A Joke A group of managers were given the assignment to measure the height of A flagpole. So they go out to the flagpole with ladders and tape measures, and they're falling off the ladders, dropping the tape measures - the whole thing is just a mess. An engineer comes along and sees what they're trying to do, walks over, pulls the flagpole out of the ground, lays it flat, measures it from end to end, gives the measurement to one of the managers and walks away. After the engineer has gone, one manager turns to another and laughs. "Isn't that just like an engineer! We're looking for the height and he gives us the length!"

ADVANCED COMPOSITES Lecture 3 The modern advanced composites began with Boron filaments Boron provide high E not provided by glass: B: σ= 400 ksi E=65 msi ρ= 2.24 g/cc Gl: σ= 500-600 ksi E=10-12 msi ρ= 2.5 g/cc Boron provide E required by many aircraft In 1960’s Boron incorporated into F-15 and F-14

Commercial Composites Commercial Fabrication Methods Thermosets Contact Molding (Hand lay up, spray up) Matched (Compression) Die molding Resin injection molding RIM Pultrusion Filament winding Continuous laminating Centrifugal casting Thermoplastics Injection molding Transfer molding Compression molding Cold stamping Rotational molding Fibers E Glass Asbestos Resin Thermosets Polyesters Phenolics Epoxies Thermoplastics Numerous

Major Materials Major Resin Major Reinforcement Fibers 1- Thermosets Glass – E, S and S1 Aramid: Kevlar 49, Kevlar 29 Carbon/ Graphite Boron Other fibers: Alumina Silicon Carbide Alumina- Boria-Silica Boron Nitride Boron Carbide Titanium Diboride Major Resin 1- Thermosets Epoxies Polyester (Thermosets) Vinyl Esters Polyimides Phenolics 2- Thermoplastics Nylon Polycarbonate Polyesters (thermoplastics)

Geometrical Aspects Advanced Composites are made up of layers, piles, lamina or laminate. 0º (Unidirectional) is the starting point Properties are dependent of: Fiber diameter Fiber length Fiber length distribution Volume Fraction of fiber (Vf) Alignment and packing of fiber

Hex vs. Square Vf is Volume of fibers The max Vf occurs when fibers are touching. For optimum properties, maximize Vf without fiber to fiber contact (why?) Vc= Wc/ρc, Vr= Wlost/ρr Vf= Wresidue/ρf Vc= Vr+ Vf + (Vvoids)

Modulus vs. Filament volume

Can affect properties: 0° Tension -- little effect Compression– significant Environmental – significant Fatigue – significant Delamination – significant Impact resistance – significant (Rule of mixture for unidirectional modulus)

Standard Code Elements Each lamina is denoted by a number representing its orientation separated by a slash Adjacent laminate with the same angle by a numerical subscript. The laminate are listed in sequence from face to the other with brackets Adjacent lamina of the same are denoted by a numerical subscript A subscript T to the bracket indicates the total lamiate is shown (0/ 45/ 90) → (50/40/ 10) means 50 % 0’s, 40 % 45’s, 10% 90’s.

Positive and Negative Angles Lamina of the same angle but opposite in sign, + and – are used. Positive angles are assumed clockwise looking toward the layup tool surface

Positive and Negative Angles Symmetric lamina Start at the face but stop at the symmetry. The subscript S indicates that only one-half of the laminate is shown Long Form The latter is preferred because it can accommodate more numbers

Symmetric of Odd Numbers If odd laminate has additional of the same angle adjacent to the center lamina, a subscript is used with the overlined to indicate the number of “half lamina either side of the center. Is the same as the even number of lamina except the center lamina listed last is overlined indicating that one half of it lies on either sides.

Appollo 11

X-15

Golf Applications 100 Million Golfer around the world.

F-22 10 F-22 has been made so far. They are under testing and evaluation. By mid of 2005, 3 F-22 a month will be made. Bush requested 24 additional jets by the end of 2005. About 25% by wieght of F-22 is made of composites including carbon/epoxy. All the exterior skin is made of carbon fiber/bismaleimade (BMI) produced by automatic tape laying.

Unmanned Helicopter TAG-M65 and TAG-M80 New unmanned helicopter is being made for tactical high risk missions. They are made of carbon/ epoxy prepregs, hand layed up in open mold. It can be carried by a foot soldier. Total length is 182 cm for M65 and the M80is about 15% longer It can carry up to 20 kg load for 8 hours. It carries a Sielent Eye cost less than $ 15,000

Quiz1 1- Advanced composites fiber materials are: Carbon, Kevlar, Boron, and: A- Glass B- Polymer C- Resin D- E-glass 2- In metal, material selection only. But in composites: A- design only B- material selection only C- non of the above D- design creator and material selection

Quiz1 Cont. 3- Of the fabrication method in advanced composite: A- Casting B- Autoclave Molding C- Forging D- bending and hammering 4- What make composite advantageous over metals besides the weight is: A- color B- oxidation C- design flexibility D- corrosion resistance

Quiz1 cont. 5- The modern advanced composites began with A- Boron filaments B- Kevlar filaments C- Carbon filaments D- Glass filaments 6- Thermosets and Thermoplastic are: A- two types of fiber B- two names for the same item C- two types of metals D- two types of resin

Quiz1 cont. 7- For optimum properties: A- lay up more 0 directional lamina B- maximize Vf without fiber to fiber contact C- lay up more multi-dimensional lamina D- add more resin 8- One that has significant effect on composites is A- corrosion B- oxidation C- delamination D- shape

Quiz1 cont. 9- The laminate [0/45/90]s, the subscript s means A- symmetric B- same angles C- same material D- surroundings 10- The laminate [45/0/902/30]T the subscript T means: A- torque B- titanium C- torsion D- total