Sound in engineering
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The document discusses various applications of sound in engineering. It describes how sound is used for noise control, ultrasound, and synthesizing digital sound. It also discusses how the design of buildings considers sound experience. Non-destructive testing techniques like acoustic emission and surface wave dispersion are used to evaluate bridges and detect defects without damage. Proofloading of bridges combines acoustic emissions measurements with applied loads to study crack formation and assess structural capacity.
Sound in engineering
- 1. Dr. ir. Eva Lantsoght 3/31/2015 Sound Applications in Engineering 1
- 2. General applications Applications in bridge engineering o NDT techniques o Acoustic emission o => Proofloading Summary 3/31/2015 Sound Applications in Engineering 2
- 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 3/31/2015 Sound Applications in Engineering 3
- 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 3/31/2015 Sound Applications in Engineering 4
- 5. 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 3/31/2015 Sound Applications in Engineering 5
- 6. 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 aquaplanning o No rutting Disadvantages o Less friction => longer distance when breaking o Raveling problems o Shorter lifetime than regular asphalt 3/31/2015 Sound Applications in Engineering 6
- 7. 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 Proofloading 3/31/2015 Sound Applications in Engineering 7
- 8. 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 3/31/2015 Sound Applications in Engineering 8
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- 10. 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 3/31/2015 Sound Applications in Engineering 10
- 11. Fast methods: o Where sound changes from clear ringing to mute and hollow Finds delaminations in concrete 3/31/2015 Sound Applications in Engineering 11
- 12. Stress-wave based method Detection of defects in concrete o Delamination Detect wave reflectors Frequency range 3 - 40 kHz 3/31/2015 Sound Applications in Engineering 12
- 13. Dynamic response characteristics to a given impulse excitation Lower range than impact echo o 0 – 1kHz 3/31/2015 Sound Applications in Engineering 13
- 14. Combine methods to get overview of condition of bridge More info: NDToolbox o www.ndtoolbox.org
- 15. 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” 3/31/2015 Sound Applications in Engineering 15
- 16. Use acoustic emission during proofloading Information about cracks before we can see them Combine with other measurement techniques 3/31/2015 Sound Applications in Engineering 16
- 17. 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 Proofloading until different load levels • No permanent damage • Unfit for use level • Repair level 3/31/2015 Sound Applications in Engineering 17
- 18. 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 3/31/2015 Sound Applications in Engineering 18
- 19. Proofloading to assess capacity of existing bridge Study cracks and deformations for applied loads Crack formation: acoustic emissions measurements Ruytenschildtbrug: testing to failure
- 21. 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 proofloading 3/31/2015 Sound Applications in Engineering 21