Presentation by Arnaud FRANCOIS, Senior Research Engineer, Cenaero

1. 1
Additive Manufacturing process simulation
Fusion
Welding
Complex flow
(multi-phase,
non-
newtonian,
reacting)
Curing of
Composites
Additive
Manufac-
turing
Hydro-
dynamic
Laser
welding
Friction (Stir)
Welding Metallurgy
Machining
Quenching
Thermal
Processing
Induction –
Autoclave –
Recovery
Draping
Arnaud FRANCOIS
Senior Research Engineer
Contact: arnaud.francois@cenaero.be
© 2017 Cenaero – All rights reservedTEKK Tour Nov. 6th 2017

2. PROD-F-015-02
2
Additive Manufacturing of metallic parts
with Laser Beam Melting
• Principle
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Main Tank
Laser
Recoater
Lift
Part
Working plate
Wiper
Source: Sirris
Source: Advanced Powders
~ 35 µm
– Ti6Al4V powder
Source: SLM Solutions

3. PROD-F-015-02
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Quality issues
• Mechanical properties are difficult to guarantee
– Porosity in dense materials
– Very sensitive to thermal conditions that evolve during the
manufacturing process
© 2017 Cenaero – All rights reservedTEKK Tour Nov. 6th 2017
Source: ULG / MMS

4. PROD-F-015-02
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Origin of defects
• LBM process window and porosity distribution [Gong et al. 2013] :
© 2017 Cenaero – All rights reservedTEKK Tour Nov. 6th 2017
Full
dense
Lack of
fusion
Excess of
fusion
Over-
heating
Zone II
Spherical shape
Zone III
Irregular shape

5. PROD-F-015-02
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AM process modelling
A multiphysics and multiscales problem
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Process
Parameters
Laser/powder
interaction
Building
Strategy
Physical
States
Powder
Post
Physics
Thermal
Metallurgy
Environnement
Liquid Solid
Mechanical

6. PROD-F-015-02
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Process Modeling
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Additive
manufac-
turing
Meso
Model
Macro
Model
Micro
Model
Thermo-mechanical
model
• Hatching
• Numerical methods
• Modeling
methodology
Hydrodynamic
model
• Liquid/solid
tracking
• Laser/powder
interaction
Structural model
• Distorsions
• Local/Global
approach

7. PROD-F-015-02
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QUALAM project
QUAlity in Additive Manufacturing
© 2017 Cenaero – All rights reservedTEKK Tour Nov. 6th 2017
• Sirris LBM machine • 3 test cases
Obtain the thermal history during the whole LBM manufacturing
process everywhere in the part

8. PROD-F-015-02
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Thermal model for Laser Beam Melting
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Argon
Building plate
Heating plate
(at 100 °C)
Ti6Al4V
powder
Solidpart
Tank
• Numerical challenges:
– 50 µm layer thickness  4000 layers
– 6 km laser beam trajectory
– Laser beam size = 150 µm
• Sirris LBM machine • Thermal model

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3D transient thermal simulation – 10 layers
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 Transient thermal simulation using in-house FEA software
 Using real process parameters
 Allow a fine analysis of the influence of process parameters:
Laser power & speed, scanning strategy and parameters, material
properties, part geometry, …

10. PROD-F-015-02
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Temperature evolution during LBM process
• Example: part with an evolving cross section
– ¼ model view showing T° after the deposit of a new powder layer
– Real manufacturing time ~ 33 hours
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200 layers 2000 layers 4000 layers

11. PROD-F-015-02
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Temperature evolution during LBM process
• Example of the “Y” part:
– Temperature evolution of the powder at the center of the Y part (top surface) just
before laser scanning start for each layer
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Heating
plate T°
Recoater feeding
(every ~ 60 layers)

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Closing remarks
 Development of a transient thermal model for LBM process (in-
house FE solver)
• Study the impact of process and laser hatching parameters
• Reduce the number of trial and errors (cost and time)
 Experimental measurements for :
• Material properties (ULG/MMS)
• Model validation and heat loss calibration from experimental
temperature measurements (Sirris & CRM)
 Perspectives - Work in progress:
• Extension to thermo-mechanical models
• Towards an integrated, multi-disciplinary process / product
conception
© 2017 Cenaero – All rights reservedTEKK Tour Nov. 6th 2017