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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
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
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
Stress and Strain
PP B
P FB
r
(a) Tension-Test Specimen
Figure 1.1 Tension-test Specimen (a) Axially Loaded and (b) Cross-Section at B
(b) Cross-Section at B
A
F
L
Engineering Stress-Strain Curve
, psi
, in/in
u
f
y
ElasticRegion
PlasticRegion
Yield Region
Figure 1.3 Stress-Strain Diagram, Labeled
Elastic Deformation
Uniform Plastic Deformation
Non-uniform Plastic Deformation
Actual Experimentation
0.2% Offset Yield Strength
Modulus of ResilienceModulus of Toughness
Necking begins at maxima
Shape of Necked Region
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)
Comparison
Ductile vs. Brittle Failure
Fracture Surfaces
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
Testing Methods
Displacement Control Open loop, Most Common
Load Control Close Loop Feedback, Expensive
Strain Control Close Loop Feedback, Expensive
Data Sheet
Data Sheet (continued)
Demonstration
Perform the tensile testing experiment on
1018 Cold Rolled Steel
Data Sheet (continued)
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