1. No category

Opportunité et défis de l'utilisation des composites
pour l'automobile
C. Binetruy1, O.Allix1, D. Guillon3, Y. Amossé4
1GeM
2LMT
Cachan
3CETIM (COMP’INNOV : Composite Innovation Openlab)
4Faurecia (Chaire Faurecia / Centrale Nantes)
christophe.binetruy@ec-nantes.fr
http://gem.ec-nantes.fr/
Cost and manufacturing driven optimization of
composite part designs
Structural part design Mechanical simula-on Material Scale Local Microstructure Performance
density × €
Manufacturing? 2
Stamping of composite prepregs
Without blankholder
With blankholder
3
Stamping of composite prepregs
4
Thermostamping of prepregs
Influence of the stamping time
Initial ply temperature : 290ºC
Tool temperature :180ºC
Stamping time : 1s
Initial ply temperature : 290ºC
Tool temperature :180ºC
Stamping time : 10s
Initial ply temperature : 290ºC
Tool temperature :20ºC
Stamping time : 1s
Initial ply temperature : 290ºC
Tool temperature :20ºC
Stamping time : 2s
5 Thermostamping of prepregs +
overmolding of LFTs
6 6 Injection/compression
7
Injection/compression
Injection unit
Mold heated by induction
Hot runner
Upper part of the press Mold Cavity Hot runner Injec-on unit Bo8om part of the press Injection from the bottom via the hot runner
8 Injection/compression
# Vf [%] h Q v [mm] [cm3/s] [mm/s] 1 42 4 50 6 2 56 6 20 3 3 56 6 20 0,5 1
Defects
•  Fibre washing in the centre
•  Bundle deformation at the
borders
•  Over-compaction in the middle
2
9 3
Compression of SMC
[3DTimon]
10
Compression of SMC
11
Compression of SMC
Fiber
Representative
volume element
Homogeneous
equivalent
medium
Part scale
p
p (orientation Thousands of
of a fiber)
fibers
Ψ (probability distribu-on func-on) Ψ(x)
a(x)
a (orienta-on tensor) 12
12
Compression of SMC
First step : Loading of the
charge
Second step : Compression
of the charge : flow of the
charge after 2 seconds
Second step : computation of
velocities and fiber
orientations
13
13
Compression of SMC
Through-thickness fiber orientation after 2s
14
Cost and manufacturing driven optimization of
composite part designs
15
Cost and manufacturing driven optimization of
composite part designs
Structural part design Mechanical simula-on Material Scale Local Microstructure Process design Process simula-on 16
Process enhanced composite part
optimization
17
Process enhanced composite part
optimization
• 
18
Process enhanced composite part
optimization
Optimization objectives
q  Full optimization cycle:
q  Design space definition
q  Topology optimization
q  Stacking sequence optimization on a
final geometry
q  Stacking sequence optimization:
q  7 zones with distinct UD ply lay-ups
q  The whole part can be enclosed by an
isotropic chopped fiber material
q  Process: RTM injection with an
injection line
q  Two optimization scenarios:
q  Without any manufacturing consideration
q  Using the RTM Process Estimator
19
Process enhanced composite part
optimization
q  Different stacking sequences for every zone
Without process considera9ons Using the RTM Process Es9mator No Yes 215.1 g 219.1 g < 2% 9.2 s 1.2 s 84% Chopped fiber ply Part Mass RTM filling -me Differences q  RTM fill patterns
Zones of flow
weld lines
Resin injection line
Fill pattern without process
consideration
Resin injection line
Fill pattern using the RTM Process
Estimator
20
Computational framework
Thermo-stamping
Overmolding
SMC
Development of rapid process
simulation models
Process simulation with advanced
rheological and flow models
Multiphysics problem
Complex
flow models
Meshless
methods
Fluid Flow
Process
combination
possible
Multiply simulation considering
thermal effects
Displacement
Temperature
Forces
Solid mechanics
Temperature
Compression moulding
Compression
molding
Heat Transfer
Deformation
Deformation
Hydraulic
press
Temperature
Solid
Liquid Interface
Interface
Liquid
Press
force
speed
Solid
Mould
•  Process
comparisons:
•  SMC, RTM, F3P
•  Grade of automation
Material
class
Machine
class
Workforce
class
Material
library
Machine
library
Workforce
library
Production
cost
Composite
part
Preparation
stage
Process
stage
Finishing
stage
Part
class
Material
cost
Advanced process simulation, virtual
material
characterization and
A
optimization of composite parts
Macrostructure:
Darcy
Introduction of the Process Estimators
Rapid manufacturability prediction
Combination
MAIN
PROGRAM
Variables:
Automation
grade
Manufacturing
volume
Cost of the
fiber
Combination
Microstructure:
Stokes
Outputs
Composite part cost
prediction
Mesostructure:
Brinkman
Replace tensile and compression
tests
Composite part
optimization
Ecole Centrale de Nantes / GeM Virtual material
characterization
21