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Lightweight Forming TechnologiesLightweight Forming TechnologiesLightweight Forming TechnologiesLightweight Forming Technologies

15/10/2014

Prof. Jianguo Lin and Dr. Mohamed Mohamed

Metal forming and Materials Modelling Group

Research – Automotive related activities

Forming Processes: e.g., Forging, Extrusion, sheet metalforming – springback and formability, joining – riveting andwelding; Hot stamping and cold-die quenching for steel andaluminium alloys; Creep Age Forming (CAF).

Testing facilities: Gleeble 3800, a range of hydraulic pressesfor forging and sheet metal forming.

The Group has 30 researchers (Post-Doc RAs and PhDs)

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1. LoCoLite project – Status: very good progress

2. LCV-TARF project-Status: very good progress

2. UlCab project has been run for 1 year and good results obtained

3. A new TSB project "LightBlank" will start next year (confirmed), 6 UK partners and Total: £1.5m.

4. Other research project related to: Hot stamping with TATA Steel; Lightweight forming for China aerospace company; etc.

Current Projects

Solution Heat treatment, cold die Forming Solution Heat treatment, cold die Forming Solution Heat treatment, cold die Forming Solution Heat treatment, cold die Forming

and Quenching (HFQ) for automotive and and Quenching (HFQ) for automotive and and Quenching (HFQ) for automotive and and Quenching (HFQ) for automotive and

aerospace applications aerospace applications aerospace applications aerospace applications

This is a patented solution for forming high strength, complex-shaped lightweight panel parts

The HFQ process is Licenced by Impression Technologies LTD (ITL)

Patented for 53 Countries in the world

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� Enable cost-effective lightweight components to be

realised.

HFQ process

� This can be done by form complex components from

high-strength sheet aluminium and Magnesium

Essential requirements

- Standardise the Material Testing Procedures

- Developing a full calibrated Material Modelling

(accurate failure prediction)

Current State of Art

Lightweight Body and Chassis Structures for

passenger cars

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The patented solution for forming high strength,

complex-shaped lightweight panel parts

Solution-Heat treatment, cold-die

Forming & Quenching (HFQ)

A range of testing facilities developed for HFQ

Presses: Capacity range: 2500KN to 20kN; Speed range: 0-25 m/s. For forming and impact testing

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FLDFLD

Q2-Is the Conventional FLD a

suitable tool to predict failure?

Q1- How to predict the

Failure accurately?

Why FLD is not a proper failure criteria to predict

Failure at elevated temperature?

(a) Temperature field

(b) Strain filed

temperature and strain rate usually vary

dynamically and spatially in a sheet work-piece

during the hot stamping

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( )/ 1n

ep

e

R k

K

σ ωε

− − −=

&

3

2

i jp p

i j e

e

Sε ε

σ= &

.. 0 5R 0 5Bρ ρ−=& &

( ) 2np

eA 1 Cρ ρ ε ρ= − −& &

( ) ( ) 1 p

ij ijkl ij ijDσ ω ε ε= − −

( ) ( )( ) 3

2

p1 1 2 H 3 e 1 e

e

e1 2 3

3.

1

ϕη

ϕ η

α σ α σ α σ η σω ε

σα α α ω

+ +∆=

+ + −& &

11 11,ε σ

22 22,ε σ

33ε

1

2

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New Continuum damage model (CDM) for

formability prediction

(1)

(2)

(4)

(3)

(5)

(6)

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CDM model Calibration using Experimental FLD for AA5754 different temperatures and strain rates

75

mm/sec 250°°°

°C

Calibration of CDM Model for AA6082 at Room

Temperature

0

50

100

150

200

250

300

350

400

450

0 0.1 0.2

Str

ess

(M

Pa

)

Strain

AA6082-20°C

-0.2

0

0.2

0.4

0.6

0.8

0 0.1 0.2

Da

ma

ge

Strain

AA6082-20C

0

0.2

0.4

0.6

0.8

1

1.2

1.4

-0.7 -0.2 0.3 0.8 1.3

Majo

r str

ain

Minor strain

EXP: 20°C

500°C

400°C

350°C

20°C

Prediction of FLC for AA6082 at different temperature

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170

17

0

Φd

4x Φ5.5on

150 PCD

ΦD(punch)

Formability

tester design

Model Validation : Formability investigation using new test design for

hot stamping process

Fo

rma

bil

ity

Sa

mp

le d

esig

n

failure features of deformed cup with the different

diameter ratio

Test Mode 1

(Circumference failure)

Test Mode 2

(Central Hole failure)

Test Mode 3

(Punch goes through the

sample without tearing)

Diameter ratio (ϒ =d/D): 0.0 0.025 0.05 0.1 0.15 0.2 0.225 0.25

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Applications of CDM model: B-pillar-Lotus

FLD

0.7

0.58

0.43

0.35

0.23

0.19

0.0

Damage

0.023

0.021

0.018

0.016

0.014

0.0

HFQ

Applications of CDM model: Lotus Bulkhead part

Die

Binder

Punch

(Fixed)

Movement of

Die

Blank Holding

pressure

Blank

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Cold Forming

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.1 0.2 0.3 0.4 0.5

Da

ma

ge

Time (sec)

Damage

A

A

B

B

A-A

B-B

FLD CDM

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0 0.05 0.1 0.15 0.2 0.25 0.3

Da

ma

ge

Time (sec)

HFQ

11

0.4

0.6

0.8

1

1.2

1.4

1.6

0 50 100 150 200 250 300 350 400

No

rma

ize

d t

hic

kn

ess

(t/

to)

Distance through the section (mm)

X

A

A

B

B

Symbols: Experimental measurementsSolid Lines: Computational measurements

Thickness Distribution

0.4

0.6

0.8

1

1.2

1.4

0 100 200 300 400 500

Nor

mai

zed

Thic

knes

s (t/

t0)

Distance through the section (mm)

X

0.4

0.6

0.8

1

1.2

1.4

1.6

0 50 100 150 200 250 300 350 400

No

rm

aiz

ed

th

ick

ne

ss (

t/to

)

Distance through the section (mm)

X

Thickening due to wrinkling

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Friction Effect

Thanks & Questions