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

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

Introduction

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

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

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

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)

Polymer-Matrix Composites (PMC)

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 2.75-4.10 0.0550-0.1300 0.20-0.33 1.5 Polyester 1.27 2.10-3.45 0.0345-0.1035 5.0-12.0 Vinyl Ester (L) 1.22 3.00-3.50 0.0730-0.0810 5.4-10.3 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) 0.1855 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)

Fibre

Natural fibres

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 0.55-0.90 47 0.37-0.61 Flax 1.40 60-80 0.80-1.50 43-57 0.57-1.07 Sisal 1.33 38 0.60-0.70 0.45-0.53 Jute 1.46 10-30 0.40-0.80 7-21 0.27-0.55 B U L K Steel 7.80 208.0 0.34-2.10 27 0.04-0.27 1480 Aluminium alloys 69.0 0.14-0.62 26 0.05-0.23 600

Weight Considerations Aramid fibers are the lightest 1.3-1.4 g/cc Carbon 1.79 g/c   Fiberglass is the heaviest 2.4 g/cc

Strength Considerations Carbon is the strongest 600-800 ksi Fiberglass 400-600 ksi Aramids 400 ksi

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

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

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

Fibre architecture

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 55-65 103-151.8 1.242-2.208 Carbon (IM7)/epoxy 55-60 138-172.5 2.208-3.036 (Highest) S-2 glass/epoxy 55-63 41.4-55.2 0.828-1.587 Kevlar/epoxy 69 0.966 Carbon (AS4)/bismaleimide 55-62 103.5-151.8 1.38-2.208 Carbon (IM7)/bismaleimide 60-66 2.622-2.76 Carbon (IM7)/cyanate ester 0.69-2.7255 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 55.2-62.1 0.5175-0.8556 55 34.5 0.552 Fabric (plain weave) thermoplastic tape Carbon HM (T650-35)/polyimide 58-62 69-124.2 0.897-1.0695

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