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Composites Ch 1,2,3
Advanced Composites Chapter 1, 2, 3
| Question | Answer |
|---|---|
| What is a composite structure? | A material formed by 2 or more materials that are combined |
| What are some early example of composite structures not described in your test? (Three) | Plywood, carbon fiber, plastic |
| How has advanced composites evolved? What is FRP? | High strength and light weight Fiber reinforced plastic |
| Why is it important to repair versus scrap composite parts? | Reduce cost |
| What three aspects concerning fabric patches are extremely important for distributing the stresses imposed on a repair? | Fiber type, weave and positioning |
| What are the advantages of using composites? | Very high strength to weight ratio, wear resistant, can be formed into dynamic shapes |
| The strength of the composites depends on three factors; they are? | Type of fibers being used, bonding material and how the part is engineered |
| What are th777 vertical fin and engine cowls made of? | Vertical fin is fiberglass and carbon Engine cowls is carbon fiber and epoxy skin covering a core of Nomex honey comb |
| Where are composites used on the Boeing 757? | Secondary structural components |
| What are Nomex panels and where are they used on the 767 aircraft? | Used for flooring and corrosion resistance Located under seats and in alleys |
| How are the propellers of the Saab SF340 constructed? | Fiberglass skin with the laminated carbon fiber spars |
| How much of the Sikorsky S-76 is composite, and what type of material is the primary weight saver? | 60% of the airframe Kevlar and honeycomb |
| What are 3 common types of reinforcing fibers and the two uncommon fibers | Common- fiberglass, carbon, graphite //// Uncommon - ceramic, boron |
| Fiberglass is made from | Small strands of molten silica glass |
| Common types of fiberglass being used in the AC industry | E-glass, S-glass, C-glass, and Trevor schoonover |
| What is matrix | Bonding substance used to fuse, strengthen, shape, and set composite material |
| Describe aramid | Aromatic poly fibers, very light weight & stretchy but strong fibers |
| What is the aramid used on A/C? What is its practical application? | Parts subject to Ralphs meat. Parts that are subject to high stress and vibration like rotor blades. |
| What are disadvantages of aramid? | Hard to work with (cut & drill). Frays easily, and resin deteriorates it. |
| Difference between carbon fiber and graphite fiber as called out in an A/C SRM | Carbon fiber is the same as graphic fiber |
| What are the characteristics of carbon that are useful for aircraft? | Very strong & stiff, rigid, electrically conductive, low thermal, expansion & wear resistant. |
| How does carbon compare to kevlar? | Carbon is stronger in compressive strength than kevlar |
| Disadvantage of carbon fiber | Corrosive when bonded to aluminum, it is also expensive. Can't be repaired |
| How is Boron fiber made? Describe its characteristics | Depositing boron into a thin filament of tungsten |
| Where are ceramic fibers best utilized? | High temp applications |
| How does resin affect the tensile strength of fabric | It decreases it |
| What is fiber science | Specific placement of fibers to produce the highest strength |
| The strength of fibers are ________ to the direction the threads run. | Parallel |
| What is warp, how is is designated, and how is it identified. | Directions of fibers as it rolls off of the roll. Up and down. |
| What is the fill. | Direction that runs 90 degrees to warp, from one edge to another. |
| What is the selvage edge and how is it used inn repairs? | Manufactured edge to stop from unraveling. |
| Why is bias important in composites? | Can be stretched along bias, for farming. |
| With regard to aramid, what does 1575de mean? | Weighs 1575 grams |
| With regard to carbon fiber, what does 4.5k tow mean? | 4,500 filaments used to make one tow. |
| What is unidirectional fiber? | All fibers run in 2 or more directions. |
| What is bidirectional or multidirectional fabric? | Fibers run in 2 or more directions. |
| What is mat fabric? | Chopped fibers that are pressed together. |
| What is the difference between plain and satin weaves? | Plain is a chessboard design, Satin is 3 over 1. |
| Fabric styles are characterized by the ___________. | Yarn construction count. |
| How is fabric's weight measured? | g/sq meter |
| What are hybrids and why are they used? | Mixes different types of fiber combinations or materials, used to reduce cost, or obtain a certain strength characteristic. |
| What are the different types of hybrids? | Interplay, interplay, selective placement |
| What is a matrix? | Bonding substance used to fuse, strengthen, shape, and set composite material |
| How is epoxy resin different from polyester resin? | Epoxy resin is much stronger and less brittle, chemical resistant |
| What is the limitation with using thermoplastics for structural components? | 750 degrees F |
| How are thermoplastics and thermosetting plastics different? | Thermoplastics can be heated and reshaped |
| Why are epoxy resins amongst the most common matrix systems used in composite fabrication and repair? | Flexible application, good adhesive characteristics, very resistant against deterioration, easy to cure at room temp and highly economical |
| How are epoxy resin systems obtainable from a hardware store different from aircraft grade systems? | Aircraft grade is stronger, more flexible, more reliable |
| What is the most important rule a technician can follow with epoxy resins? | Use SRM |
| What is the trade-off by using flexibilizers in an epoxy resin system? | Reduced tensile strength for more flexibility |
| How can "cross linking" be described? | 2 dimensional molecule to form 3 dimensional grid 3d linking between molecules |
| Where are polybutadiene resins commonly found? | Coatings, adhesives, and polting compounds |
| How do the temperature cure ranges affect the cross linking of polybutdiene resin systems? | Higher heat, the cross links more |
| Define pot life | Time between resin mix and when its no longer useful |
| Define shelf life | Time product is good in an unopened container |
| What is the problem of adding too much matrix to a composite component? | Brittle, weak, heavy |
| What is the problem of starving a component of matrix to a composite component? | Weak and lean |
| What is the proper ratio of resin to fiber in advanced composite components? | 60:40 |
| How are pre-preg materials made? | Resin is already impregnated into the fabric. |
| What is the significance of the diamond shape on the plastic backing of pre-preg material? | Indicates warp direction. |
| What are the advantages of pre-pregs. | Better impregnation, ratio, less room for human factor. |
| What are the disadvantages of pre-pregs? | Kept cold and has expiration date |
| Define adhesives. | Substance that bonds surface together. |
| Why are adhesive films used in a pre-preg repair? | Bond pre-preg patch repair. |
| What are foaming adhesives and their application? | Prevent dry areas. |
| Name some different types of fillers | Microballoons, chopped fibers, flax. |
| Difference between chopped fiber and Flax. | Fiber: cut from any fiber, Flax: fuzzy fibers woven from trouds. |
| Describe "metal matrix" and give an example. | formed when chopped fibers are mixed with molten metal. |
Created by:
JoeyRiggs11
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