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1
Content available The noise of biomedical devices for domiciliary use on the example of a nebulizer
Jakubek B., Rukat W., Grochalski K.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018017
EN
Widely available and inexpensive biomedical devices for domiciliary use may emit noise. Nebulizers are one of them. They allow taking drugs in the form of vapours thanks to vaporization under reduced pressure using an ejector (vacuum generator). The sources of noise in a nebulizer are an air compressor and a vaporizing tip. The presence of two sources with a different noise character and unfixed spatial orientation allows to classify a nebulizer as a device with extensive sound sources (DESS). The article presents the results of acoustic measurements of the nebulizer and its components. Differences in the nature of components’ noise were found and their estimates were compared. Noise hazards for the device’s user were determined and the premises for the noise parameterization of devices of this type were specified.
2
Content available The noise emitted by a vacuum cleaner treated as a device with extensive sound sources
Rukat W., Jakubek B., Madej A.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018015
EN
Vacuum cleaners can be found in almost every household. They are one of the most intense noise sources there. Noise generated by vacuum cleaners is partially of mechanical, electrical and aerodynamic origin. A suction unit is the source of mechanical and electromagnetic noise. A suction nozzle or a cleaning head as well as a flexible hose that connects the components are sources of aerodynamic noise. The noise of the suction unit depends on the load and the technical condition of the motor. The noise of the nozzle and the hose depend on the flow capacity, presence of solid particles and the type of cleaned surface. The article presents a comparison of acoustic parameters of a vacuum cleaner working on various surfaces. In addition, the noise generated by the vacuum cleaner was compared according to the standard noise testing procedure and according to the definition of devices with extensive sound sources.
3
Content available The influence of supply options of an asynchronous electric motor on emitted noise
Barczewski R., Jakubek B., Wróbel M.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018006
EN
A comparison of the noise emitted by an asynchronous electric motor for various supply options has been presented in this paper. The star connection, one phase connection (with a run capacitor) and the use of an inverter have been taken under consideration. The test results show the effect of supply options of the electric motor on the sound power level, the shape of the noise spectra and directivity changes of the sound emitted by the tested asynchronous electric motor.
4
Content available Comparison of rolling bearings’ diagnosing methods - procedures of damage introduction
Jakubek B., Jakubowicz M., Smułek W.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018011
EN
The rolling bearings’ diagnosing methods used in exploitation diagnostics are not usually dedicated to the postproduction control. However, this does not mean, that they cannot be used there. A comprehensive comparison of the sensitivity of rolling bearings’ diagnosing methods to occurrence of faults and damage should be based on measurements of new, undamaged bearings and bearings with defects. An accurate determination of the location, size and origin of defects is expected from a set of testing bearings. The paper presents a comparison of three methods of damage introduction: sandblasting, pickling and spark erosion. Procedures for introducing damage into bearing’s races have been described. In addition, race’s geometries and vibration signals generated by operating bearings were compared.
5
Content available The influence of the lubrication on the vibroacoustic signal generated by rolling bearings
Jakubek B., Barczewski R., Jakubowicz M.
Vibrations in Physical Systems
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2017
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Vol. 28
art. no. 2017004
EN
Long-life and failure-free operation of rolling bearings depends on the proper lubrication. Additionally lubrication reduces vibration and noise generated by the operating bearing. However, from the point of view of the post-production diagnostics, lubrication can lead to undesirable masking of damage and manufacturing defects. This article presents the comparison of parameters of vibroacoustic signals generated by tapered roller bearings under different lubrication conditions. The influence of the lubricant on the form of vibroacoustic signals in both amplitude and frequency terms was determined. The premises on the choice of the lubricant for the post-production diagnostics of rolling bearings have also been specified.
6
Content available The influence of the cutting tooth design and wear of a saw chain on the vibration level of a chainsaw
Rukat W., Jakubek B.
Vibrations in Physical Systems
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2017
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Vol. 28
art. no. 2017009
EN
Chainsaws are the most basic mechanical tools used to harvest and pre-treat wood. Unfortunately, these devices emit noise and vibrations exceeding the maximum permissible levels for an 8-hour working day. Many factors influence the level of noise and vibration emitted by chainsaws. Since the conscious choice of the saw chain can significantly contribute to: productivity increase, vibration reduction and the operator's permissible total exposure time extension the influence of the type of a cutting tooth and its wear on the vibration level recorded on the handles of the device has been investigated in this paper.
7
Content available Determination of acoustic parameters of devices with extensive sound sources
Jakubek B., Barczewski R.
Vibrations in Physical Systems
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2016
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Vol. 27
129--134
EN
In most cases, while the sound power level of machines and devices is determined, it is assumed that tested objects are sound sources which can fit in a so-called reference box. Such an approach takes into account the influence of local sources. Although it does not allow their localization, separate noise measurement and evaluation. There are devices which have two or more relevant sound sources. In this paper this type of devices has been defined as devices with extensive sound sources (DESS). The tested device is a functional unit but its local sound sources are distant from each other. The results showed that determining the sound power level only is not sufficient for proper parameterization of noise emitted by DESS.
8
Content available Comparison of vibration impact of an impact drill on the human body under different working conditions
Jakubek B., Rukat W.
Vibrations in Physical Systems
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2016
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Vol. 27
135--142
EN
Currently there is a wide range of different kinds of power tools on the market. In the case of impact drills the major threat to the user’s health are vibration and acoustic impacts. Knowing that the actual drilling conditions may vary significantly from standardized conditions. It is important to determine the actual maximum level of dangerous factors present during drilling. Furthermore, it is also very important to link that factors to the conditions in which they occur. Among many factors affecting the level of vibration of an impact drill, change of the working position, the length of the drill bit and the diameter of the drill bit were verified in this paper. Verification was based on a comparison of vector-weighted mean values of acceleration of vibrations RMS a registered on the handles of the impact drill, while drilling in concrete, under different working conditions.
9
Content available remote Problems of in-situ vibroacoustic testing of low-vibroactive devices
Barczewski R., Jakubek B.
Vibrations in Physical Systems
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2012
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Vol. 25
59--64
EN
This paper article outlines the problems of in situ vibroacoustic testing of low-vibroactive devices. Moreover a comparison of selected methods of object's surface velocity mapping was carried out in the paper. Primary features, advantages and limitations of these methods are stated here. On the example of tests on a refrigerator the methodology and specifics of testing of this type of devices using a laser vibrometer is also shown.
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