s , psi e , in/in su sf sy Elastic Region Plastic Yield Region Figure 1.3 Stress-Strain Diagram, Labeled
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Actual Experimentation
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0.2% Offset Yield Strength
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Modulus of Resilience Modulus of Toughness
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Necking begins at maxima
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Shape of Necked Region
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Engineering vs. True Stress-Strain
Engineering Stress = e = P / A0 True Stress = t = P / Ai Engineering Strain = e = / L0 = (Li – L0) / L0 implies Li = L0 * (1 + e) Assume volume is constant until necking: A0*L0 = Ai*Li Ai = A0/(1+e) True Stress = t = P / Ai = P (1 + e) / A0 = e (1 + e) True Strain = t = (dL)/L = Ln(Li / L0) = Ln (1 + e)
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Comparison
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Ductile vs. Brittle Failure
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Fracture Surfaces
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Testing Equipment Universal Testing Machine (UTM)
Tension, Compression and Flexure Monotonic Static Tension Test Single direction, Load increased slowly Crosshead Motion Motor-driven Screw Hydraulically-driven Crosshead ASTM Standards: E8
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Testing Methods Displacement Control Load Control Strain Control
Open loop, Most Common Load Control Close Loop Feedback, Expensive Strain Control
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Data Sheet
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Data Sheet (continued)
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Demonstration Perform the tensile testing experiment on
1018 Cold Rolled Steel
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Data Sheet (continued)
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Lab #1 Report due TODAY Individual Data Processing and Individual Write Up Lab #1 Report is due TODAY by midnight Answer Multiple Choice Questions ONLINE TODAY by midnight Answer Student Survey ONLINE TODAY by midnight Submit the Lab Report #1 in the drawer labeled “MECE204 - Strength Lab” under Mech. Engg. Mail Folders
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