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1

Vibroacoustic analysis in the assessment of the technical condition of the aircraft airframe composite elements

Mokrzan Daniel, Milewicz Julia, Szymański Grzegorz M., Szrama Sławomir

Diagnostyka

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2021

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Vol. 22, No. 2

11--20

EN

The paper presents the method of assessment of the technical condition of the leading edge of the horizontal stabilizer of an F-16 Block C aircraft made from composite materials. The described method was an experimental measurement of the acoustic pressures generated by the technically operational element and the element with the distorted structural continuity and then a comparison of these pressures in the curves of time and frequency in order to assess how the damage impacts the parameters of the acoustic wave. The test was performed in a dual-channel system, the pressure was induced through impacts on the investigated element with an impact hammer and then, based on the measured induction parameters and the generated acoustic wave, the function of frequency response was calculated, based on which the authors assessed how the structural damage influenced the curve characteristics of the acoustic pressure in the domain of frequency. The described method may be used as an efficient method of non-destructive diagnostics of the airframe elements of an aircraft.

PL

Artykuł przedstawia metodę oceny stanu technicznego krawędzi natarcia statecznika poziomego statku powietrznego F-16 Block C wykonanej z materiałów kompozytowych. Opisywaną metodę stanowił eksperymentalny pomiar ciśnienia akustycznego emitowanego przez element sprawny technicznie oraz element z naruszoną ciągłością struktury, a następnie porównanie ich przebiegu w domenie czasu oraz częstotliwości celem ustalenia w jaki sposób uszkodzenia wpływają na parametry emitowanej fali akustycznej. Badanie dokonywane było dwukanałowo, ciśnienie akustyczne wzbudzane było za pomocą uderzeń w badany element za pomocą młotka modalnego, następnie na podstawie zmierzonych parametrów wzbudzania oraz wywołanego nim fali akustycznej obliczono funkcję odpowiedzi częstotliwości, na podstawie której określono jak uszkodzenie struktury wpływa na przebieg charakterystyki ciśnienia akustycznego w dziedzinie częstotliwości. Opisywana metoda może służyć za skuteczną metodę diagnostyki nieniszczącej elementów płatowca statku powietrznego.

2

Vibroacoustic analysis of the Polish pharmacy robot Fablox

Łapka Wojciech

Vibrations in Physical Systems

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2020

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Vol. 31, nr 3

art. no. 2020312

EN

This paper describes the vibroacoustic analysis of the Polish pharmacy robots Fablox 1 and 2, as a part of research and development work to build an automated, modular pharmacy robot that meets the requirements of the false directive 2011/62 / EU to counteract the illegal distribution of drugs in the European Union. There were undertaken acoustics and vibration measurements of a pharmacy robot under typical working conditions. Point measurements of a one-third octave spectra of a sound pressure levels and RMS values of acceleration were made at measuring points located in the room and at the pharmacy robot. The acoustic tests were divided according to the location of the measurement points into measurements inside room and noise measurements in the near field of the pharmacy robots. The vibration measurements were made directly on the devices. Based on the analysis of the one-third octave spectra of the noise of the Fablox pharmacy robots, the sound components were determined, which are responsible for achieving high noise levels in room. The acoustic measurements in the near field at a distance of 15 cm from the unloading / front side of the pharmacy robot Fablox 1 and Fablox 2 in room, showed that the arithmetically averaged A-sound level on the measuring surface with closed housing for the movement of the head through all three loading modules is higher for the pharmacy robot Fablox 2 (66.9 dB) by 1.7 dB than the equivalent A-sound level for the Fablox 1 (65.2 dB). Due to the fact that the pharmacy robot is mostly used in the working environment in the pharmacy, the noise it generates has a large impact on employees and customers.

3

The Vibroacoustic Analysis of The Hydrocarbon Processing Plant Piping System Operating at Elevated Temperature

Błaszczyk A., Papierski A., Rydlewicz M., Susik M.

Mechanics and Mechanical Engineering

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2016

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Vol. 20, nr 4

605--626

EN

In this paper it is presented the vibroacoustic analysis of the selected section of the hydrocarbon processing chemical plant piping system operating at elevated temperature and subjected to dynamic load exciting vibration of the structure. The pump suction and discharge piping system is a part of chemical plant for processing hydrocarbon mixture at 270 st. C. Elevated temperature is one of static loads that influences the boundary conditions of the piping structure thus generating pump nozzle loadings leading to possible pump body deflection. Deflected shape of the pump body results in generation of flow fluctuation, visible and measurable as a pressure pulsation. This kind of fluctutation has been assumed further to be one of the dynamic loading on piping system structure. The dynamic analysis was performed to quantify the loading effect of pressure pulsation excited in the pump discharge nozzles on the structure of pipelines and the connected pump nozzles. The simulation was based on the numerical analysis of the excitation by acoustic waves propagation in subjected piping system. Measured on–site pressure pulsation at pumps nozzles has been identified and assumed to be the source of the acoustic waves. In the simulation elastic features of the piping structure as well as the fluid, and pressure loses in pipes, taken into account. Final result of the acoustic part of the simulation was spectral characteristics of the acoustic shock forces, defined further as harmonic loads for the dynamic structural analysis. To observe an influence of the acoustic excitation on the piping there was performed structural analysis of the piping system and the combined results of static and dynamic loading influence determined. This part of the analysis has been perfomed by means of FEM computer software Bentley AutoPIPE as well as some use of ANSYS FEM program. Important step in this simulation there was the theoretical modal analysis. This analysis allows to predict possible vibroacoustic resonance in the structural system under specific conditions of the coincidence between acoustic excitation and modals. The results of the combined static and dynamic loadings analysis contain the information on the node displacements, internal forces, resulting stresses in the pipe walls and loads on the pump nozzles and piping supports.

4

Wibroakustyczne diagnozowanie transformatorów

Kornatowski E.

TTS Technika Transportu Szynowego

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2012

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R. 19, nr 9

2591--2600, CD

PL

W artykule przedstawiono metodę analizy wibroakustycznej drgań konstrukcji transformatora rejestrowanych akcelerometrem przytwierdzonym do kadzi. Prezentowana metoda opiera się na dwóch założeniach: w stanie ustalonym bez obciążenia źródłem wibracji jest rdzeń, w stanie nieustalonym po włączeniu zasilania drgania spowodowane są przez uzwojenia zasilające i rdzeń. W stanie ustalonym sygnał z akcelerometru analizowany jest w dziedzinie częstotliwości, a w stanie nieustalonym – w dziedzinie częstotliwości i czasu.

EN

This paper presents a technique of vibroacoustic analysis of transformer mechanical condition, based on vibration measurement, using an accelerometer attached to the transformers tank. Presented method is based on two assumptions: 1. in no-load steady-state, the source of vibrations is the core, 2. in transient state, after power on, the vibrations are caused by the power winding and core. In the steady-state the signal from the accelerometer is analyzed in the frequency domain and in the transient state - in the frequency and time domain.

5

New Concept of Using Coherence Function in Digital Signal Analysis

Dąbrowski Z., Dziurdź J.

Machine Dynamics Problems

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2007

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Vol. 31, No. 3

25-31

EN

Quick progress in development of digital computational techniques has also been reflected in signal analysis. However, faster and more accurate arithmetic calculations are far from being a cure-all for all the problems conditioned by physical properties of phenomena. Limitations resulting from nature of the Fourier transformant or other features of non-linear relationships do not disappear. Therefore, it seems crucial that new interpretations methods are applied in order to bypass these limitations. On the other hand, many forms of description used to be of quite restricted use because of limited computing power, and the situation has changed only recently. According to the Authors, high capacity of digital analysis opens new possibilities of applying the coherence analysis. The paper considers an idea of using the coherence function for two tasks: identification of non-linear analytic model and improvement of accuracy narrow-band analysis.

6

A Power Transformer as a Source of Noise

Zawieska W. M.

International Journal of Occupational Safety and Ergonomics

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2007

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Vol. 13, No. 4

381–389

EN

This article presents selected results of analyses and simulations carried out as part of research performed at the Central Institute of Labor Protection – the National Research Institute (CIOP-PIB) in connection with the development of a system for active reduction of noise emitted by high power electricity transformers. This analysis covers the transformer as a source of noise as well as a mathematical description of the phenomenon of radiation of vibroacoustic energy through a transformer enclosure modeled as a vibrating rectangular plate. Also described is an acoustic model of the transformer in the form of an array of loudspeakers.

7

Wibroakustyczna analiza obciążenia łożyska tocznego

Dziurdź J.

Przegląd Mechaniczny

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2006

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nr 7-8

50-53

8

Wibroakustyczna analiza zmian średnicy otworów w węzłach konstrukcyjnych masztów kompozytowych

Dąbrowski Z., Dziurdź J.

Przegląd Mechaniczny

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2003

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nr 4

36-40

PL

Jednym z najbardziej istotnych i niewidocznych uszkodzeń masztów węglowych jest powiększanie się otworów wokół nitów okuć metalowych, spowodowane silnymi dynamicznymi przeciążeniami osprzętu (najczęściej o charakterze losowym) - w pracy zaproponowano nieniszczącą metodę określania uszkodzeń masztów (profili) kompozytowych metodami wibroakustycznymi oraz określania właściwych symptomów.

EN

One of the most critical and unseen damage to the carbon masts is an increase in the holes around the securing rivets, caused by strong, dynamic overloads from fixtures most frequently of a random character. There are several methods of determining the state of the holes. A suggestion is given of using a non-destructive method of estimating damages to the composite masts (profiles) based on vibroacoustics and observation of characteristic symptoms.