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2210-test 2 peters
test 2
| Question | Answer |
|---|---|
| What is a composite structure? | when 2 or more materials are used to create a structure that is much stronger than the individual components. |
| What are some early examples of composites structures (three) not described in your text? | Plywood, carbon fiber, plastic |
| How much fiberglass is used on the 747 aircraft? | 10,000 ft^2 |
| How has advanced composites evolved? What is FRP? | Combining developments in chemical bonding formulas with new existing forms of solid structural materials to form high strength, light weight components used structurally in aircraft. These are called fiber reinforced plastic (FRP) |
| Why is it important to repair versus scrap composites parts? | its more economical |
| What three aspects concerning fabric patches are extremely important for distributing the stresses imposed on a repair? | fabric type, weave, and positioning |
| What are the advantages of using composites? | high strength to weight ratio, can form complex shapes easily # of parts and fasteners can be reduced reduction of cost |
| The strength of the composites depends on three factors; what are they? | type of fiber used, bonding materials used, and how a part is engineered to take specific stresses |
| How are composites used in the Grumman X-29 to provide adequate wing strength? | carbon/graphite filament in a complex fiber pattern. Fiber orientation of the fibers limits the twist and lows the wing to return to it's original configuration once the load is removed. |
| What are the percentages of composites on the C-17? | 40% carbon fiber, 40% aramid, and 20% fiberglass |
| Where are composites used on the Boeing 757? | Graphite/epoxy and Graphite/Kevlar |
| What are Nomex panels and where are they used on the 767 aircraft? | fiberglass reinforced plastics used as skin/floors |
| What are th777 vertical fin and engine cowls made of? | Carbon and fiberglass also epoxy skins covering a core of nomex honeycomb |
| How are the propellers of the Saab SF340 constructed? | Fiberglass skins with laminated carbon fiber spars with a core o Polyurethane foam |
| How much of the Sikorsky S-76 is composite, and what type of material is the primary weight saver? | Kevlar 49 is 30% of airframe weight<-- 60% of the total weight |
| What are the three common types of reinforcing fibers and the two uncommon fibers? | Fiberglass, aramid, and carbon/graphite-comon Ceramic and Boron-uncomon |
| Fiberglass is made from? | Small strands of molten 2,300°F silica glass |
| What are the common types of fiberglass being used in the aircraft industry? | E-glass, S-glass, and C-glass |
| What is matrix? | makes part more brittle, bonds fibers together |
| Describe Aramid? | aramid fabric allows the components to resist high stress and vibration |
| What is the aramid used on aircraft? What is its practical application on aircraft? | parts that need to withstand high stress and vibration rotor blades and hub assemblies |
| What are the disadvantages of aramid? | the flexibility makes it hard to cut or drill which causes fuzzing around the fastener |
| What is the difference between carbon fiber and graphite fiber as called out in an aircraft SRM? | Carbon # 584 and Graphite #584, they are the same but the Europeans and Americans called it different things |
| What are the characteristics of carbon that are useful for aircraft? | Strong compressive strength, strong, stiff, right strength |
| How does carbon compare to Kevlar? | stronger compressive strength than Kevlar. |
| What is the disadvantage of carbon fiber? | electrically conductive, have low thermal expansion coefficients and high fatigue resistance |
| How is Boron fiber made? Describe its characteristics. | depositing boron onto a thin filament of tungsten. Excellent compressive strength and stiffness extremely hard |
| Where are Ceramic fiber best utilized? | high temp application or metal matrix |
| How does resin affect the tensile strength of fabric? | makes structure more brittle |
| What is fiber science? | selective placement of fibers needed to obtain the greatest amount of strength in various applications |
| The strength of the fibers are poronllel to to the direction the threads run. | parallel |
| What is warp, how is it designated, and how is it identified? | The threads that run the length of the fabric as it comes off the bolt designated at 0 degrees. Inserting another type of thread at periodic intervals |
| What is the fill? | threads that inter weave with the warp threads |
| What is the selvage edge and how is it used in repairs? | prevents edges of fabric from unraveling, selvage edge is removed for fabrication and repair work. |
| Why is bias important in composites? | fabrics can be formed into contoured shapes by using bias |
| Give an example of glass fiber terminology that is different from your text and explain it. | A-Glass-is same as other glass and has chemical resistance |
| With regard to aramid, what does 1575de mean? | 9000 meters of kevlar 49 yarn weighs 1575 grams |
| With regard to carbon fiber, what does 4.5K tow mean? | 4500 carbon fiber filaments make up the tow |
| What is unidirectional fiber? | all major fibers run in one direction |
| What is bidirectional or multidirectional fabric? | when fibers run in 2 or more directions |
| What is a mat fabric? | Chopped fibers that are compressed together |
| What is the difference between plain and satin weaves? | plain weaves are popular for wet layup Satin weaves contours better around complex curves |
| Fabric styles are characterized by the | Yarn construction, count weight, thickness or weave |
| How is a fabric's weight measured? | Oz per min^2 |
| What are hybrids and why are hybrids used? | different fiber combinations or materials used to reduce cost or obtain a certain characteristic |
| What are the different types of hybrids? | intraply, interply, selective placement |
| What is a matrix? | bonding materials that completely surround the fiber |
| How is epoxy resin different from polyester resin? | much stronger and less brittle, high heat and chem resistance |
| What is the limitation with using thermoplastics for structural components? | can't be used in structural component's or high heat areas 750 degree F |
| How are thermoplastics and thermosetting plastics different? | Thermoplastics can be molded with heat, thermosetting plastics can't |
| Why are epoxy resins among the most common matrix systems used in composite fabrication and repair? | flexible applications, good adhesive characteristics. easy to curve at room temp |
| How are epoxy resin systems obtainable from a hardware store different from aircraft grade systems? | A/C grades are much stronger /flexible and more reliable. |
| What is the most important rule a technician can follow with epoxy resins? | only use epoxy it calls for in SRM and use exact type/amount stated for correct ratio |
| What is the trade-off by using flexibilizers in epoxy resin system? | reduced tensile strength for extra flexibility |
| How can "crosslinking" be described? | 2 dimensional molecule to form 3D grid |
| Where are polybutadiene resins commonly found? | Coatings, adhesives, and potting compound |
| How do the temperature cure ranges affect the crosslinking of Ploybutdiene resin systems? | high heat, more crosslink established |
| Between pages 3-7 and 3-10 there approximately 13 recommendations for working with resins and catalysts; provide a brief list of the recommendations. | Know the times you have to work with, only mix the amount you need and only the type you need |
| Define pot life. | time between when resin is mixed and no longer useful |
| Define shelf life. | the time the product is good in unopened container. |
| What is the problem of adding too much matrix to a composite component? | brittle, weak, less thick, heavy. |
| What is the problem of starving a component of matrix when it is fabricated? | the part will be weak |
| What is the proper ratio of resin to fiber in advanced composite components? | 60/40 |
| How are pre-preg materials made (basically)? | resin is already in the fabric |
| What is the significance of the diamond shape on the plastic backing of pre-preg material? | indicates warp directions |
| What are the advantages of pre-pregs? | more convenient, perfect ratio |
| What are the disadvantages of pre-pregs? | has to be stored in freezer, expiration date |
| Why are dicyandiamide agents used for pre-preg curing? | very little reaction with epoxy at room temp |
| What must you be aware of when repairing pre-preg parts manufactured in an autoclave with pre-preg materials cured with a hot bonder system? | Could cause surface layers to be easily pulled back |
| Define adhesives. | Substance that bonds surfaces together |
| Why are adhesive films used in a pre-preg repair? | to bond the patch to repair area |
| What are foaming adhesives and their application? | when heat is applied, they foam up and expand |
| What is a thixotropic agent? | materials that are added to resins to control viscosity and weight |
| Name some different types of fillers. | micro balloons, chopped fibers, flux |
| What is the difference between chopped fiber and flox? | Chopped fibers are cut away from any fiber |
| Describe "metal matrix" and give an example of its application. | formed when chopped fibers are mixed with molten metal |
| Two popular core structures used in sandwich construction are ( ) and ( ) | Foam and Honeycomb |
| The ( ) of honeycomb cores can be found by tearing along one side of the honeycomb. | Ribbon Direction |
| Styrofoam can be cut with a ( ) to form the desired shape. | Hot Wire |
| One advantage of using a sandwich construction technique is? | provides for a great deal of compressive strength |
| If a foam core is damaged, in general terms it | will retain all but about 20% of its original strength |
| When replacing honeycomb structure lining up ribbon direction? | is essential to ensure an airworthy bond line |
| Honeycomb can be constructed of? | paper |
| In general, laminating a foam core between lay-ups? | tends to produce a part that is stronger than a straight laminate |
| Urethane foam | cuts nicely, but emits toxic fumes when cut with a hot wire cutter |
| Styrofoam can be used with | epoxy resins only |
| Pressure is used in the manufacture of a composite panel to | none of the above |
| Vacuum bagging helps to | remove trapped air bubbles and distribute matrix throughout the lay-up |
| Information contained in a typical SDS report would include | phone number of the manufacturer and retail supplier, phone numbers of the national poison control center, and reactivity data |
| Research and lessons learned have shown that ( ) is/are the best type of known skin protection when working with composite materials | judicial use of protective gloves and clothing |
| Mixing instructions for any matrix must be followed to the letter, and would most commonly be contained | in the MSDS |
| Extra caution must be exercised when working with solvents and composite structures | due to static electricity |
| As a technician, you should not use a face shield when | Working in an area serviced by an up-draft vent system |
| The big difference between composites and aluminum, resulting in a cost savings of approximately 20%, is the ( ) | assembly time |
| Why is heat and pressure applied during the manufacturing process of composite components? | compact fibers, removes excess resin and gases, and speed cure |
| ( ) is used in the fabrication of helicopter rotor blades, propellers and even an entire fuselage. | filament winding |
| ( ) is a manufacturing method that uses a two- part mold with the dry fabric laid into the mold. | resin transfer molding |
| ( ) is a relatively simple and low-cost automated method of manufacturing composite components where the reinforcing fibers are dipped into a resin bath and pulled into a die, which is the shape of the desired part. | pultrusion |
| The molds that are used in the manufacturing of composites are referred to as the ( ) | tooling |
| Which of the following is a method of lightning protection used in the manufacturing process. | foil |
| Explain what is meant by the term "gel coat" | colored polyester resin applied to the fibers and outer layers of the lay-up |
Created by:
Lucas1999