레이블이 #frequency analysis인 게시물을 표시합니다. 모든 게시물 표시
레이블이 #frequency analysis인 게시물을 표시합니다. 모든 게시물 표시

2024년 2월 13일 화요일

BISOPE series 55 free, natural, degree of freedom, free vibration


BISOPE series 55- free, natural, degree of freedom, free vibration

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The word freedom is also used as a vibration engineering term, and is used together with coordinate angle (degree) to mathematically express the motion and vibration phenomenon of an object. In other words, in vibration, there must be coordinates to express the vibrating object in terms of the amplitude and frequency of displacement, velocity, and acceleration, and in this case, the term ‘degree of freedom’ of vibration is used. I think freedom is the same as intrinsic (#Eigen value; natural). This is because the state that gives rise to its unique characteristics is freedom itself.

 

Degree of freedom (DOF) & Free vibration (Natural; Free vibration)

 

The number of coordinates that express the behavior of a system is called ‘degrees of freedom.’

 

To explain this, if we describe a spot

2023년 5월 17일 수요일

BISOPE series 37 Difference between shaft vibration and casing vibratio...


BISOPE series 37- Difference between shaft vibration and casing vibration(shaft vibration monitoring, bearing housing; casing vibration monitoring)

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If a dangerous state of a rotating machine is identified in advance or the machine suddenly breaks down, production is disrupted and huge asset losses occur. Therefore, in order to check the maintenance time while looking at the status (CBM), 'monitoring' must be performed and a 'monitoring system' must be installed or operated. As a monitoring method, the vibration of the facility is measured regularly in the field and sensing is performed by installing a continuous monitoring online system. But what is 'monitoring measurement technology'? The monitoring measurement technology is also divided into two parts as above, which are 'shaft vibration and casing vibration'. As for this distinction, even among those who specialize in vibration research, if you have not experienced the general field facility management method, you may not know the exact difference. This is very common in the current industrial field, but let's look at the direct differences in monitoring measurement technology that can never be confirmed theoretically.

 

Shaft & Casing, Housing vibration monitoring (shaft displacement vibration and bearing housing vibration)

 

Vibration in a rotating machine starts when the shaft rotates and excitation force (centrifugal force) is generated. Therefore, it is best to directly measure shaft vibration (shaft vibration measurement method), but this method has technical limitations. Therefore, a method of measuring where the shaft vibration is transmitted to the bearing housing or casing is often used, and this is commonly referred to as 'bearing housing vibration' or 'casing vibration'. This difference was sorted out.


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This data is very realistic and it is the result confirmed in the actual domestic industrial field, but it can be subjective and biased, so please refer to it.

 

All copyright  korea CBM  written by BISOPE , vs72@naver.com, 070-4388-0415,  www.kCBM.kr

 

#bearing vibration, #sleeve bearing, #metal bearing defect, #journal bearing, #vibration defect, #whirl, #bearing friction, #subharmonic, #non synchronous, #transient tolerance, #vibration diagnosis, #vibration analysis, #vibration Measurement, #frequency analysis, #facility diagnosis, #vibration education, #resonance analysis, #resonance measurement, #CBM, #vibration monitoring


2023년 3월 29일 수요일

BISOPE series 33 Simple vibration diagnosis and precision vibration dia...


BISOPE series 33- Simple vibration diagnosis and precision vibration diagnosis of rotating machinery

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The results of the vibration diagnosis can be confirmed as a technical report, which is largely divided into a simple diagnosis report and a detailed diagnosis report, etc., and is prepared including the cause and evaluation of the current vibration problem, and a description of countermeasures if necessary. The meaning of each report is a simple report in the case of simple evaluation of phenomena and absolute standards after temporary measurement, and detailed analysis to the extent that current causes can be analyzed and countermeasures can be found through spectrum analysis and cause analysis of various vibrations. are treated as detailed reports. In general, the definition of regular textbooks for facility diagnosis qualifications is not very different.

 

Simple diagnosis and precise diagnosis, offline and online

First of all, if you look at the methods of simple diagnosis, there are 'route measurement' and 'online monitoring system'. Inspection is commonly referred to as 'off-line' as a method in which humans intermittently investigate and record the state of equipment using a portable instrument (vibration meter, data collector). On the other hand, constant monitoring is a method of continuously monitoring by a monitoring device and is called 'on-line'. Inspection called off-line can measure many measurement points and directions, but it cannot be said to be continuous depending on the frequency of measurement. There are advantages and disadvantages between the two systems, since on-line continuously monitors and stores near real-time data from already installed sensors.

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 https://blog.naver.com/vs72


All copyright  korea CBM  written by BISOPE , vs72@naver.com, 070-4388-0415,  www.kCBM.kr

#PDM; Resonance analysis, #frequency analysis, #CBM, #vibration sensor, #vibration and noise education


2022년 11월 2일 수요일

BISOPE series 20 Why is there a difference in the speed of sound in sol...


BISOPE series 20- Why is there a difference in the speed of sound in solids and gases?

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Why is there a difference in the speed of sound in solids and gases?

 

The speed at which sound waves propagate through a medium is the definition of sound speed. The medium itself does not move, it is the propagation speed of the phase of the sound wave. When looking at the wavelength as the origin, sound waves in a narrow sense propagate through the fluid as longitudinal waves (penetrating the medium in the propagation direction), and their speed varies depending on the conditions of the medium such as temperature and humidity and the type of medium.

 

Change in momentum and rate of volume change

 

​The propagation speed of longitudinal waves is determined by the mechanical properties of the medium. Considering the change in momentum of the fluid moving in the piston (vt) with a certain cross-sectional area (A), it can be viewed as the product of the mass (ρvtA) of the fluid and the change in velocity (u). On the other hand, when the pressure increase Δp in the moving fluid is obtained, the initial volume Avt of the fluid in motion is decreased by Aut, so from the definition of the bulk modulus (;- pressure change/volume change rate)

 

Velocity of sound, modulus of elasticity - https://blog.naver.com/vs72

 

is established At this time, 'B' is the bulk modulus, and when the medium is a fluid, it corresponds to the volume modulus (volume change rate), and when the medium is a solid, it corresponds to the Young's modulus. Since it is larger than the bulk modulus of , the velocity in the medium of longitudinal waves is ultimately influenced by the difference in the velocity of sound by the difference in the volume modulus rather than the difference in the density. V solid > V liquid > V gas !

 

Difference in speed of sound - https://blog.naver.com/vs72

 

What is the difference between the speed of sound and the speed of particles?

 

As the speed at which sound waves propagate through an elastic medium, the formula is the same as above, and among them, the speed of sound in the air is expressed conveniently and c=20.06√T in relation to temperature.

On the other hand, particle velocity (v) is the vibration velocity of a medium that transmits sound waves, and when it is assumed as a plane wave, it can be expressed as v=p/ρc. (T: absolute temperature, p: pressure, ρ: density, c: speed of sound)

 

 

 

Wavelength, particle velocity - https://blog.naver.com/vs72

 

speed of sound in different media

​All copyright Korea CBM Co., Ltd. written by BISOPE

 

#vibration measurement, #vibration analysis, #frequency analysis, #resonance measurement, #resonance analysis, #3-axis vibration, #accelerometer, #fft, #bearing vibration, #vibration noise education, #equipment diagnosis, #cbm, #bearing vibration , #building vibration, #gear movement, #visope, #looseness, #environmental vibration, #rotating machine, #vibration education, #vibration monitoring, #balancing, #volume modulus, #sonic velocity, #noise and vibration

All copyright  korea CBM  written by BISOPE , vs72@naver.com, 070-4388-0415,  www.kCBM.kr



#vibration measurement, #vibration analysis, #frequency analysis, #resonance measurement, #resonance analysis, #3-axis vibration, #accelerometer, #fft, #bearing vibration, #vibration noise education, #equipment diagnosis, #cbm, #bearing vibration , #building vibration, #gear movement, #visope, #looseness, #environmental vibration, #rotating machine, #vibration education, #vibration monitoring, #balancing, #volume modulus, #sonic velocity, #noise and vibration