tensile testing

1. METHODOLOGY AND
INSTRUMENTATION
TENSILE TESTING LAB
Aaron Teager

2. Methodology
• Determine dimensions
• Mark the sample with lines at 10mm intervals
• Zero instrumentation
• Set up the equipment
• Slowly increase the load, recording the results with Hounsfield
test paper
• Remove extensometer at 0.2mm extension
• Remove the sample when it fractures and record the
necessary measurements.

3. Instrumentation
Extensometer
• Measures the change in length of an
object
• Two types: Contact and Non-Contact
• Contact is normally cheaper, yet still
have high precision
• Non – contact usually involves lasers
• Lindley dial gauge extensometer used in
experiment

4. Instrumentation
Hounsfield Hand Operated
Testing Machine
• Allows for a sample to be
tested under tension
• Often equipped with a
mercury force gauge and a
roll of test paper

5. Instrumentation
Instron Tests
• More expensive than the
Hounsfield
• Greater accuracy
• Not used in Lab because of
expense.
.

6. THEORY BEHIND TENSILE TESTING
TENSILE TEST LAB
Tomos St John

7. Force,F(N)
Elongation, Dl (m)
Plastic Deformation
Elastic Deformation
The Tensile Test

8. Elastic Deformation
Bonds stretching
Returns to it’s original size when force
is released
Metals don’t stretch much elastically

9. Plastic Deformation
Atoms slide over one another due to
dislocations in the structure
Sample won’t return to original size
Metals deform more plastically than
elastically

10. Equations
F
A
 
Stress
In Pa or N.mm2
0
L
e
L
D
 Strain
No units

11. Elastic Behavior
E e  
Hooke’s Law
E= Young’s modulus
A measure of stiffness

12. Plastic Behavior
Eng. Strain
Continuous Yielding
No unique yield point
Use PROOF STRESS
instead
Eng. Strain
Eng.Stress
Upper Yield Stress (UYS)
Lower Yield Stress (LYS)
Discontinuous Yielding
UYS is hard to pin point
LYS commonly used as yield point

13. Ductility
Either measured as
% elongation to failure
Or
% reduction in area at failure

14. ALUMINIUM
TENSILE TESTING LAB
Prajwal Vittapanhally Chandra
Shekara

15. Aluminium
• General information
 Chemical formula: Al
 Molecular weight: 26.98 gm
 It is the second most malleable metal and sixth most
ductile.
• Composition
 1000 series (Al, Si)
 3000 series (Al, Mn, Cu, Mg, Si, Fe)
 5000 series ( Al, Mg, Mn, Si, Fe, Zn)
 8000 series (Al, Sn, Ni, Si, Fe)

16. Properties of Aluminium
Physical Properties
 Density: 2.7 g/cm3
 melting point : approx 5800C
Mechanical properties
 Young's modulus - 68-72 GPa
 Poisson's ratio - 0.33
 Tensile Strength - 70-360 MPa
 Hardness- Vickers - 30-100 Hv
 Yield Strength - 30- 286 MPa
 compressive strength – 30- 286 MPa
 Elongation - 2-41 %

17. Table of results explained
Load, F [kN] Stress, σ [Mpa] Extension, [10-
6]
Strain , ε [10-6]
0.2 8.15 4 80
0.4 16.30 11 220
0.6 24.45 19 380
0.8 32.60 23 460
1.0 40.75 29 580
1.2 48.90 38 760
1.4 57.05 47 940
1.6 65.20 58 1160
1.8 73.35 71 1420
2.0 81.50 88 1760
2.2 89.65 113 2260
2.4 97.80 152 3040

18. Sample Calculations
Modulus of Elasticity = Stress/ Strain = 52.975 × 106 / 1088.3 × 10-6 = 48.69 GPa
Limit of Proportionality and Tensile Strength is Calculated by plotting Load, F[kN] vs
Extension, [10-6 m ] and Stress Vs Strain Graph.

19. Comparing graphs
0
20
40
60
80
100
120
0 500 1000 1500 2000 2500 3000 3500
Stress𝞼(MPa)
Strain, ε(10-6)
Aluminium

20. BRASS
TENSILE TESTING LAB
Yang Zhang

21. Composition
• Alloy (copper with 5-40% zinc)

22. Properties
• Young’s modulus 90-110 GPa
• Yield strength 95-500 MPa
• Tensile strength 310-550 MPa
• Elongation 5-60 %
• Vickers hardness 65-220 HV
——Good malleability and corrosion resistance
Zinc content increases
Density , electrical and thermal
conductivities decrease
The tensile strength and
Vickers hardness increase

23. Results(Overall & Extensometer)
0 0 0 0
0.3 15.8 8 160
0.6 31.6 15 300
0.9 47.4 23 460
1.2 63.3 31 620
1.5 79.1 38.5 770
1.8 94.9 47 940
2.1 111 55 1100
2.4 127 63 1260
2.7 142 72.5 1450
3 158 82 1640
3.3 174 93 1860
3.6 190 109 2180
3.9 206 129 2580
4.2 221 161 3220
Load,F(kN)
Stress
(MPa)
Extension
(10^-6m)
Strain
(10^-6)Original Length 50 mm
Final Length 69 mm
Original Area 18.97 mm^2
Final Area 14.53 mm^2
Elongation 38%
Reduction in area 23%

24. Graph (Extensometer)
0
50
100
150
200
250
0 500 1000 1500 2000 2500 3000 3500
Stress(MPa)
Strain (10^-6)

25. Results(Extensometer)
• The shape of the stress-strain curve is nearly a
straight line
• Young’s modulus is the gradient of the straight
line
•

26. Results(“Hounsfield”)
Yield
Stress
Tensile
Strength

27. Calculation& Comparison
All calculation results correspond with the textbook
values.

28. MILD STEEL
TENSILE TESTING EXPERIMENT
Muhammad Amin Ismail

29. COMPOSITON AND PROPERTIES OF
MILD STEEL
 Also known as Low-Carbon Steel.
 Composition:-
• Ferum: 99.70%wt - 99.98%wt
• Carbon: 0.02%wt – 0.25%wt
 General properties:
• Density: 7800 – 7900 kgm-3
 Mechanical properties:
Modulus of Elasticity 200 – 250 GPa
Yield Strength 250 – 395 MPa
Tensile Strength 345 – 580 MPa
Elongation 26% – 47%
Hardness 107.5 – 172.5 HV

31. TABLE OF RESULT
31
Original length (mm) 50
Final Length (mm) 66
Original Area (mm2
) 31.03
Final Area (mm2
) 28.50
% Elongation 32.00
% Reduction in Area 8.15
TABLE 2: The Cross-sectional
dimensions of Mild Steel

32. THE RELATIONSHIP BETWEEN STRESS AND
STRAIN FOR MILD STEEL
32
0
20
40
60
80
100
120
140
160
180
0 200 400 600 800 1000 1200 1400 1600
Stress,σ(MPa)
Strain, ε (10-6)
FIGURE 1: Graph of Stress vs Strain.

33. THE RELATIONSHIP BETWEEN LOAD AND
EXTENSION FOR MILD STEEL
33FIGURE 2: Graph of Load vs Extension.
Ultimate Tensile Stress
Upper Yield Stress
Lower Yield Stress

34. SAMPLE CALCULATION
34

35. 7.0 COMPARISON SECTION
TENSILE TESTING LAB
James Alexander Douthwaite

36. 7.1 Why do we compare?
36
•Allows trends to be identified and plotted.
•To determine how are results might effect real life
applications.
•To develop a standard, with which to compare others.
•It allows us to predict what might happen in later
experiments (e.g. What a combination of the materials
might exhibit).

37. 37
7.2 Our Results
8.15
16.3
24.45
32.6
40.75
48.9
57.05
65.2
73.35
81.5
89.65
97.8
0
15.8
31.6
47.4
63.3
79.1
94.9
111
127
142
158
174
190
206
221
0
12.9
25.8
38.7
51.6
64.5
77.3
90.2
103
116
129
142
155
0
20
40
60
80
100
120
140
160
180
200
220
240
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400
Aluminium Brass Steel
Stress, ɛ
(10^-6)
Strain,σ(MPa)
A comparison of the relationships between stress and strain for the metals Aluminium, Brass and Mild Steel.

38. 38
7.2 Our Results
Aluminium:Brass:Mild Steel:

39. • The three metals behaved in very different ways.
• Aluminium was the softest, more ductile of the
three samples.
• Brass behaved in a less ductile manner.
• Mild Steel was the stiffest of the three metals.
• The ultimate tensile strength (UTS) varied greatly
between metals.
39
7.3 Interpretation
It is clear from the graph that....

40. The way these metals behaved in this test reflects
how they are used in the real world.
Everyday products take advantage of materials
chosen for their unique properties.
These days materials made to very exact
specifications by splicing the properties of two or
metals together to get the characteristics needed.
40
7.4 Application

41. • Low energy plastic deformation.
• Low Density- Lightweight.
• Highly recyclable.
41
7.4 Application- Aluminium
Key properties:

42. Key Properties:
42
7.4 Application- Brass
• Relatively Low Density.
• Higher elastic/plastic limit than
aluminium, however still relatively
low- malleable.
• Corrosive/tarnish resistant due to its
zinc content.
• Decorative.

43. Key Properties:
43
7.4 Application- Mild Steel
• High UTS
• Very “stiff”- ideal for a wide range
of civil applications.
• Cheap, carbon content.

44. ERRORS & CONCLUSION
TENSILE TESTING LAB
Simon Sladden

45. Systematic Errors
 Incorrect data analysis
E.g. manual calculation of strain value led to results being
incorrect by a power of 10
 Zero error
Incorrect calibration of mercury scale on Hounsfield test
machine due to air bubble
 Engineering stress and strain
Engineering stress and strain were used to make
comparison to true stress and strain values in textbooks.

46. Random Errors
 Irregular data recording intervals
Small variations in stress & strain could have been
missed on force-extension graphs
e.g. UYS and LYS of mild-steel
 Uncontrolled temperature
Small room warms up after time with group of people.
 Reading off small scales
Small & non-conventional scales on Force-Extension graph
axes making it hard to read accurately
Micrometer scale may be misread

47. Improvements
 Use Instron Testing Machine
Digitally plots force-extension graphs at regular intervals –
more accurate
Calibration of measurement scales automatic
 Repeat testing to calculate mean values
Calculate mean values from 3 samples of each metal
 Laser extensiometer
More accurate measurement of extension without making
contact with sample.

48. Industrial Applications
 Wide range of uses for tensile testing:
 Aerospace: Turbine blades
 Automotive: Seatbelts/Bumpers/Mudflaps
 Packaging: Ring pulls/tight packaging
 Sport: Racquet strings

49. SUMMARY
 Tensile test of 3 metals
Mild Steel: Highest UTS & stiffness
Brass: Most ductile
Aluminium:
 Use to industry:
Appropriate material selection based on tensile properties
Meet safety, strength, deformation constraints
Ensure manufacturing quality and consistency
 Material applications:
Mild steel: structural material (e.g. Bridges) due to high
stiffness and strength.
Brass:
Aluminium:

50. ANY QUESTIONS?
THANK YOU FOR LISTENING