Applications of sound in engineering

1.  
Dr. ir. Eva Lantsoght
3/2/2018 Sound Applications in Engineering
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2.  General applications
 Applications in bridge engineering
o NDT techniques
o Acoustic emission
o => Proof loading
 Summary
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3.  Sound in Engineering? Acoustic
Engineering
o Design, analysis and control of sound
 Applications
o Noise control: reduce unwanted noise
o Ultrasound
o Programming digital sound of
synthesizers
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4.  Design of building ~ sound experience
 Depends on the use of the building
o Theatre: good speech intelligibility
o Concert hall: quality of sound of music
o Offices: pleasant space, not too noisy
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6.  Noise pollution = disturbances caused by unwanted
sounds
o Transport
o Industry
o Recreation
 Civil Engineering
o Development of better material mixes to reduce noise levels of
traffic
o Open graded asphalt
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7.  Used in The Netherlands (ZOAB)
 “Whisper asphalt”
 Very porous mix
o More coarse material
o Less fine material
 Advantages
o Noise reduction: 4dB at 120km/h
o Drainage of water – no aqua planning
o No rutting
 Disadvantages
o Less friction => longer distance when breaking
o Raveling problems
o Shorter lifetime than regular asphalt
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8.  Extending the service life of existing bridges
o Improved calculation methods
o Improved inspection methods
o Improved rehabilitation methods
 Inspection:
o Visual inspection
o Non-destructive inspection
o Destructive inspection
o Proof loading
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9.  Non-destructive testing method
 Evaluation of material properties (e.g. E-modulus)
 For near surface zone
 Surface wave dispersion
o Velocity of propagation as function of frequency and wavelength
o In layered system
o To obtain information about layer thickness and E
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11.  More commonly used – with electro-magnetic waves (not
sound waves)
 Objects inside depth of concrete
o Reinforcement
o Wire meshes
 Produces contour maps of subsurface features
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12.  Fast methods:
o Where sound changes from clear ringing to mute and hollow
 Finds delaminations in concrete
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13.  Stress-wave based method
 Detection of defects in concrete
o Delamination
 Detect wave reflectors
 Frequency range 3 - 40 kHz
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14.  Dynamic response characteristics to a given impulse
excitation
 Lower range than impact echo
o 0 – 1kHz
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15.  Combine methods to get
overview of condition of
bridge
 More info: FHWA
o https://fhwaapps.fhwa.dot.gov
/ndep/

16.  Acoustic waves emitted by material
 Caused by irreversible change in internal structure
o Crack formation
o Plastic deformation
 Transient elastic waves
 < 1kHz – 100MHz
o For applications: 100 kHz – 100 MHz
 Event => measurement “hit”
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17.  Use acoustic emission
during proof loading
 Information about cracks
before we can see them
 Combine with other
measurement techniques
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19.  Levels of assessment of bridges
o Hand calculation
o Linear finite element calculation
o Non-linear finite element calculation
o Probabilistic analysis
o Coupling probabilistic + NLFEA
 Still uncertainties?
o Proof loading until different load levels
• No permanent damage
• Unfit for use level
• Repair level
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20.  Extend service life of existing
infrastructure
 Effect of deterioration of materials
on structural performance
 Test 1 bridge
o But information valid for subset of
bridge stock
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21.  Proof loading to assess capacity of
existing bridge
 Study cracks and deformations for
applied loads
 Crack formation: acoustic
emissions measurements
 Ruytenschildtbrug: testing to failure

23.  Sound in Engineering – many
applications
 General applications: think
about effects of sound for
buildings, pavements, ..
 Application to bridges
o NDT techniques for better
inspection
o Acoustic emission as measurement
technique
o Acoustic emission used in proof
loading
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24. Contact:
Eva Lantsoght
E.O.L.Lantsoght@tudelft.nl
elantsoght@usfq.edu.ec