Mechanic Experi̇ments
Mechanic Experi̇ments
Mechanic Experi̇ments
1.PURPOSE OF EXPERIMENT
Experiments are carried out to reduce the vibration of the main mass by transferring the vibrat
ions created by the system vibrating at the resonant frequency to the mass spring system.
2.THEORETICAL EXPLANATION
The mass (m) depends on the spring of the spring constant k. First, the system
is in equilibrium. The direction of movement is positive ( ) down and negative (-) up.
If you pull the mass down and let go, the mass goes up and down again. After these moves
(when the energy of the system is consumed as kinetic energy), the system
stopped in equilibrium.
Frequency (f): the number of cycles performed by the system per unit time. Frequency, which
is a very important unit for vibration, is denoted by f. The frequency depends on the stiffness
of the spring (k) and the mass of the system.
The amplitude of the oscillation goes to infinity when it is equal to the natural frequency of
the system. This phenomenon is called resonance.
Period (T): This is the duration of one motion cycle. It is denoted by T and its unit is the
second.
Damping factor (C) and damping ratio (r): These definitions are damping
The amplitude and duration of the oscillations decrease. The damping coefficient is denoted by
C and its unit is kg/s,
This system has only mass (m) and spring (k). There is no silencer in the system.
Some of the mass is removed and released. Movement of the system and spring constant
By observing (k), the frequency (f) and period (T) of the system are calculated both theoretically
and experimentally.
The following equations are obtained by dividing both sides of the equation by the mass.
is being done. Here, the square root of the ratio of the spring constant to the mass as the natural
frequency of the system
inference is made.
Free damped vibration (F(t)=0 and C≠0)
This system has a damper. The damper is placed in a resistive medium that dampens the
vibration.
A piston with a bore is driven. Since the piston moves with the mass (m), the mass loses its
energy in each cycle.
and thus the vibration is damped. In other words, damping dissipates stored vibrational energy.
produced by the process. The purpose of this test is to determine (r) damping coefficient (C)
and
CONCLUSION
1)
Caliper
,Although caliper is often used in a negative sense among people, it is a tool that has very diff
erent meanings. Conspiracy also has meanings such as "backstabbing, trap, betrayal" among
the people. But thickness is actually the name of the tool.
Atigen Switch
The hex ring that plumbers use in drills is a small tool used to turn the screw.
2)
The vibration level of the test sample at key locations is controlled and monitored by a vibrati
on control system. The physical test specimen should be subjected to a vibration level
corresponding to the vibration it will experience under operating conditions in a laboratory
environment where the test can be controlled.
Vibration meter (vibrator), vibration of machines and systems. The main purpose of vibration
is to measure acceleration forces. Vibrometers are generally portable.
it provides a range of vibration analyses such as acceleration, displacement and speed, as well
as built-in temperature readings.
Frequency levels read by the device are usually reported in hertz (Hz) and kilohertz (kHz).
3)
EMİR CAN YILMAZ 200304052
EXPERIMENT1:UNBALANCE
[Experimental Methods in Engineering II _ Experiment ]
1.PURPOSE OF EXPERIMENT
We conduct this experiment to show that the instability of the equipment reaches the maximu
m point of rotation of the curved axis of the vibration spectrum.
2.THEORETICAL EXPLANATION
The balance of forces formed by all the rotating elements of the machines is called equilibriu
m. Any change in this state of equilibrium creates an imbalance.
Imbalance is the most common form of machine vibration. Theoretically, a perfectly balanced
machine has no vibration.
In practice, there is no such thing as a perfectly balanced machine. All machines are somewha
t unstable.
This imbalance creates a peak in the shaft speed (1x) spectrum curve.
Static Unbalance
The two imbalances (shown here by arrows) may be the same size and angular position and the
same distance from the center of gravity. The same applies to the double unbalance acting at
the center of gravity, in this case the center of the rotor.
If such a rotor is supported by two blade edges, it will oscillate until the
"heavy point" goes down. This means that this imbalance also works without rotation; hence it
is called "static imbalance". This causes the center of mass to move away from the geometric
centre, causing the rotor to oscillate parallel to the axis of rotation during motion.
The static imbalance at the level of the center of gravity must be corrected. This is achieved b
y removing material from the "hard point" or adding material to the opposite side.
Correction of the static imbalance in the trim plane is often carried out, especially in disk-
like rotors.
When performing vibration testing, vibration and acceleration settings are generally used for
testing.
The equation a(t)=(dv(t))/dt=-(2πf)^2 x_0 sin(2πft) in the lower right corner is the general
expression for time varying velocity. Because cos is different, it becomes a negative sin. The
position of the peak corresponds to the displacement diagram as it displaces more than 90
degrees from the velocity.
However, due to negative sin, the horoscope is reversed and this can be verified by looking at
the chart. In other words, each value can be calculated by deriving and integrating the
expression proportional to displacement, velocity, and acceleration over time.
The trigonometric function, which allows the properties of the periodic function to be used in
this way, provides great convenience when performing arithmetic operations.
4) CONCLUSION
1. What is FFT Analysis?
FFT analysis is one of the most widely used techniques for performing signal analysis in
various application areas. FFT converts signals from time domain to frequency domain. FFT
is short for Fast Fourier Transform.
Using
FFT analysis, many features of a signal can be explored far more extensively than looking at t
ime field data.
In the frequency domain, the characteristics of the signal are defined by the individual
frequency components, while in the time domain, it is defined by the waveform that contains
the sum of all the features.
Applications of FFT Analyzers
Examining measurement data in the frequency field is often an important part of signal analys
is and monitoring.
Data from a variety of sensors are used across virtually all industries in order to solve problems,
optimize designs, test prototypes, monitor machinery, and many other jobs like the ones listed
below:
Combustion analysis
FFT analysis can also be used to measure sound pressure in acoustically noisy environments.
By identifying which critical frequency ranges and loud components are included in the noise,
engineers can take steps to reduce them.
Results From FFT Analyzers
When FFT analyzers generate frequency domain data, the output results are frequency
spectrums. These spectra are often divided into forms called power spectra and cross-power
spectra.
The steps required to obtain the power spectra and the cross power spectra are shown in the
figure below.
The first step is to select the input time data into FFT time blocks. Arrival time data can be raw
sensor signals or preprocessed (eg filtered) signals. Each time block has a time interval (T) that
depends on the spectral resolution of the generated spectra. Time blocks can be configured to
use the window function and the overlap setting.
FFT time blocks are then converted from time domain to frequency domain using the FFT
algorithm. Each time block results in an instantaneous complex FFT spectrum. .
2)
Vibration control testing is a retest of the lowest operating or shock environment available in
the field or laboratory. These cells are typically inspected with an electrodynamic propulsion
system, also known as a shaker, as shown in Figure 2. Elevation levels of key locations of test
materials are controlled and monitored using a pressure control system.
Vibration control tests are part of a comprehensive series of environmental tests to ensure the
product functions properly in harsh environments. In addition to vibration and shock tests,
environmental tests include:
– Humidity
– High and Low Temperatures
– Altitude
- Acoustic
– solar radiation
– Electromagnetic Interference (EMI)
– Sand and Salt
3)
Spectral Resolution
Spectral resolution determines the range of frequency lines in the generated spectrum (also
called
resolution).The higher the spectral resolution, the more frequency bands are included in the ou
tput spectra of frequency analysis. (Sometimes the frequency of "rows" is called "box".)
Number of Lines
The number of lines () indicates how many lines will be included in the produced spectra (this
also relates to the spectral resolution).
For FFT baseband analysis over the full signal frequency range, the line resolution is
dependent upon the sample rate () and the number of lines. This can be determined by:
For FFT baseband or zoomed analysis over a selected frequency span, the line spacing can be
determined by the ratio between the frequency span and the number of lines within that span:
The time block length (aka “block duration”) indicates the duration of time data that each
spectrum requires to be made with a certain line resolution.
The greater the spectral resolution, the greater the time block length has to be.
The time block length is often referred to as , and it is related to the line resolution by
Sampling rate The sampled time data used in FFT analysis determines the upper frequency li
mit of the spectra produced This limit is defined as the Nyquist Frequency or, as follows:
4) . Predictive Maintenance Approach
The purpose of proactive maintenance is to monitor the status of the machine in use, to
intervene in the malfunction situation, to prevent possible malfunctions that may arise as a
result of the analysis, to plan the appropriate maintenance time and consumables.
In order for the predictive maintenance approach to be applied in a business, various methods
should be used. It
We can list the methods as follows:
Vibration analysis method is the most widely used and fastest method among predictive
maintenance methods. In this method, measurement is made on the machine using a receiver
that converts vibrations into electrical signals, and the electrical signal generated as a result of
this measurement is transmitted to the processing device. analyzed with a computer and
analysis software and
come to a conclusion about the machines.
Vibration levels of a compressor trend trend
When looking at vibration levels, it's important to know which vibration can cause the
malfunction and which error. The graph that appears during the measurement has two
important parameters to look at; frequency and amplitude. Depending on the machine rotation
speed, strong vibrations at certain frequencies may indicate dangerous situations. Each type of
error in the system occurs at a different frequency. In the vibration analysis made after the
measurement, it is determined which error occurred at which frequency.
5)
The spectrum graph of a pump operating at 2987 days/day (49.78 hz) with unbalance failure
is shown in the graph below. The place specified as the peak point represents the 49.72 Hz
cycle in this graph.
In the cycle diagram, imbalance disorder
hears the radial motion spectrum of unbalance error, static unbalance, moment imbalance and
dynamic imbalance approximately in the first three available from the class. By comparing
the phase measurement of the bearing,
Where the degree of imbalance is old, the imbalance can be diagnosed.
6)
Spectrum analyzers
7)
Unbalanced Fault Pressure Analysis and Phase Angle Control in Rotating Machines All
forces created by rotating elements in machines must be in balance. Any system with no
change in these forces creates an imbalance. Balanced movements are the most common
movements of machines. This system imbalance creates a peak at the frequency (1 × RPM) of
its previous counterpart in the spectrum diagram.
https://www.researchgate.net/publication/282518874_DONEN_MAKINELERDEKI_DEN
GESIZLIK_BALANSSIZLIK_ARIZASININ_TITRESIM_ANALIZI_VE_FAZ_ACISI_YA
RDIMIYLA_TESHISI
http://www1.mmo.org.tr/resimler/dosya_ekler/0fc7ce64e252ead_ek.pdf?dergi=1426
https://www.sparkmeasure.com/b-137-spektrum-analizi-nedir-.html
EMİR CAN YILMAZ 200304052
PURPOSE OF EXPERIMENT
It shows that the rigidity value, which is the ratio of the applied load to the amount of deflecti
on of the beam, is different for different materials and beams of different thicknesses.
Mod 1
14
0,2-2Hz
Mod 2
Mod 3
10(Hz) 3 knot
Approx 90
1) , 2) and 4)
Upon obtaining the characteristic equation of the Maxwell rod, first the differential equation of
motion is obtained, i.e. the equation of motion in short. The resulting equation Boundary value
problem with appropriate geometric and dynamic boundary conditions. creates the . The
problem, the boundary value problem to an eigenvalue problem assuming an exponential
solution of the differential equation of motion. transformed and associated geometric and
Since the differential equation of the eigenvalue problem is homogeneous, its solution cannot
be determined in one way,
can only be specified as a form. This is because the solution Multiplication by a constant
number is also a solution. With the help of four boundary conditions, two of which are
geometric and two are dynamic, both the shape of the solution and the solution
It was found that by increasing the length of the beam, higher values of the frequency
parameters were obtained. When the effect of the module on the frequency parameter is
examined,
results in.
The characteristic (frequency) equation that gives the characteristic value is obtained.
𝑦(𝑥,𝑡) = 𝑌(𝑥)𝑓(𝑡)
After applying mathematical operations and fixed beam boundary conditions, the natural
frequency expression in the crack-free state is
The natural frequency expression in the cracked state is the following equation
is given with
is doing. Below are the values of 𝜆𝑛𝐿 for the first four modes.
Steel=2.06x1011 N/m2
ρ steel=7850 kg/m3
ν steel=0.29,
3)
We have our vibrator and thin rod in our experiment. The thickness of the thin rod relative to
its length does not have much of an effect.
We also have a control unit that controls the vibrator.
There is a place in this unit where we adjust the amplitude. Then we can adjust the
frequency.
REFERANCES :
https://dergipark.org.tr/
https://acikerisim.uludag.edu.tr/bitstream/11452/11736/1/621584.pdf