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Motivation: A little Fun with Composites!

Nobody sails metal boards!

Carbon/Epoxy SAE fun

ME 412

First a little Business Adds/Drops after class today call me crazy add max (10 teams) *(3,4)

That is what I have specimens for 38ish people LAB

lots-o-reading on PLEARN print out lab handout quick read ASTM specs and Vishay strain info

BOOKs El Cartel now known as Cal Poly Store should have some by Friday?

Lets Get Going

Motivation Composite Materials Dig into some the subject Why Composites? A little on cost and manufacturing

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Somewhat New Cal Poly Composite Work

8 foot radius wind turbine rotor Carbon/E-glass-Epoxy Vacuum-infused Bonded Root Joint

Paper study 9 meter blade MS Thesis right now Compression Molding (zero waste?) MS

Crash Energy Management Table Light-Rail Application Honeycomb Sandwich Multi-Purpose

More Composites Projects Supermileage Wheels

Geez 4 ish years ago Only way to learn composites mfg. by doing of course

Tooling two piece clamshell Mold and prepreg layed up in autoclave ready to go

Cured part out of mold

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Composites what and why?

What is a composite?

Why Composites?

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Why Composites The specifics stiffness, strength Performance Charts Misleading I thought composites were good, Biaxial-Iso laminates barely win?

Figure 2.9 Daniel and Ishai performance map of fibers used in structural composites

Figure 1-24 Jones Strength and stiffness of composite materials

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Analysis Example: Specific Stiffness/Strength Calculations

Divide strength or stiffness by Weight Density In silly American units Some typical values alum vs carbon/epoxy

Carbon/Epoxy

Su1 = 350 ksi Su2 = 8ksi E1 = 27 msi E2 = 1.35 msi g = .055 lb/in3

Aluminum 7075-T6 Su = 75 ksi E = 10 msi g = .100 lb/in3

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lb in inlb in =

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The Specifics Advanced composites vs. metal, wood, filled polymers

Some Designer Points Wood is good, metal too Metal specific stiffness nearly

identical If loads are in one direction

composites are phenomenal But if you miss the loads,

composites will fail, transverse properties are scary low

Fiber must be in the direction of loads!

Force, Flow Load Pathare keys for any structural designer (DESIGN the FBD) then pick the material

Get control of the geometry early for composites to have a chance, metal replacement hard, black alum is inefficient

File: Material_specifics.xls

Material System Su E Weight Su/Dens E/DensityDensity

(ksi) (msi) (lb/in3) 103 in 106 inSteel

4130 (Normalized) 90 29 0.283 318 102Aermet 100 280 28 0.281 996 100

Aluminum 7075-T6 75 10.3 0.101 743 102

Titanium (6AL-4V) 150 16 0.16 938 100

Carbon (graphite)/ EpoxyHigh Modulus (Long) 170 40 0.055 3091 727High Modulus (Trans) 3.5 0.9 0.055 64 16

Int Modulus (long) 350 27 0.06 5833 450Int Modulus (trans) 8 1.35 0.06 133 23

AS4 Quasi-Iso --- 13.8 0.06 --- 231

S2 Glass/Epoxy (long) 220 5.6 0.07 3143 80S2 Glass/Epoxy (trans) 5 1.5 0.07 71 21

Nylon (30% Glass) 25 1 0.05 500 20Nylon 11 0.175 0.04 275 4

Sitka Spruce 7 1.57 0.015 467 105

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What else should the designer analyst worry about when trading structural materials

Fracture Toughness (LEFM research area for composites) Fibers arrest cracks but fiber is directional Hard to put fibers through thickness, delams (stitch and needle)

Impact Strength (again still active research area) strength after impact, FOD again composites can be good (F1, Indy cars, fighter aircraft)

Fatigue endurance Fibers again stop crack progression Composites can be very good in fatigue (rotorcraft blades) Look out for the other (joints and environment)

Creep Fibers good, matrix not so good, data?

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Other material design criteria continued Hardness, wear

polymer matrix is soft. Wear is proportional to pressure, velocity, hardness

Dimensional stability can be good or bad, directional and of course matrix and fiber dependant

Thermal Stability Same as dimensional, but watch out for high temps (which are really low

relative to metals) with polymer matrix composites. There are metal and refractory matrix materials as well!

Hygroscopic sensitivity Matrix swells and strains with water, watch out for chemical compatibility

Weatherability Consider paints and coatings

Erosion resistance Corrosion resistance

Watch out for batteries at your joints! Consult galvanic series, coat and shield

Conductivity Electrical conducts or doesnt conduct (lightning strike, EMI shielding) Thermal

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So composites have SPECIFIC advantages. Many other issues not addressed yet?

How to make it? Cost or life-cycle cost, LCC?

Raw material cost (200$/lb in 70s to 20$/lb?) by 1990s for commercial apps)

Design Cost Component fabrication costs Assembly cost Operating cost (weight, fuel transportation

apps, launch) Maintenance cost Salvage value, cost

Initial costs

Life-cycle costs

Sustainability recycle and reuse issues are active research areas and problematic for thermosetting resin systems!

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Composites cost advantage? When weight matters compost can win, the relative value of weight savings

What is the Cross-Over Point for AUTOs Trucks ETC?? 6 bucks a gallon? An interesting economics problem Now? BMW I3 next slide

Material utilization factor can be good

Mufac = raw matl. Weight / final part weight Or it costly put Ti, Alum chips on the floor

Jones, Fig 1-27 Value of Weight Savings in Structures (old data but relative nature still applies)

BMW I3 No Longer Urban CONCEPT Vehicle

124 mpg equivalent Range 81mi

http://blogs.motortrend.com/1501_is_bmw_i3_profitable.html The quirky-looking BMW i3 is the first carbon-fiber-intensive car thats both affordable and built in significant volumes. Those two qualifiers might fit more comfortably in quotation marks, given the $42,300 starting price and modest 100-a-day production rate, but theyre apt by comparison with the Lambos, McLarens, Ferraris, and Boeing 787s also built of the tough black fibers.

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Composites Cost Advantage?

Labor cost is directly related to part count. Composite structures are generally composed of fewer parts Integral part design is usually lighter too, they go hand in

hand. But this can all evaporate if a lay-up takes many technicians

many hours to accomplish, or you scrap huge parts. This is all controlled by design. One must think about this up

front and all along with mfg. engineers. Composites must be concurrently engineered for costs to be

competitive.

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Brief Overview Manufacturing Techniques

Cost analysis leads us to manufacturing or fabrication You all will be inventing this. But lets briefly review current practice,

methods some of which were discussed in ABC book. What is the oldest, simplest and most commonly used method for

fabrication of a composite with a thermosetting resin system? Advantages, disadvantages?

Which method may be best for tanks or torque tube driveshaft medium or high volume production?

What is VARTM and RTM?

Brief Overview Manufacturing Techniques

1. Filament Winding 2. Tape Wrapping 3. Fiber Placement 4. Autoclave Layup 5. Bladder molding 6. Liquid Molding (VRI, RTM, VARTM) 7. Injection Molding, SRIM 8. Sheet Molding Compound (Compression

Molding

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Always Think About How to Build It?

This is not restricted to Composites! Composites = Concurrent Engineering

All at once team thinks about Shape Materials Mfg. Design

Tools Process and QC

Analysis/Design Layup schedule Lamina Type

Joints, Bonds, Inserts Test Plan