Viscoelasticity, frictionandgeometry:whichistheirroleingoverningthebehavior of adhesive systems? Despite the long standingeffort onthese issues, capturingandmodelingdissipativephenomenaandnon-linearities inherent inreal processesisatoughchallenge, leavingseveralquestionsandproblemsunresolved. This thesis explores someof theseparticular aspects insoft contactmechanics withaprimaryemphasisonpeelingprocesses. Inthefirstpart, anoverviewof thepeelingmechanismisprovidedwhere themost important resultsandmodelsarediscussed. Mainconceptsof linearviscoelasticityarealsogiventodefine themathematical framework foranalyzingviscoelasticpeeling. Weaddress the singlepeelingof thinviscoelastictapes inthecaseof stuckandfrictional sliding interfaces.WhileaKendall-likebehavior ispredictedintheabsenceof slippage, whenconsidering frictional dissipation inthemodel sensibledifferencesemerge. Higherpeelingforcesareobservedatlowpeelinganglesandthesystemtoughness becomesvelocity-dependentinagreementwithexperimentalobservationandphenomenologicalmodels.WealsoinvestigatetheV-peelingconfigurationaddressing thenonsteadypropagationwhichoccurs as the effect of time-dependentmaterialbehaviorandsystemgeometryvariation.Nonmonotonicevolutionofpeeling quantitiesresultsfromthecontinuouscreepoftapeduringthedetachmentprocess whichcanalsoarrestforparticularcombinationsofinitialparametersandloading conditions. Interestingly,forimpactloadingconditionsanenhancementofpeelresistanceispredictedsuggestingthatviscoelasticitycouldbecrucialforthesuperior adhesiveperformanceofnaturalpeelingsystems. Inthe lastpart,wediscussan experimentalstudyonslidingcontactbetweenasphericalglassrobeandaPDMS substratecarriedviaanadhocdevicewhichallowsforthemeasureofsurfaceinplanedisplacements.Weconsistentlyobserveacontactareareductionandashape asymmetryasapossibleeffectofgeometricalandmaterialnon-linearitiesarisingin thetensile/compressivezoneatthetrailingandleadingedge, respectively,where highlevelsofstrainareachievedandnormal-tangentialuncouplingpredictedfrom linear-elasticity isbroken. Mechanical confinementalso leads toamodification of couplingbehaviorwithrespect to infinitecontactconditions, suggestingthat geometricalaspectsarepivotaltobetterunderstandingfrictionaladhesivecontact.

Peeling behavior of thin viscoelastic tapes

Ceglie, Marco
2023

Abstract

Viscoelasticity, frictionandgeometry:whichistheirroleingoverningthebehavior of adhesive systems? Despite the long standingeffort onthese issues, capturingandmodelingdissipativephenomenaandnon-linearities inherent inreal processesisatoughchallenge, leavingseveralquestionsandproblemsunresolved. This thesis explores someof theseparticular aspects insoft contactmechanics withaprimaryemphasisonpeelingprocesses. Inthefirstpart, anoverviewof thepeelingmechanismisprovidedwhere themost important resultsandmodelsarediscussed. Mainconceptsof linearviscoelasticityarealsogiventodefine themathematical framework foranalyzingviscoelasticpeeling. Weaddress the singlepeelingof thinviscoelastictapes inthecaseof stuckandfrictional sliding interfaces.WhileaKendall-likebehavior ispredictedintheabsenceof slippage, whenconsidering frictional dissipation inthemodel sensibledifferencesemerge. Higherpeelingforcesareobservedatlowpeelinganglesandthesystemtoughness becomesvelocity-dependentinagreementwithexperimentalobservationandphenomenologicalmodels.WealsoinvestigatetheV-peelingconfigurationaddressing thenonsteadypropagationwhichoccurs as the effect of time-dependentmaterialbehaviorandsystemgeometryvariation.Nonmonotonicevolutionofpeeling quantitiesresultsfromthecontinuouscreepoftapeduringthedetachmentprocess whichcanalsoarrestforparticularcombinationsofinitialparametersandloading conditions. Interestingly,forimpactloadingconditionsanenhancementofpeelresistanceispredictedsuggestingthatviscoelasticitycouldbecrucialforthesuperior adhesiveperformanceofnaturalpeelingsystems. Inthe lastpart,wediscussan experimentalstudyonslidingcontactbetweenasphericalglassrobeandaPDMS substratecarriedviaanadhocdevicewhichallowsforthemeasureofsurfaceinplanedisplacements.Weconsistentlyobserveacontactareareductionandashape asymmetryasapossibleeffectofgeometricalandmaterialnon-linearitiesarisingin thetensile/compressivezoneatthetrailingandleadingedge, respectively,where highlevelsofstrainareachievedandnormal-tangentialuncouplingpredictedfrom linear-elasticity isbroken. Mechanical confinementalso leads toamodification of couplingbehaviorwithrespect to infinitecontactconditions, suggestingthat geometricalaspectsarepivotaltobetterunderstandingfrictionaladhesivecontact.
2023
Inglese
Carbone, Giuseppe
Menga, Nicola
Demelio, Giuseppe Pompeo
Politecnico di Bari
File in questo prodotto:
File Dimensione Formato  
36 ciclo-CEGLIE Marco.pdf

accesso aperto

Dimensione 7.1 MB
Formato Adobe PDF
7.1 MB Adobe PDF Visualizza/Apri

I documenti in UNITESI sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14242/64892
Il codice NBN di questa tesi è URN:NBN:IT:POLIBA-64892