1. Review COMPOSITE SANDWICH PANEL UNDER BUCKLING BEHAVIOUR
Joko Sedyono
Supervisor: Dr Homa Hadavinia
Department of Mechanical Engineering, Kingston University London, Roehampton Vale Friars Avenue London SW15 3DW

2. Content Introduction Buckling Under Monotonic Loading
Metal-Matrix Composites (MMC)
Ceramic-Matrix Composites (CMC)
Polymer-Matrix Composites (PMC)
Buckling Under Monotonic Loading
Buckling Under Impact Loading
Method of Measurement of Out-of-Plane Deflection Point and Full Field
Post Buckling

3. Introduction

4. Composite Material
Two inherently different materials that when combined together (macroscopic scale) produce a material with properties that exceed the constituent material (Shafer, 2010)

5. Composites can be classified by their matrix material:
-Metal matrix composites (MMC’s)
-Ceramic matrix composites (CMC’s)
-Polymer matrix composites (PMC’s)

6. MMC - Metal Matrix Composites
-The matrix is relatively soft and flexible.
-The reinforcement must have high strength and stiffness
-Since the load must be transferred from the matrix to the reinforcement, the reinforcement-matrix bond must be strong.
MMC use:
-Two types of particulates ( dispersion strengthened alloys and regular particulate composites)
-Or long fiber reinforcements
Keulen, 2010

7. CMC – Ceramic Matrix Composites Polymer Matrix Composites
-The matrix is relatively hard and brittle
-The reinforcement must have high tensile strength to arrest crack growth
-The reinforcement must be free to pull out as a crack extends, so the reinforcement-matrix bond must be relatively weak
Polymer Matrix Composites
-The matrix is relatively soft and flexible
-The reinforcement must have high strength and stiffness
-Since the load must be transferred from matrix to reinforcement, the reinforcement-matrix bond must be strong
(Keulen, 2010)

8. Polymer-Matrix Composites (PMC)

9. Table 2 Mechanical Properties of Polymer Matrix
Material
Density
(ρ)
(g / cm3)
Tensile
Modulus (E)
Gpa
Strength (σ)
Poisson's
Ratio
Cure
Shrinkage
(%)
Thermoseta
Epoxy
1.25
1.5
Polyester
1.27
Vinyl Ester
(L) 1.22
PMR-15
1.32
3.90
0.0386
ACTPb
1.34
(H) 4.10
0.0827
Thermoplastica
PEEK (Victrex)
1.31
3.24
0.1000
0.40
PPS (Ryton)
1.36
3.30
PSUL (Udel)
1.24
2.48
0.0703
0.37
PEI (Ultem)
3.00
0.1050
PAI (Torlon)
1.40
3.03
(H)
LARC-TPI (Durimid)
1.37
3.45
0.1380
0.36
aCast at 23oC; L: lowest; H: highest
bThermid 600 (National Starch and Chemical Corporation)

10. Fibre

11. Natural fibres

14. Table 8 Mechanical Properties of Fibres and Conventional Bulk Materials
Material
Diameter
(µm)
Density
(ρ)
(g / cm3)
Tensile
Modulus (E)
GPa
Strength (σ)
Specific
Modulus
(E/ρ)
Strength
(σ/ρ)
Poisson's
Ratio
Melting
Point
(oC)
F I B R E S
G L A S S
E-glass
10.0
2.54
72.4
3.45 29
1.36
0.20
1540
S-glass
2.49
86.9
4.30 35
1.73
0.22
P A N CARBON
T-300 (Amoco)
7.0
1.76
231.0
3.65
131
2.07
AS-4 (Hercules)
1.80
248.0
4.07
138
2.26
T-40 (Amoco)
5.1
1.81
290.0
(H) 5.65
160
(H) 3.12
IM-7 (Hercules)
5.0
1.78
301.0
5.31
169
2.98
HMS-4 (Hercules)
8.0
345.0
2.48
192
1.38
GY-70 (BASF)
8.4
1.96
483.0
1.52
246
0.78
PITCH CARBON
P-55 (Amoco)
2.00
380.0
1.90
190
0.95
P-100 (Amoco)
2.15
(H) 758.0
2.41
(H) 353
1.12
ARAMID
Kevlar 49 (DuPont)
11.9
1.45
131.0
3.62 90
2.50
0.35
Kevlar 29
12.0
80.0
2.80 55
1.93
500
Kevlar 149 (DuPont)
1.47
179.0
122
2.35
Technora (Teijin)
1.39
70.0
3.00 50
2.16
EXTENDED CHAIN POLYETHYLENE
Spectra 900 (Honeywell)
38.0
0.97
117.0
2.59
121
2.67
Spectra 1000 (Honeywell)
27.0
(L) 0.97
172.0
177
3.09
Boron
140.0
2.70
393.0
3.10
146
1.15
CERAMIC
SiC Monofilament
3.08
400.0
3.44
130
SiC Nicalon (Nippon c.) multifilament
14.5
2.55
196.0
2.75 77
1.08
Al2O3 (Nexter 610 (3-M)
10-12
3.90 97
0.79
Al2O3 (Nexter 720 (3-M)
3.40
260.0
2.10 76
0.62
NATURAL
Hemp
1.48 70 47
Flax
1.40
60-80
43-57
Sisal
1.33 38
Jute
1.46
10-30
7-21
B U L K
Steel
7.80
208.0 27
1480
Aluminium alloys
69.0 26
600

15. Weight Considerations
Aramid fibers are the lightest
g/cc
Carbon
1.79 g/c
Fiberglass is the heaviest
2.4 g/cc

16. Strength Considerations
Carbon is the strongest
ksi
Fiberglass
ksi
Aramids
400 ksi

17. Kevlar is the toughest Fiberglass Carbon
Impact Resistance
Kevlar is the toughest
Fiberglass
Carbon

18. Stiffness Considerations
Carbon is the stiffest
30-40 msi
Aramids
14 msi
Fiberglass
10-13 msi

19. Cost Considerations Fiberglass is cost effective $5.00-8.00/lb.
Aramids
$20.00/lb
Carbon
$30.00-$50.00/lb

20. Fibre architecture

21. Table 9 Mechanical Properties of Various Prepreg Materials [7]
Prepreg Material
Fibre
Volume
Fraction
(%)
Tensile
Modulus
(GPa)
Strength
Unidirectional thermoset
Carbon (AS4, T-300)/epoxy
55-65
Carbon (IM7)/epoxy
55-60
(Highest)
S-2 glass/epoxy
55-63
Kevlar/epoxy 69
0.966
Carbon (AS4)/bismaleimide
55-62
Carbon (IM7)/bismaleimide
60-66
Carbon (IM7)/cyanate ester
S-2 glass/cyanate ester
48.3
1.242
Unidirectional thermoplastic
Carbon (IM7)/PEEK
57-63
179.4 (highest)
2.829
Carbon (G34/700)/Nylon 6
110.4
1.4904
Aramid/Nylon 12 52
46.92
1.4145
Carbon (AS4)/PPS 64
120.75
1.9665
Carbon (IM7)/polyimide 62
172.5
2.622
Fabric (plain weave) thermoset
Carbon (AS4)/epoxy 55
34.5
0.552
Fabric (plain weave) thermoplastic tape
Carbon HM (T650-35)/polyimide
58-62

30. Figure 30 Photos and Schematic Drawing of A Micro-Braided Yarn [8]