Hybrid Adhesive Joints

309 Pages·2011·10.62 MB·English

by  Saied M. H. Darwish (auth.)

Advanced Structured Materials
Volume 6
Volume 6
Series Editors
Prof. Dr. Andreas Öchsner, Technical University of Malaysia, Skudai, Johor,
Malaysia
Prof. Dr. Lucas Filipe Martins da Silva, University of Porto, Porto, Portugal
Prof. Dr. Holm Altenbach, University of Halle-Wittenberg, Halle, Germany
For furthervolumes:
http://www.springer.com/series/8611
Common engineering materials reach in many applications their limits and new
developments are required to fulfill increasingdemands on engineering materials.
Theperformanceofmaterialscanbeincreasedbycombiningdifferentmaterialsto
achieve better properties than a single constituent or by shaping the material or
constituentsinaspecificstructure.Theinteractionbetweenmaterialandstructure
may arise on different length scales, such as micro-, meso- or macro-scale, and
offers possible applications in quite diverse fields.
This bookseries addressesthefundamental relationship betweenmaterialsand
their structure on the overall properties (e.g. mechanical, thermal, chemical or
magnetic etc.) and applications.
The topics of Advanced Structured Materials include but are not limited to
• classical fibre-reinforced composites (e.g. class, carbon or Aramid reinforced
plastics)
• metal matrix composites (MMCs)
• micro porous composites
• micro channel materials
• multilayered materials
• cellular materials (e.g. metallic or polymer foams, sponges, hollow sphere
structures)
• porous materials
• truss structures
• nanocomposite materials
• biomaterials
• nano porous metals
• concrete
• coated materials
• smart materials
Lucas Filipe Martins da Silva
•
Alessandro Pirondi Andreas Öchsner
•
Editors
Hybrid Adhesive Joints
123
Prof.Dr. LucasFilipe MartinsdaSilva Prof.Dr. AndreasÖchsner
Departamento de EngenhariaMecânica Department of AppliedMechanics
Faculdade de Engenhariada Faculty ofMechanical Engineering
Universidade doPorto Technical University ofMalaysia
RuaDr. RobertoFrias 81310UTM Skudai,Johor
4200-465Porto Malaysia
Portugal e-mail: [email protected]
e-mail: [email protected]
Assoc. Prof.Alessandro Pirondi
Dipartimentodi IngegneriaIndustriale
Universitá degli StudidiParma
Viale G.P.Usberti 181/A
43124Parma
Italy
e-mail: [email protected]
ISSN 1869-8433 e-ISSN1869-8441
ISBN 978-3-642-16622-8 e-ISBN978-3-642-16623-5
DOI 10.1007/978-3-642-16623-5
SpringerHeidelbergDordrechtLondonNewYork
(cid:2)Springer-VerlagBerlinHeidelberg2011
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Preface
Adhesivelybondedjointsareincreasinglybeingusedinaerospaceandautomotive
industries.Theuseofadhesivebondingratherthanmechanicalfastenersoffersthe
potential for reduced weight and cost. However, there are still a number of issues
thatneedtobesolvedbeforethistechniqueisfullytrustedbytheindustry.Dueto
the polymeric nature of the adhesive, the joint resistance to harsh environments
(temperatureandhumidity)anditsdurabilitymustbetakenintoaccount.Another
pointisthefactthatthestressdistributionisconcentratedattheendsoftheoverlap
givingrisetoprematurefailures,especiallywithcomposites.However,whenused
in combination with traditional methods of joining such as bolts, rivets or spot
welds, part of the problem can be solved. That is why adhesively bonded joints
with different methods of joining are being considered. The idea is to gather the
advantages of the different techniques leaving out their problems. Some of the
advantages of hybrid joints are a higher static and fatigue strength and a higher
stiffnesswithrespecttosimplejoints,atwo-stagecrackingprocessbeforethefinal
failure and improved durability. They also offer the technological advantage of
keeping parts in place while the adhesive is curing. That is why hybrid joining is
increasingly used by the automotive industry. Another possibility to increase the
jointstrengthofsimpleadhesivejointsistousemorethanoneadhesivealongthe
overlap.Allthesejointsaretreatedhere:weld–adhesive,rivet–adhesive,clinch
– adhesive, bolt – adhesive, and adhesive – adhesive. A section dedicated to
threadlockingandinterference-fitadhesivejointsisalsoincluded.Allsectionsare
treated from a scientific point of view with modelling issues supported by simple
couponstestingandatechnologicalpointofviewwheretheideaistopresentmore
applied results with practical cases.
The editors would like to thank the authors for their patience with the prepa-
ration of this book. Finally, we especially thankDr Christoph Baumann, Springer
editor, who made this book possible.
Dr. Lucas F M da Silva
Prof. Alessandro Pirondi
Prof. Andreas Öchsner
v
Contents
Science of Weld: Adhesive Joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Saied M. H. Darwish
Technology of Weld-Adhesive Joints . . . . . . . . . . . . . . . . . . . . . . . . . 37
Holger Gaul and Gert Weber
Technology of Rivet: Adhesive Joints. . . . . . . . . . . . . . . . . . . . . . . . . 79
Fabrizio Moroni and Alessandro Pirondi
Science of Clinch–Adhesive Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Alessandro Pirondi and Fabrizio Moroni
Technology of Clinch–Adhesive Joints . . . . . . . . . . . . . . . . . . . . . . . . 149
Tomasz Sadowski and Tadeusz Balawender
Science and Technology of Bolt-Adhesive Joints. . . . . . . . . . . . . . . . . 177
Jan R. Weitzenböck and Dag McGeorge
Science of Friction–Adhesive Joints . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Eugenio Dragoni and Pierfranco Mauri
Technologies of Threadlocking and Interference-Fit
Adhesive Joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Felix Kleiner and Wolfgang Fleischmann
Science of Mixed-Adhesive Joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
James G Broughton and Michael D Fitton
Technology of Mixed Adhesive Joints. . . . . . . . . . . . . . . . . . . . . . . . . 283
Lucas F. M. da Silva
vii
Science of Weld: Adhesive Joints
Saied M. H. Darwish
Abstract Weldbondingis acombinationofresistancespot weldingandadhesive
bonding.Itisahybridprocessthatcombinestheadvantagesofthetwoindividual
processes.Therearetwotechniquesforconductingweldbonds:theflow-inandthe
weld-through techniques. Theweldbonding procedure provides many advantages,
e.g.: improved crash performance, fatigue behavior and corrosion resistance. The
degreeofacceptanceofweld-bondapplicationshasbeenincreasing,astheprocess
hasbeenunderstoodanditsmechanicalpropertiesdeveloped.Thepresentchapter
addresses both techniques (flow-in and weld through) from implementation to
modeling,includinganalysisandcharacterization.Practicalimplicationsaswellas
fields of application are also highlighted.
1 Introduction
Bondingofmetalsisbecomingincreasinglyimportant,bothinabsolutetermsand
relative to mechanical fastening. The applications of adhesive bonding are found
in the assembly of many products including aircrafts [36], cars, trucks, and office
furniture[9].Thisisbecauseadhesivebondingoffersmoreuniformdistributionof
stresses, increased fatigue life, weight saving and the prevention or reduction of
corrosion between dissimilar materials, added to the ability to join small and
delicate parts .
Darwish et al. [19, 20, 23, 26] used adhesive in manufacturing a bonded gear
box. In machine tool manufacturing, adhesives are used [5] for bonding gear
S.M.H.Darwish(&)
DepartmentofIndustrialEngineering,FacultyofEngineering,KingSaudUniversity,
KSA,800,Riyadh11421,SaudiArabia
e-mail:[email protected]
AdvStructMater(2011)6:1–36 1
DOI:10.1007/8611_2010_35
(cid:2)Springer-VerlagBerlinHeidelberg2010
PublishedOnline:11September2010
2 S.M.H.Darwish
wheels, joining elements of hydrostatic bearings and transmissions with load
bearing surfaces. In the electrical and electronic industry, adhesives are used in a
variety of ways. These range from holding microcircuits to bonding coils in
mammothelectricalgenerators.Inadditiontomechanicalfastening,adhesivesare
required in electrical applications to seal and protect substrates and to conduct or
insulateheatandelectricity[5].DarwishandDavies[19,20]developedadhesively
bonded metal cutting tools, while [27] have tested the performance of adhesively
bondedmetalcuttingtools.Bondedstructurescanbeoftwotypesbasedoneither
purelyadhesiveoronadhesive/mechanicalconnections[44].Thepurelyadhesive
connectionsincludeshaft–hubjoints,laminatedmetal–metaljointsandthree-layer
honeycomb structures. The bonded mechanical types include bonded-welded,
bonded-riveted and bonded-screwed connections. The combined connections
(bonded-welded,bonded-rivetedandbonded-screwed)ensurehighfatiguestrength
of the structures and are extremely economical, because they do not require any
fixtures during the polymerization process.
The manufacturing and sale of aerospace, transportation and civil structures
invariably require joining components of different materials and compositions.
Because manufacturers are constantly being pressured for lower cost and reduced
weight, different materials are being combined in many products. As different
materialsareusedwithinagivenstructure,there willmostdefinitely beaneedto
somehow join them.
While methods such as adhesive bonding and mechanical fastening have been
used in the past to join dissimilar materials [7] work in this area is now moving
towards less labor intensive methods, geared more toward automation [6, 34, 39,
40].Neitheradhesivebondingnormechanicalfasteningisparticularlywellsuited
for inline application with the substrate fabrication methods. Moreover, adhesive
bondingmaypresentquestionsfromalongtermjointdurabilitystandpoint,while
mechanicalfasteningmaypresenttheriskofin-servicegalvaniccorrosion,aswell
as the potential to introduce stress concentrations at the joint.
One of the promising methods being considered for the joining of dissimilar
materials is resistance welding. The advantages of resistance welding process
include typically short process times and heat focused specifically at the material
interfaces.Thisprocessiseconomicalsincenoweldmaterialisneeded.Resistance
welding can easily be automated and in most cases only assistants or robots are
neededtosupplythematerial.Theprocessalsohasthepotentialforasophisticated
type of control that cannot be implemented for adhesive bonding and mechanical
fastening. The combination of dissimilar materials or dissimilar thicknesses may
cause large problems which often can be solved by the application of solid phase
welding processes. Studies of the bonding mechanisms in solid phase welding
processes made by [31, 39], have revealed that large improvements can be
obtained by introducing special surface treatment techniques like strategic inter-
layers,inordertofacilitatebondingofmetalcombinationswhichwouldotherwise
be difficult or impossible to join. This strategic surface coating can be passive or
active surface coating.
ScienceofWeld:AdhesiveJoints 3
Weldbonding is a combination of resistance spot welding and adhesive bond-
ing.Apaste adhesiveisnormallyappliedtoonesheet andthenthejointisclosed
[44].Aspotweldisthenmadethroughtheadhesive.Theelectrodeforcedisplaces
theadhesivetoobtainelectricalcontactbetweenthesheetsandtheweldismadein
thenormalway.Astheheatingoftheweldisverylocalized,littledamageoccurs
in the adhesive around the weld. The adhesive is finally cured to complete the
assembly. Heat curing paste type adhesives are normally used as these are stable
andhaveaconsistentviscosityatroomtemperature.Typically,suchadhesivesare
cured inanovenat upto180(cid:3)C for30 min.Someadhesivesare availableintape
form andincorporate metal particle filler which allows initial electrical contact to
be made for spot welding.
Weld-bonded joints were first developed and used in the Soviet Union in
manufacturing planes ofthe type AN-24. Theweld-bonding process is essentially
thespot-resistanceweldingofpartsthatsubsequentlyhavetheiroverlappingareas
adhesively bonded. TheSovietUnioninitiallyperfected thistechnology,whichis
known there as ‘‘glue welding’’. The approach was a ‘‘flow-in’’ method (Fig. 1a),
whereby parts were first welded together, and then the adhesive was flowed into
the joint. A low-viscosity adhesive is used which penetrates the overlap joint by
capillaryactionandissubsequentlycured.ThetechniqueusedintheUnitedStates
istheweld-throughmethod(Fig. 1b),wherebytheadhesiveisappliedtotheparts
to be cured, spot welded and subsequently cured.
Fig.1 Weldbonding:athe
flow-intechnique,btheweld-
throughtechnique
4 S.M.H.Darwish
In comparison with mechanical fasteners, weld-bonding offers the following
benefits: (1) reduced manufacturing costs and suitability for automation; (2) high
staticstrength;(3)improvedfatiguestrength;(4)improvedcorrosionresistance;(5)
eliminationofsealingoperations;and(6)reductionoftheshopnoiseduetoriveting.
The process combines the benefits of adhesive bonding for joining thin sheet
assemblies, together with a fast, automated point joining technique, which elim-
inatestheneedforjiggingduringthecuringoftheadhesive.Adhesivebondshave
limitedstrengthinpeelorcleavage,sothespotweldsprovidepeel-stoppingpoints
in the event of overloading, for example in impact tests.
In the lightweight body frame mass production of automobiles, the application
of hybrid bonding techniques becomes more and more important. The weldb-
onding procedure provides many advantages, e.g. improved crash performance,
fatiguebehaviorandcorrosionresistance[33].Therefore,thetechnologyisstateof
the art in many branches of joining metal sheets. Especially for newly developed
highstrengthmultiphasesteels,alsocalledadvancedhighstrengthsteels(AHSS).
Thisjoiningtechniquehasmoreadvantagesthanotherjoiningproceduresforthin
steelsheets.TheapplicationofAHSSmaterialsinconjunctionwitheconomically
efficient and reliable joining processes, helps saving costs and conserving
resources (weight reduction, energy minimization) and provides at the same time
improved safety of the passenger cell (crash optimization).The present chapter is
concentrated on experimental and theoretical aspects of spot welded and weld-
bonded joints. These range from preparation of specimens, metallographic
examination, tensile as well as dynamic characteristics of spot welded and weld-
bondedjoints.Thesealsoincludefiniteelementmodeling,analysisoftensile-shear
and tees adhesively bonded and weld-bonded specimens.
2 Experimental Details
Across the engineering spectrum, of joining techniques welding is an essential
processinthemanufactureofcomponents,assembliesorcompletemachines.Spot
welding is the best known and the most frequently used method of resistance
welding, as it can be applied to a wide variety of articles instead of rivets,
solderingandbrazing[42,43].Theadvantagesofthespot-weldingprocess[1,11,
30, 35, 38, 41] include typically short process times and heating focused specif-
icallyatthematerialinterfaces.Thisprocessiseconomicalsincenoweldmetalis
needed. Resistance welding can easily be automated and in most cases, only
assistants or robots are needed to supply the material. Control of the quality of
welded joints is essential, if the fabricated parts have to perform satisfactory in
service.
Uniform spot weld quality can be obtained through the use of proper equip-
ment, rigid adherence to established welding procedure, close control of machine
settingsandtheuseofqualifiedpersonnel.Destructiveandnon-destructivetesting
is generally essential to check the quality of spot welds. Destructive testing are