레이블이 #accelerometer인 게시물을 표시합니다. 모든 게시물 표시
레이블이 #accelerometer인 게시물을 표시합니다. 모든 게시물 표시

2024년 4월 24일 수요일

BISOPE series 59 Two measurements and methods for vibration evaluation


BISOPE series 59- Two measurements and methods for vibration evaluation

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When measuring the vibration of an object (test object, mechanical structure, building, etc.) and trying to quantify and evaluate its size, we are asked that it is difficult because the evaluation unit required by the vibration standard and the output unit output from the vibration sensor are not the same. . For example, according to the management manual provided by the machine manufacturer and construction company for evaluation, it is said to evaluate in terms of displacement. However, if the measurement sensor currently being measured is an acceleration sensor, is it possible to obtain it by converting to displacement (simply integrating twice)? This is about ? What should I do right?


2023년 2월 8일 수요일

65 FFT 기초용어모음 진동계측기 설정


FFT 기초용어모음-진동계측기 설정

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대화이건 책이건간에 사용하는 용어가 서로 일치하지 않으면 전혀 다른 이해를 할 수 있고 그래서 또 다른 결과도 나올 수 있다. 사실 대한민국을 포함하여 계측기 제조사들은 국가도 다르고 기술범위도 약간씩 차이가 있어서 용어를 달리 사용하는 경우가 많다. 따라서 그 지식을 습득하려는 사람들은 많은 자료나 많은 종류의 계측기를 사용해본 후에야 비로소 그 용어들의 차이를 알게 된다는 것이다. 여기서는 FFT 진동계측기 또는 진동소음관련 소프트웨어의 사용시 측정 엔지니어들과 서로 지식을 공유하고 나누는 대화 중에 정리해야할 기본용어 및 상식을 간단하게라도 정리하였다. (요청시 계속 업데이트 예정)

진동소음 계측용어: 윈도우, 피크홀드, 트리거, 오더, 리키지​, 에일리에이싱

용어

의미

Leakage

누설, 신호를 Block size로 취득할 때, Block의 시작과 끝점이 일치하지 않아서 발생하는 오류결과(스펙트럼 상 진폭과 주파수에 오류 및 부신호 발생)

Window

Leakage오류를 최소화하기 위해 가상신호(윈도우함수)를 곱해서 Block의 시작과 끝점을 기준점(0)으로 수렴하게 하는 함수

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

관련키워드

#FFT, #Averaging, #Leakage, #Order tracking, #Aliasing, #Peakhold, #resonance, #진동교육, #주파수분석, #공진측정, #공진분석, #진동센서, #공사장모니터링

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