Major Accomplishments in Composite Materials and Sandwich Structures

837 Pages·2010·22.07 MB·English

by  Yasushi Miyano

Major Accomplishments in Composite Materials
and Sandwich Structures
“This page left intentionally blank.”
I.M. Daniel E.E. Gdoutos Y.D.S. Rajapakse
(cid:129) (cid:129)
Editors
Major Accomplishments
in Composite Materials
and Sandwich Structures
An Anthology of ONR Sponsored Research
123
Editors
I.M.Daniel Y.D.S.Rajapakse
Dept.Civil&Environmental OfficeofNavalResearch
Engineering SolidMechanicsProgram
NorthwesternUniversity ArlingtonVA22203-1995
2137TechDrive USA
EvanstonIL60208 [email protected]
CatalysisBldg.
USA
[email protected]
E.E.Gdoutos
Dept.ofCivilEngineering
Lab.forAppliedMechanics
DemocritusUniversityofThrace
67100Xanthi
Greece
[email protected]
ISBN978-90-481-3140-2 e-ISBN978-90-481-3141-9
DOI10.1007/978-90-481-3141-9
SpringerDordrechtHeidelbergLondonNewYork
LibraryofCongressControlNumber:2009930153
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Preface
Thisbookcontainsacollectionofmajorresearchcontributionsoverthelastdecade
intheareaofcompositematerialsandsandwichstructuressupportedbytheOffice
of Naval Research (ONR) under the direction of Dr. Yapa D.S. Rajapakse. The
SolidMechanicsResearchProgramatONRsupportsresearchinmechanicsofhigh
performancematerialsfortheeffectivedesignofdurableandaffordableNavalstruc-
tures.Suchstructuresoperateinsevereenvironments,andaredesignedtowithstand
complexmulti-axialloadingconditions,includinghighlydynamicloadings.Theef-
fectivedesignofthesestructuresrequiresanunderstandingofthedeformationand
failure characteristics of structural materials, and the ability to predict and control
their performance characteristics. The major focus is on mechanics of composite
materialsandcompositesandwichstructures.Theprogramdealswithunderstand-
ingandmodelingthephysicalprocessesinvolvedintheresponseofglass-fiberand
carbon-fiber reinforced composite materials and composite sandwich structures to
static,cyclic,anddynamic,multi-axialloadingconditions,insevereenvironments
(seawater,moisture,temperatureextremes,andhydrostaticpressure).
This anthology consists of 30 chapters written by ONR contractors and recog-
nizedexpertsintheirfieldsandservesasareferenceandguideforfutureresearch.
Thetopicscoveredinthebookcanbedividedintothreemajorthemes:
(cid:2) Mechanical and failure behavior of composite materials and structures under
staticanddynamicloading
(cid:2) Mechanicalandfailurebehaviorofsandwichmaterialsandstructuresunderstatic
anddynamicloading
(cid:2) Constituent materials, including fiber, polymer matrix materials, and core
materials
Thevarioustopicsdiscussedwithineachthemeareasfollows:
Mechanicalandfailurebehaviorofcompositesmaterialsandstructures
understaticanddynamicloading
Thestaticbehaviorisdiscussedinfourchaptersasfollows:
“Accelerated Testing for Long-Term Durability of Various FRP Laminates
for Marine Use,” by Y. Miyano and M. Nakada, develops an accelerated testing
v
vi Preface
methodologybasedonthetime-temperaturesuperpositionprincipleforthepredic-
tionoflong-termfatiguelifeofvariousFRPlaminatesformarineuseundervarious
temperatureandwaterenvironments.
“Carbon Fiber – Vinyl Ester Interfacial Adhesion Improvement by the Use of
anEpoxyCoating,”byF.Vautard,L.XuandL.T.Drzal,investigatestheoriginsof
lowinterfacialadhesionofcarbonfiber–vinylestercomposites.Itwasfoundthat
curingvolumeshrinkageisthemaincauseofpooradhesion,andthatanengineered
interphaseconsistingofapartiallycross-linkedepoxysizingthatcouldchemically
bondtothecarbonfiberandformaninterpenetratingnetworkwiththevinylester
matrix,improvestheinterfaceadhesion.
“APhysicallyBasedCumulativeDamageFormalism,”byR.M.Christensen,de-
rivesageneralcumulativedamagemethodologyfromtherelationofcrackgrowth
rateasapowerlawofthestressintensityfactor.Themethodologyappliesinthecase
ofcreeptofailureundervariablestresshistoryaswellasforcyclicfatiguetofailure
undervariablestressamplitudehistory.Theadvantagesofthedevelopedmethodol-
ogyovertheLinearCumulativeDamagetheoryareshownbyseveralexamples.
“DelaminationofCompositeCylinders,”byP.DaviesandL.A.Carlsson,studies
thedelaminationresistanceoffilamentwoundglassepoxycylindersforarangeof
winding angles and fracture mode ratios using beam fracture specimens, and the
influenceofdelaminationdamageonthefailureofexternallypressurizedcompos-
ite cylinders. It was found that the delamination fracture resistance increases with
increasing winding angle and shear fracture, and that the cylinder strength is in-
sensitive to the presence of single delaminations, and that impact damage causes
reductioninfailurepressure.
Thedynamicbehaviorisdiscussedinfourchaptersasfollows:
“Modeling of Progressive Damage in High Strain-Rate Deformations of Fiber-
ReinforcedComposites,”byR.C.BatraandN.M.Hassan,developsamathematical
model for analyzing high strain-rate deformations of fiber-reinforced composites
subjected to shock loads. The formulation of the problem includes evolution of
damageduetofiberbreakage,fiber/matrixdebonding,matrixcrackinganddelam-
ination. Energies dissipated in these failure modes are computed and the effect of
various parameters is examined. The mathematical model is validated by compar-
ingcomputedresultswithexperimentalfindings.AFigureofMeritisintroducedto
characterizetheperformanceoflaminatedcompositessubjectedtoimpactloads.
“Post-Impact Fatigue Behavior of Woven and Knitted Fabric CFRP Laminates
for Marine Use,” by I. Kimpara and H. Saito, studies the damage evolution in
carbon-fiber-reinforcedlaminatesunderpost-impactfatigueandwaterenvironment.
Thedamagewascharacterizedbynon-destructiveanddirectobservationmethods.
Evidenceofinterfacialdegradationcausedbywaterabsorptionwasfound.
“Dynamic Interaction of Multiple Damage Mechanisms in Composite Struc-
tures,” by R. Massabo`, deals with the interaction of multiple damage mechanisms
inmultilayeredstructuresunderstaticanddynamicloading.Thisworkestablishes
alinkbetweenmaterialandstructuralperformanceandgivesbasicinsightforim-
provementsinthesurvivabilityofshipstructuresviamaterialandstructuraldesign.
Preface vii
“A Review of Research on Impulsive Loading of Marine Composites,” by
M.PorfiriandN.Guptaprovidesageneraloverviewoftheworkperformedonthe
effectofblastwavesonmarinematerialsandstructures.
Mechanicalandfailurebehaviorofsandwichmaterialsandstructures
understaticanddynamicloading
This theme deals with mechanical and failure behavior of sandwich materials
andstructuresunderstaticanddynamicloading.Thestaticcaseisdiscussedinten
chaptersasfollows.
“Failure Modes of Composite Sandwich Beams,” by I.M. Daniel and
E.E. Gdoutos studies the failure modes in axially loaded composite sandwich
columns and sandwich beams under bending and shear. Failure modes include
facesheet failure, facesheet debonding, indentation failure, core failure, and
facesheet wrinkling. The transition from one failure mode to another for vary-
ing loading or state of stress and beam dimensions was discussed. Experimental
resultswerecomparedwithanalyticalpredictions.
“Localised Effects in Sandwich Structures with Internal Core Junctions: Mod-
elling and Experimental Characterisation of Load Response, Failure and Fatigue,”
byM.JohannesandO.T.Thomsen,addressesthemodellingandexperimentalchar-
acterisationofsandwichstructureswithinternalcorejunctionsunderin-planeand
transverseshearloading.Theselocaleffectsleadtoanincreaseoffacesheetbend-
ingstressesandcoreshearandtransversenormalstresses.Theinfluenceofthelocal
effectsonthefailureofsandwichstructuresunderquasi-staticandfatigueloading
isinvestigated.
“DamageToleranceofNavalSandwichPanels,”byD.Zenkertfocusesondam-
age tolerance modeling and testing of sandwich panels for marine applications. It
presents a review of testing methods for extracting properties and data required
fordamagetoleranceassessmentofcorematerials.Sometypicaldamagetypesare
definedandmodeledwiththeobjectiveofpredictingtheireffectonloadbearingca-
pacity.Theuseofsuchmodelsinprovidingasystematicdamageassessmentscheme
forcompositesandwichshipstructuresispresented.
“Size Effect on Fracture of Composite and Sandwich Structures,” by
E.E. Gdoutos and Z.P. Bazˇant reviews the work performed on the scaling and
size effect in the failure of advanced composites, foams and sandwiches. The size
effectisfoundtobeessentiallydeterministiccausedbyenergyreleaseduetostress
redistribution.Thesizeeffectoftheabovematerialsispresentedinsixsectionsfor
fiber-composite laminates subjected to tension, compression and flexural loading,
toclosed-cellpolymericfoamsandtosandwichpanelsundereccentriccompression
andwithskinimperfections.Foreachcase,experimentalresults,thesizeeffectlaw
andconcludingremarksaregiven.
“Elasticity Solutions for the Buckling of Thick Composite and Sandwich
CylindricalShellsUnderExternalPressure,”byG.Kardomateaspresentselasticity
solutionsforbucklingproblemsofthickorthotropiccylindricalshellsandsandwich
viii Preface
shells with orthotropic constituent materials under uniform external pressure. It is
shown that the predictions of shell theory can produce in many cases highly non-
conservative results on the critical loads. The results of the study can be used to
assess the accuracy of the classical and existing improved shell theories for thick
compositesandsandwichshellconstructions.
“An Improved Methodology for Measuring the Interfacial Toughness of
Sandwich Beams,” by Q. Bing and B.D. Davidson, presents a modified peel test
and a modified method of data reduction based on beam theory for determining
the interfacial toughness of sandwich structures with composite facesheets. From
experimentsandnonlinearfiniteelementanalyses,itisshownthatthisapproachcan
beusedforaccuratedeterminationoftheinterfacialfracturetoughnessofsandwich
structuresundervariousenvironmentalconditions.
“StructuralPerformanceofEco-CoreSandwichPanels,”byK.Shivakumarand
H. Chen studies the performance of sandwich beams made of a fire-resistant core
material,Eco-Core,andglass/vinylesterfacesheets.
“The UseofNeural Networks toDetect Damage inSandwich Composites,”by
D.Serrano,F.A.Just-Agosto,B.ShafiqandA.Cecchini,presentsaneuralnetwork
based approach using a combined vibration and thermographic technique for the
detectionofdamageinsandwichcomposites.
“OntheMechanicalBehaviorofAdvancedCompositeMaterialStructures,”by
J.Vinson,presentsanoverviewoftheresearchperformedonthedeterminationof
mechanicalpropertiesofcompositeandsandwichmaterials.
“Application of Acoustic Emission Technology to the Characterization and
Damage Monitoring of Advanced Composites,” by E.O. Ayorinde, uses acoustic
emission technology for monitoring and characterization of damage in sandwich
composites.
The dynamic loading case of the same theme is discussed in seven chapters as
follows:
“BallisticImpactsonCompositeandSandwichStructures,”byS.Abratepresents
acriticalreviewoftheexistingliteratureonballisticimpactofcompositesandsand-
wich structures. Models for predicting the ballistic limit and the extent of damage
are described. It is noted that the experimental data can be fitted by the Lambert-
Jonas equations to obtain a good estimate of the ballistic limit from results of
penetratingimpacts.
“PerformanceofNovelCompositesandSandwichStructuresunderBlastLoad-
ing,” by A. Shukla, S.A. Tekalur, N. Gardner, M. Jackson and E. Wang, uses a
high speed imaging technique to study the damage modes and mechanisms un-
der air blast loading of different composite material systems, including traditional
two-dimensional woven laminated composites, layered composites, and sandwich
panels. It is observed that layering of glass fiber composites with a soft interlayer
provides better blast resistance. Also good blast resistance properties are obtained
byconstructionsusingpoly-ureaandglassfibercompositesandsandwichmaterials
made by sandwiching a soft layer between woven composite skins. It was found
that,thegradationofmaterialsinthesandwichcanhelpmitigatetheblastdamage.
Preface ix
“Single and Multi-site Impact Response of S2-Glass/Epoxy Balsa Wood Core
SandwichComposites,”byU.K.VaidyaandL.J.Deka,dealswithanexperimental
study supported by finite element analysis of the single-site and multi-site impact
damageresponseofS2-Glass/epoxybalsawoodsandwichcomposites.Aprogres-
sive failure model based on Hashin’s criteria is used to predict failure. The effect
of projectile diameter, impact location and constituent material properties on the
impactdamageisinvestigated.
“Real-Time Experimental Investigation on Dynamic Failure of Sandwich
Structures and Layered Materials,” by L.R. Xu and A.J. Rosakis, studies the gen-
erationandevolutionofdynamicfailuremodesinmodelsandwichspecimensand
layered materials subjected to out-of-plane low-speed impact by using high-speed
photography and dynamic photoelasticity. Shear-dominated interfacial cracks that
propagate with intersonic speeds, even under moderate impact speeds, constitute
the dominant dynamic failure mode. The interfacial cracks kinked into the core
layerandbranchedathighspeedscausingbrittlecorefragmentation.
“CharacterizationofFatigueBehaviorofCompositeSandwichStructuresatSub-
ZeroTemperatures,”byS.M.Soni,R.F.GibsonandE.O.Ayorindestudiestheeffect
oftemperatureovertherangeof22ıCto(cid:2)60ıConthefailuremodesunderstatic
andcyclicloadingandonthefatiguelivesofcarbon/epoxyandglass/epoxycompos-
itesandwichbeams.Itwasobservedthatfatiguefailuresatthesubzerotemperatures
arecatastrophicandwithoutanyearlysignificantwarning,whereastheywerepre-
cededbylossofstiffnessatroomtemperature.
“ImpactandBlastResistanceofSandwichPlates,”byG.J.Dvorak,Y.A.Bahei-
El-Din and A.P. Suvorov studies the response of conventional and modified sand-
wichplatedesignsunderstatic,impactandblastloads.Inthemodifiedplatedesigns,
ductileinterlayersareinsertedandbondedbetweentheexposedouterfacesheetand
thecore.
“ModelingBlastandHighVelocityImpactofCompositeSandwichPanels,”by
M.S.HooFatt,L.PallaandD.Sirivolupresentsanalyticalmodelsfortheprediction
ofthedeformationandfailureofcompositesandwichpanelssubjectedtoblastand
highvelocityprojectileimpact.
Constituentmaterials,includingfiber,polymermatrix,andcorematerials
Thethirdthemedealingwithmechanicalandfailurebehaviorofconstituentma-
terialsisdiscussedinfivechaptersasfollows:
“Effect of Nanoparticle Dispersion on Polymer Matrix and Their Fiber
Nanocomposites,” by M.F. Uddin and C.T. Sun investigates the effect of disper-
sionofnanoparticlesonmechanicalpropertiesofnanocompositesviaconventional
sonication,sol-gelandmodifiedsonicationmethods.Itwasfoundthatthenanocom-
posites fabricated via a sol-gel method have improved and consistent properties
compared to nanocomposites fabricated by the other methods. The silica/epoxy
nanocompositeswereusedtomakefiberreinforcedcompositesusingtheVARTM