1

IMPACT ENGINEERING

FOR MATERIALS AND STRUCTURES

Professor Guoxing Lu

Chair, Dept of Mechanical and Product Design Engineering

Faculty of Science, Engineering and Technology

Swinburne University of Technology, Melbourne, Australia

5th International Conference on Advances in Mechanical Engineering

August 16-18, 2017 Krabi, Thailand

OUTLINE OF PRESENTATION

• INTRODUCTION

• THIN-WALLED STRUCTURES

• POROUS AND CELLULAR SOLIDS

• SANDWICH PANELS

Introduction: an accident in Hong Kong (Dec. 1998)

Gadd Severity Index (GSI)

000,10

5.2 T

dtaGSI

Head Injury Criterion (HIC)

000,1)(1

)max(...

5.2

12

12

2

1

t

t

dttatt

ttCIH

Thin-walled Structures: axial crushing of

circular tubes [Guillow, Grzebieta]

Thin-walled Structures: Deformed specimen from

FEA and experiment [Huang Xiaodong]

Thin-walled Structures :

Splitting Circular Tubes: Experimental set-up [Huang

Xiaodong]

Typical force-displacement curves for mild steel

tubes with D=74.0mm, t=1.8mm

Photographs of typical mild steel specimens

6045 75

Thin-walled Structures : axial splitting of

square tubes [Huang Xiaodong]

Thin-Walled Structures

• Sections of different profiles under axial

loading

22

Axial crushing of patterned tubes [Chen Yan, Song Jie]

Load-displacement curves of

square tubes with/without pattern

Deformed profiles of square tubes

with/without pattern

Axial crushing of tubes with

windows

T0 T1

Thin-walled Structures: Bending of rectangular

beams [Huang Xiaodong]

FEA result:

Angle=0, 50, 100, 150, 200, 250 and 300

FEA Vs Analytical Model Previously

Proposed

Non-dimensional Plot

tb

M2

0vs. angle in radian

Empirical formula:

1102

0

teCC

tb

M

7.00

t

b

eC024.0

0 6.006.0

8020 t

b

t

bC 007.01.11

t

b

et12.0

1 6.212.0

for

HONG KONG STARTS TO INSTALL NEW

GUARDRAILS (SING TAO, 7/1/02)

35

Composite Structures

Carbon fibre composites

Fig. 10. The deformation modes of empty CFRP tubes at a velocity

of: (a) 0.05 mm/s, (b) 0.5 mm/s, (c) 5 mm/s and (d) 50 mm/s.

36

Composite Structures

COLLISION OF SHIPS: CUTTING OF A PLATE BY A WEDGE

[Calladine]

Lu & Calladine, Int J Mech Sci, 32, 293-313, 1990

SHIP COLLISION: CUTTING OF A PLATE BY A WEDGE

7.13.13.1 tYlCW

39

Natural cellular materials

Cork

Bone

Coral

40

Man-made cellular materials

◄ Hexagonal honeycombs

Open-cell nickel foam by vapor deposition

technique ►

◄ Open-cell polymer foam

Aluminum foam coated by aluminum skins ►

◄ Closed-cell polymer foam

41

Cellular Materials used

for Energy Absorption

Typical stress-strain curves of cellular

materials

Densification Strain (locking strain):

1 1d s Theoretically:

Practically: 1 1.4d

43

Stress level rises

with relative density

Introduction: dynamic effects

General impact behavior of cellular materials

– Quasi-static loading: Elastic stage, plateau stage, densification

– Dynamic loading: Dynamic enhancement, compaction waves

¦Å¦Åd

¦ Ò

¦ Òp

plateau stage

R-P-P-L model

densification

elastic stage

Typical distributions of cell deformation for the initial

impact velocities of (a) V=107.5 m/s and (b) V=22.4 m/s,

respectively (Tan et al. 2005)

Tan PJ, Reid SR, Harrigan JJ, Zou Z, Li S. Dynamic compressive strength properties of aluminum foams. Part I ——

experimental data and observations. J Mech Phys Solids 2005;53(10):2174-205.

Static stress-strain relationship of the cellular

material and the R-P-P-L material model

44

Introduction

• Rigid, perfectly-plastic, locking (R-PP-L) material model

20d p

d

V

• Critical velocity based on Wave trapping theory

0

cr

crV c d

0c d d Velocity of the stress wave

For elastic, perfectly plastic

material,

, cr Yd d E E

0

YcrV

E

45

Experiments

• Testing equipments

Instron High Speed Testing System

Split Hopkinson

Pressure Bar

MTS Machine

Material Responses: A typical aluminium honeycomb

specimen and an intact honeycomb cell [Ruan Dong]

47

=10-3 s-1, =0%

=10-3 s-1, η=100%

=102 s-1, η=0%

=102 s-1, η=100%

One-way buckling of honeycombs under quasi-static and high strain rate out-of-

plane compression

Material Responses: aluminium foams

[Ruan Dong]

Experiments Table 2. Nominal specimen dimensions

Specimen Types

Diameter (D,

mm)

Length (L, mm)

I 50 50

II 50 25

Alporas 10% 50mm*50mm Cymat 10% 50mm*50mm Cymat 17% 50mm*25mm

Results and discussion

0.0 0.2 0.4 0.6 0.8

0

2

4

6

8

10

E

ng

ine

eri

ng

str

ess,

, M

Pa

Engineering strain,

strain rate=10-1

s-1

/s=7.86%

strain rate=10-1

s-1

/s=10.76%

strain rate=10-1

s-1

/s=9.03%

strain rate=10-1

s-1

/s=8.63%

strain rate=10-1

s-1

/s=9.80%

strain rate=10-3

s-1

/s=9.74%

strain rate=102 s

-1 /

s=8.30%

strain rate=102 s

-1 /

s=11.34%

strain rate=102 s

-1 /

s=9.03%

strain rate=102 s

-1 /

s=8.65%

strain rate=102 s

-1 /

s=10.26%

Stress-strain curves for Alporas foams at different strain rates

High speed camera images for

Alporas foams

High speed camera images for

Cymat foams

Strain rate sensitivity

10-3

10-2

10-1

100

101

102

103

0

20

40

60

80

100

120

Alporas

Cymat

Alporas Average

Cymat Average

No

rma

lize

d p

late

au

str

ess,

* pl/(/

s)n

, M

Pa

Strain rate,

Alporas

Cymat

Normalized plateau stress related to strain rate for Alporas and

Cymat foams

Direct impact of cellular

materials

Metals and Composites 金属和复合材料

Tensile test on TWIP steel at 20 m/s

双相钢

76

Tensile test on Kevlar at 5 m/s

Kevlar复合材料

Testing Facilities

77

High speed camera (probably the

latest camera in Australia) Phantom v2512

•Speed over 25,000 frames-per-second at full

resolution

•1280 x 800 resolution

•1 µs minimum exposure standard

Selected Research Projects Materials: Shear thickening materials and their Industry

application (Anti-submarining seat design)

79

Selected Research Projects Structures: Hybrid tubes

three-point bending of foam filled tubes Intrusion beam

Orange, intrusion

beams of a sedan

(Bryant, 2006).

http://www.ford.com/microsites/sustainability-report-2008-09/issues-vehicle-

performance-vehiclesafety-occupant

Sandwich structures used for light weight structure and energy absorber

Aluminium face sheet Aluminium Foam

Aluminium sandwich panels

Aluminium face sheet

Indenters/projectiles: flat, hemi-spherical, and conical headed

All have the same mass

Preparation of the specimens:

Experiment set-up for impact perforation tests:

Impact perforation tests using gas gun • Highest allowable gas pressure: 15MPa

• Highest speed possible: 400m/second

• Internal diameter of the barrel : 12.50mm

Results and discussion (1) - impact velocity

A plot showing the relationship of impact velocity and the ratio of dynamic

and quasi-static perforation energy. (Hemi-spherical head)

60 80 100 120 140 160 180 200

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6(E

d/E

s )

Vi (m/s)

Φ :dynamic enhancement

factor,

: Dynamic energy:

: Static energy,

: Impact velocity

21

2p p bE m V

98

Sandwich panels subjected to

foam projectile impact

Experimental Setup

A cylindrical

foam projectile A photograph of the

experimental setup

M.A. Yahaya, D. Ruan, G. Lu , M.S. Dargusch

International Journal of Impact Engineering 75 (2015)

100

99

Samples before and after tests

Sandwich panels subjected to

foam projectile impact

Photographs of samples before

and after tests

Cores of sandwich panels

100

Deformation of sandwich panels with various aluminium honeycomb cores

Sandwich panels subjected to

foam projectile impact

101

Deformation of sandwich panels, air sandwich panels and monolithic plates

Sandwich panels subjected to

foam projectile impact

Comparison between sandwich panels

with various aluminium honeycomb cores

Comparison between sandwich

panels (A, B and C), air sandwich

panels (G) and monolithic plates (M)

102

Sandwich panels: Blast threats to engineering

structures [Zhu Feng, Shen Jianhu, Zhao Long

Mao, Wang Zhihua]

Murrah Building, Oklahoma City, 1995

Bishopsgate, London, 1993

Russian armored car, Chechenia, 2000 US navy ship, Yemen, 2000

Central railway station, Madrid, 2004

Structural

fracture

Progressive

collapse

Large plastic

deformation

& Ballistic

penetration

103

Explosion tank

Diameter: 5.0m

Height: 5.0m

Reinforced concrete

Maximum charge: 2.5kg

104

Sketch of the whole experimental setup

PVDF pressuregauge

Speci menCharge

Four-cable ballistic pendulum

106

Sandwich panel: Honeycomb core panels (HCP)

Geometry of the core

Dimension of the panel

Specimen

fc

L

L = 300mm

c = 12.5 mm

f = 0.5mm; 0.8mm; 1.0mm

109

Experimental observations

(1) Front face-sheet deformation/failure

Global deformation (Mode G) Localized deformation (Mode L)

116

Empirical equation for predicting the back face

deflections

117

Geometry and dimension of specimens –

Aluminium foam core panels (AFCP)

Aluminium foam core

Specimen

• Relative density of core (6% and 10%)

• Face thickness (0.8 and 1.0mm)

• Mass of charge (20g, 30g and 40g)

10 panels were tested and

3 parameters were analyzed:

120

Core failure

121

FE simulation (HCP panels)

Geometric model:

A cell (enlarged)

Charge (enlarged)

With LS-DYNA 970

• Face-sheets and core: Bi-linear elasto-plastic material

• Charge: High explosive

Material model:

122

Phase I: Process of the charge explosion

t=0 t=5 μs t=8 μs

t=13 μs t=25 μs t=30 μs

123

Phase II: Process of explosion product – structure

interaction

t=32 μs t=38 μs t=43 μs

t=52 μs t=62 μs t=58 μs

124

Phase III: Panel deformation

under its own inertia

t=65 μs t=120 μs

t=360 μs t=800 μs

Applications of Curved Sandwich

Structures

Curved sandwich panels

Material: ALPORAS® Aluminium Foam

Length:400mm

Width:400mm

Face sheet thickness:0.5-1.6mm

Core thickness:10~30mm

Radius of curvature: 300-600mm

Large block of

metal foam

Aluminium alloy

5005 H34

sheets

FORTIS AD825

epoxy liquid glue

Frames for

Clamping the

specimen during

curing

700

2400

1800

40

0

90

0

Pendulum system

• Length: 2.5m

• Width: 0.5m

• Height: 2.62m

• Total Weight:

161-167Kg

• Period: 3.0-

3.2s

• Balance

weight: 49.8kg

Deformation/failure patterns-front

face

Global deformation

Local indentation

Wrinkling

Deformation/failure patterns-Back

face

Global deformation

Wrinkling

FE model validation

(2) deformation profile

Fully bonded

Corresponding

experiments

FE model validation

(2) deformation profile

Without bonding

Corresponding

experiments

Bio-Impact Mechanics

冲击动力学在生物医学方面的应用

154

Craniectomy protective headgear

开颅手术后病人带的头部保护罩

CT Exoband protective helmet

A flex protective headgear, Orthomerica

Q cap, KLS Martin Group

Bio-Impact Mechanics

155

v Finite Element model of a human head

Applications:

injury

assessment

in sports,

army,

construction

workers,

fall of persons

Bi-directional Evolutionary Structural

Optimization（BESO)

Optimization algorithm: Remove low-efficient

materials and add high-efficient materials to the

ground structure.

Advantages: Simple concept; Easily

implementation; Robustness and high efficiency

Applications: Optimization of Structures and

Materials

Optimization of Structures and

Materials 结构和材料的优化

Research Topics: Optimal design of various engineering structures

Design of microstructures of functional materials

Concurrent design of structures and materials

Optimization of photonic and phononic crystals, and

metamaterials

158

（卢国兴、余同希, Energy Absorption of Materials and

Structures, Woodhead Publishing, Cambridge,UK,2003;

中文版: 化学工业出版社2006）

Conclusion and future work

• Cellular materials and their structures offer good energy absorption performance

• Their structural performance can be adjusted and may be optimised in design

• Design concept should be extended to other areas of applications in industries such as mining and sports, and civil engineering!

• Concrete/steel structures, composites (FRP)

Thank You

Further contact details:

glu@swin.edu.au

160