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Modeling of Complex Properties of Vacuum
Packed Particles Using Evolutionary Algorithms
RobertZalewski
1
,PawełChodkiewicz
2
,andMariuszPyrz
3
1
WarsawUniversityofTechnology,InstituteofMachinesDesignFundamentals,
Narbutta84,02-524Warsaw,Poland
robertzalewski@wp.pl
2
WarsawUniversityofTechnology,InstituteofMachinesDesignFundamentals,
Narbutta84,02-524Warsaw,Poland
pawel@chodkiewicz.com.pl
3
WarsawUniversityofTechnology,InstituteofVehicles,
Narbutta84,02-524Warsaw,Poland
mariusz.pyrz@wp.pl
Abstract.
A conglomerate, composed of granular materials encapsu-
lated in a tight, flexible envelope, and submitted to an internal under-
pressure,changesitspropertiesinthefunctionofthevacuumrange.The
underpressure level, controlled by a vacuum pump, enables controlling
the behavior of such a medium. This particular ability could be useful
insomespecificapplications.
In this paper authors consider different mathematical formulations
fordescriptionofnonlinearpropertiesofVacuumPackedParticles.Bas-
ingonvariousexperimentaltestssuchascompressiontestswithdifferent
strainratesorstressrelaxationteststheauthorsdiscusstheencountered
problems in defining a global rheological model for considered extraor-
dinarymaterials.
Keywords:
Geneticalgorithms,VacuumPackedParticles,Experiments,
Modeling.
1
Introduction
In the lastthirty yearsthe increasedinterest in so called ”smartmaterials” is
observed.Suchmaterialsadjusttheirpropertiesaccordingtochangesofexternal
fields(electric,magnetic)orotherfactors.Inthispapertheauthorswanttoin-
troduceanew”controllablestructure”thatisVacuumPackedParticles(VPP).
Theirconfigurationinsomesenseissimilartosuchwellknown”intelligentma-
terials”asMRandERfluids[1,2].
VacuumPackedParticlesarebuildofloosegranularmaterialencapsulatedina
hermeticenvelope[3].Itispossibletochangetheirphysicalpropertiesgenerating
aninternalunderpressurebypumping outsomeairfromthestructureusinga
vacuumpump.Forhighervaluesofpartialvacuum,loosegrainstransforminto
a more rigid structure, thanks to the jamming mechanism [4,5]. It was shown
in[6]thatfortheappropriatevalueofunderpressureVPPsbehavesimilarlyto
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