BMW
Group
The mixed Material Concept of the
new BMW X5
Markus Pfestorf
BMW Group
www.autosteel.org
Content
BMW
Group
•
•
•
•
•
•
•
Technical Features
Stiffness
Passive Safety
Materials
Components
Driving Performance
Conclusion
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Technical Features
Dimension of the Car
Track width
1644mm/64.7in (+ 61/+2,4)
BMW
Group
Wheelbase 2933mm/115.5in (+ 113/+4.5)
Total length 4854mm/191.1in (+ 187/+7.4)
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Technical Features
Unique Chasis Technology
BMW
Group
Variable
steering
ratio
Double
wishbone
front axle
Integral IV
rear axle
50 %
Wide track
Low centre
of gravity
50 %
Excellent handling and roadholding capabilities
and a comfortable ride without compromise
Handles like a true BMW
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BMW
Group
Technical Features
Intelligent Light Weight Contruction
Runflat tyres 4th
generation fitted
as standard
Aluminium
engine hood
Magnesium
carrier for
instrument
panel
Intelligent use of ultra
high strength steel
Cast aluminium
front strut tower
15 per cent higher torsional stiffness ~27.000 Nm/°
Almost the same weight in spite of enlarged dimensions
Innovative technologies for optimum active and passive safety
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Stiffness
Torsional Stiffness
BMW
Group
40.000
4,0
3,3
Torsional Stiffness cT
30.000
25.000
3,0
27.000
23.500
2,5
20.000
2,0
15.000
1,5
10.000
1,0
5.000
0,5
0
L=
Previous X5
mGer
Ct x A
[
New X5
Kg
Nm/° x m²
x 10³
cT
3,5
]
0
Lightweight Coefficient L
3,7
Nm/°
A
L
Lightweight coefficient
mGer. Weight of body in white
(without doors and closures)
ct
Static torsion
(including screens)
A
Area (wheel base x track width)
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Stiffness
Design Solutions
BMW
Group
Stiff Front End by
Diagonal Strut
(Aluminium)
Stiff Rear End due to
the Torsion Ring
Additional Stiffness by
bracing the trunk lid
between the D-pillars
(Weight Saving: 6 kg)
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Passive Safety
Most Important Crash Tests
BMW
Group
Rear Impact:
Others:
–
– FMVSS 301: 80 km/h, 70% overlapp, undeformable Barrier
AZT Frontcrash: 15 km/h, 10°, 40% overlapp,
undeformable Barrier
–
AZT Rear-Crash: 1000 kg Barriere, 15 km/h, 10°,
40% overlapp, undeformable Barrier
–
Roll Over
Side Impact:
Front Impact:
– EU-NCAP: 64 km/h, 40% overlap, deformable Barrier
– US-NCAP 0°: 35mph, 100% overlap, undeformable Barrier
– US IIHS 40%: 64 km/h, 40% overlap, special Barrier
– EU-NCAP Side: 950 kg Barrier, 50 km/h
– EU-NCAP Side Pole: 29km/h to Pole
– US IIHS Side: 1500 kg Barrier, 50 km/h
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Passive Safety
Loadpath for Front Crash
BMW
Group
Distribution of induced Forces
Deformation after the Euro-NCAP
Minimum Yield Strength
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BMW
Group
Passive Safety
EU-NCAP Front Crash
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BMW
Group
Body in White Materials
Overview of Materials
Steel Grades (min. yield Strength)
CR4 (DDQ) HD, CR4 (DDQ) HDG,
CR4 (DDQ) HSDG, CR5 (EDDQ) HD
CR 180B HD, CR 180B HDG,
CR 180A HD, CR 180AT HD
CR 210B HD, CR 210B HDG,
CR 210AT HD
CR 250B HD, CR 250B HDG,
CR 250 A HD, CR 250 AT HD
CR 280B HD, CR 280B HDG
CR 380X (HSLA) HD
CR 420X (HSLA) HD,
CR 420X (HSLA) HDG
CR 950DL (Dual Phase), HD 680C
22MnB5
Aluminum
AlMg3
AlMg4,5Mn0,4
AlSi9Cu3(Fe)
AlMgSi
AlMg0,4Si1,2
AlSi10MgMn
Plastics
Thermoplastic Resin
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Body in White Materials
Percentage of Steel Grade
BMW
Group
Minimum Yield Strength
Deep Drawing Steel
25%
Steel Grade
180 MPa
11%
Deep Drawing Steel
(25%)
200 -220 MPa
6%
260 MPa
6%
Others
4%
Thermoplatic
2%
AlMgSi Alloy
2%
AlMg Alloy
1%
> 900 MPa
3%
600-700 MPa
6%
300-340 MPa
13%
AlMgSi Alloy
(2%)
AlMg Alloy
(1%)
Others
(4%)
Thermoplastic
(2%)
Dual Phase Steel
(2%)
380-450 MPa
21%
Bake Hardening Steel
(24%)
Boron Steel
(3%)
Complex Phase Steel
(4%)
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IF-Steel
(13%)
Microalloyed Steel
20%
Body in White Materials
Average minimum Yieled Strength
BMW
Group
500
Average min. Yieled Strength Rp0,2
475
MPa
400
350
New X5
3´series Sedan
3´series Sports W.
300
?
3´series Coupé
1´series
6´series Convertible
6´series Coupé
3´series
5´series
Sports Wagon 7´series
3´series
5´series
5´series
Z4´Coupé
Sedan
Z4 Sports Wagon
3´series
200
3´series previous X5 Compact
7´series 5´series
Coupé
3´series
Sports
Wagon
150
Convertible
250
1994
1996
1998
2000
2002
2004
Start of Production
2006
n
Rp0,2 i * m i
Rp0,2 =
i=1
n
mi
n
number of parts
m
weight of the part
Rp0,2 min. yield strength
i=1
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2008
2010
Body in White Materials
Average Gauge
BMW
Group
1,7
mm
3´series Convertible
1,5
Z4
1,4
Average Gauge
6´series Convertible
1,3
6´series Coupé
1,2
3´series Sports Wagon
previous X5
7´series
1,1
5´series
1,0
0,9
1992
New X5
5´series Sports Wagon
1´series
7´series
1994
1996
1998
2000
2002
2004
2006
Start of Production
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2008
2010
Components
Max. Styling Freedom in Front End
BMW
Group
Pedestrian Safety
Fender (PP-EPDM)
Bonnet (Aluminum)
Washer fluid container
Front Head Lights
Crash Beam
Front End
Passive Safety / Stiffness
Fog light
Relocated
cooler
Benefits:
• Flexible Design
• Less Gaps / reduced Gap Dimensions
• Weight Saving
• Pedestrian Safety (ACEA, Japan, Europe)
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BMW
Group
Components
Cast Aluminum Front Strut Tower
Mechanical Values:
Yield Strength Rp0,2: 120 - 140 MPa
Tensile Strength Rm: 200 - 240 MPa
Benefits:
• Weight Saving (-50% compared to Steel Sheet)
• Optimized Package
• Increased Stiffness
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BMW
Group
Components
Simulation of the Forming Process
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BMW
Group
Components
The B-Pillar Reinforcement
Thickness s
s = 1.2
s = 1.6
s = 2.2
Weight Saving: 2 kg/Side
s = 1.4
s = 1.2
(compared to a hot stamped Part
with a constant Thickness)
Mechanical Values:
Yield Strength Rp0,2: > 950 MPa
Tensile Strength Rm: > 1300 MPa
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BMW
Group
Roll gap
Control
Components
Manufacturing of the B-Pillar Reinf.
Correction
Longitudinal
profile check
1. Manufacturing of tailored rolled blanks
Advantages of a tailored rolled Blank
Compared to a tailored welded Blank
– With many different thicknesses: Cost Benefit
– Now weekening of strength level by a weld seem
– Notch free transition at varying thickness
varying
thickness
Source: Mubea
2. Direct Hot Stamping
Tailored
rolled Sheet
22MnB5
Heating
> 900°C
Hot Stamping +
rapid Cooling
trimming
• By Laser
• By Tool
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Scale
remocal
BMW
Group
Driving Performance
Racetrack Nuerburgring Nordschleife
Power to
weight ratio
[kg/HP]
time
taken
[s]
Previous X5
9,3
9,07
New X5
9,9
8,54
Length of the Racetrack
Nuerburgring Nordschleife:
20,8 km
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Conclusion
BMW
Group
–
Higher functional Requirements in the new BMW X5 are met
by a consequent Implementation of innovative Light-Weight
Design
–
Process-suitable Design of structural Components allow for
the use of Multi Phase Steels, hot formed Materials and
Aluminum Castings
–
Due to new Design of Carrier Structure Torsional Stiffness
raised from 23500 Nm/° to 27000 Nm/°
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