The University of Texas Permian Basin
College of Engineering
Department of Mechanical Engineering
Ehsanul Kabir, Ph.D
MENG-4205 Thermo-Fluid Lab
Impact Test
November 30, 2020
Table of Contents
Abstract ........................................................................................................................................................................ 2
Introduction .................................................................................................................................................................. 2
Methodology ................................................................................................................................................................. 3
Theory ....................................................................................................................................................................... 3
Apparatus/Equipment/Materials ................................................................................................................................ 5
Figure 1: The Charpy and Izod Impact Testing Unit (EEICI) [2] ........................................................................ 5
Figure 2: The Protractor Point [2]........................................................................................................................ 6
Figure 3: Charpy and Izod Hammers [2] ............................................................................................................. 6
Figure 4: Supporting clamps [2] .......................................................................................................................... 7
Figure 5: Placement of plastics on supporting clamps [2].................................................................................... 7
Procedure .................................................................................................................................................................. 8
Results ........................................................................................................................................................................... 9
Table 1: Data collected while performing the Izod Test ...................................................................................... 9
Table 2: Data collected while performing the Charpy Test .................................................................................. 9
Table 3: Results calculated by performing the Izod Test ..................................................................................... 9
Table 4: Results calculated by performing the Charpy Test ................................................................................. 9
Figure 6: White material after impact on the Izod Test...................................................................................... 10
Figure 7: Blue material after impact on the Izod Test ........................................................................................ 10
Figure 8: Clear material after impact on the Izod Test ....................................................................................... 10
Figure 9: White material after impact on the Charpy Test ................................................................................. 11
Figure 10: Blue material after impact on the Charpy Test ................................................................................. 11
Figure 11: Clear material after impact on the Charpy Test ................................................................................ 11
Discussion ................................................................................................................................................................... 15
Conclusion .................................................................................................................................................................. 15
References ................................................................................................................................................................... 17
Appendix..................................................................................................................................................................... 18
1
Abstract
The purpose of this experiment is to observe materials toughness and indirectly its
ductility. To do so, this experiment utilizes the Charpy and Impact testing unit (EEICI) from
Edibon, that is equipped with a pendulum supported on bearings, that can be fixed with either a
Charpy or Izod hammer, a protractor that indicates the angle and three plastics (white, blue,
clear) . For both the Charpy and the Izod, begin the experiment by placing the pendulum on the
releasing mechanism with a starting angle of 150°. Release once and collect the first angle from
the protractor, then release again from 150° to collect the second angle. Repeat three times for
both hammers. Once completed, run the experiment by placing a plastic onto the supporting
clamps and release the pendulum from 150, then collect the angle given by the protractor. This is
repeated for both hammers and each plastic. Analyzing the data shows that the clear plastic
absorbed the most energy (5.49 Joules) in both methods of testing, while the blue material
absorbed the least amount of energy (1.09 Joules) during the Charpy Test and absorbed the same
amount of energy (1.90 Joules) as the white material during the Izod Test.
Introduction
The purpose of this experiment is to test the impact strength of each of the three materials
being observed. There are two testing methods used, the Izod Impact Test and the Charpy Impact
Test. The two methods vary only by the position and orientation in which the sample is secured
prior to impact. The primary goal is to calculate the amount of potential energy when the
pendulum is all the way up then calculate the amount of energy remaining after it has struck the
sample. These two values may then be subtracted to find the amount of work or energy it takes to
break each sample which corresponds to the impact strength of each material, respectively.
2
This method of impact testing is incredibly important to the world in which we live
today. While these tests may not always replicate the exact situation that a material will
experience once in use, they provide practical modes of failure, and values for the impact
strength of a material which can then be used in numerous ways. The most important information
gathered from these tests is how the material fails. This is critical to the use of certain materials
in the design of structures. For example, a brittle material which fails almost instantly due to one
crack propagating the entire sample upon impact, would never want to be used in a structural
application. If a structure begins to fail it should do so gradually, like a ductile material so that
everyone has the ability to get out and then proceed to make repairs rather than collapsing
immediately like a brittle material which could injure or kill the occupants.
Methodology
Theory:
The Izod and Charpy Tests are both forms of impact tests that are used to determine the
strength of materials. They both work similarly, in that they both utilize a hammer attached to a
pendulum to break materials. However, the difference lies in the way that the material specimens
are held. During the Izod test the specimen is placed vertically and clamped down on the bottom
end and is placed so that the face with the notch faces the direction that the hammer is coming
from. During the Charpy Test the specimen is placed horizontally so the notched side is facing
away from the direction that the hammer comes from. In both impact tests the initial angle every
time is α = 150°. Using the initial angle (α), the initial energy (𝐸!) can be found as:
𝐸! = 𝑚 × 𝑔 × 𝑙 × '1 − 𝑐𝑜𝑠(𝛼)0
3
(1)
Where, 𝑚 is the mass of the hammer, 𝑔 is gravity (𝑔 = 9.81
" ),
#!
and 𝑙 is the length of the
pendulum. Both devices have their own constant, initial energy. Now, the final energy (𝐸$) can
be found by using a similar equation to equation 1:
𝐸$ = 𝑚 × 𝑔 × 𝑙 × '1 − 𝑐𝑜𝑠(𝛽)0
(2)
Where, 𝛽 is the angle given by the indicator, 𝑚 is the mass of the hammer, 𝑔 is gravity
(𝑔 = 9.81 "!), and 𝑙 is the length of the pendulum. Next, the absorbed energy (𝐸%) can be found
#
by using the initial energy (𝐸!) and final energy (𝐸$) as follows:
𝐸% = 𝐸! − 𝐸$
(3)
Now, the indicator loss (𝑊&') can be found by:
𝑊&' = 𝑊( − 𝑊)
(4)
The indicator loss is found by running the impact tests without specimens three different
times on each device. 𝑊) is found by using the angle shown by the indicator as it is pushed from
0° to where the pendulum stops. To find 𝑊( the indicator is left where the pendulum stopped to
find 𝑊). The angle that is displayed after the pendulum has pushed the indicator further is used
to find 𝑊(. Both 𝑊( and 𝑊) utilize equation 2 to be calculated. The total indicator loss is
calculated three times for each test and then averaged together to find one total indicator loss
(𝑊&' +,+) for each test:
𝑊&' +,+ =
4
-"#$ .-"#! .-"#%
/
(5)
Where, 𝑊&'( is first calculated indicator loss, 𝑊&') is the second calculated indicator loss,
and 𝑊&'/ is the third calculated indicator loss. The energy due to friction losses (𝐸01) on both
devices can be found utilizing the total indicator loss (𝑊&' +,+) and the initial energy (𝐸!), found
on their respective devices:
𝐸01 = 𝐸! − 𝑊&' +,+
(6)
Apparatus/Equipment/Materials:
Figure 1: The Charpy and Izod Impact Testing Unit (EEICI) [2]
Figure 1 displays the Charpy and Izod Impact Testing Unit (EEICI). The EEICI is
composed of a pendulum supported on bearings with an arm of 330mm long and a releasing
mechanism that’s set at the initial position of the test (150°). The EEICI has a protective clear
5
cover that shields the user when conducting the experiment. The EEICI also has a protractor
pointer that measures the angle after impact from the pendulum.
Figure 2: The Protractor Point [2]
Figure 2 displays the Protractor Point that measures the angle after impact from the
pendulum.
Figure 3: Charpy and Izod Hammers [2]
Figure 3 displays the Charpy and Izod hammers utilized in this experiment. The left
image is the Charpy and the right image is the Izod.
6
Figure 4: Supporting clamps [2]
Figure 4 displays the supporting clamps used for the plastics uses. The image on the left
is used for the Charpy experiment and the image on the right is used for the Izod experiment.
Figure 5 below will display how the plastics are placed onto the supporting clamps.
Figure 5: Placement of plastics on supporting clamps [2]
Figure 5 displays how the plastics will be placed on the supporting clamps. It is important
to note that this is how the experiment will be conducted.
7
Procedure:
It is important to note that the experiment for the Charpy and Izod hammers will be
conducted the same with the exception of the placement of the plastics on the supporting clamps.
To begin the experiment, place the pendulum on the releasing mechanism with a starting angle of
150° and set the protracting pointer at an angle of 0°. Without placing anything on the supporting
clamps, lower the protective clear shield and release the pendulum. Once the pendulum is done
moving, obtain the angle indicated by the protracting pointer. Without moving the protractor
pointer back to zero, place the pendulum back on the releasing mechanism and lower the
protecting shield then release the pendulum. Once the pendulum comes to a stop, obtain the
angle indicated by the protracting pointer. Repeat this three times and for both the Charpy and
Izod hammers. After completing the previous steps for each hammer, refer to Figure 5 to
continue the experiment for each of the plastics provided. Place one of the plastics onto the
supporting clamps, refer to figure 5 for proper placement, and set the pendulum at the starting
position of 150° on the releasing mechanism. Lower the protective shield and release the
pendulum. Once the pendulum comes to a stop, observe the fracture of the plastic, and obtain the
angle indicated by the protracting pointer. Repeat this step for each of the plastics for the Charpy
and Izod hammers.
8
Results
Table 1: Data collected while performing the Izod Test
Table 2: Data collected while performing the Charpy Test
Table 3: Results calculated by performing the Izod Test
Table 4: Results calculated by performing the Charpy Test
9
Figure 6: White material after impact on the Izod Test
Figure 7: Blue material after impact on the Izod Test
Figure 8: Clear material after impact on the Izod Test
10
Figure 9: White material after impact on the Charpy Test
Figure 10: Blue material after impact on the Charpy Test
Figure 11: Clear material after impact on the Charpy Test
11
Tables 1 and 2 organize the data that was collected while performing the Izod and Charpy
Tests, respectfully, on the EEICI unit. Both methods of testing were initially performed without a
specimen present 3 times, to determine how friction from the indicator effects the energy of the
devices. The first angle listed in the sections with no material listed represents the angle that the
device achieved with friction and the second value represents the angle achieved without friction.
Once, the friction losses observations were complete, 3 different specimens were inserted
separately into both devices to observe the energy absorbed by each specimen during impact.
Tables 3 and 4 display the values calculated from performing Izod and Charpy Tests.
Both tables show that the clear material absorbed the most energy, or is the most ductile, in both
methods of testing. While the blue material absorbed the least amount of energy during the
Charpy Test and absorbed the same amount of energy as the white material during the Izod Test.
Figures 6 through 8 show the way each material fractured while performing the Izod
Test. Figure 6 shows the white material, Figure 7 shows the blue material, and Figure 8 shows
the clear material. The types of fractures formed during the Izod Test show that each material is
ductile. When the clear material was tested, the specimen did not fracture until the pendulum
swung back down. This shows that the clear material is the most ductile out of the three
specimens.
Figures 9 through 11 show the way each material fractured while performing the Charpy
Test. Figure 9 shows the white material, Figure 10 shows the blue material, and Figure 11 shows
the clear material. These figures confirm what was observed during the Izod Test; all the
materials are ductile while the clear material has the highest ductility. The clear material having
the highest ductility is proven by the fact that it did not fully fracture. This means that it absorbed
the highest amount of energy, which makes it the most ductile.
12
Sample Calculations:
First, looking at Table 3. Equation 1 can be used to find the initial energy of the
pendulum:
𝐸! = 𝑚 × 𝑔 × 𝑙 × '1 − 𝑐𝑜𝑠(𝛼)0
𝐸! = 1.425 × 9.81 × 0.33 × '1 − 𝑐𝑜𝑠(150)0
𝐸! = 8.608259757 𝐽
Next, the final energy of the white material in Table 3 can be found using equation 2:
𝐸$ = 𝑚 × 𝑔 × 𝑙 × '1 − 𝑐𝑜𝑠(𝛽)0
𝐸$ = 1.425 × 9.81 × 0.33 × '1 − 𝑐𝑜𝑠(117)0
𝐸$ = 6.707479909 𝐽
Now, the energy absorbed by the white material in Table 3 can be found using equation
3:
𝐸% = 𝐸! − 𝐸$
𝐸% = 8.608259757 − 6.707479909
𝐸% = 1.900779848 𝐽
13
Now, looking at Table 1 the indicator loss can be found three different times using
equation 4:
𝑊&' = 𝑊( − 𝑊)
𝑊&'( = '1.425 ∗ 9.81 ∗ 0.33 ∗ (1 − cos(128))0 − '1.425 ∗ 9.81 ∗ 0.33 ∗ (1 − cos(123))0
𝑊&'( = 0.327637 𝐽
𝑊&') = '1.425 ∗ 9.81 ∗ 0.33 ∗ (1 − cos(130))0 − '1.425 ∗ 9.81 ∗ 0.33 ∗ (1 − cos(122))0
𝑊&') = 0.520679 𝐽
𝑊&'/ = '1.425 ∗ 9.81 ∗ 0.33 ∗ (1 − cos(130))0 − '1.425 ∗ 9.81 ∗ 0.33 ∗ (1 − cos(122))0
𝑊&'/ = 0.520679 𝐽
Next, the average of the indicator losses must be found using equation 5:
𝑊&' +,+ =
𝑊&' +,+ =
𝑊&'( + 𝑊&') + 𝑊&'/
3
0.327637 + 0.520679 + 0.520679
3
𝑊&' +,+ = 0.456332 𝐽
14
Referring to Table 3 the energy due to friction losses can be found using equation 6:
𝐸01 = 𝐸! − 𝑊&' +,+
𝐸01 = 8.608259757 − 0.456332
𝐸01 = 8.151928047 𝐽
Discussion
No discussion questions were provided for the experiment.
Some sources of possible error in this experiment could have included mechanical and
human errors. Some mechanical errors that could have happened during this experiment include
the EEICI machine not working the way it was intended to. The EEICI machine could have not
been calibrated right, with something malfunctioning in a way that it could have not let it get
calibrated. This could have also been a result of human errors as calibration is conducted and
monitored by humans. Some other human errors could include the arm of the EEICI machine not
being put on the correct angle that it needed to fully break some of the more ductile samples.
A way this experiment could be improved is to have a more automated EEICI machine
where human interaction is not needed as much. The hinged cover door of the machine could be
automated to where less humans need to be involved as to improve results and reduce errors.
Conclusion
In conclusion, the results for the Izod test on Table 1 show that the final angle of the
white and blue test samples ended with the same angle, at 117 degrees. The last sample, the clear
one, ended with the lower final angle at 71 degrees.
15
Table 2 shows the results of the Charpy test on the test samples. The blue test sample had
the largest final angle at 118 degrees, while the white stopped at 109 degrees and the clear one
had the smallest final angle at 55 degrees.
Tables 3 and 4 show the results of the calculations of the initial energy and the energy
due to losses of the Izod and Charpy tests respectively. The Izod test had a larger initial energy
than the Charpy test with 8.608259757 J. The difference of the initial energies is 3 J. The energy
due to friction losses was also larger for the Izod test at 8.17928047 J with the difference
between the tests being approximately 4 J. The test samples with two biggest differences
between them were the white and blue test samples for the Izod test.
16
References
[1] EDIBON. “EEICI.” Charpy and Izod Impact Testing Unit, 2016,
www.edibon.com/EQUIPOS/EEICI/EEICI_EN.pdf.
[2] EDIBON EEICI unit of Charpy and Izod Impact Testing Practice Manual
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Appendix
18