139

24

15 6 Body Development Dept. Vehicle Develop Div.

No.322015

SKYACTIV-BODY Development of SKYACTIV-BODY Structure for New Roadster

1 2 3 Takayuki Kimura Katsunori Sakai Kazuki Yamauchi

4 5 6 Kenji Maruyama Taiki Yotsuyanagi Yasuhisa Okazawa

CX-5SKYACTIV-BODYFRNVH

NVH

3217kg2230kg211kg197kg

Summary New Roadster is a product that is made by getting back to basics of Roadster Everybody can enjoy

and focused on improving Jinba-Ittai performance. Following CX-5AtenzaAxela, FR open body structure is applied the same approach of SKYACTIV-BODY and aimed to improve handling and stability, crash safety and NVH performance by lighter weight than the first Roadster. And we aimed to embody the beautiful sporty styling and a feeling of vitality by design theme KODO: SOUL of MOTION.

Consequently, body stiffness (fundamental of handling and stability and NVH performance) and crash safety are improved and the weight of body in white results in 197kg (3rd Roadster 217kg, 2nd Roadster 230kg, 1st Roadster 211kg) which is the lightest weight in open car segment. This paper outlines development activities for a light weight open body structure

1.

4FR

NVH

NVH

1989

2.

2.1 SKYACTIV-BODY(1)

140

No.322015

PPF FF4WD &

2.2

Fig. 1

Fig. 1 SKYACTIV-BODY Vision 2.3 NVH

Fig. 2 topology

Fig. 2 Topology Analysis

3.

3.1 3

780MPa4

780MPa440MPa1.6t 1.2t / 1.4t

CAE

Fig. 3

Fig. 3 Front Frame Structure

3.2

2.3

FF Next-FRFront engine Front drive

Closed BodyFront engine Rear drive

Open Body1

3

1

3

33

2

Twisting Condition Bending Condition

Connect Front Suspension Tower to Backborn Frame

CAE Model

OPTIMIZATION

Crushable Zone

Suspension Tower

Axial compression force

Cross-shaped Frame

141

No.322015

Fig. 41500MPa5

Fig. 4 Dash Cross Member

3.3

SKYACTIV-BODY

ONE MAZDA 1

Fig. 5

Fig. 5 High Mount Backbone Frame1

2

Fig. 6

Fig. 6 High Mount Backbone Frame2

3.4

1

30 Fig. 7

Fig. 7 Side-Sill

3.5

90mm

SKYACTIV-BODY

New Model

Previous Model

Hole in the section Separated a section and hole

New ModelPrevious Model

Steering shaft through hole

Mildly-curveCurvature

Curvature Mildly-curve

New ModelPrevious Model

Plan View

Side View

Plan View

Side View

ContinuousDiscontinuous

New ModelPrevious Model

Previous Model New Model

Not Verticality to Input Direciton Verticality to Input Direciton,So Hold On

Input

Strength

InputStrength

142

No.322015

Fig. 8

Fig. 8 Rear-Side Frame

3.6

112gFig. 9

Fig. 9 Lid-Filler

4.

Fig. 10

Fig. 10 Weld Bond

5.

5.1 Multi-

disciplinary Design OptimizationMDO6CAE

Fig. 119801180MPa1500MPa

Fig. 125862

Fig. 11 High-Tensile Steel Usage Rate

Fig. 12 Occupant Protection

New Model

Previous Model Al Hot Stamp 1180MPa 980MPa 780MPa 590MPa 440/390MPa 270MPa

0% 20% 40% 60% 80% 100%

High-Tensile Steel Double-HAT

Push LifterLift Spring

Actuater

Stopper BracketFemale Hinge Spring

Lid PanelShaft

Hinge Bracket

New Component Parts

Previous Model

New Model

Weld bonded sections

SAFETY ZONE

SAFETY ZONE

Hot Stamp 1180MPa 980MPa

Front

143

No.322015

5.2 1180MPa1500MPa

ONE MAZDAFig. 13

Fig. 13 Hot Stamp Material

6. CAE

6.1

CAE

Fig. 14

Fig. 14 Front Body Structure

Fig. 15

Fig. 15 Rear Body Structure

Fig. 16

Fig. 16 Front Suspension Body Structure 6.2 MDO

NVH

MDO

3.9kg

1180MPa High Tensile Steel

Compression ForceHot Stamp

Previous Model New Model

Input Input

Input

New ModelSide View

Front View

SUSPENSIONTOP

LOAD DISPERSING

SUSPENSIONTOP

STRUT TOWER BAR

SIDE SILL

SIDE SILL

Previous Model New Model

SUSPENSION FIXED POINT

BRACE

LOAD DISPERSING

SIDE SILL

Previous Model New Model

PACKAGE

InputInput

LOAD DISPERSING

SUSPENSIONTOP

144

No.322015

MDO340gFig. 17

Fig. 17 MDO Application

7.

7.1

Table 1

Table 1 Stiffness

7.2

NCAP

7.3 SKYACTIV-BODY

FR

3217kg2230kg211kg197kgFig. 18

Fig. 18 Body in White Weight Per Projected Area

3248kg225kg

8.

SKYACTIV-BODY

1SKYACTIV-Body No.29pp.61-672011 2No.24pp.66-712006

Bod

y w

eigh

t [kg

]

Vehicle plane area [m2]

Previous model3rd Roadster

JPN - A

EU - A

BICBest in class line

New modelJPN - B

1st Roadster

Large

Light

2nd Roadster

PreviousModel

NewModel

Torsional Stiffness 100% 109%

Front Damper Stiffness 100% 119%

Rear Damper Stiffness 100% 117%

132 Parts primarily in under body at 1st MDO (below left side)

54 Parts primarily in under body at 2nd MDO (below right side)

http://www.mazda.com/contentassets/caf0e8a523d64cd7b30b10f7c762b3ea/files/2011_no012.pdfhttp://www.mazda.com/contentassets/caf0e8a523d64cd7b30b10f7c762b3ea/files/2011_no012.pdfhttp://www.mazda.com/contentassets/efa12b3f26b4485c89b89ae0ef1b5ec2/files/2006_no014.pdf