Light Weight Hot Stamped Laser Welded Blanks Side Structures for

Light Weight Hot Stamped Laser Welded Blanks

Side Structures for Narrow Offset Crash

Gagan Tandon & Shawn Devaraj

ArcelorMittal Tailored Blanks (AMTB) Americas

Background/Overview

C segment S-in motion vehicle virtual solution developed by ArcelorMittal Global R&D

was chosen as the baseline model

Multiple changes were made in the baseline to obtain a modified baseline design such

that it meets all the current key safety requirements including the new IIHS Small

Overlap also known as Small Offset Rigid Barrier (SORB) and IIHS Side Impact

Crashworthiness Evaluation (SICE)

IIHS Small Overlap is very challenging to meet with simultaneous reduction in mass

Highlight benefits of using hot stamped laser welded blanks (HS LWB) door ring (also

called body side outer aperture reinforcement) through part consolidation

HS LWB door ring solution has good Small Overlap Test performance with mass

reduction vs. competitive baseline benchmark using multi-part spot welded design

HS LWB design is lighter due to better joint integrity allowing for optimized gauges

HS LWB door ring solution also meets all other key safety requirements

Showcase mass reduction and performance improvements using HS LWB door ring solution

1. Front Rails were flared for better contact

with the barrier

2. One patch was added on the A Pillar outer

3. Two patches were added on the A Pillar Inner

4. Hot stamped spot welded multi-part design

around door aperture area

5. Usibor® 1500 to Usibor® 1500 spot weld

failure criteria used

Background/Overview

Design Changes on Baseline to meet new IIHS Small Overlap test requirements

Very competitive and contemporary modified baseline design was chosen for comparison

3

1

Usibor® 1500

Ductibor® 500 4

HS LWB B-Pillar

Additional 1.20 kg was added per side to meet the requirements

2

Reinforcements

Id Material

name

Gauge

(mm)

Mass

(Kg)

6 Usibor® 1500 1.2 1.00

7 HSLA380 1.3 1.41

8 HSLA320 2.0 0.44

9 HSLA280 2.0 0.33

10 HSLA280 2.0 0.28

11 Usibor® 1500 1.3 0.52

Bill Of Materials: Outer Reinforcement

Modified Baseline

Spot-Welded

Multipart Design

Hot Stamped LWB Door

Ring Design with Part

Consolidation

Multi-part Spot Welded Outer

Id Material

name

Gauge

(mm)

Mass

(Kg)

1 Ductibor® 500 1.8 2.90

2 Usibor® 1500 2.0 3.24

3 Usibor® 1500 1.2 1.78

4 Usibor® 1500 1.4 2.94

5 Usibor® 1500 1.4 3.93

HS LWB Door Ring

Id Material

name

Gauge

(mm)

Mass

(Kg)

1a Ductibor® 500 1.8 0.85

1b Usibor® 1500 2.0 2.07

1c Usibor® 1500 1.8 1.66

1d Usibor® 1500 1.4 1.23

1e Usibor® 1500 1.2 2.43

1f Usibor® 1500 1.2 3.53

Reinforcements

Id Material

name

Gauge

(mm)

Mass

(Kg)

2 HSLA280 2.0 0.28

3 HSLA280 2.0 0.33

4 HSLA320 2.0 0.44

5 HSLA380 1.3 1.41

6 Usibor® 1500 1.3 0.52

Total mass = 18.77kg/side Total mass = 14.75kg/side (-4.02 kg/side -21.42%)

1e

1a

1b

1c 1d

1f

2

3

4

5

6

Part consolidation & 21.42% mass savings achieved with equivalent performance

IIHS SMALL OVERLAP

PERFORMANCE

IIHS Small Overlap – Model Setup

Setup Conditions:

Vehicle speed: 40 MPH (64.4 km/h)

Overlap: 25% of vehicle width

Model set up according to IIHS crash test protocol

Small Overlap Rigid Barrier (SORB) or Small Overlap Test

IIHS Small Overlap – Animations

HS LWB door ring Modified Baseline

Modified Baseline & HS LWB door ring have comparable and good structural performance

IIHS Small Overlap – Intrusions

0

50

100

150

200

250

300

350

400

0

50

100

150

200

250

300

350

400

Lower Hinge

Pillar

Footrest Left Toepan Brake Pedal Rocker Upper Hinge

Pillar

Intr

usio

n (

mm

)

Marginal

Acceptable

Good

Modified Baseline

HS LWB Door Ring

POOR

MARGINAL

ACCEPTABLE

GOOD

Measurement Points

HS LWB door ring design shows lower intrusions especially relevant at two hinge pillars

IIHS Small Overlap - Door Aperture Intrusion

HS LWB door ring design shows lower intrusions in door aperture area

∆x = 26.39

∆x = 24.67

Deformed HS LWB door ring

Deformed modified baseline

Location Modified

Baseline

intrusion

HS LWB

door ring

Intrusion

∆x

Front Door

Hinge Upper

56.11 29.72 26.39

Front Door

Hinge Lower

43.90 19.23 24.67

IIHS Small Overlap – Plastic Deformations Modified Baseline HS LWB door ring

@55ms

• Front rail crushes with shotgun inner.

• Hinge pillar starts crushing.

@55ms

• Front rail crushes with shotgun inner.

• Hinge pillar starts crushing.

BIW side view

HS LWB door ring design shows better load transfer and lower intrusions

@105ms

• Relatively less rotation seen in car

from the top.

• Causes higher plastic deformation of

floor pan, hinge pillar, and A Pillar.

@105ms

• Car starts rotating because of better

load transfer.

• Reduced buckling on A Pillar.


BIW side view



@160ms

• End of event. Good rebound due to

better joint integrity.

@160ms

• End of event. Limited rebound due to

higher intrusion and plastic

deformation.

BIW side view



BIW bottom view

@35ms

• More load transferred to main crash

rails.

• Increases plastic strains in wheel well

and floor pan.

@35ms

• More load transferred to shot gun.

• Effectively reduces plastic strains in

floor pan and main crash rail.


@75ms

• Weld seam integrity is maintained.

• Effectively reduces plastic strains in

floor pan.

@75ms

• Relative movement between hinge

pillar and sill.

• Increases plastic strains in wheel well

and floor pan.


BIW bottom view


@110ms

• Continuous Laser weld seam helps

with lower intrusions of floor pan.

• Helps deflection of car around barrier.

@110ms

• More intrusion causes hinge pillar to

slide over side sill causing higher floor

pan crush.

• Hence, higher intrusions.


BIW bottom view


A1

IIHS Small Overlap – Section Forces

Equivalent section forces observed due to LWB joint continuity that helps with load transfer

A2 A3

A4 A5 A6 A7

A8 A9

HS LWB door ring

Modified Baseline

IIHS Small Overlap – Section Forces

Improved joint integrity with LWB helps distribute loads to the sill and roof sections

S1 S2 S3 S4

R1

R2

HS LWB door ring

Modified Baseline

IIHS SIDE IMPACT

Additional Verifications

IIHS Side Impact– Animation

HS LWB door ring Modified Baseline

Equivalent behavior with HS LWB Door Ring

IIHS Side Impact Intrusions

Intrusion plot is post rebound (@120ms)

Str

uctu

ral ra

tin

g r

an

ge

SUMMARY

Modified Baseline HS LWB door ring

Design

Mass (LH+RH) Kg 37.54 29.50

Mass Savings Kg/Vehicle 8.04

Crash

Performance

IIHS SIDE IMPACT

SINCAP

214POLE-AF5

214POLE-AM50

IIHS Small Overlap

IIHS Roof Crush

Stiffness

Performance

Global Bending

Global Torsion

Modal Analysis Bending:

Torsion:

Bending:

Torsion:

Executive Summary

HS LWB door ring saves 8.04kg (21.42%) per vehicle with equivalent or better performance

Validation runs for all key loadcases were performed to confirm HS LWB door ring design meets

all major crash requirements and global stiffness targets were met by adding structural adhesives

Close/at target Close/below target Away from target Above target

Conclusions

For critical loadcases like IIHS Small Overlap and IIHS Side Impact (SICE), load

transfer is key

HS LWB door ring, as opposed to spot welded hot stamped multi-part design,

allows for mass reduction of 8.04 kg due to better joint integrity

Implementation of hot stamped laser welded blanks (HS LWB) door ring helps

save mass, with the same or better crash performance

Optimization of the body side inner design (ongoing) is expected to bring further

mass reduction while meeting crash performance.

Introduction of new hot stampable steel grades like Ductibor® 1000 and

Usibor® 2000 will allow for further weight reduction in future designs

HS LWB Door Ring saves 8.04 kg per vehicle with good performance

Q&A

Thank You !

Documents

Light Weight Hot Stamped Laser Welded Blanks Side Structures for