1. ATPA
- Advanced Transfer Path Analysis -
&
Use ICR ATPA

2. • ATPA: BACKGROUND
• ATPA & OTHER METHODS
• PROCEDURE STEPS
• APPLICATIONS
• PRODUCT
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3. ATPA:
BACKGROUND
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4. • ATPA is an advanced tool for the vibro-acoustic diagnostics that provides
information on the contributions to the overall noise of each element to study.
•ATPA is the only product capable of providing information on the source
contributions both regarding coherent and noncoherent addition.
•ATPA is a product exclusively created, developed and lauched onto the market by
ICR.
• ATPA is a reference product for the railway manufacturers being used for Alstom
and CAF.
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5. The origins of ATPA lie in the need to solve two different problems:
•Determining the noise produced by each one of the forces acting on a mechanical
system (TPA).
•Quantifying the contribution of each part of a vibrating system to the total noise
measured at a given location
B A
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6. 60’s
The method of solving the problem A was to cover all the interior of the vehicle
with heavy acoustic isolating materials and after to uncover the surfaces one by
one. Was the called Strip method.
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7. Strip-tease 1975
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8. 60’s
The method of solving the problem B was to completely unlink the engine
from the car by supporting it with external elements and after to link the
engine supports to the car one bye one.
The forces are not really found by this method but their effects on the noise
are quantified.
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9. •Transmission path analysis methods started at the mid 70’s with the work on
MIMO (Multiple Input Multiple Output) systems by Potter, Bendat, Piersol, Dodds
and Robson among others. The MIMO approach aims at computing the set of
optimum values that best fit real measured data. As a such, it only requires
operational measurements and can hence be classified as a one step method.
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10. 70’s MULTIPLE COHERENCE METHOD
R.J. Alfredson, L.L.Koss, J.Bendat,C.J. Dodds and R.Potter
p  a1H1  a2H2  ......  an Hn
Applying this equation in a set of different times we can calculate de Hi
values in a least square error sense. This allows to know the contributions
of each subsystem to the interior pressure (SPL).
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11. •At the early 80’s, Magrans (J. Sound Vibr.) defined the force TPA approach in its
nowadays format as well as the basis for the ATPA (Advanced TPA) that will be
exposed in this presentation.
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12. 80’s GTDT Method
The only measurable TF is the GTF (Global Transfer Function).
The signal flows through all subsystems and all of them contribute to the SPL.
These contributions are not superimposable.
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13. 80’s GTDT method (Magrans, J.S.V. 1980)
The Paths are defined using the DTF (Direct Transfer Function).
This DTF is not measurable but is the only TF that we can use to know the
interior pressure by superposition of subsystems contributions.
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14. 80’s GTDT method
DTFs TD can be computed from the measured GTF TG
GTDT method
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15. With only the GTF >Forces TPA
Equivalent to the engine unlink old method
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16. With DTF>ATPA using acceleration
Equivalent to the old strip method
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17. Forces TPA
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18. ATPA
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19. Acoustical example: Helmholtz equation on a 2D rectangular space.
GTF DTF
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20. •TPA with the Forces/acceleration Global Transfer function speaks only about
the external Forces and his contribution to the noise or vibration in the object, not
about “paths”. The black box remains closed. It is a “sensitivity “ method.
•ATPA with the DTF speaks about the paths that links the subsystems in the test
object.
•Also through the DTF we can know how the vibration or noise of a subsystem
contributes to the noise or the vibration in another subsystem.
•ATPA opens the black box , ATPA works with “signals” (acceleration, velocity,
displacement, Energy).
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21. ATPA & OTHER METHODS
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22. • Other’s TPA only works in coherent identification (low frequency).
• ICR ATPA provides information on the contribution of all frequency ranges,
coherent and energy identification (high and low frequency).
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23. • TPA implies time dismantling part of the system and can produce fundamental
changes to the structure such as a reduction of the stiffness in the area
surronding a connection.
• ATPA is an easy and fast method and enables measurements to be made on
the full system without dismantling anything.
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24. •TPA allows to determine
the contribution to the
overall noise that is due to
the force acting on the
wheel.
•TPA does not give
information on the particular
contribution of each
structural component or
subsystem.
•ATPA gives this information
because quantifies the FF
transmission path of each
element of any structure.
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25. In summary, F SPL
• Classic TPA acts as a
black box connecting an
input force with an SPL
output.
a1 a3
SPL
• ATPA quantifies the vibro- a0 a4
acoustic connections F
(transmission paths) among
a5
various subsystems and a2
evaluates their mutual
interaction.
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26. •The results of LMS and Brüel & Kjaer Reciprocity methods only represents the
reality when panels are unlinked, if not the results will superimposed because is a
global transfer.
•When the source is the panel the signal will arrive from everywhere to the
microphone that has replaced the source, like it arrives , in the direct experiment ,
from the source to the to the panel.
• The measured values are global transfers and can’t be superimposed
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27. •Microflown Reciprocity method has no error in the theory (Daniel Fernandez Comeñasa,
Andrea Grosso, Jelmer Wind, Hans-Elias de Bree and Keith Holland. Further Development TPA: Scan & Paint TPA as a fast tool for
but shows that the result obtained is not which is
Sound Source Ranking.SAE International (2012)
wanted. The paper result is that we can know the pressure in a point (i)
measuring by reciprocity μ and β and the presures and accelerations in operational
mode a (acceleration) and p (pressure) in all subsistems..
pr    k pk  k ak 
k
• But this is a not relevant physical state and by the way is not the strip case.
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28. • ATPA really identifies the elements which contributes to overall noise as the
“Strip”, which applied the superposition principle which can be expresed with this
formula:
pr    k ak
k
• This is the Strip situation, only one panel radiating and the others blocked.
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29. PROCEDURE STEPS
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30. ANALYZER
Step 1: 1 2 31 32
STATIC TEST 1 2
31
32
CROSS FUNCTIONS ANALYSIS
Step 2:
OPERATING DATA RECORDING Step 3:
OPERATING COMPUTATION
TEST 1
RECORDER
2
…
31
OPERATING
CONTRIBUTIONS
32
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31. APPLICATIONS
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32. RAILWAY
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33. Objective: To reduce the noise inside a train passengers area.
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34. 03/05/2012 ATPA 34

35. dB
10
20
30
40
50
60
70
80
20
150
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280
409
539
669
798
928
1058
1188
1317
1447
1577
Averaged narrow band results
1706
1836
1966
2095
2225
2355
2484
Hz
2614
2744
2873
3003
ATPA
3133
3263
Measured Spectrum vs Synthesised
3392
3522
3652
3781
3911
4041
4170
4300
4430
4559
4689
4819
4948
Measured
Synthesised
35

36. Averaged dBA results
Target_Mic-48
75 76
68
Ctrl_1 66
58
58
End1_Panel_B-43 46
44
58
Floor_A_e2-40 65
66
70
Roof_cnt_e2-37 44
46
45
Roof_B_e2-34 38
46
42
Roof_cor_B_e2-31 50
52
48
Up_Pan_B_e2-28 51
54
47
Side_Win_B_e2-25 52
47
49
Side_Win_B_e1-22 51
45
45
Low_Pan_B_e2-19 52
52
39
Roof_A-16 45
42
50
Roof_cor_A-13 52
52
43
Up_Pan_A-10 55
41
52
Window_A_e2-07 48
57
48
Window_A_e1-04 45
46
52
Low_Pan_A_e1-01 49
30 35 40 45 50 dBA 55 60 65 70 75 80
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37. Time history dBA Comparison. from t:4.6636 s. to t:4.666 s.
70
65
60
55
dBA
50
45
Synthesised
40 Target-Mic-48
35
4.6644 4.6646 4.6648 4.665 4.6652 4.6654 4.6656 4.6658 4.666
t [s]
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38. Low frequency results
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39. Low frequency results
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40. Objective: to reduce the noise inside a train cabin.
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42. Original Noise: 81 dB
dBAs Promedio Grupos
[33]Medido 81(81)
[32]Sintetizado 81(81)
[9]Suelo 75(81)
[26]MicroVentanaDerecha 75(80)
[28]MicroJuntaPuertaInterior 73(78)
[29]MicroChapaBajoPupitreDerecho 70(76)
Resto 70(74)
[31]MicroVentilaciónDrontal 69(73)
[30]MicroChapaInferiorFrontal 68(70)
Techo 63(65)
Armario 61(61)
60 65 70 75 80
Final Noise: 76 dB
Result: Interior cabin noise reduced in 5 dB B
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43. Case 1
1
3
2
4
5
6
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44. Case 2: prediction and solution of vertical damper problem
Initial, prediction and measured
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45. BUILDING
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46. Objective: to identify and solve the problems of UNE EN ISO 12354 standard in determining
contributions of direct and indirect sources.
Configuration 1
Configuration 2
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47. Reconstruction for configuration 1 Reconstruction for configuration 2
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48. Objective: study of noise transmission paths in windows through frames, the joints
between window and frams, the joints between glass and frames, etc.
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49. WIND POWER
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50. Objective: study the aerial and structural contribution of two ventilation pipes in case of
noise emitted by a wind turbine.
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51. Valores Globales en dBA
65
Medido
Sintetizado
Ruido de Fondo
60
55
dBA
50
45
40
50 Hz 40 Hz 35 Hz 30 Hz 25 Hz 0 Hz
Modo Funcionamiento
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52. PLOTTER
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53. Objective: reduction of a plotter radiated noise .
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54. Narrow Band Results
dBA Results
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55. PRODUCT
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56. 50-hour course whereby the transmission paths are established and assessed
through Direct Transfer.
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57. The “subsystem” concept, which is essential in the ATPA application, is defined as
well as the theoretical basis.
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58. ICR usually works for 30 working days in conjunction with the client´s staff to
perform a series of tests that may show how the method works and provides the
client with the physical principles governing the method.
A Measurement Protocol is the final document of the Know-How transfer
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59. • ICR provides its
software in compiled
Matlab and also
programs the input
processing for specific
files of the client in
Matlab.
• The software is custom
designed for each client
so that its application
matches their needs.
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60. •Taylor-made application
•Sources contribution: Classical TPA method.
•Emitters contributions: Advanced TPA method.
•Frequency range from 0 to 5 kHz.
•Not required to measure forces (#LMS, Brüel &
Kjaer).
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61. Only the leading manufacturers of rolling stock
use ICR ATPA method
&
Use our ATPA method
&
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