Meeting Gruppo di Lavoro

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29 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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AIAS


Meeting Gruppo di Lavoro

Tecnologie di Giunzione


Vicenza, 27
-
28 Marzo 2008

Prof. Ing. Alessandro Pirondi

Università di Parma, Dipartimento di Ingegneria Industriale

-

Academic Research

-

Technology Transfer

-

Education and Symposia


Adhesive bonding


Welding

OUTLINE

-

Academic Research

-

Education


Ongoing research and perspectives

eretta, Poli MI)



Application

-

Lightweight jib for long
-
distance concrete casting

-

Structural adhesive (3M 9323 A/B) + woven grafite
-
epoxy laminate

[Goglio, Rossetto, Dragoni, AIAS ‘02, Parma]



Flow
-
chart of the project

ADHESIVE BONDING:
Research

-
Fracture toughness, Fatigue Crack Growth (FCG)


(experimental)

-
Fatigue strength and fatigue life prediction



(experimental)

-
Failure simulation with a Cohesive Zone Model (CZM) (numerical)

OUTLINE

-

Structural adhesives (Multibond 330, Hysol 9514, Hysol 9466)

-

Adherends: construction steel or aluminum alloy

-

Lab air


Adhesives and environmental conditions considered


Studies

WHY FRACTURE...?


Bonding technology faults, service conditions


Literature survey

-

About 100 papers collected spanning over the last 10 years

-

Applications in: residual strength of joints with defects



fatigue life prediction



durability ranking (fitness
-
for
-
purpose)

h
h

t
a
0
W
b

a
0
=
45 mm
W = 120 mm
h =
15 mm
t =
0.3 mm
b =
30 mm
shims
teflon
(s=0.05mm)

P
P
DCB

(Double

Cantilever

Beam)

FRACTURE AND FCG TESTS

CTS

(Compact Tension
-
Shear)

Tensile loading (Mode I)

Mixed Tensile
-
Shear

loading (Mixed
-
Mode I/II)



P

FRACTURE AND FCG TESTS


Qualifying points of the research (non
-
conventional features)

-

Automated crack length evaluation from compliance measurement

-

Fracture toughness correction to account for elasticity of the


adhesive layer

-

Mixed
-
Mode I/II conditions


Exploitation of the results

-

Testing procedures

-

Fatigue life prediction methodology


Outcomes

-

3 peer
-
reviewed papers on international journals + 1 submitted

-

several national and international conferences


Clip
-
gages

(compliance monitoring=crack length
evolution)

FATIGUE TESTS


Applied load


Single
-
lap joint

0
5
10
15
20
25
0
20000
40000
60000
80000
100000
120000
140000
Number of cycles
Crack length, a [mm]
steady
-
state

accelerating

a

a

FATIGUE TESTS: defect evolution

-

Time (cycles) to nucleate a defect negligible



m
max min
da
C G
dN
G f P P,a
C,m adhesive properties
 
  

-

Time (cycles) to propagate to rupture (N
f
):

c
0
a
f
m
a
c
0
da
N
C G
L W
a
2
a ( possible ) initial crack






rupture

b

L

FATIGUE TESTS: life prediction

from FCG tests

FATIGUE TESTS: life prediction

FATIGUE TESTS: life prediction


Example: Hysol 9514 single
-
lap joint

0
1
2
3
4
5
6
1000
10000
100000
1000000
10000000
Cycles to failure, Nf
Average Shear Stress [Mpa]
Pred. 60mm
exp 40mm
exp 60mm
exp 80mm
Pred. 80mm
Pred. 40mm
Adhesive contribution

to peel strength

Adherend contribution

to peel strength

(from: Hutchinson, Evans, Acta Mater.
48
, 2000, 125
-
135 )


Concept

SIMULATION: cohesive zone model


Use

-

Calibration of parameters on (standard) fracture tests

-

Simulation of failure of different geometries


Advantages

-

Efficient way to model potentially failing interfaces, including


adhesive joints

-

Model transferability (not to be tuned case
-
by
-
case)


Potential applications

-

Structural joints static and fatigue failure

-

Composites static and fatigue delamination

-

Impact delamination (shock absorbers, car bodies, ...)

-

Peeling of flexible laminates

-

...

SIMULATION: cohesive zone model

0
100
200
300
400
500
600
700
800
0.00
0.50
1.00
1.50
2.00
2.50
3.00
Displacement (mm)
Load (N)
Experiment
Simulation

T
-
peel test: CZM calibrated on DCB fracture test (Multibond 330)*

CZM SIMULATION: example

Courtesy Prof. M. Rossetto, Politechnic of Turin, Italy

ADHESIVE BONDING:
Technology
Transfer


AISI 316L stainless steel


Brazing


Max pressure 15bar


Max temperature 70
°
C


Overall cost: 11.5



Cost of brazing: 4.25


(37% tot.!)

Adhesive bonding ?

Plate heat exchanger


Proposed solution


Current solution


Bolt(s) to sustain loading


MS adhesive for sealing


Overall cost 25% lower !


2x2cm
2



10x10cm
2
tesseras


Patch: 45x90cm
2



Preassembly system: adhesive dots on the back


Current adhesive solution: plastisol (single
-
component)




highly flexibile




low cost




cure time 15’ at 190
°
C



Wear of anti
-
sticking coating


Energy (heating) costs

alternative ?


Current solution


Proposed solution


Two
-
component, high
-
flexibility adhesive (developed specifically by Henkel)


Cure time 20’ at room temperature


Higher adhesive cost


No energy costs for heating


Compactness of the new process line (no oven)

Wall decoration preassembled patches

-

Two
-
component adhesive dispenser

Component A injectors

Component B injectors


Engineering

Wall decoration preassembled patches

-

Polimerization tower (20’ storage capacity)

-

Sustained loading conditions

-

High average shear stress

Creep

Railway track joint (RFI
-
Henkel)


Sustained loading testing


Application

Composite joint design (project driven

by S. Beretta, Poli MI)



Application

-

Lightweight jib for long
-
distance concrete casting

-

Structural adhesive (3M 9323 A/B) + woven grafite
-
epoxy laminate

[Goglio, Rossetto, Dragoni, AIAS ‘02, Parma]



Flow
-
chart of the project

ADHESIVE BONDING: education



Academic

-

Seminars

-

Viscoelastic behaviour (polymers in general, about 6h)



On
-
the
-
job and collective courses

-

“Simulazione ad elementi finiti di giunzioni incollate”.


8h, Dallara Automobili, Parma

-

“TECNOLOGIE DI GIUNZIONE NON TRADIZIONALI:


INCOLLAGGIO E FRICTION STIR WELDING”. 4h, CISITA, Parma.

-

“GIUNZIONI/COLLEGAMENTI”.
Corso di Alta Formazione
“Materiali,


Progettazione e Innovazione di Prodotto”, UNIVERSITA’ DI PARMA

-

“ESEMPI APPLICATIVI DEL METODO DEGLI ELEMENTI FINITI:


CONTATTO, ASSEMBLAGGIO, GIUNZIONI”.
Corso di Formazione


“Gli Elementi Finiti nella Progettazione Meccanica”, CSPMI, Reggio E.


EDUCATION



Symposia

-

Yearly Henkel
-
Loctite workshop, 2000, 2005

2
°

posto in classe 3


Utilizzo di materiali compositi (fibra di carbonio
-
resina epossidica)


Utilizzo di incollaggi



Motore semiportante




Progetto 2007



Progetto 2008

WELDING:
research

-
Fracture toughness, Fatigue Crack Growth (FCG)


(experimental)

-
Fatigue strength and fatigue life prediction



(experimental)

-
Residual strength prediction




(numerical)

OUTLINE

-

Friction Stir Welded joints

-

Materials: aluminum alloy, aluminum


alloy matrix composite

-

Lab air


Joints and environmental conditions considered


Studies

FRACTURE AND FCG TESTS

*
*
( )
d
C
dP
a f C

 

-

Al/Al
2
O
3

butt joints

FRACTURE AND FCG TESTS


Qualifying points of the research (non
-
conventional features)

-

FSW applied to Al/Al
2
O
3

particulate composites

-

Automated crack length evaluation from compliance measurement

-

Crack closure evaluation and analysis

-

Crack path evaluation


Exploitation of the results

-

Testing procedures

-

Joining technique qualification


Outcomes

-

2 peer
-
reviewed papers on international journals (under re
-
review)

-

several national and international conferences

-

Al overlap joints

FATIGUE TESTS

10
20
30
40
50
60
1,00E+04
1,00E+05
1,00E+06
1,00E+07
1,00E+08
Number of cycles (N)
s 
MPa

Experimental
Nasgro model-threshold 2,7 MPa*m^0.5
Nasgro early mode II propagation: 200 microns
Nasgro early mode II propagation: 100 microns
FATIGUE TESTS: defect evolution
and life prediction

RESIDUAL STRENGTH PREDICTION

Transferability Kahn tear test


large M(T) panels

Al
-
alloy FSW butt joint

CTOA

F

COD

K
eff

Δ
a

1:50 scale (in
-
plane)

WELDING:
education



Academic

-

Seminars

-

Overview of weldability and design (about 10h)



On
-
the
-
job and collective courses

-

“Simulazione ad elementi finiti di giunzioni saldate”.


8h, Dallara Automobili, Parma

-

“TECNOLOGIE DI GIUNZIONE NON TRADIZIONALI:


INCOLLAGGIO E FRICTION STIR WELDING”. 4h, CISITA, Parma.

-

“GIUNZIONI/COLLEGAMENTI”. 4h.
Corso di Alta Formazione
“Materiali,


Progettazione e Innovazione di Prodotto”, UNIVERSITA’ DI PARMA

-

“ESEMPI APPLICATIVI DEL METODO DEGLI ELEMENTI FINITI:


CONTATTO, ASSEMBLAGGIO, GIUNZIONI”. 8h.
Corso di Formazione


“Gli Elementi Finiti nella Progettazione Meccanica”, CSPMI, Reggio E.


ONGOING RESEARCH AND
PERSPECTIVES

HYBRID JOINTS



Origin: PhD student stage at Henkel



Program

Literature research

Market analysis

Testing parameters (DoE from market analysis)

Manufacturing

Testing / FE simulation

Influence of parameters

Design guidelines



Typologies of hybrid joints considered

-

Weldbonded (spot); Ultrasonic weldbonded (spot); rivetbonded; clinchbonded

-

Al/Al; Fe/Fe; Al/Fe (non weldbonded) + structural adhesive

-

Overlap joint

HYBRID JOINTS

-
Ultrasonic weldbonding prel. results (joints manufactured at Poli MI)

Solo spotweld ultrasonico

Ibrido con frenafiletti

Ibrido con retainer

Retainer

Strutturale

Ibrido con strutturale

HYBRID JOINTS

Rivetbonding damage and failure simulation

HYBRID JOINTS

Clinchbonding damage and failure simulation

(da letteratura)

SELF
-
HEALING

?

That

s all Folks!

COLLABORATIONS

-

Prof. Gianni Nicoletto

-

Ing. David Fersini

-

Ing. Fabrizio Moroni

-

Ing. Matteo Vettori

-

Dr. Pierfranco Mauri

-

Dr. L.M. Volpone

-

Ing. C. Dalle Donne

-

....