Composite manufacturing and testing ENG 364 Materials Engineering Laboratory PRAC 2 - Tensile testing. Aim 1. To understand the behaviour of different materials under tension. 2. To determine the...

Composite manufacturing and testing
ENG 364 Materials Engineering Laboratory
PRAC 2 - Tensile testing.
Aim
1. To understand the behaviour of different materials under tension.
2. To determine the following mechanical properties of metals:
· 0.1% Proof stress
· Ultimate Tensile Strength
· % elongation
· % reduction of area
· Young’s Modulus (Elastic Modulus)
· Elastic limit
3. From data draw conclusions about the material type.
4. Consolidate theory on dislocation movement, and strain hardening.
5. Visualize a material failure under a microscope.
Readings and Specification:
You must read the following Australian Standard before coming to the class. The standard can be accessed by going to the link http:
www.cdu.edu.au/li
ary/search/a-z_databases.html#A and using your student credentials for login. Only two students/staff can be logged on at the same time. Logout as soon as you have finished.
AS 1391, Metallic materials—Tensile testing at ambient temperature.
Things to consider:
You need to measure the load and extension of the sample undergoing tension.
Load is read off a load cell meter.
You need to measure the extension using a dial gauge.
The tensile test will be conducted on a bench-top tensile tester.
Recording
    Sample 1 -
    
    Sample 2 -
    
    Sample 3 -
    Force (kN)
    Δ
    
    Force (kN)
    Δ
    
    Force (kN)
    Δ
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
Post Test
7.
When the test piece fractures, remove the fractured pieces from the grips. Be careful not to erase your gauge marks.
8.
Place the fractured pieces together and measure the elongation between the gauge marks.
9.
Note the failure surface and view under a stereo microscope.
Calculations:
From the test results determine the mechanical properties.
· Yield stress or 0.1 % proof stress
· Ultimate Tensile Strength
· % elongation
· % reduction of area
· Young’s Modulus (Elastic Modulus)
On the stress strain curve indicate:
· Yield stress or 0.1 % proof stress
· Ultimate Tensile Strength
· Elastic limit
· Plastic region
Report Format: Not more than 4 pages
The report should contain:
· Date and Title
· Results, charts, discussion including comparison to theory, predictions and e
or
· Conclusions and suggestions for improvement.
· Answers to questions given below.
Questions
You must answer the following questions as well.
1. What determines the Young’s Modulus of materials?
2. If the yield strength of a material is increased three times by heat treatment, how many times will the elastic deflection increase for the same load?
3. If a material is loaded above yield strength but below ultimate tensile strength and unloaded, what will be its yield strength when reloaded? You could draw schematic diagram to illustrate this.
4. Name some typical uses for the materials tested based on your test results.
    Section
    Allocated marks
    Entry of data during the lab class
    20
    For the materials provided, calculate
Yield stress
Ultimate Tensile Strength
% elongation
% reduction of area
Young’s Modulus (Elastic Modulus)
    25
    Conclusions with suggestions for improvement
    15
    Answers to questions
    40
    
    TOTAL = 100

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