DaSilva Prezentare Adhes Bond

1

Joining in Car Body Engineering 2011

Tutorial 1: Adhesive bonding technologies

Lucas F M da Silva

Lucas da Silva JCBE2011 Adhesive bonding technologies 1

Faculty of engineering of the University of PortoDepartment of Mechanical Engineering

Contents

Introduction Theory of adhesion Adhesive selection Adhesive selection Joint design Surface treatment Joint fabrication methods Control (destructive and non-destructive

)


tests) Applications in the automotive industry

2

Introduction Applications

de Bruyne (1957)

De Havilland Comet

Aeronautical industry

De Havilland Comet


Introduction Applications

Aeronautical industry


3

Introduction ApplicationsAerospace industry Dsagulier (2010)


Introduction ApplicationsAutomotive industry


Lotus Elise

4

Introduction ApplicationsAutomotive industry


Introduction ApplicationsRail industry

Hexcel Composites


5

Introduction ApplicationsMarine industry


Introduction ApplicationsCivil industry


6

Introduction ApplicationsElectrical industry


Shoe industry

Introduction Technologies involved


7

Introduction Technologies involved

Petrie (2000)


Introduction Advantages Uniform stress distribution


8

Introduction Advantages Uniform stress distribution better fatigue strength Vibration damping better fatigue strength

Powis (1968)


Introduction Advantages

Ability to joint dissimilar materials

Kinloch (1997)

Ability to join thin-sheet material efficiently

Frequently represent the most convenient and cost effective joining technique


joining technique

9

Introduction Advantages An increase in design flexibility (e.g. honeycomb structures) Smooth shapes (no bolt or rivet or weld) Continuous contact between surfaces In general, reduce costs


Introduction Disadvantages

Peeling loads

Peel (one substrate is flexible)

Cl (th t b t t


Cleavage (the two substrates are rigid)

10


Avoid localised stress

Best solution load in shear

Avoid localised stress



Limited resistance to extreme conditions such as heat and humidity.

Need to fixing tools to keep the substrates in position until cure is complete important economic disadvantage.

To obtain good results, a surface treatment is often required. Adhesives are frequently cured at high temperatures. Quality control more difficult but recent developments in NDI

techniques.


No universal failure criterion.

11

Theory of adhesion Forces involved

Primary bonds e- are transferred or shared strong: 100-1000 kJ/molstrong: 100 1000 kJ/mol

Ionic

Covalent


Metallic

Theory of adhesion Forces involvedSecondary bonds no e- transferred or shared interaction of atomic/molecular dipoles weak < 100 kJ/mol weak < 100 kJ/mol

van der Waals London forces or dispersion

(induced dipoles) Debye forces (permanent

dipole and induced


Hydrogen

dipole and induced dipole)

Keesom forces (permanent dipoles)

12

Theory of adhesion Forces involvedAll the bonds are forces acting in very short distances (some

angstroms (1 A = 10-10 m = 0.0001 m)


Theory of adhesion Surface roughness

1 ( )L

R h d


0

( )Ra h x dxL

=

0.5 m

13

Theory of adhesion Surface roughness

Roughness = 1000 x distance of action of the bonding forces

But if liquid...


Theory of adhesion Phase change

Good wetting but without strength

Hardening...

Liquid


Solid

14

Theory of adhesion Phase change

Hardening process (cure)

L f l t ( hit l f d) Loss of solvent (e.g. white glue for wood) Cooling from the molten state (hot melts) Chemical reaction (most of structural

adhesives)


Theory of adhesion Wetting


15


Contact l angle,

0 90 180

SV = SL + LV cos Young (1805)


cos 1 0 -1

Spreading Complete wet. Partial wet. SL= SV Low wetting No wetting


Unbalance of atraction forces at the surface surface energy

Surface energy,

surface energy


16


Surface energy,



Surface energy of liquidsWilhelmy plate, weight of a drop, capillarity, etc.

FL 2

Fl

=


17


Surface energy of solidsCritical surface tension, C

Zisman (1950)Zisman (1950)



Surface energy of solidsDispersion and polar components

Fowkes (1963)

d p = + +

( )( ) ( )

( )( ) ( )

2/1

2/1

2/12/1

2/1cos1 D

SD

PLP

SDL +

=+


( ) ( ) ( ) ( )2/12/12 SDLSDL

Watts (2010)

18

Theory of adhesion Spreading

Principle of minimum energy

< the liquid spreadsL < S the liquid spreadsL > S the liquid does not spread

Surfaces of high energy S = 500 ~ 5000 mJ m-2(metals and their oxides, glass and ceramics; generally hard materials with high melting points)


materials with high melting points) Surfaces of low energy S = 5 ~ 100 mJ m-2

(most of organic solids and polymeric materials; generally soft materials with low melting points)



19


How can the user intervene?

Increase the surface energy of the solid

Contamination of surfaces (powders, greases, oils, adsorbed gases, humidity, etc.) low surface energy

The surface treatments can eliminate the


The surface treatments can eliminate the contaminants and modify the chemistry of surfaces of low energy (polymers)

Theory of adhesion Theories of adhesion

Mechanical Adsorption Diffusion Electrostatic


20


Mechanical

Example: rubber with textile

But... Smooth surface


Increase of surface areaElimination of weak boundary layersBetter wettingMore energy dissipation


AdsorptionPhysical adsorption

Surface forcesG d tti

Chemical adsorption

Good wettingMost importantOccurs in all bonds

Ch i l b d


Chemical bondAcid-basePrimaryBonding agents

21

1. Adhesive selection2. Joint design3. Surface treatment4. Fabrication5. Control


5. Control

Adhesive selection Classification

Function (structural and non-structural) Chemical composition (thermoplastics, thermosets,

elastomers hibrids)elastomers, hibrids) Hardening mechanism (chemical reaction, loss of

solvent or water, hardening from the melt) Physical form (liquid, paste, solid) Cost Substrates


Substrates Method of application

22


Function

Adhesives

Structural Non-structural

EpoxiesPolyurethanes

RubbersPolyesters


yAcrylics

PhenolicsAromatics

yHot meltsInorganic


Chemical composition


23


Kinloch (1997)Chemical compositionHybrids (e.g. thermoset + rubber)


Adhesive selection ClassificationChemical compositionHybrids (e.g. thermoset + rubber) da Silva & Adams (2005)


24

Adhesive selection Composition

Base or binder Hardener and catalyst

S l t Solvents Diluents Fillers Carriers or reinforcements

O


Other additives

Adhesive selection Hardening

1. Chemical reactiona. Two partsb. One part, cure by catalyst or hardenerc. Cure by humidityc. Cure by humidityd. Cure by radiation (light, UV, electrons beam, etc.)e. Catalized by the substratef. Adhesives in solid form (tape, film, powder, etc.)

2. Loss of solvent or watera. Resinous solvent adhesives b. Reactivatable adhesives


c. Contact adhesives

3. Hardening from the melt

25

Adhesive selection Hardening

VULCANIZAO(CROSS-LINKING)

Chemical reaction Condensation reaction (polyimides,

polybenzimidazole, phenolics)p y p ) Addition reaction (epoxies, urethanes, acrylics)


Adhesive selection Epoxies

Most important Strong but brittle Low shrinkageLow shrinkage 1 or 2 parts Exothermic cure Can be B-staged Diglycidyl ether of bisphenol A

(DGEBA)


(DGEBA) Cured with amines (room temp.) Most are hybrid epoxies

26


Two part epoxyForm 2 parts in paste Method of application Manual mixture

Mi t d t t d li tiMixture and automated application Cure Room temperature (can be

accelerated at high temperature) Service temperature 40 to 100C Advantages Strength and durability Disadvantages Slow curing

Mixture (voids) Environment resistance

Water GoodSolvent Good


resistance Solvent GoodOil Good

Health and safety Dermatosis Breathing problems

Applications Aircraft, helicopters, cars, trains, sport equipment, etc.


One part epoxy

Form Film, paste Method of application Manual Cure Temperature (~150C) Service temperature 40 to 180C Advantages Strength and durability Disadvantages Storage

Cures at high temperature Environment resistance

Water Excellent Solvent Excellent Oil Excellent


Health and safety DermatosisBreathing problems

Applications Aircraft, helicopters, cars, trains, sport equipment, etc.

27


Hexcel Composites



Toughened epoxies Inclusions of CTBN Increased toughness

Kinloch (1997)Increased toughness

Lower Tg Lower strength


28


Epoxy-phenolic Epoxy resin + phenolic resin High temperature resistance High temperature resistance Continuously until 175C Very good strength to environment, oil, solvents Low toughness Aeronautical applications


Bonding honeycomb sandwich composites


Epoxy-nylon Improved toughness and

peel strength

Kinloch (1997)

peel strength Limited resistance to the

environment Max temperature 80C Good filleting capacity

B d l i i ki t


Bond aluminium skins to honeycomb core

29


Epoxy-polysulfide Excellent toughness, peel strength and flexibility,

chemical resistancechemical resistance Max temperature 50-80C 2 parts paste Room temperature cure High deformation applications

C t i


Bond concrete in floors and roads Sealants, glass bonding, bond rubber to metals

Cotronics

Adhesive selection Polyurethanes

Form Solutions, pastesMethod of application Cartridge Cure Room temperature and moisture (1

part) Can be accelerated with temperature (2 parts)

Service temperature 200 to 120CAdvantages Good strength at low temperatures

Toughness Wetting ability

Disadvantages Moisture cure Limited temperature resistance

Environment Water Fair


resistance Solvent Fair/Good Oil Fair/Good

Health and safety Avoid physiological risks Applications Cryogenic applications

Automotive industry

30

Adhesive selection Polyurethanes

Total / Le joint Franais


Adhesive selection Acrylics

Anaerobics Cyanoacrylates Cyanoacrylates Modified acrylics Cure rapidly Bond many substrates, including plastics Fast assembly operations


31

Adhesive selection Acrylics Anaerobics

Form 1 part liquid or paste Method of application Small container or automatic

application Cure By absence of oxygenCure By absence of oxygen

Cures in min or h at 25C or in 10 min at 120C

Service temperature 55 to 150C Advantages Little surface preparation Disadvantages Thin bondlines Environment resistance

Water Good Solvent Depends on formulation Oil Good


Oil GoodHealth and safety No major problems Applications Liquid lock washer

Small assembly works

Loctite

Adhesive selec. Acrylics Cyanoacrylates

Form 1 part liquid Method of application Small container or automatic

application Cure Substrate moisture

Cures in sec or min at 20C Service temperature 30 to 80C Advantages Fast cure Disadvantages Cannot bond large areas due to fast

cure Brittle Bad gap filling

Environment resistance

Water Weak Solvent Fair/good


resistance Solvent Fair/goodOil Good

Health and safety Can bond to skin due to fast cure Applications Rapid assemble of light structures

Optical and electronic industry

Loctite

32

Adhesive selec. Acrylics Modified acrylics

Form 2 parts Method of application Small container or automatic

applicationppCure Catalysed by an initiator that allows

a fast cure Service temperature 40 to 120C Advantages Fast cure

Can bond unprepared surfaces Good environment resistance

Disadvantages Lower strength and stiffness than epoxies



Water GoodSolvent Good Oil Good

Health and safety No major problems Applications Rapid assemble of structures

Adhesive selection Phenolics

Cure at high temperature (140C) and pressure

Volatiles released during cure gporous bondlines

Good resistance to environment and temperature

Wood bonding Cheap


Cheap Brittle and low peel strength Hybrid phenolics generally used

33


Form Solutions, powder, films Method of application Manual, brush, film Cure Temperature and pressure Service temperature 40 to 180CService temperature 40 to 180CAdvantages Good strength to fire

Cheap Disadvantages Difficult processing

Brittle Porous bondlines


Water Excellent Solvent Good Oil Good


Oil GoodHealth and safety Low smoke and low level of

toxicity Applications Wood

Metal (hybrid phenolics)


Nitrile-phenolics Vinyl-phenolic

N h li Neoprene-phenolic

http://en.wikipedia.org/wiki/Brake_lining


http://www.boardtek.com.tw/Metal.htm

34

Adhesive selection Polyaromatics

Polyimide, bismaleimide, polybenzimidazole

Ladder structure High temperature adhesives Expensive Difficult processing

Brittle and low peel strength


Brittle and low peel strength Difficult to toughen


Form Supported film Method of application Sandwich assembly Cure Temperature (250C) and pressure p ( ) pService temperature 40 to 280C Advantages Strength at high temperatures Disadvantages Very difficult processing

Brittle at room temperature Porous bondlines Expensive


Water Excellent Solvent Excellent


Oil Excellent Health and safety No major problems Applications Applications at high temperature

Aeronautical and aerospace industry

35


Hexcel Composites


Adhesive selection Selection process

Substrate

Design and loading

Production requirements Adhesive

selectionExperimental

validation


Service environment

36

Adhesive selection Selection processSubstrateSpreading condition principle of minimum energy

L < S the liquid spreadsL > S the liquid does not spreadL > S the liquid does not spread



-phe

nolic

phen

olic

ene-

phen

olic

cino

l for

mal

dehy

de

l for

mal

dehy

de

min

e fo

rmal

dehy

de

orm

alde

hyde

omat

ic

ter

reth

ane

obic

acry

late

ied

acry

lic

Shields (1984)Substrate

Epo

xy

Nitr

ile-

Vin

yl-p

Neo

pre

Res

orc

Phen

ol

Mel

am

Ure

a fo

Poly

ar

Poly

est

Poly

ur

Ana

ero

Cya

noa

Mod

ifi

Metals Ceramics Wood Paper Leather Textile Elastomers Neoprene Silicone Polyurethane


yThermoplastics PVC (flexible) PVC (rigid) Cellulose acetate PE (film) PE (rigid) PP (film) PP (rigid) PC Teflon

37

Adhesive selection Selection processSubstrateResidual thermal stresses



Production requirements

Adhesive form Method of application Working time Cure conditions (temperature, pressure, time) Holding time Shelf life


Safety and health issues Cost

38


Production requirements

Type of adhesive Common forms available

Cure method

Processing conditions

d m e uid en

t so

lutio

n,

lsio

n

ent r

elea

se

mic

al re

actio

n

m te

mpe

ratu

re

h te

mpe

ratu

re

sure

requ

ired

sure

not

requ

ired Petrie (2000)

Solid

Film

Past

e

Liqu

Solv

emul

Solv

Che

m

Roo

m

Hig

h

Pres

s

Pres

s

Epoxy (polyamine) Epoxy (polyanhydride) Epoxy (polyamide) Epoxy-phenolic Epoxy-nylon Epoxy-polysulfide Nitrile-phenolic Vinyl-phenolic Neoprene-phenolic Resorcinol formaldehyde Phenol formaldehyde


yMelamine formaldehyde Urea formaldehyde Polyimide Bismaleimide Polybenzimidazole Polyester + isocyanate Polyester + monomer Polyurethane Cyanoacrylate Acrylic

Adhesive selection Selection processDesign and loading


39

Adhesive selection Selection processService environment

Adhesive Tg (C)

Epoxies Toughened epoxy

50-150

da Silva et al. (2007)

g p yEpoxy phenolic Epoxy nylon Epoxy polysulfide

200 50 50

Phenolics Nitrile phenolic Vinyl phenolic Neoprene phenolic

120 70 70

High temperature adhesives


High temperature adhesivesBismaleimide Polyimide

210-280 340-430

Polyurethanes 20-50 Anaerobics 120 Cyanoacrylates 80 Modified acrylics 60-120


Experimental validationPhysical and chemical propertiesColour viscosity shelf life working life density TColour, viscosity, shelf life, working life, density, Tg,

etc...Mechanical propertiesFailure strength tests (shear, tension, compression),

fracture tests (mode I, II)D bilit


DurabilityTemperature, moisture

40


Experimental validationTensile test EN ISO 527-2

BS 2782BS 2782



Tension vs compression

Experimental validation

Tension vs. compressionc = 1.2 to 1.4 t


41


ASTM D 695Experimental validationCompression test



Experimental validationThick Adherend Shear Test (TAST)

ISO 11003 2 ASTM D 5656ISO 11003-2, ASTM D 5656

ISO 11003-2


ISO 11003-2, ASTM D 5656da Silva et al.(2008)

42


Experimental validationShear test (Arcan)



Chen et al. (2010)

Experimental validationShear test (Torsion)

Gali et al. (1981)


43


ASTM D 3433

Experimental validationToughness (Double cantilever beam (DCB) test)

ASTM D 3433


356

12.7

6.35

6.35 a = 510

25.4

Adhesive selection Selection processExperimental validationMechanical properties

Tljsten (2005)


44

Adhesive selection Selection processExperimental validationMechanical properties


Adhesive selection Selection processExperimental validationMechanical propertiesAdhesive Manufacturer Tension Compression Shear GIc

(J/m2) GIIc (J/m2) E

(MPa) y (MPa)

r (MPa)

r (%)

y (MPa)

r (MPa)

G (MPa)

y (MPa)

r (MPa)

r (%) ( ) ( ) ( ) ( ) ( ) ( ) ( )

Epoxies Araldite AV138 Huntsman 4590 41.0 41.0 1.30 1559 25.0 30.2 5.50 345.9 3000 Hysol EA 9394 Loctite 4420 31.0 59.8 4.64 35.9 68.9 1140 25.0 40.4 8.36 Hysol EA 9321 Loctite 3870 22.0 46.0 3.80 34.0 1030 20.0 33.0 6.35 Supreme 10HT Master Bond 3240 25.0 45.5 2.00 1460 37.1 37.1 16.1 0.30 Araldite AV 119 Huntsman 3450 67.1 67.1 4.10 1260 47.0 47.0 50.7 0.37 Hysol EA 9150 Loctite 2852 79.0 5.00 99.9 1056 0.35 Hysol EA 9359.3 Loctite 2650 42.5 42.5 4.50 145 660.0 35.3 35.3 63.0 Hysol EA 9330 Loctite 2646 38.6 2.40 53.1 965.0 0.37 Hysol EA 9628f Loctite 2377 51.7 7.50 79.3 624.0 1401 Araldite 2015 Huntsman 1850 22.5 4.40 560.0 14.0 20.0 40.3 525.7 4700 Redux 810 Hexcel Comp. 1730 40.0 5.53 02 Rapid Delo 1000 24.0 20.0


Hysol EA 9361 Loctite 670 7.99 44.0 Polyurethanes Araldite 2026 Huntsman 200 18.0 50.00 Sikaflex 256 Sika 1.351 8.26 8.26 330 2901 Bismaleimides Redux HP655f Hexcel Comp. 3620 80.7 80.7 2.39 694.0 Redux 326f Hexcel Comp. 4850 50.9 50.9 1.28 1615 37.9 37.9 3.70 Modified acrylics DP-8005 3M 590 13.0 5.30 178.6 5.3 8.40 180 1360 Araldite 2024 Huntsman 760 20.0 42.5

45

Adhesive selection Selection processExperimental validationTg


Adhesive selection Selection processExperimental validationTg DMA


46

Adhesive selection Selection processExperimental validationTemperature

55C

70

da Silva & Adams (2005)

-55C

22C

100C20

30

40

50

60

Shea

r stre

ss (M

Pa)


200C0

10

0 0.1 0.2 0.3 0.4 0.5

Shear strain

Adhesive selection Selection processExperimental validationHumidity Bordes et al. (2009)


47



5. Control

Joint design Stress analysis

Two possibilities:

Analytical methods design Numerical methods (finite element

method) research


48


Simple analysis


blP

=


Volkersen (1938)


49

Joint design Stress analysisVolkersen (1938)

Load balance of upper adherend:

( ) 11 1 1 1 1dbt bdx d btd t + = + =


( )1dx t

Load balance of lower adherend:

( ) 22 2 2 2 22

dbt d bt bdxdx t = + + =

Joint design Stress analysisVolkersen (1938)

Joint equilibrium:

1 1 2 2P bt bt = +


Shear deformation in the adhesive:

( ) 1 2 1 21 2a a a a a 1 2

1 1 1 1du dud du uG t dx G dx t dx dx t E E

= = = = =

50


Volkersen (1938)1 2

a a 1 2

1 1dG dx t E E

=

2

2

ddx t

= 11

ddx t

= + +

2 2 2a1 1 2 2 1 1 2

12 2 2a a a a 1 2

1 Gt d t d dd tG dx G dx G dx dx t E E

= = =

2 Gd

From 1 1 2 2P bt bt = +2

11

12 t

tbtP =


2a1 1 2

1 2a 1 2

Gdtdx t E E

=

Substituting in

221

1 02 0d Cdx

+ = with 2 aa 1 1 2 2

1 1Gt E t E t

= +

a0

a 2 2 1

G PCt bE t t

=


Volkersen (1938)( ) ( ) ( )( )

0 0 01 2 2 2

1

sinhcosh cosh 1

sinhxC C CPx l

bt l

= + + +

dFrom 11

ddx t

=

( ) ( ) ( )( )0 1 0 11

1 2 2

coshsinh cosh 1

sinhxC t C td Pt x l

dx l l

= = + +

Substituting C0 and 2 and usingPbl

=


bl

( )( ) ( ) ( )( ) ( )1 cosh coshsinh

x l k l x xk l

= +

2 a

a 1 1 2 2

1 1

2 2

1 1

1

Gt E t E tE tkE t

= +

= +

51


Goland & Reissner (1944)

Not deformedBending moment M = Ft/2


Deformed

Bending moment M = kFt/2k < 1


Goland & Reissner (1944)


52


Hart-Smith (1973)



Hart-Smith (1973)


53


Finite element method

KD = R


Any geometryAll stresses

Parametric studies more difficult

KD R

Joint design Failure modes


54

Joint design Failure criteria

In the adhesive Brittle adhesive maximum stress (Volkersen or (

G&R) Ductile adhesive maximum strain (Hart-Smith) Very ductile adhesive (> 20% in shear) global

yielding Fracture mechanics


Fracture mechanics Damage mechanics


Global yieldingCrocombe (1989)

pblP =max


55


Global yieldingda Silva et al. (2009)



MetalsHart-Smith (1973)


56


MetalsAdherend yielding

Adams et al. (1997)

pblP =max

ybtP =max

btPt =

btkP

kPtMbtM

3

R)&(G 2 and 6

sup

2sup

=

==

( )( )kbtP

btkP

y

t

31

31

max

supmax

+=

+=+=


For low loads and short overlaps, k = 1For joints which are long compared to the adherend thickness (l/t = 20), k = 0

4max ybtP =


CompositesHart-Smith (1973)


57


Singularities



Singularities adherend rounding

Zhao et al. (2010)


58


Fracture mechanicsTo solve proble of singularities

But...

Difficult to relate K with experimental results

Diffi lt h th i

Crack


Difficult when there is plastic deformation

Groth (1985)


Damage mechanicsde Moura et al. (2002)

u u=

,i u i >

top bottom u u=

Initiationi

u,i,

,0

u i ii u i

u i i

=

Softening


c , ,12i u i u i

G = Propagation

o,i u,i i

, 0,u i i

59


Damage mechanics Loureiro et al. (2010)


Joint design Optimisation

Fillets


60


Fillets Grant et al. (2009)



Adherend shaping

Cherry & Harrison (1970)Adams et al. (1986) da Silva & Adams (2007)Hildebrand (1994) Rispler et al. (2000)Sancaktar & Nirantar (2003)


Sancaktar & Nirantar (2003)Kaye & Heller (2005)

61


Adherend shaping

4550


51015202530354045

Failu

re lo

ad (k

N)

Basic designTaper and adhesive fillet


05

-55C 22C -55C 22C -55C 22C

Supreme10HT

AV119 Adams et al(1986)


Mixed adhesive joint

Sancaktar & Kumar (2000)Pires et al. (2003)

Temiz (2006)Bouiadjra et al. (2007) das Neves et al. (2009)

Marques & da Silva (2008)


da Silva & Lopes (2009)

Marques & da Silva (2008)

62

Joint design OptimisationMixed adhesive joint

da Silva & Lopes (2009)


Joint design OptimisationMixed adhesive joint



63


Hybrid jointsLiu & Sawa (2001)

Liu et al. (2004) G i t l (2006)Grassi et al. (2006)

Pirondi & Moroni (2009)



Hybrid jointsPirondi & Moroni (2010)


64

Joint design Tubular joints


Joint design T joints

Adams et al. (1997)da Silva & Adams (2002)

Apalak (2002) Marcadon et al. (2006)


65


10

12

1210


2

4

6

8

10

Failu

re lo

ad (k

N)

1.5 mm

10 mm

Base thickness

9

12

7


0

2

(d)(c)(b)(a)



(b) Apalak et al FE stress predictionObserved locus of failure(a)

Locus of failure

Maximum stresses

Yield

Progressive failure


Locus of failure

Maximum stressesSudden failure

66

Joint design Corner joints


Adams et al. (1997)Apalak and Davies (1993)Feih and Shercliff (2005)

Joint design

da Silva et al. (2009)http://ni.fe.up.pt/~rteixeira/rjoints


67



5. Control

Surface treatment

Hagemaier (1990)


68

Surface treatmentCharacteristics that affect adhesion

ContaminationOils, greases, fingerprints, mold release

agents etc low surface energyagents, etc. low surface energy decrease adhesion


Surface treatmentCharacteristics that affect adhesion

Weak boundary layerContaminant films, oxide layers, rust,

corrosion scale and loose surface particlescorrosion, scale, and loose surface particles, etc.


69

Surface treatment General principles

In surface treatment, the following operations can occur:

1- Material removal2- Chemical modification of the surface3- Change of the surface topography


Surface treatment Importance

Aluminium joints bonded with an epoxy adhesive

Kinloch (1987)


70

Surface treatment Assessment

Water-break test


Surface treatment Assessment

Destructive test

Adhesive failure

Bad treatment

G d t t t

Cohesive failure


Good treatment

71

Surface treatment Selection

1. Initial strength2. Durability3. Initial condition of the substrates4. Type of substrate and nature of the

surface5. Production factors (cost, time, etc.)


Surface treatment MethodsPassive processes No chemical alteration Clean the surface Remove substances that are weakly attachedActive processes Chemical transformation Metals formation of a well defined oxide or structure Polymers formation of polar groups that increase


Polymers formation of polar groups that increase surface energy and adhesion

Last treatment when high strength and durability are required

72

Surface treatment Methods

Passive processes Abrasive methods SolventsSolvents Chemical cleaningActive processes Acid etching Anodizing (metals)


Anodizing (metals) Flame treatment, corona discharge, plasma

(polymers)

Surface treatment MethodsSteel (shot-blasted)

da Silva et al. (2008)


73


Al (acid etching) Critchlow et al. (2006)



Metals

Loctite

Metals


74


Polymers

Loctite

Polymers




5. Control

75

Fabrication Steps

Adhesive applicationStorage

Metering and mixingFixturing of parts

pp


Hardening

Fabrication Storage

Adhesives degrade ith li ht h idit twith light, humidity, etc.

Viscosity increases with time determines the shelf-life


Van Twisk & Aker (1990)

76

Fabrication Storage

Ambient temperatureAmbient temperature

L


Low temperature(fridge or freezer)

Fabrication Storage

Effect of ambient conditions

Van Twisk & Aker (1990)


77

Fabrication Storage

Refrigerated or frozen productsHexcel Composites


Fabrication Metering and mixing


78

Fabrication Adhesive application

Liquid Brush, simple rollers, syringes, squeeze

b ttl i d l t Easy to apply A lot of waste Any geometry

bottles, pressurized glue guns, etc.


Good wetting


Paste Guns, spatula Simple Simple Low waste


79


Paste Application pattern to avoid air entrapment


Translation Rotation


Paste Sika (2009)


80


Film Minimum waste

N i i No mixing Easy Good reproducibility Uniform thickness Flat surfaces


Expensive

Fabrication Fixturing of parts

Keep surfaces in contact Avoid adhesive thickness variationsAvoid adhesive thickness variations Allow good wetting of the surface Avoid formation of voids and porosity

(adhesives that cure by condensation such as phenolics and polyimides)


p p y )

81


Equipment Clamps

ARIANE 5 satellite adaptor


Dsagulier (2010)


Equipment Moulds


82


Equipment Press



Equipment Autoclave

NPL


Aschome

83


Equipment Vacuum-bag



Adhesive thickness Influence on joint strength (0.1 to 0.2 mm)

G t t l (2009)Grant et al. (2009)


84


Adhesive thickness Microspheres or carriers (films)



Adhesive thickness Shims


Shim (controls the thickness and filet)

85


Adhesive thickness Wires

TWI


Fabrication Hardening

Chemical reaction (most of structural adhesives)adhesives)

Loss of solvent or water (e.g. white glue of wood)

Hardening from the melt (hot melts)


86


Chemical reaction Depends on adhesive, room temperature or high

temperaturetemperature May need pressure (e. g. phenolics) Examples:

Epoxy 120C, 1hBismaleimide (for high temperatures) 175C, 2h + 230C, 2h

Cure is accelerated with temperature


Cure is accelerated with temperature Tg increases with the cure temperature but beware of

degradation of adhesive


Chemical reaction Time depends on temperature

PermabondESP 110


87


Equipment Temperature of adhesive Ovens (good air circulation)(g ) Hot press



Equipment Local heating (induction or dielectric)


88


Equipment Local heating

Hexcel Composites


Fabrication Safety and environment

Schindel Bidinelli

Use gloves and masks Well ventilated area with

air e traction Schindel-Bidinelliair extraction Safety equipment Keep in a safe place

solventsE th i ti


Exothermic reaction use thin bondlines

89



5. Control

Control Destructive tests

Lap joints Peel Impact Impact Fatigue Creep Environment


90


Single lap joints

ASTM D 1002



Modified lap jointsLaminated lap shear specimen

ASTM D 3165

Double lap specimen


ASTM D 3528

Double lap specimen

91


PeelASTM D 1876

ASTM D 3167ASTM D 1781


T-peelFloating roller peel

Climbing drum peel


Peel Blackman (2010)


92


Peel Adhesive thickness

Rider (1964)



ImpactASTM D 950


93


ImpactHarris & Adams (1985)



Impact (wedge impact peel)ISO 11343


94


Impact (Split Hokinson Pressure Bar) Goglio (2010)

Strain gauges

Projectile

Specimen

Strain gauges

Incident pulse distance

a)

b)

Second (transmitter) bar First (incident) bar


time

Reflected pulse Transmitted pulse


Impact (Inertial wheel impact) Loureiro et al. (2010)

Impactor

Inertia wheel

Swing armLoad cell

AC Motor


SpecimenAnvil

95


FatigueASTM D 3166 Banea et al. (2009)



FatigueFernndez et al. (2010)

S i 2Specimen 2

da e/dN (CBBM) = 0.0058x1.7956 0.01

0.10.1 1

G Imax/G Ic

(mm

/cyc

le)

sss

dae/dN


da /dN (BEFM)= 0.0046x 1.4131

0.0001

0.001

da/dN

da/dN

96


CreepASTM D 2294



Creep ASTM D 2294


97


EnvironmentASTM D 896



Environemnt (Boeing wedge test)ASTM D 3762


98

Control Non-destructive tests

Defects Poor adhesion Porr cohesive strength

V id di b d it Voids, disbonds or porosity



Visual inspection Porosity, misalignments, non-uniform adhesive

thickness, etc.

Hart-Smith (2010)


99


Tap test Tapping on the bonded joint

Sh l t d dh i Sharp clear tone good adhesion Dull hollow tone void or unattached area Can be instrumented (solenoid operated

hammer and microphone pickup)



Ultrasonic method Petrie (2000)


100


Ultrasonic method Assler (2006)



Acoustic emission Joint must be loaded (semi-destructive) Stress waves emitted by crack propagation or micro-cracking

d d ith i l t i t dare recorded with piezoelectric transducers The only method that can detect poor adhesion


Magalhes (1999)

101


Radiography Voids or discontinuities Contrast improved with metal powder or other suitable p p

filler


Magalhes (1999)


Thermal methods Petrie (2000)


102

Control Post-fracture tests

Optical microscopy Failure mechanism

S f l i Surface analysis



Scanning electron microscopy Surface analysis


Failure surface of a toughened adhesive

Failure surface of an untoughened adhesive

( )


103


Scanning electron microscopy Surface analysis Banea & da Silva (2010)



Atomic force microscopy Surface analysis da Silva et al. (2008)


104


X-ray Photoelectron Spectroscopy (XPS) Chemical composition of the surface


Surface of a bi l i id



bismaleimide


Fourier transform infrared (FTIR) Identification of a material Suarez (2010)


FTIR spectrum of vulcanized styrene-butadiene rubber

105

Applications in the automotive industry RequirementsRequirements Areas of application Adhesives Strength Durability


y Repair

Automotive industry RequirementsBonding of multi-materials

Mangino (Fiat)

Dune Buggy 1970s Renault Espace 1984-1996

Volvo V70 XC AWD 2000Fiat 8V 1954


Chevrolet Corvette 1953

BMW M3 Sport Coup 2003Ford Thunderbird 2002

Ferrari Enzo 2003Aston Martin V12 Vanquish 2002

106

Automotive industry RequirementsBonding of multi-materials in S-Class Coup of

DaimlerChrysler

Flegel (2002)Flegel (2002)


Automotive industry Requirements

Automatic application Good filling capacity (~1 mm) Fast hardening Cognard Fast hardening Flexible and tough Crash test Reduce cost

D bilit ( 15 )

Cognard


Durability (~15 years) Repair

107

Automotive industry Areas of application

Body shopHem flange bonding

Burchardt (2010)



Body shopAnti-flutter bonding

Burchardt (2010)


108

Automotive industry Areas of applicationBody shopHybrid bonding


Automotive industry Areas of applicationAssembly lineDirect glazing Sika


109




Aston Martin DB9 CoupeNorton (2010)


1C epoxy

110

Automotive industry Adhesives

Tljsten (2005)Tljsten (2005)


Automotive industry StrengthIncrease in stiffness compared to welded structures


Flegel (2002)

111

Automotive industry Strength

Plastic deformation of the adherend controls failure (see joint design)

Grant et al. (2009)



Use flexible and ductile adhesives (crash suitable)

Burchardt (2010)


112


ImpactDroste (2006)



Jost (2000)Impact


113

Automotive industry DurabilityFatigue strength

Dilger (2005)


Automotive industry DurabilityTemperature (-30 to +80C)

Burchardt (2010)Structural adhesive

1C PU


114

Automotive industry DurabilityHumidity

Davies (2010)


Automotive industry RepairDismantable adhesives Sato (2010)


115

Bibliography


Bibliography


Documents

DaSilva Prezentare Adhes Bond