The document discusses tensile testing procedures and principles. It outlines the components of a universal testing machine used for tensile testing, including the load frame, load cell, crosshead, and output devices. It then provides details on conducting a tensile test, including specimen preparation, loading procedure, and data collection. Examples are given demonstrating how load and elongation data can be used to determine material properties and how finite element analysis can simulate the effects of strain hardening.

1. Barkatullah University Institute of Technology
Presentation on ….
Submitted to: Presented by
MECH ENGG
III Sem.
1

2. OUTLINE
Introduction
Tensile Test- Basic Principles
Terminology
Objectives of the Lab
Tensile Test (Material and Equipment)
Tensile Test Example (Video , Material
Properties and Simulation)

3. INTRODUCTION
A universal testing machine, also known as a
universal tester, materials testing machine or
materials test frame, is used to test the tensile
stress and compressive strength of materials. It
is named after the fact that it can perform many
standard tensile and compression tests on
materials, components, and structures.

4. COMPONENTS
Load frame - usually consisting of two strong
supports for the machine. Some small
machines have a single support.
Load cell - A force transducer or other means of
measuring the load is required. Periodic
calibration is usually called for.
Cross head - A movable cross head (crosshead) is
controlled to move up or down. Usually this is
at a constant speed: sometimes called a
constant rate of extension (CRE) machine.

5. Output device - A means of providing the test
result is needed. Some older machines have
dial or digital displays and chart recorders.
Many newer machines have a computer
interface for analysis and printing.
Conditioning - Many tests require controlled
conditioning . The machine can be in a
controlled room or a special environmental
chamber can be placed around the test
specimen for the test.
Test fixtures, specimen holding jaws, and related
sample making equipment are called for in
many test methods.

6. The set-up and usage are detailed in a test method, often
published by a standards organization. This specifies the
sample preparation, fixturing, gauge length (the length
which is under study or observation), analysis, etc.
The specimen is placed in the machine between the grips
and an extensometer if required can automatically record
the change in gauge length during the test. If an
extensometer is not fitted, the machine itself can record
the displacement between its cross heads on which the
specimen is held.

7. However, this method not only records the change in length
of the specimen but also all other extending / elastic
components of the testing machine and its drive systems
including any slipping of the specimen in the grips.
Once the machine is started it begins to apply an increasing
load on specimen. Throughout the tests the control
system and its associated software record the load and
extension or compression of the specimen.
Machines range from very small table top systems to ones
with over 53 MN (12 million lbf) capacity.

8. Test Specimen:
• The tensile test can be conducted
with either a round bar or sheet
specimen.
Gauge • The round bar specimen used for the
markings
current test complies with the ASTM
standards.
• A 2 inch gage length is marked on
the specimen prior to testing.
• The specimen is held in the clamps
at either end. Load and movement
are applied to the bottom clamp.

9. TENSILE TEST
Extensometer: • The elongation during testing is
measured with respect to the
gauge length using an
extensometer.
• As the specimen elongates, the
extensometer reading
(elongation of the specimen) is
recorded, either real-time or at
discrete time intervals.
• For the current test, an analog
extensometer will be used.
Analog Digital

10. TENSILE TEST
Procedure:
Mark a 2 inch gage length on the tensile test specimen using
the dial calipers and marker.
Measure the diameter of the specimen using dial calipers.
Load specimen in the machine grips and remove most of the
slack by moving the lower crosshead.
Attach and zero the extensometer; secure it with a lanyard
so it will not fall and break if specimen fracture occurs
before the extensometer can be removed.
Zero the load indicator and open the right side hydraulic
valve about ½ turn.

11. TENSILE TEST
Procedure (continued):
As the sample is loaded, close the valve and record the load and
elongation at regular load intervals (e.g. every 1000 pounds) up
to the yield point (when the load starts increasing more slowly
and the strain starts increasing more rapidly).
Continue to load the sample until the extensometer range is
exceeded, then remove the extensometer.
Continue to load the sample until it breaks; pay close attention to
the load indicator and record the load at failure.
Observe and record the maximum load on the follower needle.
Using the dial calipers, measure the final gage length and gage
diameter of the fractured specimen (note: when you calculate
the fracture strength, use the fracture area calculated from the
measured final diameter).

12. TENSILE TEST EXAMPLE
Load vs. Elongation (Data obtained from the tensile test):
Material Data:
Load Vs. Elongation
Al 6061
12000
Y = 40 ksi
TS = 49 ksi 10000
8000
Load (lb)
6000
4000
2000
0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Elongation (in.)

13. TENSILE TEST EXAMPLE
Engineering Stress vs. Strain (calculated from Load vs. Elongation data):
Material Data:
Engineering Stress vs. Engineering Strain
Al 6061
60000
Y = 40 ksi
TS = 49 ksi 50000
Engineering Stress (psi)
40000
30000
20000
10000
0
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Engineering Strain (in/in)

14. TENSILE TEST EXAMPLE
Effect of Strain Hardening:
The influence of work/strain hardening on the load
vs. elongation during the tensile test can be
demonstrated using finite element (FE)
analysis.
Consider two materials with the following flow
stress data:
 Stainless Steel: K = 188 ksi; n = 0.33
 Aluminum Alloy: K = 80 ksi ; n = 0.10.
The tensile test simulations for these two
materials show the effect of strain hardening on
the load required for deformation and the
uniform elongation prior to the onset of
necking.

15. TENSILE TEST EXAMPLE
Effect of Strain Hardening:
180
Material 1 Material 2
160
140
True Stress (ksi)
120
100
80
60
40
20
0
0 0.1 0.2 0.3 0.4 0.5 0.6
True Strain (in/in)

16. TENSILE TESTING SIMULATION
Aluminum 6111-T4 (σ=80.7ε0.23Ksi)
Load-Elongation curve of Al 6111
10
9
8
7
Load (Klbs)
6
5
4 Load-Elongation curve
3
2
1
0
0 0.5 1 1.5 2
Elongation (in)
Before the test

17. TENSILE TESTING SIMULATION
Aluminum 6111-T4 (σ=80.7ε0.23Ksi)
Load-Elongation curve of Al 6111
10
9
8
7
Load (Klbs)
6
5
4 Load-Elongation curve
3
2
1
0
0 0.5 1 1.5 2
Elongation (in)
Uniform elongation

18. TENSILE TESTING SIMULATION
Aluminum 6111-T4 (σ=80.7ε0.23Ksi)
Load-Elongation curve of Al 6111
10
9
8
7
Load (Klbs)
6
5
4 Load-Elongation curve
3
2
1
0
0 0.5 1 1.5 2
Elongation (in)
Neck formation

19. TENSILE TESTING SIMULATION
Aluminum 6111-T4 (σ=80.7ε0.23Ksi)
Load-Elongation curve of Al 6111
10
9
8
7
Load (Klbs)
6
5
4 Load-Elongation curve
3
2
1
0
0 0.5 1 1.5 2
Elongation (in)
Necked region Post-uniform elongation

20. Simulation results- Fracture
Fracture occurs after a certain amount of elongation that is influenced
by the n-value
(a) n=0.2 (b) n =0.4 (c) n = 0.6