레이블이 forced vibration인 게시물을 표시합니다. 모든 게시물 표시
레이블이 forced vibration인 게시물을 표시합니다. 모든 게시물 표시

2023년 11월 21일 화요일

BISOPE series 46 How do sound waves travel where there is no light refr...


BISOPE series 46- How do sound waves travel where there is no light? (refraction and diffraction)

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We are taught that light is faster than anything else, so we miss the meaning of having powerful energy. Therefore, wherever the light reached, there was hot energy. However, it was not always so where the sound reached. I could hear the sound even in the dark. I heard it even though it was blocked.

If sound and light are transmitted to an invisible place, let's say that they can be seen as passing through an obstacle or being reflected secondarily on another plane. But if you can hear sound in the back corner where there is no such thing, how on earth can you explain this?

Huygens–Fresnel principle

 

Waves appear in the form of light, sound, surface waves, earthquakes, vibrations, etc., and have characteristics of reflection, refraction, and diffraction. Light is a transverse wave in which the direction of vibration of the medium and the direction of propagation of the wave are different, but sound is a longitudinal wave having a wave of low density (low density, high density medium) in the direction of propagation of the wave. If the sound propagation direction is referred to as a sound ray, the perpendicular plane is called a 'wavefront' (a plane obtained by connecting all points of the same phase when the wave propagates).

The principle by which sound can be heard in a confined, narrow, and dark place is explained by Huygens' principle. “Each point on one wavefront becomes the point source of the next wavefront, and a spherical wave is generated. The envelope that touches all of the spherical waves created by these point sources becomes the next wavefront.” Huygens' principle can be used to explain the phenomena of reflection, refraction, interference, and diffraction of waves.

 

division

Refraction

Diffraction

explanation

bending of the sound ray

Propagation of sound in areas behind obstacles

theory

Snell's Law

 

When the medium changes, the angle of incidence and angle of transmission change.

Huygens–Fresnel principle

phenomenon

- deflects to the lower speed of sound

 

- Refraction towards the lower temperature.

 

- bends in the direction the wind blows

- The larger the wavelength, the more diffraction occurs.

 

-The smaller the size of the obstacle (the smaller the hole, the more diffraction.


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2022년 11월 23일 수요일

BISOPE series 22 Non synchronous rotation component vibration defects


BISOPE series 22- Non-synchronous rotation component vibration defects

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When analyzing the frequency, it is the first step to distinguish the relationship with the number of revolutions. Among them, harmonics that are compared to synchronous components and are not calculated as integer multiples of TS (turning speed) are called asynchronous(Non-synchronous) components. It refers to a frequency component that is both related to the number of revolutions and has nothing to do with the number of revolutions at all. Among them, the case related to the number of revolutions is a frequency generated by rolling bearings, belts, chains, etc., and is an asynchronous component because it does not fit into an integer multiple. On the other hand, frequencies that are not related at all to rotational speed correspond to frequency groups caused by resonance, electrical faults, fluid excitation, and friction, which are also asynchronous components.

Non Synchronous faults

 

For patterns and signals of defects whose frequencies are not integer multiples of TS or are not related at all, just look for those that are not related to rotation events. That is, the inner and outer rings of rolling bearings do not fit in integer multiples because they continue to rotate according to a certain pattern formula when the shaft rotates once. Also, in the case of other shafts connected by a belt or in the case of the oil whirl, although it is related to the increase or ......

Observation of asynchronous components is generally not good. In particular, frequencies below 1X TS are not normal at all. Oftentimes, it is a defect in itself. It is important to know how it was in the past and how it compares to similar machines, but it is important to analyze and find the cause because it can be a serious matter that needs to be proven through additional tests.

 

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



 


2022년 11월 16일 수요일

BISOPE series 21 Spectrum setting method Max frequency setting


BISOPE series 21- Spectrum setting method-Max frequency setting

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In the spectrum, which is a graph for vibration analysis, “How many Hz should the maximum frequency be set?”, “What is the Fmax?”, “How much is the sample frequency?” If you are hearing these questions, you need to understand what the Max frequency is. Inquiries related to this can be divided into two types. One may ask what the term 'maximum frequency' itself is, and the other will mean how much to set the maximum frequency. Here we will try to answer your questions related to this.

 

The maximum analysis frequency (Max frequency) should be placed so that the frequency of interest is centered...

 

Fmax=2.56*Fs

 

maximum frequency; The maximum analysis frequency is expressed as ‘fmax’ and is t............

 

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

https://blog.naver.com/vs72