1.1 The aim of the experiment
The aim of the experiment is to test the usefulness of the ultrasonic waves, by passing them through different
solids one can find out a lot of physical properties like young’s modulus , defects, Poisson ratio, Velocity of
sound in respective material this is due to the response of the received ultrasonic waves.
1.2 Theory of experiment
Ultrasonic testing (UT) is a family of non-destructive testing (NDT) techniques based on the propagation of ultrasonic waves in the object or material tested. In most common UT applications, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz, and occasionally up to 50 MHz, are transmitted into materials to detect internal flaws or to characterize materials. A common example is ultrasonic thickness measurement, which tests the thickness of the test object, for example, to monitor pipework corrosion.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution. It is used in many industries including steel and aluminium construction, metallurgy, manufacturing, aerospace, automotive and other transportation sectors.
1. 1
SOKOINE UNIVERSITY OF AGRICULTURE
Collage of Agriculture
DEPARTMENT OF ENGINEERING SCIENCES AND TECHNOLOGY
BSc. IRRIGATION AND WATER RESOURCES ENGINEERING
DOTO, MUSA GESE
IWR/D/2016/0011
MATERIAL TESTING PRACTICAL REPORT
UTRASONIC TESTING
Venue: COET-University of Dar es salaam
Instructor: MR BURTON
Date of submission: JULY 2018
2. 2
ABSTRACT
This report concerned about Ultrasonic test conducted in the Material Lab at CoET-University of Dar es salaam
which is the one among the non-destructive tests which make up by the use of ultrasound in determining the
material constants like Young’s Modulus, Poisson ratio, Velocity of sound in respective material.
Also the ultrasonic flaw detection is thus finding numerous uses in the inspection of Castings, forgings, stamping
rails, railway lines; car excels and wheel turbine blades and disk. Based on the course of this experiment the
following analyses were done:-
a. Demonstration of the use of the ultrasonic device as a test tool for measurement of length, depth and
thickness.
b. To perform flaw detection in block of steel.
i
3. 3
TABLE OF CONTENTS
Abstract ……………………………………………………………………………………………………….i
ACKNOWLEDGEMENT…………………………………………………....................................................iii
1. INTRODUCTION……………………………………………………...………………………………….1
1.1 The aim of the experiment………………………………………………………………………...1
1.2 Theory of the experiment……………………………………………………………………...…..1
1.3 Advantages of Ultrasonic Test…………………………………………………………………….2
1.4 Dis-advantages of Ultrasonic Test………………………………………………….……………..2
2. EXPERIMENTAL METHODS…………………………………………………………….…………….3
2.1 Equipments used in Ultrasonic Test …………………………………………………….………..3
2.2 Specimen …………………………………………………………………….……..……….……3
3. EXPERIMENTAL PROCEDURE S…………….………………………………………….…………….4
4. RESULTS AND DISCUSSION………………………………………………………………….……....4
4.1 Results………………………………………………………….……………………………...….4
4.1.1 Experiment 1 results (length determination)…………………………………………… 4
4.1.2 Experiment 2 results (Flaw detection for steel block labeled T and S at each end) …….5
4.1.2.1 TABLE (T)……………………………………………………………………..5
4.1.2.2 TABLE (L) …………………………………………………………………….5
4.1.3 Graph of depth (T , L) vs flaw number……………………………………………….…5
4.1.4 Results from calculations ………………………………………………………………6
4.2 Discussion…………………………………………………….………………………………....6
5 ERRORS AND CONCLUSION ……………………………..………………………………………….6
5.1 SOURCES OF ERROR………………………………………..………………………………..6
5.2 CONCLUSION …………………………………………………………………………………6
REFERENCES..............................................................................................................................................7
ii
4. 4
ACKNOWLEDGEMENT
I would like to express my grateful appreciation to the practical coordinator of the department of engineering
science and technology at SUA, PROF. LAZARO for providing a conducive economic situation that enabled me
to travel well without any obstacles to UNIVERSITY OF DAR ES SALAAM. Also special thanks are directed to
University Of Dar Es Salaam management for their kindness for allowing me to conduct my practical at their
university. Last but not least I extend my sincere thanks to MR BURTON for his valuable contributions and
advices on completion of my UTRASONIC TEST practical.
iii
5. 1
1. INTRODUCTION
1.1 The aim of the experiment
The aim of the experiment is to test the usefulness of the ultrasonic waves, by passing them through different
solids one can find out a lot of physical properties like young’s modulus , defects, Poisson ratio, Velocity of
sound in respective material this is due to the response of the received ultrasonic waves.
1.2 Theory of experiment
Ultrasonic testing (UT) is a family of non-destructive testing (NDT) techniques based on the propagation of
ultrasonic waves in the object or material tested. In most common UT applications, very short ultrasonic
pulse-waves with center frequencies ranging from 0.1-15 MHz, and occasionally up to 50 MHz, are
transmitted into materials to detect internal flaws or to characterize materials. A common example is
ultrasonic thickness measurement, which tests the thickness of the test object, for example, to monitor
pipework corrosion.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on
concrete, wood and composites, albeit with less resolution. It is used in many industries including steel and
aluminium construction, metallurgy, manufacturing, aerospace, automotive and other transportation sectors.
On May 27, 1940, U.S. researcher Dr. Floyd Firestone of the University of Michigan applies for a U.S.
invention patent for the first practical ultrasonic testing method. The patent is granted on April 21, 1942 as
U.S. Patent No. 2,280,226, titled "Flaw Detecting Device and Measuring Instrument". Extracts from the
first two paragraphs of the patent for this entirely new nondestructive testing method succinctly describe the
basics of such ultrasonic testing. "My invention pertains to a device for detecting the presence of
inhomogeneities of density or elasticity in materials. For instance if a casting has a hole or a crack within it,
my device allows the presence of the flaw to be detected and its position located, even though the flaw lies
entirely within the casting and no portion of it extends out to the surface.The general principle of my device
consists of sending high frequency vibrations into the part to be inspected, and the determination of the time
intervals of arrival of the direct and reflected vibrations at one or more stations on the surface of the part."
In ultrasonic testing, an ultrasound transducer connected to a diagnostic machine is passed over the object
being inspected. The transducer is typically separated from the test object by a couplant (such as oil) or by
water, as in immersion testing. However, when ultrasonic testing is conducted with an Electromagnetic
Acoustic Transducer (EMAT) the use of couplant is not required.
There are two methods of receiving the ultrasound waveform: reflection and attenuation. In reflection (or
pulse-echo) mode, the transducer performs both the sending and the receiving of the pulsed waves as the
"sound" is reflected back to the device. Reflected ultrasound comes from an interface, such as the back wall
of the object or from an imperfection within the object. The diagnostic machine displays these results in the
form of a signal with an amplitude representing the intensity of the reflection and the distance, representing
the arrival time of the reflection. In attenuation (or through-transmission) mode, a transmitter sends
ultrasound through one surface, and a separate receiver detects the amount that has reached it on another
surface after traveling through the medium. Imperfections or other conditions in the space between the
transmitter and receiver reduce the amount of sound transmitted, thus revealing their presence. Using the
couplant increases the efficiency of the process by reducing the losses in the ultrasonic wave energy due to
separation between the surfaces.
6. 2
Figure 1
1.3 Advantages of Ultrasonic Test
1. High penetrating power, which allows the detection of flaws deep in the part.
2. High sensitivity, permitting the detection of extremely small flaws.
3. In many cases only one surface needs to be accessible.
4. Greater accuracy than other nondestructive methods in determining the depth of internal flaws and
the thickness of parts with parallel surfaces.
5. Some capability of estimating the size, orientation, shape and nature of defects.
6. Some capability of estimating the structure of alloys of components with different acoustic properties
7. Non-hazardous to operations or to nearby personnel and has no effect on equipment and materials in
the vicinity.
8. Capable of portable or highly automated operation.
9. Results are immediate. Hence on the spot decisions can be made.
1.4 Dis-advantages of Ultrasonic Test
1. Manual operation requires careful attention by experienced technicians. The transducers alert to both
normal structure of some materials, tolerable anomalies of other specimens (both termed “noise”) and
to faults therein severe enough to compromise specimen integrity. These signals must be
distinguished by a skilled technician, possibly requiring follow up with other nondestructive testing
methods.
2. Extensive technical knowledge is required for the development of inspection procedures.
3. Parts that are rough, irregular in shape, very small or thin, or not homogeneous are difficult to
inspect.
4. Surface must be prepared by cleaning and removing loose scale, paint, etc., although paint that is
properly bonded to a surface need not be removed.
5. Couplants are needed to provide effective transfer of ultrasonic wave energy between transducers and
parts being inspected unless a non-contact technique is used. Non-contact techniques include Laser
and Electro Magnetic Acoustic Transducers (EMAT).
6. Inspected items must be water resistant, when using water based couplants that do not contain rust
inhibitors. In these cases anti-freeze liquids with inhibitors are often used.
7. 3
2. EXPERIMENTAL METHODS
2.1 Equipments used in Ultrasonic Test
a) Piezoelectric Transducer
is an electroacoustic transducer use for conversion of pressure or mechanical stress into an alternating
electrical force. It is used for measuring the physical quantity like force, pressure, stress, etc., which is
directly not possible to measure. Transducer probe used was both Transmitting and receiving made of
Ziconate and Barium Carbonate (BaCo3) which cause vibrations.
Figure 2
b) Cathode ray tube
This contains Vacuum which interprets and displays the vibrations from the Transducer sensor.
Figure 3
c) Couplant
This is the liquid with high viscosity (example Oil) that smeared on top of the specimen which help in
evenly distribution of Transducer vibrations through the specimen.
2.2 Specimens.
No Materials Size (mm)
1. Steel 50 x 90
2. Steel 50 x 120
3. Steel 50 x 150
4. Aluminum 55 x 90
5. Brass 50 x 90
6. Steel block 200 x 200 x 25
7. Plastick 30 x 90
Note: Plastic specimen did not respond to any vibrations applied on it, hence neglected.
8. 4
3. EXPERIMENTAL PROCEDURES
1. General instructions on how to operate the Ultrasonic equipments.
2. Setting of test range for specimens (10) : 200mm ,coefficient x 2
3. A drop of Oil (not too much) was put on each of the specimens.
4. The probe was applied on each specimen, and the respective positions of the back wall echo were noted
based on the following experiments
a) Determination of Length
b) Determination of material constants (young’s modulus and velocity for steel, Aluminum and Brass)
using the following formula
√
Where E = Young’s Modulus
ρ= Density of the material
ν = Poisson’s Ratio
CL = Velocity of longitudinal wave
Given the following materials constant
Assuming that the velocity steel is 5920 m/s
c) Flaw detection
5. Procedure 2, 3 and 4 were repeated for all other specimens.
6. Data recorded
4. RESULTS AND DISCUSSION
4.1 Results
4.1.1 Experiment 1 results (length determination)
SPECIMEN POSITION(DIVISION(mm))
In CRT
LENGHTH(mm)
1 7.50 15.00
2 6.00 12.00
3 4.50 9.00
4 2.80 5.50
5 1.50 3.00
Specimen Poisson’s Ratio( ν ) Density (x 103
Kg/m3
)
Steel 0.30 7.85
Brass 0.36 8.50
Aluminum 0.34 2.70
9. 5
4.1.2 Experiment 2 results (Flaw detection for steel block labeled T and S at each end)
4.1.2.1 TABLE (T)
Flaw No. Location [cm] Depth [cm]
(a) (b) Mean
1 5.5 5.50 5.50 13.81
2 8.0 8.15 8.15 7.80
3 10.5 11.00 11.00 4.40
4 14.0 14.00 14.00 10.40
4.1.2.2 TABLE (L)
Flaw
No.
Location [cm] Depth
[cm]
Comparison
(a) (b) mean Equivalent
flaw from
table (T)
Corresponding
depth (T)
1 4.80 4.50 4.65 8.40 2 7.80
2 7.40 8.00 7.70 12.00 4 10.40
3 10.80 10.90 10.85 6.00 3 4.40
4 13.50 13.60 13.55 15.00 1 13.81
(test range for specimens (10) : 200mm ,coefficient x 2)
4.1.3
0
2
4
6
8
10
12
14
16
1 2 3 4
DEPTH
FLAW NUMBER
GRAPH OF DEPTH (T , L) VS FLAW NUMBER
DEPTH (T)
DEPTH (L)
L
L
T
T
10. 6
4.1.4 Results from calculations
The calculation of Young’s modulus for the materials steel, aluminium and Brass
The speed of sound in steel is 5920 m/s.
√
E=
E= (5920)2
(7850)
E=204.371GPa
The young’s modulus of steel is 204.371Gpa
For Aluminium
4.5 5920m/s=4 ; = 6660m/s
E=
E= (6660)2
2700 (1+0.34) (1-2 0.34)/(1-0.34)
E=77.808GPa
The young’s modulus of aluminium alloy is 77.808GPa
For Brass
4.5 5920m/s=6 ; = 4440m/s
E=
E= (4440)2
8500 (1+0.36) (1-2 0.36)/ (1-0.36)
E= 99.702GPa
The young’s modulus of brass is 99.702GPa
4.2 DISCUSSION
1. From the graph in 4.1.3 shows the fractures or cracks shown in L are the same shown in T. thus the
amount of cracks in table T and L will be more or less the same in most situations.
2. The Ultrasonic test gives the materials constants range as young’s modulus of steel obtained is
204.371GPa ranges between 200 to 210GPa of normal steels.
5 ERRORS AND CONCLUSION
5.1 SOURCES OF ERROR
1. Parallax on measuring the readings from the oscilloscope and the use of the Steel rule for length
determination.
2. Power variation (rise and fall) which may results into fluctuation of probe signal and signal for display
system.
3. The selection of the maximum peak of pulse as it was associated with other recoil pulses.
4. Imperfect contact of the probe and the specimen even though the oil drops were added.
5.2CONCLUSION
The Ultrasonic test is nearly much accuracy among The Non-destructive testing methods since its gives
the nearly correct information needed from the object without damaging it. Using this method it is
possible to maintain the material condition at cheap. Example Airplane checkup.
11. 7
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N. Dowling, Mechanical Behavior of Materials, Prentice Hall, 1993.
ASTM and TS Standards.
ASM Metals Handbook, 9th ed. Vol. 12.
The collaboration for NDT education
www.ndt-ed.org
The American Society for Nondestructive Testing
www.asnt.org
Abraham, O., Leonard, C., Cote, P. & Piwakowski, B. (2000). Time-frequency Analysis of
Impact-Echo Signals: Numerical Modeling and Experimental Validation. ACI
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