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30 Cards in this Set

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Describe DFM
Designing products while keeping manufacturing in mind.
What does DFM stand for?
Design for manufacturing
What is the purpose of DFM?
Meet end use requirments with low cost design, low cost material and low cost process combos.
List and describe two types of unsaturated Polyester resins.
Orthophthalic: Cheap, general purpose, MW < Iso and Terra, poorer thermal stability and chem resistance.
Isophthalic: Greater strength, heat resistance, thoughness and flexibility over ortho
Terraphthalic
Bisphenol A Fumarate: Hard, rigid and thermally stable.
Chlorendic: Extremely righid, some fire retardancy, outstanding thermal stability and resistance to oxidizing enviros.
Give three reasons to use an unsaturated polyester over an epoxy.
Low cost
Lower weathering resistance
Lower physcial properties
Give three reasons to use a vinylester over a polyester
Better mechanical properties
Better fiber wet out
Tailor properties easier
Less shrink
Is it important to have the correct ratios of epoxy resin and hardner?
Yes. Important to have the correct ratio to achieve optimum properties..
Two advantages of a thermoplastic matrix over a thermoset.
Doesn't need to be frozen
Inexpensive
No special processing equipment necessary
Less processing time
Lower equipment costs
Describe three kinds of fiberglass:
E: Excellent electrical insulator
S: 40% improved physical strength over E.
A: High alkaline glass
C: Combo of borosilicate and sodalime, great chem resist.
D: Low dielectric composition.
R: Alkali resistant (concrete)
Hollow Fiber: Tube like, aircraft
Te: Japanese S glass (better)
What plays the biggest role in determining the properties of a fiberglass product?
Glass type plays the largest role.
Two starting materials of carbon fiber and characteristics of each.
Pitch: High modulus, low strain to failure rate, high cost, can be difficult to handle.
Pan: High strength, improved strain to failure, workable and availabe in many forms.
List and describe surface treatments for carbon fiber
Whiskerization: Tiny ceramic crystals are grown perpendicular to fiber axis.
Pyrolitic: Addition of pyrolitic carbons by vapor deposition.
Polygrafting: Introducing a p'mer to bridge any voids and gaps between matrix and fibers
What is interlaminar shear strength?
The attraction or shear strength between sheets so the sheets do not delaminate.
Roving:
Collection of continuous strands or filaments parallel to each other.
Woven Roving:
Many rovings woven into heavy, coarse fabrics.
Mats:
Chopped strand: nonwoven
Continuous
Vail
Yarn:
Fibers are twisted slightly.
Textured yarn:
Textured by air breaking surface filaments. Bulkier.
List four properties of aramid:
Poor UV resistance
Good impact resistance
Poor bonding abilities
Fire retardant
Good creep resistance
Weak in bending
What is the first thing you do when given a project? (Part of the material selection process)
Determine the products funtions and objectives.
How do you obtain fire retardancy in polyesters and vinylesters?
Add clays: Bad effects on properties
Add halogens: small effect on properties
Why don't we see high performance polyethylene fibers more in composites?
They're inert and won't bond very well.
What is the primary function of the facing material in sandwich construction?
To provide bending and in plane shear support. Caries the edgewise, bending and shear loads.
Design checklist for a composite structure:
1. Clear objective
2. Quantitative measures for using composites.
3. Mfg. approach
4. Known material and properties of that material
5. Material procurement
6. Joint concepts
7. Verify design
8. Inspections.
Should you use design data from tables?
Always test it yourself due to variation.
Name 3 core types and reason to use each:
Wood: Relatively inexpensive, easy to work with
Honeycomb: Different shapes for different contours available
Foam: Spray in place! Radar transparancy
When performing a hand lay up, what are four things the tool needs or does?
Consider resin flow
Correct CTEs
Draft at least 1 degree
Surface finish
Tolerances
Room for tacky tape.
Three reasons to use hand lay up and three not to.
Good:
- Low tooling cost
- Low skilled labor needed
- Large parts can be made
- More complex parts
Bad:
- Labor intensive
- One tooled surface
- Long cycle time
- High waste
- Part to part variation
Describe the difference between RTM and VARTM.
RTM: Two tooled surface, no vacuum assist.
VARTM: Vacuum pulls resin, one tooled surface
If the part has not been symmetrically hand laid up, what happens?
The part will warp and curl because of internal stresses.