# Presentation Slides

```Lab #1 Report due TODAY





Individual Data Processing and Individual
Write Up
Lab #1 Report is due TODAY by midnight
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
P
P
B
(a) Tension-Test Specimen
r
P
B
F
(b) Cross-Section at B

F
A


L
Figure 1.1 Tension-test Specimen (a) Axially Loaded and (b) Cross-Section at B
Engineering Stress-Strain Curve
Non-uniform Plastic Deformation
Uniform Plastic Deformation
Elastic Deformation
 , psi
u
f
y
Yield
Regio
n
Elastic
Regio
n
Plastic
Regio
n
 , in/in
Figure 1.3 Stress-Strain Diagram, Labeled
Actual Experimentation
0.2% Offset Yield Strength
Modulus of Resilience
Modulus of Toughness
Necking begins at maxima
Shape of Necked Region
Engineering vs. True StressStrain
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)


Monotonic Static Tension Test





Tension, Compression and Flexure
Motor-driven Screw
ASTM Standards: E8
Testing Methods

Displacement Control




Open loop, Most Common
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