AIAS Meeting Gruppo di Lavoro Tecnologie di Giunzione

AIAS Meeting Gruppo di Lavoro Tecnologie di Giunzione Vicenza, 27 -28 Marzo 2008 Prof. Ing. Alessandro Pirondi Università di Parma, Dipartimento di Ingegneria Industriale

OUTLINE • Adhesive bonding - Academic Research - Technology Transfer - Education and Symposia • Welding - Academic Research - Education • Ongoing research and perspectives

eretta, Poli MI) • Application - Lightweight jib for long-distance concrete casting - Structural adhesive (3 M 9323 A/B) + woven grafite-epoxy laminate • Flow-chart of the project [Goglio, Rossetto, Dragoni, AIAS ‘ 02, Parma]

ADHESIVE BONDING: Research

OUTLINE • Adhesives and environmental conditions considered - Structural adhesives (Multibond 330, Hysol 9514, Hysol 9466) - Adherends: construction steel or aluminum alloy - Lab air • Studies - Fracture toughness, Fatigue Crack Growth (FCG) (experimental) - Fatigue strength and fatigue life prediction (experimental) - Failure simulation with a Cohesive Zone Model (CZM) (numerical)

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)

FRACTURE AND FCG TESTS DCB (Double Cantilever Beam) P Tensile loading (Mode I) Mixed Tensile-Shear loading (Mixed-Mode I/II) d CTS (Compact Tension-Shear)

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 • Outcomes - 3 peer-reviewed papers on international journals + 1 submitted - several national and international conferences • Exploitation of the results - Testing procedures - Fatigue life prediction methodology

FATIGUE TESTS • Clip-gages (compliance monitoring=crack length evolution) • Applied load • Single-lap joint

FATIGUE TESTS: defect evolution a a steady-state accelerating

FATIGUE TESTS: life prediction - Time (cycles) to nucleate a defect negligible - Time (cycles) to propagate to rupture (Nf): b rupture L from FCG tests

FATIGUE TESTS: life prediction • Example: Hysol 9514 single-lap joint

SIMULATION: cohesive zone model • Concept (from: Hutchinson, Evans, Acta Mater. 48, 2000, 125 -135 ) Adherend contribution to peel strength Adhesive contribution to peel strength

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 -. . .

CZM SIMULATION: example • T-peel test: CZM calibrated on DCB fracture test (Multibond 330)* Courtesy Prof. M. Rossetto, Politechnic of Turin, Italy

ADHESIVE BONDING: Technology Transfer

Plate heat exchanger • Current solution • AISI 316 L stainless steel • Brazing • Max pressure 15 bar • Max temperature 70°C • Overall cost: 11. 5€ • Cost of brazing: 4. 25€ (37% tot. !) Adhesive bonding ? • Proposed solution • Bolt(s) to sustain loading • MS adhesive for sealing • Overall cost 25% lower !

Wall decoration preassembled patches • Current solution • 2 x 2 cm 2 10 x 10 cm 2 tesseras • Patch: 45 x 90 cm 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 alternative ? • Energy (heating) costs • 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 - Polimerization tower (20’ storage capacity) • Engineering - Two-component adhesive dispenser Component A injectors Component B injectors

Railway track joint (RFI-Henkel) • Application - Sustained loading conditions - High average shear stress • Sustained loading testing Creep

Composite joint design (project driven by S. Beretta, Poli MI) • Application - Lightweight jib for long-distance concrete casting - Structural adhesive (3 M 9323 A/B) + woven grafite-epoxy laminate • Flow-chart of the project [Goglio, Rossetto, Dragoni, AIAS ‘ 02, Parma]

ADHESIVE BONDING: education

EDUCATION • Academic - Seminars - Viscoelastic behaviour (polymers in general, about 6 h) • On-the-job and collective courses - “Simulazione ad elementi finiti di giunzioni incollate”. 8 h, Dallara Automobili, Parma - “TECNOLOGIE DI GIUNZIONE NON TRADIZIONALI: INCOLLAGGIO E FRICTION STIR WELDING”. 4 h, 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. • Symposia - Yearly Henkel-Loctite workshop, 2000, 2005

• Progetto 2007 2° posto in classe 3 • Progetto 2008 • Utilizzo di materiali compositi (fibra di carbonio-resina epossidica) • Utilizzo di incollaggi • Motore semiportante

WELDING: research

OUTLINE • Joints and environmental conditions considered - Friction Stir Welded joints - Materials: aluminum alloy, aluminum alloy matrix composite - Lab air • Studies - Fracture toughness, Fatigue Crack Growth (FCG) (experimental) - Fatigue strength and fatigue life prediction (experimental) - Residual strength prediction (numerical)

FRACTURE AND FCG TESTS - 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 • Outcomes - 2 peer-reviewed papers on international journals (under re-review) - several national and international conferences • Exploitation of the results - Testing procedures - Joining technique qualification

FATIGUE TESTS - Al overlap joints

FATIGUE TESTS: defect evolution and life prediction

RESIDUAL STRENGTH PREDICTION Transferability Kahn tear test large M(T) panels Al-alloy FSW butt joint 1: 50 scale (in-plane) CTOA F Keff COD Δa

WELDING: education

• Academic - Seminars - Overview of weldability and design (about 10 h) • On-the-job and collective courses - “Simulazione ad elementi finiti di giunzioni saldate”. 8 h, Dallara Automobili, Parma - “TECNOLOGIE DI GIUNZIONE NON TRADIZIONALI: INCOLLAGGIO E FRICTION STIR WELDING”. 4 h, CISITA, Parma. - “GIUNZIONI/COLLEGAMENTI”. 4 h. Corso di Alta Formazione “Materiali, Progettazione e Innovazione di Prodotto”, UNIVERSITA’ DI PARMA - “ESEMPI APPLICATIVI DEL METODO DEGLI ELEMENTI FINITI: CONTATTO, ASSEMBLAGGIO, GIUNZIONI”. 8 h. Corso di Formazione “Gli Elementi Finiti nella Progettazione Meccanica”, CSPMI, Reggio E.

ONGOING RESEARCH AND PERSPECTIVES

HYBRID JOINTS • Origin: Ph. D student stage at Henkel • Typologies of hybrid joints considered - Weldbonded (spot); Ultrasonic weldbonded (spot); rivetbonded; clinchbonded - Al/Al; Fe/Fe; Al/Fe (non weldbonded) + structural adhesive - Overlap joint • Program Literature research Market analysis Testing parameters (Do. E from market analysis) Manufacturing Testing / FE simulation Influence of parameters Design guidelines

HYBRID JOINTS -Ultrasonic weldbonding prel. results (joints manufactured at Poli MI) Strutturale Solo spotweld ultrasonico Ibrido con strutturale Ibrido con frenafiletti Ibrido con retainer Retainer

HYBRID JOINTS Rivetbonding damage and failure simulation

HYBRID JOINTS (da letteratura) Clinchbonding damage and failure simulation

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 -. .