UMR 8201
Research activities in the fields of metal and glass forming Keywords
Cold and hot forming, Tribology, Surface functionalities, Material behaviour, defectology, Thermal analysis, heat treatments, Experimental and numerical developments.
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Staff 2012
Status Members 2009
Members 2012
Professors 4 4 + 2 (50%)
Associate Professors 2 4
Engineers / Technicians 1 / 2 1 / 2
Total of permanent staff 9 12
Post Doc. / Contract Researchers 3 7
PhD Students (on-going) 7 7
Total 19 26
Invited Professors 0 3
International Chair 0 1
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UMR 8201
Research activities according to two scientific themes…
…applied to five Strategic Projects justified by societal, environmental and industrial needs
Strategic Project 1
Strategic Project 2
Strategic Project 3
Strategic Project 4
Strategic Project 5
Scientific theme 1
Scientific theme 2
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Scientific Themes
Identification of objective data to characterize surfaces undergoing extreme loadings: high temperatures, high contact pressures, high sliding speeds. Example of scientific challenges
Unbiased measurement of roughness parameters;
Fluid/Solid coupling between rough deformable surfaces;
Damage of materials in the surface vicinity;
Thermal exchange at glass/mould interface.
Theme 1: material behaviour in the surface vicinity under extreme conditions
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Scientific Themes
Understanding of material structure and behaviour evolutions due to the complex thermo-mechanical loadings imposed by forming processes. Taking into account of material changes on process response. Example of scientific challenges
Downscaling of process analysis to define links between
manufacturing processes and material properties;
Objective prediction of the damage of materials in core
induced by thermal and/or mechanical loadings;
Accurate modelling of radiation in glass modelling.
Theme 2: material/process coupling.
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SP4: SAFETY QUALITY Defectology at high temperature
SP3: PRODUCTIVITY High speed processes
SP1: SENSORY QUALITY Roughness and surface functionalities
SP2: ENERGY SAVING Cold forming & lightweight design
SP5: NICHE RESEARCH in Glass forming and tempering
Strategic Projects:
LAMIH and TEMPO strategic goals
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Strategic Projects:
Sensory quality: roughness and surface functionalities
Reliability of roughness and hardness measurements
Effect of process on surface functionality (brightness, wettability, hardness…)
University of Lyon
Technical University of Compiègne
Theme 1
Theme 2
(M. Bigerelle, C. Hubert, R.Deltombe)
LAMIH-C2S Research team
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Strategic Projects:
Energy saving: cold forming & light weight design
Lubrication of cold forming processes
Defects induce by forming sequences. Developments of
fast sheet forming computations
Theme 1
Theme 2
Theme 2
Technical University of Compiègne
Technical University
of Denmark
(L. Dubar, M. Dubar, A. Dubois, C. Hubert, T. Garcon, B. Laurent)
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Strategic Projects: Productivity: high speed processes
Effect of process parameter on material behaviour
Theme 1
Theme 2 University of Bordeaux
University of Châlon/Champagne
Tribology of high speed machining
University of Basque Country
(L. Dubar, M. Watremez, C. Hubert, T. Garcon, B. Laurent)
TEMPO-DF2T research team
LAMIH-C2S Research team
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Strategic Projects:
Safety quality: defectology at high temperature
Lubrication and tool damage in hot rolling and forging Heat gradient and defect
occurrences. Work hardening/softening at high temperatures.
Theme 1
Theme 2
University of Venezuela
(M. Dubar, JD Guérin, A. Dubois, T. Garcon, B. Laurent)
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Strategic Projects:
niche research induced by the material Glass forming and tempering
Lubricants & lubrication of glass forming processes
Modelling of glass forming and tempering
Theme 1
Theme 2 Lab. Of Photoelasticity, Estonia
Fraunhoher Institute ITWM,
Germany
University of Cliveland
University of Princeton
(D. Lochegnies, F. Bechet, P. Moreau)
TEMPO-DF2T research team
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Some scientific bottleneck removed
Radiation in 2D glass forming modelling. Stress in-homogeneity analysis in glass tempering. (SP5)
Development of advance friction law for high speed sliding contact. (SP3)
Innovative staggered algorithm for modelling of rough surfaces lubrication. (SP2)
Expert system to analyses roughness effect on surface functionality. (SP1)
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Presentation of Scientific Project 1
Modelling of Lubrication Mechanisms at Mesoscale
presented by Cedric HUBERT
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Context of the study Mixed lubrication regime
is often required
• to reduce friction • to master the final surfaces roughness
The real contact area is of major importance in the contact management
Two phenomena are involved
in the contact
• the dry tool/workpiece contact • the lubricant pressurization
part
tool
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Developed modelling strategy
Simplified surface topography
Real surface topography
Fluid/Structure interaction model Experimental tribotest
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Finite Element model of the process
Finite Element strip profile
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Developed modelling strategy
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Developed modelling strategy General procedure
lubricant film thickness
pocket pressure
tool/strip relative speed
lubricant film thickness
plateau length
lubricant viscosity
lubricant flow
initiates the first F/S increment
starts new F/S increment
calculates the fluid exchanges
sets fluid fluxes as boundary conditions
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Developed modelling strategy General procedure
initiates the calculation
(fully coupled F/S)
starts new F/S increment
calculates fluid exchanges sequentially
sets fluid fluxes as boundary conditions
Micro Plasto Hydro-Static Lubrication (forward escape)
Micro Plasto Hydro-Dynamic Lubrication (Backward escape)
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The experimental setup Tribotester
Strips surface profile
triangle cross sectioned grooves
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Experimental investigations Running conditions • 2 drawing speeds, 2 viscosities
• Parameters are crossed
aluminium strip
Vs1 = 5mm.s–1
Vs2 = 50mm.s–1
η1 = 60cSt (η1 = 0.054Pa.s)
η2 = 660cSt (η2 = 0.595Pa.s)
η1 = 60cSt
η2 = 660cSt
reduction: r = 16%
viscosities are given at 40°C
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Experimental investigations Validation of the fluid exchange assumption • Exchange by backward escape (MPHDL)
• Exchange by forward escape (MPHSL)
Vs = 5mm.s–1, η = 60cSt, 125fps, played at 30fps
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Experimental investigations Model calibration • Determination of h by means of roughness measurements
• h is assumed to be the arithmetic roughness of the plateaus • measured by means of a laser interferometer, normal to drawing direction
drawing
Vs2 = 50mm.s–1, η1 = 60cSt
0µm
-3µm
1 2 3
Vs2 = 50mm.s–1, η2 = 660cSt
-10µm
0µm 1 2 3
Vs2, η1 Vs2, η2
h (µm) 0.3µm 0.747µm
• Determined values of h (µm)
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Experimental/numerical comparison Pockets depth evolution • Result for case Vs1, η1
2 1 3
• Contact gap behaviour • 1: contact entry, the pocket (opened) loses a large amount of lubricant • 2: the pocket is closed and exchanges lubricant with the neighbouring ones • 3: contact exit, the pocket is opened and releases the remaining pressure
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Ongoing investigations on surfaces
Example of initial surface
Example of final surface
initial pocket region
deformed pattern
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Ongoing investigations on surfaces
Hydrostatically deformed plateaus surface
Affects the h parameter measurement Can not be reproduced in the present model
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Ongoing investigations
Determination of a reliable, less local and statistical
film thickness
•
Analysis of virgin and deformed surfaces to understand
the lubricant paths
•
Scale down the whole model or parts of it
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Presentation of Scientific Project 2
Advanced frictional laws for high speed machining
presented by Michel WATREMEZ
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High Speed Processes
Context: Numerical approaches are necessary for:
• productivity • tool wear • residual stresses.
Existing numerical approaches with current friction models: not very good correlation with process variables.
Advanced frictional laws for high speed machining
Error related to contact conditions in the tool-chip interface: - rheological behaviour - representative friction model.
Tool
Workpiece
Chip
Zone 1
Zone 2
Zone 1:
Ø Low sliding velocity Ø Contact pressure value higher than 1 Gpa Ø Interfacial temperature about 1075 K
Zone 2:
Ø High sliding velocity (Vchip) Ø Lower contact pressure Ø Interfacial temperature up to 1375 K
originality:
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Study of the first zone with the Upsetting Sliding Test Input parameters
• Geometry of contactor • Temperature of contactor from ambient to 150°C • Displacement velocity from 0 to 0.5m.s-1
• Geometry of specimen • Temperature of specimen from ambient to 1200°C • Relative penetration Output parameters • Normal force until 30 kN • Tangential force until 25 kN • Track (profilometry) • Temperature (pyrometer)
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contactor
tangential force
specimen
Friction track
p
normal force
contactor moving
direction
UST parameters: • relative penetration • contactor geometry • sliding velocity • contactor and specimen temperatures.
Specimen
Friction track
Contactor
50 mm
30 mm
19 mm
Numerical model of UST
• first to determine input parameters • then to evaluate m by inverse method
Contactor
Specimen part
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METHODOLOGY FOR FRICTION ANALYSIS
Numerical machining model
Numerical model of U.S.T.
Test performance
1) Numerical machining model à Contact characteristics (contact pressure, sliding velocity, temperature).
2) Numerical model of U.S.T. à input parameters (penetration, temperature and displacement velocity).
3) Tests à Forces in both normal and tangential directions.
4) Numerical model of U.S.T. (inverse
method) à Friction coefficient
à Several configurations: frictional law.
5) Numerical machining model.
Methodology for friction analysis
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TOOL
WORPIECE
Exit chip
Exit material
Entry material
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Machining model
• ALE (Arbitrary Lagrangian Eulerian) formulation. • take into account the area closer to the cutting edge, where the chip is formed. • workpiece: deformable body / tool: rigid. • workpiece composed with one entrance and two exits. • thermoviscoplastic behaviour: Johnson-Cook constitutive law.
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-nTk
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-nTk
0. =¶¶
-nTk
)(. TKnTk D=
¶¶
-
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-nTk
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-nTk
)(. ¥-=¶¶
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- TTKnTk
WORKPIECE
TOOL
Machining model
• ALE (Arbitrary Lagrangian Eulerian) formulation. • take into account the area closer to the cutting edge, where the chip is formed. • workpiece: deformable body / tool: rigid. • workpiece composed with one entrance and two exits. • thermoviscoplastic behaviour: Johnson-Cook constitutive law.
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Machining model
Progress of chip formation during an orthogonal cutting Simulation for a machining time of 12 ms
(a) 0 ms
(b) 0.4 ms
(c) 0.8 ms
(d) 1.2 ms
(e) 1.6 ms
(f) 2.0 ms
(g) 2.5 ms
(h) 12 ms
The chip thickness and the chip-tool contact length gradually
change to their final size.
Geometry and forces: stabilized after 2,5 ms
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Number of tested configurations 1 2 3 4 5 6 7 8 9 10 11
Penetration (mm) 80 80 100 100 80 80 100 100 120 120 120
Speed (mm.s-1) 200 400 200 400 200 400 200 400 60 200 400
Temperature (K) 650 650 650 650 750 750 750 750 950 950 950
0
2,5
5
7,5
10
12,5
20 30 40 50 60 70 80 90Déplacement (mm)
Forc
es (k
N)
Stationary zone
Fn
Ft
Displacement (mm)
Tests results of the sixth configuration.
Test conditions n° Tspe (K) p (mm) V(mm.s-1) FT (kN) FN (kN) FT/FN
6 752 0.084 400 3.1 10.6 0.30
Numerical model of U.S.T. Using of an iterative method to optimize the friction coefficient of Coulomb by minimizing the gap between experimental and numeral data for each configuration.
m = 0,24
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Numerical post-treatments results Local contact variables extracted from numerical modelling for the sixth configuration:
• Contact pressure distribution, • Temperature gradient field, • Relative sliding velocity
• average contact pressure of 1 Gpa • average interfacial temperature of 880 K • average sliding velocity of 340 mm.s-1
Specimen Specimen
Specimen Contactor
1.5 GPa 1120 K
1185 K
heterogeneity
m = 0,24
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Implementation of the advanced frictional law in the developed numerical model of orthogonal cutting :
432
int1cc
gc
n Tvc ×××= sm
c1 c2 c3 c4 0.919 -0.251 -0.463 0.480
Improvement of predicted process variables
0,31
0,41
0,5
Contact lengths (mm)
µ constant Advanced law Experimental results
0
200
400
600
800
1000
Cutting force (N) Thrust force (N)
µ constant Advanced law Experimental results
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Ongoing activities Extrapolate the law for higher velocities • High speed tribometer developed by Tempo
Tool
Workpiece
Chip
Zone 1
Zone 2
Contactor (H13A)
Pin (C45)
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Integration of physical, rheological and microstructural phenomena in modelling of high speed machining: Most researches with Johnson-Cook model • Strain rates unsuitable for high speed machining
• No recrystallisation taken into account in the chip
Microstructural analysis chip
Development of sub-routine to
consider recrystallisation phenomenon in simulations
Lurdos’s law
Voce’s law
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Austempered Ductile Iron (ADI) Spheroidal graphite (SG) iron heat treated from its austenitic temperature
Manufacturing ADI components
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Mechanical properties Lower Bainite 250 °C < Quench < 325 °C
Rm (MPa) 1400 – 1600
Re 0,2 (MPa) 960 - 980
A (%) 1 - 2
Usual spruing : after cooling
Automotive connecting rod
Surface degradation
The spruing operation is done before graphitization to save energy
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Experimental study Hot cutting test bench : LMPF Châlons en Champagne
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Rake angles : -10°; 0°; +10°
Cutting speeds : 0.8; 1.3; 1.6 m/s
Isothermal work-holding device
Specimen SG iron (EN-GJS-700) Temperature : 1000°C
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Experimental study Hot cutting test bench : LMPF Châlons en Champagne
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Rake angles : -10°; 0°; +10°
Cutting speeds : 0.8; 1.3; 1.6 m/s
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Recrystallization during experiments
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Ductile behavior linked with dynamic recrystallization of the matrix
Brittle behavior explained by a dynamic recrystallization delay Assessment
• For low cutting speeds : hot deformation with local dynamic recrystallization Restoring deformability –> Ductile fracture • Higher cutting speed with negative rake angle Surface degradation –> Brittle fracture
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Numerical modelling Thermo-mechanical behavior of SG iron
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Vc
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Strain rate study
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Cutting speed (1.3 m/s) Width 3 mm Width 4 mm
250 °C 221 s-1 132 s-1
550 °C 208 s-1 103 s-1
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Ongoing activities Shear tests: compression on hat shaped specimens Split Hopkinson Pressure Bar (SPHB) at high temperature
46
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Scientific production Key figures 2009-2012
Peer reviewed papers
10
20
2009 2010 2011 2012
Conferences & workshops Books / chapters in book
10
20
2009 2010 2011 2012
44 40
Peer reviewed papers / year / researcher (1 year = 6 man months)
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Scientific production Key figures 2009-2012
PhD Thesis defended 7
HDR defended 2
HDR: French post-doctoral degree to supervise PhD Student
MOCELLIN K. (2011). from CEMEF, Sophia Antipolis, France New strategies to the numerical simulation of forming processes
KUBIAK K. (2012). from University of Leeds, UK Morphology of surfaces in solid-solid and solid-liquid dynamic interfaces and its influence on friction, wear and wettability
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Industrial partnerships Key figures 2009-2012
Ñ Bosch Ñ Agrati
(PSA, Volkswagen, BMW…) Ñ Auberts & Duval Ñ Setforge Ñ CETIM
Ñ Condat S.A. Ñ Fuchs Ñ Mobil Oil Ñ Sogelub
Ñ PSA Ñ Daimler Ñ SNECMA
Ñ APERAM (Arcelor-Mittal Steel)
Ñ Tata Steel Ñ Vallourec
Steel metallurgists
Lubricant manufacturers
Car & aerospace manufacturers
Car & aerospace subcontractors
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Examples of industrial transfer: Key figures 2009-2012
innovative rolling schedules; (increase of production of 20%)
lubricant selection methodology;
(ability to test new environmentally friendly lubricants for industrial application in cold/hot forging or rolling)
edge-trimming process optimization;
(new process adjustments to suppress the “saw tooth” defect)
new lubricant for glass forming. (development of a new lubricant to limit glass/mould sticking)
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Academics partnerships Key figures 2009-2012
CRIBC SIRRIS
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Focus on some scientific and/or socio-economics impacts
Key figures 2009-2012
Organisation of Friction and wear in material processing symposia of ESAFORM conferences since 2008 ICFG Permanent Member, corresponding member for France; Organiser of ICFG 46th plenary meeting in 2013 On-going application to CIRP.
Vice-Chairman of National Committee of Rolling; member of GDR Verres 3338; member of TC25 Glass Forming of the International Commission on Glass.
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Short term prospective: direct continuation of present studies
STRA
TEG
IC P
ROJE
CTS
RESEARCH THEMES THEME 1: Surfaces under extreme loading
THEME 2: Coupling materials / forming processes
SP1: Roughness and surface functionalities SP2: Cold forming & light weight design
SP3: High Speed Processes
SP4: Defectology at high temperature SP5: Glass Forming and Tempering
Tool life in cold heading of steel parts with white lubricants Study of white layers, wear by diffusion in High Speed machining
oxide layer fracture and roll defect in hot rolling
Effect of lubrication formulation on tribology
Roughness of material with temperature
Electrical and thermo-mechanical behaviour of CuNiSi alloys (railway app.) Hopkinson bars to characterise flow curves for High Speed Processes at high temperatures soft hardening associated with dynamic recrystallization of stress strain curves of steels
2D model for the tempering of a glass sheet with radiation
High precision measurement of hardness
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Middle & long term perspectives: Focus on the evolutions of the microstructure of material during forming and their effects on material behaviour.
new numerical developments • fluid/solid/thermic
interactions at asperity scale, • meshless method to
detect crack initiation, • computation of
damage.
Downscaling of analyses: • new testing benches to
access local data (stress, strains...)
• The possibility to test material within SEM
or tomograph will be investigated.
formulation of a super element, able to predict damage in surface vicinity, taking into account the microstructure evolution with thermal and mechanical loading history.
Experimental actions
Numerical actions
Final objective
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Thank you for your attention
