Post on 31-Mar-2015
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AN INVESTIGATION OF A PERIODIC STRUCTURE TO SUPPRESS THE TRANSMISSION OF ENERGY IN AN ELASTIC TUBE, AND EXPERIMENTAL 6 DOF TECHNIQUES TO DETECT IT
Ole Holst-Jensen1*, Sergey Sorokin et al2
1Minus10dBStokrosevej 29, 8330 Beder, Denmark
ole.holst@minus10db.dk
2Department of Mechanical Engineering, Aalborg UniversityPontoppidanstraede 101, Aalborg East, DK 9220, Denmark
svs@ime.aau.dk
RASD July 2010
Periodic beam structures• Organisation: Makunet
– Machine acoustic network– Major Danish industrial partners– Institute of Mechanical Engineering at Aalborg
University Denmark
• Purpose of this project– Use periodic structures to control pipe vibration in
pipes and plates– Develop engineering tools for the design of
periodic structures• Theoretical optimisation tool• Measurement tool
RASD July 2010 2
• Background• Experimental setups
• Pipe with highly damped termination• Beam with reflecting termination
• Theory• Results with damped termination• 6 degree of freedom experimental
technique • Application to beam with reflecting
termination• Conclusion
Transmission control
RASD July 2010 3
4
Background
RASD July 2010
0 40 80 120 160 200 240 280 320 360 400[Hz]
300u
1m
3m
10m
30m
0.1
0.3
1[rad/s²]
PLF - z_rotation (Real) \ FFTPLF - z_rotation Mark 1 (Real) \ FFT
Red: Motor spectrum
Blue: impact spectrum
Varying speed driveOperating range:20 to 60 Hz shaftspeedExample: 38 Hz
Pipe with highly damped termination
RASD July 2010 5
• Tube ø 34 / 27, steel• Length: 4000 mm• Blocks: 75 x 75 mm h: 220 mm• Block weight: 4000 g• Damping stiffening: 19 x 19 mm
RASD July 2010 6
Pipe with highly damped terminationEffect of damping
Frequency Response H1(Signal 5,Signal 1) - Mark 1 (Magnitude)FRF : 4m tube 0 damp o blk : Input : FFT Analyzer
0 200 400 600 800 1k 1.2k 1.4k 1.6k 1.8k 2k
100m
300m
1
3
10
30
100
300
[Hz]
[(m/s²)/N] Frequency Response H1(Signal 5,Signal 1) - Mark 1 (Magnitude)FRF : 4m tube 0 damp o blk : Input : FFT Analyzer
0 200 400 600 800 1k 1.2k 1.4k 1.6k 1.8k 2k
100m
300m
1
3
10
30
100
300
[Hz]
[(m/s²)/N]
Frequency Response H1(Signal 5,Signal 1) - Mark 2 (Magnitude)FRF : 4m tube w damp 0blk : Input : FFT Analyzer
0 200 400 600 800 1k 1.2k 1.4k 1.6k 1.8k 2k
100m
300m
1
3
10
30
100
300
[Hz]
[(m/s²)/N] Frequency Response H1(Signal 5,Signal 1) - Mark 2 (Magnitude)FRF : 4m tube w damp 0blk : Input : FFT Analyzer
0 200 400 600 800 1k 1.2k 1.4k 1.6k 1.8k 2k
100m
300m
1
3
10
30
100
300
[Hz]
[(m/s²)/N]
Undamped
Damped
Beam with reflecting termination
RASD July 2010 7
• Måling og analyse i 6 frihedsgrader
8
Theory: Boundary equations
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2
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RASD July 2010
Experimental Insertion Loss
PeritubeInsertion Loss: 10*log10({no blocks}/{3 blocks})
-30
-20
-10
0
10
20
30
40
50
0 200 400 600 800 1000 1200 1400 1600 1800 2000
f Hz
IL d
B
IL 0blk 3blk IL 0blk 2blk IL 0blk 1 blk
RASD July 2010 9
PeritubeInsertion Loss: 10*log10({no blocks}/{3 blocks})
-30
-20
-10
0
10
20
30
40
50
0 200 400 600 800 1000 1200 1400 1600 1800 2000
f Hz
IL d
B
IL 0blk 3blk IL 0blk 3 blk01 IL 0blk 3blk02
3, 2 and 1 blocks 3: Heavy, light, medium blocks
RASD July 2010 10
Comparison Insertion Loss
11
Background6 Degree of freedom measurement
RASD July 2010
•Simple method of separating modes •Torsional modes are often not recognized in simple measurements•Evolution of vibration measurements:
• One axis• Three axis• 6 axis
•Mulitchannel digtal techniques makes realtime 6 DOF possible
Test setup
RASD July 2010 12
• Comparison of plain beam and beam with three blocks• Two types of blocks
– Aluminium 10 x 10 x 100mm beam with thread– Block 1: 47 g weight on top– Block 5: 156 g weight on top
• Axes – X – vertical xx – bending horizontal plane– Y – horizontal yy- bending vertical plane– Z – longitudinal zz –torsion longitudinal
RASD July 2010 13
Setup7: 0 blocks - 3 block1 47 g
0 50 100 150 200 250 300 350 400 450 500[Hz]
2u
10u
50u
200u
1m
5m
20m[m/s²]
PLF - x_ave (Magnitude) \ FFT \ W2 0blkPLF - x_ave Mark 1 (Magnitude) \ FFT \ W2 3blk1 glue 100mm S:500mm
0 50 100 150 200 250 300 350 400 450 500[Hz]
2u
10u
50u
200u
1m
5m
20m[m/s²]
PLF - y_ave (Magnitude) \ FFT \ PLF - y_ave Mark 1 (Magnitude) \ FFT \
0 50 100 150 200 250 300 350 400 450 500[Hz]
2u
10u
50u
200u
1m
5m
20m[m/s²]
PLF - z_ave (Magnitude) \ FFTPLF - z_ave Mark 1 (Magnitude) \ FFT
0 50 100 150 200 250 300 350 400 450 500[Hz]
5u
20u
100u
500u
2m
10m
50m[rad/s²]
PLF - x_rotation (Real) \ FFTPLF - x_rotation Mark 1 (Real) \ FFT
0 50 100 150 200 250 300 350 400 450 500[Hz]
5u
20u
100u
500u
2m
10m
50m[rad/s²]
PLF - y_rotation (Magnitude) \ FFTPLF - y_rotation Mark 1 (Magnitude) \ FFT
0 50 100 150 200 250 300 350 400 450 500[Hz]
5u
20u
100u
500u
2m
10m
50m[rad/s²]
PLF - z_rotation (Real) \ FFTPLF - z_rotation Mark 1 (Real) \ FFT
RASD July 2010 14
Setup7: 0 bloks - 3 block5 203 g
0 50 100 150 200 250 300 350 400 450 500[Hz]
2u
10u
50u
200u
1m
5m
20m[m/s²]
PLF - x_ave (Magnitude) \ FFT \ W2 0blkPLF - x_ave Mark 1 (Magnitude) \ FFT \ W2 3blk5 glue loose 100mm S:500mm
0 50 100 150 200 250 300 350 400 450 500[Hz]
2u
10u
50u
200u
1m
5m
20m[m/s²]
PLF - y_ave (Magnitude) \ FFT \ PLF - y_ave Mark 1 (Magnitude) \ FFT \
0 50 100 150 200 250 300 350 400 450 500[Hz]
2u
10u
50u
200u
1m
5m
20m[m/s²]
PLF - z_ave (Magnitude) \ FFTPLF - z_ave Mark 1 (Magnitude) \ FFT
0 50 100 150 200 250 300 350 400 450 500[Hz]
5u
20u
100u
500u
2m
10m
50m[rad/s²]
PLF - x_rotation (Real) \ FFTPLF - x_rotation Mark 1 (Real) \ FFT
0 50 100 150 200 250 300 350 400 450 500[Hz]
5u
20u
100u
500u
2m
10m
50m[rad/s²]
PLF - y_rotation (Magnitude) \ FFTPLF - y_rotation Mark 1 (Magnitude) \ FFT
0 50 100 150 200 250 300 350 400 450 500[Hz]
5u
20u
100u
500u
2m
10m
50m[rad/s²]
PLF - z_rotation (Real) \ FFTPLF - z_rotation Mark 1 (Real) \ FFT
RASD July 2010 15
Conclusions• Pipe with highly damped termination
– Eigenfrequencies match theory– Insertion loss show agreement between theory and experiment with stop
bands, when using energy and acceleration levels• Beam with reflecting termination
– 6 DOF measurement on rigid body termination can separate modes– Eigenmodes are suppressed
• Further investigations: – Parametric studies– Application to industrial setting