This document discusses various applications of sound in engineering. It describes how sound is used for noise control, ultrasound, and synthesizers. In building design, sound is an important consideration depending on the intended use of the space. Applications in bridge engineering include non-destructive testing techniques like acoustic emission testing during proof loading to detect cracks before they are visible. The document also discusses using specialized asphalt mixes to reduce traffic noise pollution and extending the lifespan of bridges through improved inspection, calculation, and rehabilitation methods.

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