The document discusses additive manufacturing (AM) process simulation and modeling. It focuses on laser beam melting, which uses a laser to fuse powdered material to build up 3D parts layer by layer. Thermal modeling is important because AM processes involve complex thermal conditions that influence part quality and properties. The document describes a thermal modeling project that uses finite element analysis to simulate temperature evolution during the laser beam melting process and better understand defect formation. The goal is to reduce trial and error and improve process control by studying the impact of various laser parameters and strategies.

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
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2. PROD-F-015-02
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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

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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
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Source: ULG / MMS

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Origin of defects
• LBM process window and porosity distribution [Gong et al. 2013] :
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Full
dense
Lack of
fusion
Excess of
fusion
Over-
heating
Zone II
Spherical shape
Zone III
Irregular shape

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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

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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

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QUALAM project
QUAlity in Additive Manufacturing
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• Sirris LBM machine • 3 test cases
Obtain the thermal history during the whole LBM manufacturing
process everywhere in the part

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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, …

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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

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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
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