series-production automotive hood in integral cfrp design
TRANSCRIPT
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 1 #93090 · 11sd0038.pptx
Institut für Kraftfahrzeuge
RWTH Aachen University
Series-Production Automotive Hood in
Integral CFRP Design
European HyperWorks Technology Conference
2011
Bonn, November 9th 2011
Dipl.-Ing. Kristian Seidel, Univ.-Prof. Dr.-Ing. Lutz Eckstein
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 2 #93090 · 11sd0038.pptx
Agenda
Introduction
Motivation
Project Description
Requirements
Simulation and Design of CFRP
Summary
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 3 #93090 · 11sd0038.pptx
Introduction
FRP in Automotive Research at ika
Production
• Fibre manufacturing
• Semi-finished products
• Polymer processing
• Handling
Vehicle
• Full vehicle competence
• Functions & requirements
• Integration & assembly
• Testing & assessment Chassis
Body
Drivetrain E / E
Acoustics Driver
Assistance
Material
• Characterisation
• Simulation
• Optimisation
• Verification
Fib
re r
ein
forc
ed
pla
stics
in a
uto
mo
tive
en
gin
ee
rin
g
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 4 #93090 · 11sd0038.pptx
Agenda
Introduction
Motivation
Project Description
Requirements
Simulation and Design of CFRP
Summary
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 5 #93090 · 11sd0038.pptx
Motivation
Future Mobility
Energy costs will increase further in medium term
Fuel consumption and emissions will be strongly financially sanctioned in the future
Emissions gain major impact on mobility, e.g. in congested urban areas
„Harmonising the qualities efficiency,
safety and driving experience.“
Vehicle
Concepts
Architecture &
Functions
Materials
SAFETYDRIVING
PLEASUREDriving please despite ADAS
Vehicle
EFFICIENCY
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 6 #93090 · 11sd0038.pptx
Motivation
Potential of Fibre Reinforced Plastics
Stiffness and strength of fibre reinforced plastics (FRP) are strongly depending
on the direction (anisotropy)
Carbon fibre reinforced plastics (CFRP) have highest specific properties
Superior buckling stiffness and dent resistance of FRP e.g. outer panels
Particularly for structural parts fibres have to be aligned to the load to achieve
considerable weight reduction
103%
57%
60%
44%
105%
31%
5%
23%
9%
32%
88%
15%
41%
17%
91%
144%
14%
61%
19%
152%
365%
35%
96%
30%
436%
0%
20%
40%
60%
80%
100%
Steel (500 MPa) Aluminium (400 MPa)
CFRP uni-directional CFRP quasi-isotropic
GFRP uni-directional CFRP quasi-Gsotropic
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 7 #93090 · 11sd0038.pptx
Prestige
Versatility / benefit
Price
Driving experience
Potential of FRPs in cars
Future vehicle development
1985: 9 Segments 2008: 40 Segments
Flexible and economic production for lower production volumes
[Source: Volkswagen AG]
Rising diversity of derivates
Decreasing production volume
Higher level of individualisation
Costs
/ u
nit
Production volume
Metal
current future
Economic FRP production
FRP current
FRP future
Lower fixed costs offer advantages for
lower production volumes
Exploitation of higher production volumes
by reducing variable costs
Flexible production by variable
manufacturing facilities
future EV
FRP future with EV
Versatility / benefit
Price
Driving experience
Prestige
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 8 #93090 · 11sd0038.pptx
Agenda
Introduction
Motivation
Project Description
Requirements
Simulation and Design of CFRP
Summary
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 9 #93090 · 11sd0038.pptx
Project goals:
Technological and economical potential analysis
Simulation of CFRP under static and dynamic loads
Load, material and production suited design
Enhancement of production concepts (gap impregnation)
regarding cycle times and class-A surface quality
Funding:
Ministerium für Innovation, Wissenschaft und Forschung
(MIWF) within funding call Hightech.NRW
Duration: 01/2010 – 12/2012
Partner:
Hightech.NRW
CFRP Body Panels
Technology demonstrator
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 10 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Production
Production scenario: 10,000 units p.a.
Gap impregnation
Fast impregnation
Low pressure
High level of automation
Low cycle times
Production process chain
Material supply
Trimming
Preform manufacturing
Gap impregnation
Finishing
Storage
Reduction of production costs
Gap
impregnation
TrimmingMaterial
supply
Preform
manufacuring
Storage
Finishing
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 11 #93090 · 11sd0038.pptx
Agenda
Introduction
Motivation
Project Description
Requirements
Simulation and Design of CFRP
Summary
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 12 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Benchmark
Design benchmark
Functional benchmark
Global stiffness
Torsion stiffness
Longitudinal stiffness
Lateral stiffness
Local stiffness
Buckling stiffness
Dent resistance
Acoustics
Noise intensity
Sound transition loss
Pedestrian protection
Euro NCAP head impact
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14
Kra
ft [N
]
Deformation [mm]
Analyse Beulsteifigkeit Motorhaube VW Golf VI (MJ 2010) - Messpunkt BS1
10.01.2011
Ci = 77,2 N/mm
SOC
-12
-10
-8
-6
-4
-2
0
100 300 500 700 900 1100 1300
dB
[W
/m²·
N]
Terz [Hz]
Transferfunktion
Focus 2010
Auris
Prius
Volvo C30
Golf VI
Mittelwert
0
20
40
60
80
100
120
0 5 10 15 20 25 30 35 40 45
Kra
ft [N
]
Auslenkung [mm]
Torsionssteifigkeit
Ford Focus (MJ 2010)-Außenblech
Ford Focus (MJ 2010)-Strukturinnenblech
Toyota Auris (MJ 2010)-Außenblech
Toyota Auris (MJ 2010)-Strukturinnenblech
Toyota Prius (MJ 2010)-Außenblech
Toyota Prius (MJ 2010)-Strukturinnenblech
Volvo C30 (MJ 2010)-Außenblech
Volvo C30 (MJ 2010)-Strukturinnenblech
VW Golf VI (MJ 2010)-Außenblech
VW Golf VI (MJ 2010)-Strukturinnenblech
Ford Focus (MJ2011)-Außenblech
Ford Focus (MJ 2011)-Strukturinnenblech
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
0,000 0,005 0,010 0,015 0,020 0,025 0,030 0,035 0,040 0,045 0,050
Ac
ce
lera
tio
n [
g]
Time [s]
Beschleunigung-Zeit-Diagramm
resultierende Beschleunigung
Fußgängerschutzversuch 27.05.2011
Ford Focus Serienhaube Impaktpunkt 193090SK001
v = 39,641 km/hHIC_15 = 510,9
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 13 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Buckling Stiffness & Dent Resistance
Buckling Stiffness
Elastic buckling (e.g. polishing, oil canning)
Circular indentor (d = 50 mm)
Force up to 250 N
Dent Resistance
Plastic deformation (e.g. Hail, stone impact)
Spherical indentor (d = 25 mm)
Force up to 200 N
Solver: RADIOSS 10.0 (explicit)
0
50
100
150
200
250
300
0 2 4 6 8 10
Forc
e [N
]
Displacement [mm]
Buckling Stiffness / Dent Resistance
BS3 SimulationBS5 SimulationBF4 SimulationBF5 SimulationBS3 TestBS5 TestBF4 TestBF5 Test
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 14 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Pedestrian Protection
Euro NCAP Head Impact
40 km/h, 50°
Child head (3.5 kg)
Head Injury Criteria:
ΔHIC ≈ 3 %
1000)tt(t
t
dt)t(a)tt(
1maxHIC 12
5,22
112
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 15 #93090 · 11sd0038.pptx
Agenda
Introduction
Motivation
Project Description
Requirements
Simulation and Design of CFRP
Summary
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 16 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Degrees of Freedom for FRP Design
Standard Design
Shape
Material Thickness
FRP Design
Fibre
Material
Matrix
Material
Fibre
Orientation
Laminate
Layup
Volume
Content
Additional degrees of freedom when designing fibre reinforced plastics
Lack of experience and uncertainties require advanced CAE support
Intelligent optimisation procedures ensure utilisation of material properties
Reduction of development costs
Maximised weight saving Reduced part costs
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 17 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
CFRP Optimisation
Free-shape / free-size optimisation
(OptiStruct 10.0.5)
Combined optimisation strategy
Topography of inner panel (free-shape)
Load adapted laminate layup (free-size)
Fibre orientation outer panel (discrete size)
Considered load cases:
Torsion
Longitudinal, lateral bending
Buckling stiffness
Design concept
Shape change Shape change
Design refinement
•Review of node set for
free-shape optimisation
• Interpretation of design concept
•Consideration of package requirements
•Generation of final mesh
Final design
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 18 #93090 · 11sd0038.pptx
Free-size / Composite size / shuffling optimisation
(OptiStruct 10.0.5)
Hightech.NRW - CFRP Body Panels
CFRP Optimisation
Ply book concept (free-size)
Fibre orientation outer panel (discrete size)
Ply book concept
Shell thickness
0.5-1.75 mm
Ply thickness
• Interpretation of free-size results
•Definition of patches
Final ply book (reduced number of plies)
Fibre orientation & thickness inner panel
(discrete & composite size)
Stacking sequence (composite shuffling)
Final ply book
Thickness
0.5 mm < t < 1.5 mm
2 full plies
12 local plies
Δm ~ 65%
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 19 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Material characterisation
Tensile test DIN EN ISO 527 – 4 (non-unidirectional)
Tensile test DIN EN ISO 527 – 5 (unidirectional)
Compression test DIN EN ISO 14126 (non- / unidirectional)
Tensile shear test DIN EN ISO 14129 (in plane shear)
Shear test DIN EN ISO 14130 (interlaminar shear)
Dynamic tensile and shear tests
Tension / shear
Lf = 150 mm (0° / 90° / +45°)
Compression
Lf = 10 mm (0° / 90°)
Shear (interlaminar)
10x20 mm (0° / 90°)
Tension / shear (dynamic)
Lf = 75 mm (0° / 90° / +45°)
[BA
SF
]
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 20 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
CRASURV Model
CRASURV material model (RADIOSS /MAT/COMPSH)
Anisotropic, visco-elasto-plastic, strain rate dependant material behaviour
Damage and failure in tension, compression and shear based on plastic work
Advanced Tsai-Wu failure model
Initial Tsai-Wu is shifted to account for hardening and softening
σmax
σres
σ
WpWp2Wp1
maximum
stress
residual
stress
elasticity
plasticity
failure
erosion [Altair]
2: Tsai-Wu after hardening
and softening in some directions
1: Tsai-Wu after hardening
0: Initial Tsai-Wu
3: Residual Tsai-Wu
σ1
σ2
[Altair]
Welastic
Wplastic
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 21 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Material modelling of CFRP
Layered Shell Method (RADIOSS /SH_SANDW or /SH_COMP)
Laminate layers are represented as integration points
within one shell element
Good trade-off between calculation time and accuracy for crash simulation
0
200
400
600
800
0,0 0,5 1,0 1,5
Spannung [M
pa]
Dehnung [%]
Zugversuch
Simulation
Versuch
020406080
100120140
0 5 10 15 20 25 30 35
Spannung [M
pa]
Dehnung [%]
Schubversuch
Simulation
Versuch
0
200
400
600
800
0,0 0,5 1,0 1,5 2,0 2,5
Spannung [M
pa]
Dehnung [%]
Druckversuch
Simulation
Versuch
tension
str
ess [
MP
a]
strain [%]
simulation
test
simulation
test
compression
str
ess [
MP
a]
strain [%]
simulation
test
shear
str
ess [
MP
a]
strain [%]
Composite panel: 2 layers FEM Model: 5 layers
Z
X, Y 1-2 integration points per layer
(material and orientation)
Shell element on mid-surface
[Altair]
CRASURV material model (RADIOSS /MAT/COMPSH)
Comparison of test and simulation
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 22 #93090 · 11sd0038.pptx
0,0
1,0
2,0
3,0
0 50 100
Kra
ft [k
N]
Weg [mm]
CFK monolithisch 1 mm
FK002Simulation
Hightech.NRW - CFRP Body Panels
Drop tower test
Monolithic CFRP plate (1x400x400 mm)
Hemispherical impactor (Ø 114 mm)
Impactor velocity up to 30 km/h
Impactor mass: 9 kg
Solver: RADIOSS 11.0 (explicit)
Drop tower test CFRP
Forc
e [kN
]
Displacement [mm]
CFRP Monolithic 1 mm
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 23 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Pedestrian Protection with CFRP
Deceleration of the head is determined by a combination of mass inertia and
stiffness/strength of the hood
Short pulse induced by mass inertia results in a short HIC window and low HIC
values for steel hood
Missing pulse due to mass reduction (e.g. CFRP) has to be compensated by
stiffness/strength which results in a wider HIC window
Acceleration is distributed over a
longer time period which results
in higher intrusions
0
500
1.000
1.500
0
50
100
150
0 10 20 30
HIC
[ ]
acce
lera
tio
n [g
],
dis
pla
ce
me
nt [m
m]
time [ms]
Steel - acceleration CFRP - accelerationSteel - displacement CFRP - displacementSteel - HIC CFRP - HIC
Inertia dominated
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 24 #93090 · 11sd0038.pptx
Agenda
Introduction
Motivation
Project Description
Requirements
Simulation and Design of CFRP
Summary
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 25 #93090 · 11sd0038.pptx
Hightech.NRW - CFRP Body Panels
Summary
Pedestrian protection
Manufacturing
Paint process
... 100% 40% 50%
Reference Hood
CFRP Hood (stiffness)
CFRP Hood
Weig
ht
[kg]
-65 % ?
Increased need for lightweight design and improved production processes
offer potential for CFRP applications also for higher volumes
Potential of CFRP can only be utilised with load adapted fibre orientation
Additional degrees of freedom in FRP design require advanced CAE support
(Appropriate simulation models, optimisation tools, …)
Expected lightweight potential for CFRP hood of -50 to -60 %
Hightech.NRW technology demonstrator at the end of 2012
40 -
50 % 35 %
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 26 #93090 · 11sd0038.pptx
Thank you for your attention!
© ika 2011 · All rights reserved 09.11.2011 Slide Nr. 27 #93090 · 11sd0038.pptx
Institut für Kraftfahrzeuge
RWTH Aachen University
Steinbachstraße 7
52074 Aachen
Germany
Phone
Fax
Internet www.ika.rwth-aachen.de
Contact
Dipl.-Ing. Kristian Seidel
+49 241 80 25641
+49 241 80 22147