New Controllable Sound Absorbers Made of Vacuum Packed Particles - New Contributions in Information Systems and Technologies - page 289

- comprehensiveresearchregardingstructuresresponsebetweenunderpressure
levelsbetween0and0.01MPa(mostofthestructuralchanges”qualitative
andquantitative”takeplacebetweenthesevaluesofcontrolparameter),
- evaluating the influence of the grains' compaction level on acoustic char-
acteristics (in presented experiment the compaction value received a fixed
valueN=0.32).Thevalueofthediscussedparameterinfluencesthesizeand
shape of air cavities inside the structure and in consequences its acoustic
properties,
- examining the influence of shape/size of the grains' material on acoustic
absorptionproperties(inpresentedresearchgrainsizesweresimilar).
- checking if the grains' material mechanical properties such as elasticity,
strength,etc.caninfluenceacousticcharacteristics.
SpecialGranularStructureshavesomefeaturesthatarecommontosmartma-
terials[3].However,theirconsiderableadvantagesoverclassicsmartstructures
arerelativelylowpriceandcommonavailability.Mostofearlierworkdedicated
to SGS regarded mechanical properties of these materials. This research is a
continuationofearlierexperimentsdevotedtoextraordinarygranularsystems.
Investigating the influence of underpressure on acoustic properties is interest-
ingfrombotharesearchandvibroacousticapplicationpointofview.Especially
interestingseemstobeapplicationofconsideredgranularsystemasapartofcon-
trollabledampingstrategyforslenderobjectsvibrations[18]orasasemi-active
pedestrian protection system component during collision [19]. The possibility
of controlled noise reduction would surely make difference not only in certain
industrialapplicationsbutalsoineverydaylife.
References
1. Allard,J.F.,Atalla,N.:Propagation ofsoundinporousmedia.Wiley(2009)
2. Attenborough,K.:Acousticalcharacteristicsofrigidfibrousabsorbentsandgran-
ularmaterials.J.Acoust.Soc.Am.73,785-799(1983)
3. Bajkowski, J., Jasiński, M., Mączak, J., Radkowski, S., Zalewski, R.: The active
magnetorheological support as an element of damping of vibrations transferred
fromthegroundtolarge-scalestructuresupports.KeyEngineeringMaterials518,
350-357 (2012)
4. Biot, M.A.: Theory of elastic waves in a fluid porous solid I, II. J. Acoust. Soc.
Am.28,168-178(1956)
5. Ersoy,S.,K¨u¸c¨uk,H.:Investigationofindustrialtea-leaf-fibrewastematerialforits
soundabsorptionproperties.AppliedAcoustics70,215-220(2009)
6. Fatima, S., Mohanty, A.R.: Acoustical and fire-retardant properties of jute com-
positematerials.AppliedAcoustics72,108-114(2011)
7. Hong, Z., Bo, L., Guangsu, H., Jia, H.: A novel composite sound absorber with
recycledrubberparticles.JournalofSoundandVibration304,400-406 (2007)
8. PNEN-ISO10534-2:Determinationofsoundabsorptioncoecientandimpedance
inimpedancetubes
9. Pyrz, M., Zalewski, R.:Modeling of granular mediasubmittedto internalunder-
pressure.Mech.Res.Commun.37,141-144 (2010)