presentation of the mastermaster lab lab research activities - … · 2012. 6. 26. · • 25m2...

MaSTeR Lab @ CIRI AeronauticaU O Meccanica e Tecnologie applicate all‘AereonauticaU.O. Meccanica e Tecnologie applicate all Aereonautica

Presentation of the MaSTeRMaSTeR LabLab research activities

I. Meneghin, G. Ivetic, G. Molinari, S. Guglielmi, L. Donati, E. TroianiL. Donati, E. Troiani

MaSTeR Lab - II Faculty of EngineeringVia Fontanelle 40 47121 Forlì (FC) - ItalyVia Fontanelle 40, 47121 Forlì (FC) Italy

www.masterlab.unibo.it [email protected]

Ricerche in CorsoRicerche in CorsoPartnersArgomenti:

• Damage Tolerance [DT] caratterizzazione di pannelli aeronautici irrigiditi

Industriali Accademici

g

• Laser Shock Peening [LSP] Pallinatura Laser, tecnologia in grado di aumentare la vita a fatica di componenti metallici

• Friction Stir Welding [FSW] di leghe di alluminio• Friction Stir Welding [FSW] di leghe di alluminio

• Crashworthiness – Resistenza all’urto di strutture in materiali compositi

•Utilizzo di Nanofibre in strutture in Composito per aumentare le proprietà di resistenza interlaminare

• Degradazione delle proprietà meccaniche di strutture in g p pcomposito a causa dell’effetto combinato di igroscopia e fatica

• Monitoraggio di strutture in materiale composito tramitegg pfibre di Bragg

Attrezzature di LaboratorioAttrezzature di LaboratorioMechanical and metallographic material characterization • 100kN servo-hydraulic test machiney

• Rotating bend machine

• Metallographic laboratory (optical and stereo microscope, hardness test equipments )

Carbon Fiber Reinforced Plastic (CFRP) manufacturing

equipments )

• NDT analysis equipments (ultrasonic cam)

Carbon Fiber Reinforced Plastic (CFRP) manufacturing

• 25m2 cleaning roomg

• 2 autoclaves (1. 0,9m wide, 3 m long, 2. 0,5m wide, 1 m long)

Laser Shock Peeningg

Research Goal Development of the Laser Shock Peening [LSP] technology to improve the fatigue performances of metallic structural componentsimprove the fatigue performances of metallic structural components

Research Efforts • Setting-up of the LSP experimental facility at UNIBO

• Experimental tests on LSP treated components (fatigue• Experimental tests on LSP treated components (fatigue performances and residual stress measurements)

• Comparative analyses with conventional residual stress establishment techniques (e g shot peening or cold working andestablishment techniques (e.g. shot peening or cold working and stress wave for open holes)

• Numerical simulation of the LSP effect on the fatigue performances of the treated components by Abaqus®of the treated components by Abaqus®

• Knowledge transfer through international industrial and academic collaborations (Airbus and UP Madrid)

Research Results Optimized LSP process set-up in accordance to the investigated structures (thin-walled aluminum structures).

Validated numerical model for the prediction of the LSP effect on theValidated numerical model for the prediction of the LSP effect on the fatigue performances


A high power laser pulse (order of GW/cm pulse duration 10 100 nsec) is focused on the surface to be treatedA high-power laser pulse (order of GW/cm, pulse duration 10 – 100 nsec) is focused on the surface to be treated

• The laser light pulse passes the tamping layer without (ideally) substantial absorption losses (e.g. water transparent for Nd-YAG radiation 1064nm)

• The absorption layer (ideally) is totally absorptive which in turn causes a rapid evaporation of the material into• The absorption layer (ideally) is totally absorptive, which, in turn, causes a rapid evaporation of the material into the plasma state (high pressure plasma).

• The plasma is prevented from rapid expansion by the tamping layer

• After evaporative breakdown of the tamping layer the plasma expands rapidly from high pressure to ambient• After evaporative breakdown of the tamping layer, the plasma expands rapidly from high pressure to ambient and the reacting transient force (backstroke) causes a compression shock propagating into the metal substrate


LSP Vs Shot Peening


One-side treatment

Two-side treatmentTwo-side treatment


Roughness of the treated surfaceg

Induced residual stresses (hole-drilling)

Friction Stir Weldingg

Research Goal Development of the Friction Stir Welding [FSW] process for l l i d t i l li tilarge-scale industrial applications

R h Eff t S tti f th FSW f T j i t fi tiResearch Efforts • Setting-up of the FSW process for T-joint configuration

• Mechanical and metallographic characterization of the produced FSW joints

• Numerical analysis of the FSW process and of the structural performances of the T-joint configuration

• Enhancement of the structural performances of the T-joint by p j ymeans of an optimization of the FSW parameters and position of the weld beads

Research Results • Efficient welding solution that takes advantages of both extruded profiles and FSW technology

• The proposed protrusion fillet solution for joining extruded• The proposed protrusion fillet solution for joining extruded profile with FSW has been awarded by a patent


Friction Stir WeldingFriction Stir Welding

Solid-state welding process

• A cylindrical-shouldered tool, with a profiled threaded/unthreaded probe (nib or pin) is rotated at a constant speed and fed at a constant traverse rate into the joint line between two pieces of sheet or plate constant speed and fed at a constant traverse rate into the joint line between two pieces of sheet or plate material

• Frictional heat is generated between the wear-resistant welding tool shoulder and pin, and the material of the work piecesp

• Frictional heat causes the stirred materials to soften without reaching the melting point (solid-state process)

• As the pin is moved in the direction of welding, the leading face of the pin, assisted by a special pin p g g p y p pprofile, forces plasticised material to the back of the pin while applying a substantial forging force to consolidate the weld metal.


FSW of aluminum sheets on extruded profiles

3

10

PIN Sheet

3

10

3

10

3

10

3

10

PIN Sheet

Possible applications50

ExtrudedProfile

5050

ExtrudedProfile

Pin

Spindle rateSpindle rateFeeding Rate

Sheet

Sh t

Extruded profile

Sheets

Friction Stir WeldinggFSW of aluminum sheets on extruded profiles

FSW process for large-scale industrial applications

Shaping the extruded profile for material filling and sheet clamping

• The idea is to use a suitable profile shape (appendices) in order to enlarge process tolerances;

• The appendix are used as ‘outside’ material that fills sheets gaps during processing;pp g p g p g;• The T-shape appendix performs also a clamping effect on the sheets;• University of Bologna (RM 2008 A000438) patent

I-shape T-shapeI shape T-shape


FSW f l i h t t d d filFSW of aluminum sheets on extruded profiles

Joint Production

Process Monitoring

FEM Optimization

Joint Testing

Microstructural Analysis


FSW of aluminum sheets on extruded profiles

the perfect sheets contact is not due filler material effect from extruded profile

I-shape extruded profilep

Corrosion Effects on Al• Comparison of fatigue tests on original and corroded AA-

2024T351 specimens;• EXCO Test (EXfoliation COrrosion Test) with a corrosion EXCO Test (EXfoliation COrrosion Test) with a corrosion

solution of NaCl, KNO3 and HNO3 in water for 8 days;• Fatigue tension-tension tests under constant proportional

loading (R=0.1, f=10 Hz); 3 stress levels (195, 215 and 250 MPa);

• Original specimens have the same notched section of corroded Original specimens have the same notched section of corroded ones (data are comparable);

Corroded Original

Cycles

Crashworthiness of CFRP

Research Goal Development of a reliable coupon-size test method for the d t i ti f b tidetermination of energy absorption

R h Eff t D l t f t f lf tiResearch Efforts • Development of a new geometry for self-supporting specimens

• Experimental verification of the developed test method

• Development a numerical model of progressive damage for structures made of CFRP materials with Abaqus®- Explicit

Research Results The innovative test method has provided reliable results and has been presented to wide scientific communityhas been presented to wide scientific community


The ability of a craft, or one of its components, to sustain Crashworthiness y , p ,a crash event with minimal, or otherwise acceptable, damage to the occupants, cargo and structure.

Crashworthiness

Specific Energy Absorption EASEASpecific Energy AbsorptionlA

EASEA [J/g]


Existing Test solutionsFlat specimenCrush on a Radius Flat specimen

ARL ‐ NASA


Innovative self-supporting test


Numerical Model

Degradation of CFRPgat

ura

Tem

pera +80°C

Flessione e taglio interlaminare

ImpattoTempo

-20°C

cani

che

Trazione

età

Mec

cP

ropr

i

I i Cicli/TempoIgroscopia

Rinforzi di Nanofibre in CFRP

CompositoNanofibra

Fibre ottenute per elettrospinning

Monitoraggio Strutture in Compositogg p

Permette di monitorare le deformazioni di una stuttura in esercizio, mediante l’utilizzo di fibre di Bragg direttamente dentro la struttura in composito

presentation of the mastermaster lab lab research activities - … · 2012. 6. 26. · • 25m2...

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