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