Upload
eugenia-ross
View
221
Download
0
Tags:
Embed Size (px)
Citation preview
Non contact acquisition of sonic emissions of bearingsAssoc. Prof.: Kiril M. Alexiev, Petia D. Koprinkova-Hristova; Dr.: Vladislav V. Ivanov, Volodymyr V. Kudriashov, Iurii D. Chyrka
AComIn Technology Transfer Workshop onAdvanced Techniques in NonDestructive Testing
Sozopol, June 18-19, 2015
Outline
• The Acoustic Camera overview and resolution enhancement
• Experiment description
• Comparison of spectra estimates from single microphone and from the focalized Acoustic Camera
• Obtained spectra estimates for different bearings
2
Acoustic Camera Applications:Acoustic Imaging and Signal Analysis
Pictures from WWW3
The Acoustic Camera
4
Software list:a) Acoustic Test Consultant - Type 7761;b) Beamforming - Type 8608;c) FFT Analysis - Type 7770;d) Time Data Recorder - Type 7708.Manufacturer: Brüel & Kjær (Sound and Vibration Measurement A/S)
• PULSE LabShop Customized Solution Version 17.1.2• Array Acoustics Post-processing ver.: 17.1.2.308
Frequency range: from 10Hz to 20kHzWavelength range: from 34.3m to 17.15mm
Criteria:Half power (-3dB)
5 5
Trg. 2 Trg. 1
Resolution Enhancement
6
Resolution Enhancement
B&K “Array Acoustics Post-processing” 1 response Capon mod. 2 responses
dB
Center frequency fc =10 kHz. Frequency bandwidth f ≈ 2.3 kHz. fc/f ≈23%Range ~0.8 m. Spacing between centers of the speakers ~0.1 m
Before After (Obtained result)
Trg. 1 Trg. 2Trg.
222SESESESE zkzykyxkxkr C
HSECSESE fXfFfXfQ 0
C
HSEMCSE
SEfXfFfX
fR
1
1 ikjtifjiatkutksN
i
,exp2exp,,1
SSE vkrifik 2,
7 7
Beamforming based-on modified Capon algorithm
dB dB
Center frequency fc =5 kHz. Frequency bandwidth f =0.5 kHz. fc/f =10%Range ~0.75 m; Spacing ~0.14 m
“Delay and Sum” Beamforming Capon mod.
Before After (Obtained result)
Trg. 1 Trg. 2Trg.
Photo
8
Spectra Estimates
9
Parameters for SKF bearing SKF ”type” 6205.
Number of rolling elements N 9
Rolling element diameter B, mm 7.938
Pitch diameter P, mm 39.04
Contact angle , deg. 0
Rotational speed F, rpm Unknown.Slightly variable.
Pitch diam
eter, P
Rolling element diameter, B
SKF old Opened
10
Verified with SKF “Bearing Frequencies Calculator”. Bearing SKF ”type” 6205.
Parameters on Rotational speed F, rpm & Shaft speed frequency, Hz
Min: 1820 & 30.3(3) Max: 1830 & 30.5
Fundamental train frequency FTF, Hz
12.0828 12.1492
Ball pass frequency BSF, Hz
71.5076 71.9005
Ball pass frequency outer race BPFO, Hz
108.7455 109.343
Ball pass frequency inner race BPFI, Hz
164.2546 165.157
Rolling element defect frequency, Hz
143.015 143.801
Bearing Fundamental FrequenciesSKF old Opened
The first bearing band
11
SKF old Opened
Acquisition time, T = 0.25, [s]Frequency resolution, f = 4, [Hz]Quantity of autospectra averages = 100
Good sample emission is more powerful
Bad sample emission is more powerful
Spectra estimates
12
Acquisition time, T = 0.25, [s]Frequency resolution 1, f1 = 4, [Hz]No averaging
Acquisition time is TFrequency resolution 2, f2 = 256, [Hz]Quantity of autospectra averages = 64
Non-stationary signals
13
The considered spectra difference is at higher frequency range. Thus, such peaks were not removed, yet.
Spatial Filtering
14
An isotropic radiator,a theoretical point source of a waves
An irregular array of transducers
Normalized radiation patterns
0 dB–3 dB
0 dB–3 dB
-Mainlobe
-Sidelobes
-Grating Lobe(s)
Contrast
Angle
–10 dB
Enhancement of Spectra Difference
15
The difference is not getting w
orse due to application of the m
icrophone array
Beamwidth ~60o
Beamwidth >~120o
The Generated Acoustic Map 1
16
Lower Signal-to-noise ratio
- 55 dB
Center frequency, fС=10, [kHz]Bandwidth f = 1, [kHz]
The Generated Acoustic Map 2
17
Higher Signal-to-noise ratio
- 55 dBup grow, PSF
Center frequency, fС=10, [kHz]Bandwidth f = 1, [kHz]
Spectra Estimates
18
SKF old Opened
Hereinafter:Acquisition time, T = 0.25, [s]Frequency resolution, f = 4, [Hz]Quantity of autospectra averages = 100
Spectra Estimates
19
SKF old Opened
The difference is much lower than in previous Measurements Session due to greasing
Spectra Estimates
20
SKF old Opened
At the room, the background varies at low freq.
Spectra Estimates
21
2. WBF Good
Two “same” spectra
About 20 dB difference
Spectra Estimates
22
3. NSK
Spectra Estimates
23
4. KBS
Spectra Estimates
24
5. HF
Spectra Estimates
25
6. CNR
Spectra Estimates
26
7. VMF
Spectra Estimates
27
8. SKF
Spectra Estimates
28
8. SKF
29
Main goal is to find collaboration with industry/business.
Project AComIn "Advanced Computing for Innovation“ FP7 Capacity Programme.
Host – Institute of Information and Communication Technologies at the Bulgarian Academy of Sciences.
Aco
usti
c C
amer
a A
ppli
cati
ons
1. Noise pollution Airport noise Urban/Street noise Instrument noise
2. Noise identification (Find the source of specific noise)
Sound quality analysis Data/music recording Multimedia product analysis
3. Diagnostic approaches Spectral analysis Time-frequency analysis Trend detection in sound intensity signals Noise intensity analysis Shock response analysis etc, including post-processing in third-party software
4. Occupational health Noise exposure Hearing protection Human vibration Noise reduction Factory hall acoustic
5. Military/security applications Noise barrier detectors Noise localization Noise recognition
6. Scientific tool for research in Beamforming Random antenna array development Acoustic signal analysis Acoustic holography Signal processing/filtering etc.
7. Educational Useful for experiments/demonstrations 30
Conclusions
• Frequency resolution of the Acoustic Camera is modified from 1/3 octave to 4 Hz.
• Comparison of the spectra shows opportunity to detect difference to good bearings.
• Non-contact diagnosis is implemented.
Future Plan:
Automatic detection of defects (using the spectra) will be implemented for priori unknown background noise.
31