100% • modulus of elasticity <1MPa • suitable for dynamic loads • stress distribution is uniform Strain [%] Tough-elastic adhesives • epoxies, polyurethanes • strength 5-30N/mm2 • elongation at break 20-100% • elongation at break 20-100% • modulus of elasticity 1-10MPa • modulus of elasticity 1-10MPa ">100% • modulus of elasticity <1MPa • suitable for dynamic loads • stress distribution is uniform Strain [%] Tough-elastic adhesives • epoxies, polyurethanes • strength 5-30N/mm2 • elongation at break 20-100% • elongation at break 20-100% • modulus of elasticity 1-10MPa • modulus of elasticity 1-10MPa ">
1e5 Glass Structures l5 Me Glued Connection
1e5 Glass Structures l5 Me Glued Connection
1e5 Glass Structures l5 Me Glued Connection
Introduction
Introduction
Structural
adhesives
Structural adhesives
Type of adhesives
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Introduction
Objectives
Introduction
First structural sealant glazing system, 1971, Dow Corning
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress distribution
models
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress distribution
models
Baitinger
Structural
adhesives reduction in weight of connection
Type of adhesives ability to joint thinner materials
Material properties
better stress distribution at joints
Surface pre-
treatment improved joint strength
Typology and
design cases ability to join dissimilar materials
Structural design scope for sealing as well as joining
Stress distribution
models
increased flexibility in the choice of component materials
aesthetic improvement
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Structural adhesives
Objectives
Material properties
some adhesives are stronger than glass failure can occurs
within glass more likely leads to complete structural failure
Surface pre-
treatment
behaviour of glued joint is very dependent on preparation
Typology and
design cases
etching improve adhesion BUT reduce strength of glass
Structural design adhesive properties are temperature-dependent
Stress distribution drop in temperature simultaneously shrink glass and metal and
models
increase stiffness of the adhesive
behaviour of two-part adhesives very dependent on how
accurately and well the parts are mixed
capillary action can separate glued joint suitable primer is
crucial
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Structural adhesives
Objectives
Failure modes
Introduction
Adhesion Cohesion
Structural
adhesives substrate substrate
Type of adhesives
adhesive adhesive
Material properties
substrate substrate
Surface pre-
treatment
Dispersive adhesion
Typology and
design cases intermolecular interaction, van der Waals forces, contact angle
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment Stress peaks in the ends of a lapped
connection formed with a hard
Typology and
design cases
adhesive
Structural design
Stress peaks in the area of the drilled
holes of a bolted connection under
Stress distribution load
models
Introduction
Adhesive can be differentiated according to modulus of elasticity and
Structural shear into: HARD = BRITTLE, TOUGH-ELASTIC, FLEXIBLE
adhesives
Type of adhesives
Material properties
hard, brittle adhesive
layer
Stress
Surface pre-
treatment
Stress distribution
models
flexible, elastic adhesive
layer
Strain
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Structural adhesives
Objectives
Flexible elastic adhesives
Introduction
Structural
adhesives silicones, modified silicones
Type of adhesives
(MS polymer), polyurethanes
100
Surface pre- elongation at break more than
treatment 80 150%
Typology and 60 suitable for linear bonded
design cases
40 joints, dynamic loads
Structural design
20 thickness of approx. 5mm
Stress distribution fills gaps and equalises
models 0
stresses
0 1 2 3 4 5 6
tendency to creep = short-term
adhesive layer thickness [mm]
strength several times higher
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Structural adhesives
Objectives
1,0
0
0 1 10 102 103 104 105 106
number of load cycles
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Structural adhesives
Objectives
Hard - brittle adhesives
Introduction
Surface pre-
treatment extremely high strength at
80
optimal thickness
Typology and
design cases 60 unable accommodate
Structural design 40 construction tolerances and
equalise stresses
Stress distribution 20
models suitable for point fixing
0
high thermal expansion
0 0,2 0,4 0,6 coefficient = imposed strains
adhesive layer thickness [mm] brittle failure without warning
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Structural adhesives
Objectives
Qualitative comparison of various adhesives
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
strength temperature moisture- /UV- joint accommodation transparency
Structural design
resistance resistance thickness of deformations
Stress distribution
models
polyurethanes acrylate
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Type of adhesives
Objectives
Acrylate
Introduction
Types
Structural
adhesives cyanocrylate, methacrylate (2 components)
and UV-curing acrylate
Type of adhesives
Material properties
General properties
Surface pre-
treatment in general a high shear strength
Typology and
small optimal thickness (generally less than
design cases 0.5 mm)
Structural design
methacrylates: good durability, UV-acrylates:
some durability problems
Stress distribution
models UV-acrylates: transparent
brittle
Structural applications
e.g. adhesive layers in structural double-sided
tape
e.g. indoor applications like bonded door
hinges etc.
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Type of adhesives
Objectives
Epoxy
Introduction
Structural
Types
adhesives generally: 2 components: an epoxide resin and a polyamide hardener
Type of adhesives curing: UV-curing, cold curing and hot curing variants
hybrid epoxy with increased elasticity (toughened epoxy)
Material properties
Surface pre-
treatment General properties
Typology and high strength and stiffness
design cases
small optimal thickness (generally less than 0.5 mm)
Structural design brittle
Stress distribution
models
Structural applications
e.g. aircrafts, boats, metal structures,
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Type of adhesives
Objectives
Polyurethane
Introduction
Structural
Types
adhesives physical and chemical curing variants, 1-component and 2-component
Type of adhesives
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Type of adhesives
Objectives
Silicone
Introduction
Structural
Types
adhesives one component (air curing) and two component (chemical curing) variants
Type of adhesives hot curing film (TSSA)
Material properties
Stress distribution
models Structural applications
structural sealant glazing (ETAG 002)
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Type of adhesives
Objectives
Hybrid polymers
Introduction
Structural
Types
adhesives modified silane molecules (1-component and 2-component)
Type of adhesives
Structural design
Stress distribution
Structural applications
models e.g. structural bonding of faade panels
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Type of adhesives
Objectives
Interlayer material for
Introduction
laminated glass
Structural
adhesives Types
Type of adhesives SentryGlas (SG)
Material properties
Polyvinyl Butyral (PVB)
Surface pre-
treatment
General properties
Typology and standard thickness: multiples of 0.38 mm
design cases
visco-elastic (time- and temperature dependent)
Structural design
medium (SG) to low (PVB) strength and stiffness
Stress distribution
models
Structural applications
laminated glass
splice laminates
hybrid components
experimental point fixings
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Material properties
Objectives
Strength of adhesives depends on:
Introduction
Structural
type of adhesive and thickness of the adhesive layer
adhesives
environment (chemical, UV radiation, moisture ageing)
Type of adhesives
temperature (adhesive tends to flow)
Material
properties magnitude of load and load duration
Surface pre- surface preparation (degreasing, priming, roughness = etching)
treatment
joint dimensioning and geometry
Typology and
including shape of glued edges
design cases reduction of strength in time
strength
Structural design
time
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Material properties
Objectives
Introduction
Durability of adhesive bonds
Structural Lifetime?
adhesives
10/25/50/100 years
Type of adhesives
Material
properties External factors Standardised ageing
Surface pre- low (-20 C) and high (+80 C) test temperature
treatment humidity
Typology and UV
design cases
sodium chloride
Structural design
nitric/carbonic acid (acid rain)
Stress distribution faade cleaning products
models
mechanical ageing
dynamic (load cycles)
static (creep/relaxation)
Ellsworth Residence
2009, Architect Michael P. Johnson
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Material properties
Objectives
Introduction
Material tests according to ISO 527-1, 2
Structural
test specimen
adhesives
Type of adhesives
Material
properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress distribution
models
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Material properties
Objectives
Material tests according to ISO 527-1, 2
Introduction
Obtained results for each adhesive:
Structural
adhesives stress strain diagram of the adhesive
Youngs modulus
Type of adhesives
Poissons ratio
Material
properties
elongation at break
tension strength of the material in accordance with ISO 527
Surface pre-
treatment this tension strength is not equal to the tension load carrying capacity of the
connection
Typology and
design cases
Structural design
Stress distribution
models
Stress [MPa]
Strain [-]
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Material properties
Objectives
Introduction
Durability temperature and UV dependency
45
Structural reference
adhesives -20C
40
Type of adhesives +80C
Material
maximal tested strength [N/mm] 35 UV
properties
30
Surface pre-
treatment
25
Typology and
design cases 20
Structural design
15
Stress distribution
models
10
SG
S1
S3
S5
S4
M2
M3
A2
A6
A8
E3
E5
P1
P2
Belis et al. (UGent)
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Material properties
Objectives
Environmental influences, artificial ageing acrylic adhesive
Introduction
temperature [C] Specimens in weterometer
Structural every 20min water shower
adhesives or UV-radiation
Type of adhesives
constant temperature
Material (+80C or -20C) without
properties UV-radiation or water
shower UV1 - adhesive
Surface pre-
treatment
Structural design
time [hour]
Stress distribution
models Some faults
after lab. ageing
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Material properties
Objectives
Environmental influences, artificial ageing
Introduction
Type of adhesives 7
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Materials Substrates
Objectives Glass
Introduction tin side / air side (see float process)
Structural Stainless steel
adhesives
SAE grade for building applications: 316 (EN: G-X 6 CrNiMo 18-10)
Type of adhesives
AISI 304, 316, 316L, 316Ti
Material
properties Anodised aluminium
Surface pre- anodisation depth: 25 m
treatment
Coatings
Typology and
design cases significantly varying adhesion levels!
Structural design to be avoided as substrate
Stress distribution Timber
models
humidity (shrinking)
heterogeneity
Glass fibre reinforced polymers
in experimental stage
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Surface pre-treatments
Objectives RATHER EXCEPTIONAL
Introduction
OBLIGATORY OPTIONAL
Structural
adhesives
Type of adhesives
Surface pre-
treatment
Typology and
design cases
Stress distribution
models
Plasma cleaning
Cleaning
Degreasing
(e.g. isopropylalcohol)
Adhesion promoters
UV blocking primers Abrasive blasting 28
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Surface pre-treatments
Objectives
Importance of clean surface - testing contaminated surfaces
Introduction
Structural
4,5
adhesives reference
oil on glass
Type of adhesives 4,0 H2O on glass
sand on glass
Material properties
3,5 oil on metal
Maximal tested strength [N/mm]
Typology and
design cases 2,5
1,0
0,5
0,0
S1 S3 S3 P1 M2 M3
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Procedure to create adhesive joints
Objectives
Introduction
1. Surface pre-treatment
Structural design
thickness control
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Typology & design cases
Objectives
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
Point fixing Linear adhesive bond Large area bond
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Typology & design cases
Objectives
Introduction
Point fixing
Structural
adhesives e.g. bonded inserts
Type of adhesives e.g. point-fixed faade
Material properties elements
Surface pre-
treatment
Typology and
no drilling in glass needed
design (strength)
cases
Structural design
better thermal performance
Stress distribution small bonded area, high
models strength needed
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Typology & design cases
Objectives
SEELE STAIR, DSSELDORF, 2006 APPLE STORE, SHANGHAI, 2010
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
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Typology & design cases
Objectives
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
Surface pre-
treatment
only low strength needed due to
Typology and large bonded surface
design
cases
Structural design
differential thermal expansion!
Stress distribution
models
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Typology & design cases
Objectives
Introduction
Large area bond
Structural
adhesives
e.g. splice laminates
Type of adhesives e.g. connection column-beam
Material properties
Surface pre-
treatment moment-stiff connection
Typology and identical coefficient of thermal
design
cases expansion
Structural design
Stress distribution
models
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Typology & design cases
Objectives
Overlapping glass elements
Introduction
Large area adhesive bond
Structural
adhesives (e.g. by acrylates, epoxies or films)
Type of adhesives Objective:
to connect glass segments of a beam,
Material properties
column, fin
Surface pre-
treatment to extend its overall size, or
Typology and to produce stiff and transparent
design corners
cases
Structural design
Stress distribution
models
Typology and
design
cases Main disadvantages:
Structural design difficult to make (air inclusions);
Stress distribution production preferably under
models
climatic controlled conditions
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
Detail of 21m glass beam at Glastec 2010 Detail of 21m glass beam at Glastec 2010
(EuroGlas) (EuroGlas)
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Typology & design cases
Objectives
Large area bonds: splice beam connections
Introduction
Manufacturing challenge:
Structural
adhesives introducing adhesive into the planar joint, barely 2 mm wide, without any
bubbles
Type of adhesives
to achieve homogenous curing of a relatively large amount of adhesive
Material properties
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
Introduction
Large area bonds: splice beam connections
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design
cases
Structural design
Stress distribution
models
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Structural design
Objectives
Safety coefficients
Introduction
Structural
Current practice
adhesives One general safety coefficient (5/10/20/100/)
Type of adhesives Non-transparent
Material properties Over-conservative or unsafe?
Surface pre-
treatment
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Structural design
Objectives
Strength determination of adhesive connection in tension
Introduction
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Structural design
Objectives
Strength determination of adhesive connection in tension
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress distribution
models
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Structural design
Objectives
Strength determination of adhesive connection in shear
Introduction
Structural
F
1) CHOSENADHESIVES
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress distribution
models
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Structural design
Objectives
Strength determination of adhesive connection in tension
Introduction
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress distribution
models
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Structural design
Objectives
Materials models for numerical solution by FEM
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
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Structural design
Objectives
Failure mode
Introduction
Substrate failure
Structural
adhesives
Type of adhesives
Material properties
Cohesive failure
Surface pre-
treatment
Typology and
design cases
Structural design
Adhesive failure
Stress distribution
models
TO BE AVOIDED
(Maybe except if design stresses are
significantly below adhesive failure
stress levels)
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Stress distribution models
Objectives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress
distribution
models
P
x ,a
bl
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Stress distribution models
Objectives
Introduction
Volkersen: differential shear stress
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress
distribution
models
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Stress distribution models
Objectives
Introduction
Goland & Reissner: bending moment
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress
distribution
models
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Stress distribution models
Objectives
Goland & Reissner: peel stress
Introduction
Structural
adhesives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress
distribution
models
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Stress distribution models
Objectives
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress
distribution
models
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Stress distribution models
Objectives
Introduction Reference: P = 1 kN 2 mm y
Structural L = 12 mm x
0,25 mm
1 kN
adhesives
2 mm 12 mm
Type of adhesives
Material properties
Surface pre-
treatment
Typology and
design cases
Structural design
Stress
distribution
models
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Stress distribution models
Objectives
Effect of load level
Introduction
2 mm y
Structural Example: P = 2 kN x
0,25 mm
adhesives 2 kN
L = 12 mm
Type of adhesives
2 mm 12 mm
Material properties
120
Surface pre-
treatment
100 Simplified (Reference)
Typology and
design cases
80 Simplified
Structural design
(x) [MPa]
Goland en Reissner
20
(Reference)
Goland en Reissner
0
0 0,2 0,4 0,6 0,8 1
x/l [-]
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Stress distribution models
Objectives
Effect of bonding length
Introduction
Structural
Example: P = 2 kN 2 mm y
0,25 mm
adhesives L = 24 mm x
2 kN
Type of adhesives
2 mm 24 mm
Material properties
60 Volkersen (Reference)
Stress
distribution 50
models Volkersen
40
30 Goland en Reissner
(Reference)
20
Goland en Reissner
10
0
0 0,2 0,4 0,6 0,8 1
x/l [-]
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Stress distribution models
Objectives
Effect of Youngs modulus
Introduction
2 mm y
Structural Example: E = 0.5, 5 or 50 GPa
0,25 mm
adhesives x
1 kN P = 1 kN
Type of adhesives L = 12 mm
2 mm 12 mm
Material properties
80
E = 50 GPa
60
Volkersen E= 50
40 GPa
20
0
0 0,2 0,4x/l [-]0,6 0,8 1
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References
Educational pack of COSTActin TU0905 Structural Glass - Novel design methods and next generation
products
HALDIMANN, M.; LUIBLE, A.; OVEREND, M..
Structural Use of Glass. Structural Engineering Documents 10 , IABSE, Zrich:2008. ISBN 978-3-85748-
119-2
ETAG 002, Guideline for European technical approval for structural sealant glazing kits (SSGK)
LAURIKS, L.; WOUTERS, I.; BELIS, J.; QUENTIN, C.
Lap shear tests on adhesive bonds of historic iron and mild steel. Stahlbau, 80(6) (2011) 413-418
BELIS, J.; VAN HULLE, A.; OUT, B.; BOS, F.; CALLEWAERT, D.; POULIS, H.
Broad screening of adhesives for glass-metal bonds. Glass Performance Days, 2011, pp. 286-289
CALLEWAERT, D.; VAN HULLE, A.; BELIS, J.; BOS, F.
The problem of a failure criterion for glass-metal adhesive bonds. Glass Performance Days, 2011, pp.
654-657
LAURIKS, L.; WOUTERS, I.; BELIS, J.
Determination of the adhesion of modern adhesives to historic iron by lap shear tests. Glass Performance
Days, 2011, pp. 348-353
MACHALICKA, K.; ELIASOVA, M.
Glued connection in glass structures In: Eurosteel 2011 6th European Conference on Steel and
Composite Structures. Brussels: ECCS European Convention for Constructional Steelwork, 2011, vol. 1,
p. 387-392. ISBN 978-92-9147-103-4.
NETUSIL M.; ELIASOVA, M..
Behaviour of the glued joint in hybrid steel-glass beam, Pollack Periodica : An International Journal for
Engineering and Information Sciences. April 2010, vol. 5, Nr. 1, pp. 97-108. ISSN 1788-1994.
WELLER, B., SHADOW, T.
Designing of bonded joints in glass structures. In: Proceedings of International Conference Glass
Performance Days, Tampere, Finland, 2007 p.74-76
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Thank you
for your kind attention
60