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### 34 Cards in this Set

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 Anisotropic Different properties in different directions Orthotropic One set of three mutually perpendicular planes of symmetry Quasiisotropic Three or more plies oriented at equally spaced angles. OR 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? Tension 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? 4 What are the elastic constants needed for the Q matrix? EL ET VLT GLT [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 Deflection 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? \$>N2 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