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34 Cards in this Set

  • Front
  • Back
Different properties in different directions
One set of three mutually perpendicular planes of symmetry
Three or more plies oriented at equally spaced angles.
A laminate of quasiisotropic plies
How do you avoid tensile/bending coupling?
Use a symmetric laminate
How do you avoid bending/twisting coupling?
For every ply oriented at + theta there is a ply oriented at - theta, equidistant from the midplane of the laminate
Balanced Laminate
For each ply at theta there is a ply at - theta. (Says nothing about being equidistant)
When is interfacial stress maximized?
When plies have greatest angluar differences. Ex: 0 and 90 Degrees.
Unidirectional is good in what loading?
How do you prevent cracking in unidirectionals?
Add a little angular difference rather then pure uni.
What is the Q Matrix?
Stiffness Matrix
What is the S Matrix
Compliance Matrix
What is the S Inverse Matrix?
Q Matrix
How many elastic constants are needed for the Q matrix?
What are the elastic constants needed for the Q matrix?
[0/+-15/30/45/10]s What is the B matrix?
All zeros! Because the laminate is symmetric
What is the A matrix?
Extensional Stiffness Matrixq
What is the D matrix?
Bending Stiffness Matrix
What is the B matrix?
Coupling Stiffness Matrix
Four main modes of failure
Facing Failure
Shear Failure of the Core
Core Crushing
What is the most effecient and idealistic bridge?
All modes fail at once
Name Four Edge Treatments for Honeycomb
- Extrusion
- Potting Compound to fill edges
- Taper laminate to solid
- Fold facing over to cover edge
- Add solid insert
- Wrap facing over solid part
- Crush core into taper - fill
- Foam insert on edges
How do you taper a facing?
Stagger ply lengths - make each ply shorter
Four key process variables to autoclaving?
1. Temp
2. Pressure
3. Time, soak time, ramp rates
4. Vacuum
Four kinds of autoclave gases you can use.
1. Nitrogen
2. Compressed Air
3. Carbon Dioxide
4. Argon
Three methods of heating the clave.
1. Elec
2. Nat. gas
3. Steam
Why is temperature a critical variable?
- Need uniform temperatur
- circulation system
- Consider shadowing.
Why would you use Nitrogen in an autoclave?
+ Abundant
+ Non-toxic
+ Relatively inert
+ Inexpensive
Why would you use compressed air?
Least expensive
Why is compressed air dangerous to use?
Flammable (Contains oxygen)
Drawbacks to using carbon dioxide?
Heavier then air, can collect in pockets
Why use argon?
Very inert
Extreme conditions
Six things you want done in an autoclave.
1. Void elimination
2. Conformance to tooling
3. Remove excess resin
4. Solvent removal
5. Fiber wet-out
6. Cure resin
What is debulking
Every 3-5 plies of pre-preg, apply a vacuum bag and draw vacuum. Removes traped air.
Minimum Viscosity
The lowest viscosity the resin achieves during course of cure cycle