Composite Structures And Transparent Plastic Materials

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Composite Structures And Transparent Plastic Materials - Quiz

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Questions and Answers
  • 1. 

    Metal fasteners used with carbon/graphite composite structures

    • A.

      Must be constructed of high strength aluminum-lithium alloy

    • B.

      Must be constructed of material such as titanium or corrosion resistant steel

    • C.

      May be constructed of any of the metals commonly used in aircraft fasteners.

    Correct Answer
    B. Must be constructed of material such as titanium or corrosion resistant steel
    Explanation
    Metal fasteners used with carbon/graphite composite structures must be constructed of material such as titanium or corrosion resistant steel. This is because carbon/graphite composite structures are highly susceptible to galvanic corrosion when in contact with certain metals, such as aluminum. Titanium and corrosion resistant steel are chosen as they have a low galvanic potential and are less likely to cause corrosion when in contact with carbon/graphite composites.

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  • 2. 

    Hole filling fasteners (for example, MS20470 rivets) should not be used in composite structures primarily because of the

    • A.

      Possibility of causing delamination

    • B.

      Difficulty in forming a proper shop head.

    • C.

      Increased possibility of fretting corrosion in the fastener

    Correct Answer
    A. Possibility of causing delamination
    Explanation
    Hole filling fasteners should not be used in composite structures primarily because of the possibility of causing delamination. Delamination refers to the separation or splitting of layers within the composite material, which can weaken the structure and compromise its integrity. Hole filling fasteners, such as MS20470 rivets, do not adequately distribute the load across the composite layers, leading to stress concentration and potential delamination. Therefore, alternative fastening methods that minimize the risk of delamination should be used in composite structures.

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  • 3. 

    Sandwich panels made of metal honeycomb construction are used on modern aircraft because this type of construction

    • A.

      May be repaired by gluing replacement skin to the inner core material with thermoplastic resin

    • B.

      Has a high strength to weight ratio.

    • C.

      Is lighter than single sheet skin of the same strength and is more corrosion resistant

    Correct Answer
    B. Has a high strength to weight ratio.
    Explanation
    Sandwich panels made of metal honeycomb construction are used on modern aircraft because they have a high strength to weight ratio. This means that they are able to provide a high level of structural strength while being lightweight, which is crucial for aircraft where weight is a critical factor. The honeycomb structure allows for the distribution of load and provides rigidity, making it a suitable choice for aircraft construction.

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  • 4. 

    (1) When performing a ring (coin tap) test on composite structures, a change in sound may be due to damage or to transition to a different internal structure.(2) The extent of separation damage in composite structures is most accurately measured by a ring (coin tap) test.

    • A.

      Only No.1 is true

    • B.

      Only No.2 is true

    • C.

      Both No.1 and No.2 are true

    Correct Answer
    A. Only No.1 is true
    Explanation
    The given correct answer states that only statement No.1 is true. This means that when performing a ring (coin tap) test on composite structures, a change in sound may be due to damage or to transition to a different internal structure. However, statement No.2, which claims that the extent of separation damage in composite structures is most accurately measured by a ring (coin tap) test, is not true.

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  • 5. 

    Which of these methods may be used to inspect fiberglass/ honeycomb structures for entrapped water?1. Acoustic emission monitoring2. X-ray3. Backlighting

    • A.

      1 and 2

    • B.

      2 and 3

    • C.

      1 and 3

    Correct Answer
    A. 1 and 2
    Explanation
    Acoustic emission monitoring and X-ray methods can be used to inspect fiberglass/honeycomb structures for entrapped water. Acoustic emission monitoring involves detecting and analyzing the high-frequency sounds emitted by the structure when it undergoes stress or deformation. This method can identify the presence of water by detecting the characteristic sounds produced by water movement. X-ray inspection, on the other hand, uses electromagnetic radiation to penetrate the structure and create an image that can reveal the presence of water. Both methods are effective in detecting entrapped water in fiberglass/honeycomb structures.

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  • 6. 

    One of the best ways to assure that a properly prepared batch of matrix resin has been achieved is to

    • A.

      Perform a chemical composition analysis

    • B.

      Have mixed enough for a test sample

    • C.

      Test the viscosity of the resin immediately after mixing

    Correct Answer
    B. Have mixed enough for a test sample
    Explanation
    To assure that a properly prepared batch of matrix resin has been achieved, it is important to have mixed enough resin for a test sample. This ensures that there is an adequate amount of resin available for testing purposes, allowing for accurate analysis of its properties and performance. By having a sufficient quantity of resin, any potential issues or inconsistencies in the mixing process can be identified and addressed before using the resin in actual applications. This step helps to ensure the quality and reliability of the final product.

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  • 7. 

    Composite inspections conducted by means of acoustic emission monitoring

    • A.

      Pick up the "noise" of corrosion or other deterioration occurring

    • B.

      Create sonogram pictures of the areas being inspected

    • C.

      Analyze ultrasonic signals transmitted into the parts being inspected

    Correct Answer
    A. Pick up the "noise" of corrosion or other deterioration occurring
    Explanation
    Composite inspections conducted by means of acoustic emission monitoring involve using sensors to detect and pick up the "noise" generated by corrosion or other forms of deterioration occurring in the inspected areas. This technique allows for the early detection of potential issues before they become more severe. It does not involve creating sonogram pictures or analyzing ultrasonic signals, but rather focuses on detecting and monitoring the acoustic emissions produced by the deterioration process.

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  • 8. 

    What precaution, if any, should be taken to prevent corrosion inside a repaired metal honeycomb structure?

    • A.

      Prime the repair with a corrosion inhibitor and seal from the atmosphere

    • B.

      Paint the outside area with several coats of exterior paint

    • C.

      None. Honeycomb is usually made from a man made or fibrous material which is not susceptible to corrosion.

    Correct Answer
    A. Prime the repair with a corrosion inhibitor and seal from the atmosphere
    Explanation
    To prevent corrosion inside a repaired metal honeycomb structure, it is necessary to prime the repair with a corrosion inhibitor and seal it from the atmosphere. This is because metal structures are susceptible to corrosion when exposed to moisture and oxygen. By applying a corrosion inhibitor, it helps to protect the metal from chemical reactions that cause corrosion. Additionally, sealing the repaired area from the atmosphere helps to prevent moisture and oxygen from coming into contact with the metal, further reducing the risk of corrosion.

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  • 9. 

    One method of inspecting a laminated fiberglass structure that has been subjected to damage is to

    • A.

      Strip the damaged area of all paint and shine a strong light through the structure

    • B.

      Use an eddy current probe on both sides of the damaged area

    • C.

      Use dye penetrant inspection procedures, exposing the entire damaged area to the penetrant solution.

    Correct Answer
    A. Strip the damaged area of all paint and shine a strong light through the structure
    Explanation
    Stripping the damaged area of all paint and shining a strong light through the structure is a method used to inspect a laminated fiberglass structure that has been subjected to damage. By removing the paint and illuminating the structure with a strong light, any cracks, delaminations, or other damage can be easily identified. This method allows for a thorough examination of the structure to determine the extent of the damage and assess its structural integrity. Using an eddy current probe or dye penetrant inspection procedures may be suitable for other types of inspections, but in this case, the most effective method is to strip the paint and use light to inspect the structure.

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  • 10. 

    How many of the following are benefits of using microballons when making repairs to laminated honeycomb panels?
    1. Greater concentrations of resin in edges and corners.
    2. Improved strength to weight ratio.
    3. Less density.
    4. Lower stress concentrations.

    • A.

      2, 3, and 4

    • B.

      1, 2, and 4

    • C.

      1, 3, and 4

    Correct Answer
    A. 2, 3, and 4
    Explanation
    Using microballons when making repairs to laminated honeycomb panels provides several benefits. Firstly, it allows for greater concentrations of resin in edges and corners, which helps to strengthen these vulnerable areas. Secondly, it improves the strength to weight ratio of the panels, making them lighter without sacrificing durability. Thirdly, microballons have a lower density, which further contributes to reducing the overall weight of the panels. Lastly, their use helps to lower stress concentrations, which can help prevent cracks and other forms of damage. Therefore, the correct answer is 2, 3, and 4.

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  • 11. 

    The length of time that a catalyzed resin will remain in a workable state is called the

    • A.

      Pot life

    • B.

      Service life

    • C.

      Shelf life

    Correct Answer
    A. Pot life
    Explanation
    Pot life refers to the length of time that a catalyzed resin remains in a workable state. It is the time period during which the resin can be applied or manipulated before it starts to harden or cure. Pot life is an important consideration in various industries, such as construction and manufacturing, as it determines the time available for working with the resin before it becomes unusable.

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  • 12. 

    A category of plastic material that is capable of softening or flowing when reheated is described as a

    • A.

      Thermoset

    • B.

      Thermoplastic

    • C.

      Thermocure

    Correct Answer
    B. Thermoplastic
    Explanation
    A thermoplastic is a category of plastic material that is capable of softening or flowing when reheated. Unlike thermosets, which undergo a chemical change when heated and cannot be reshaped, thermoplastics can be melted and reshaped multiple times without undergoing any chemical change. This property makes thermoplastics highly versatile and widely used in various industries for applications such as injection molding, 3D printing, and packaging.

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  • 13. 

    The classification for high tensile strength fiberglass used in aircraft structures is

    • A.

      S

    • B.

      G

    • C.

      E

    Correct Answer
    A. S
    Explanation
    The classification for high tensile strength fiberglass used in aircraft structures is S.

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  • 14. 

    Superficial scars, scratches, surface abrasion, or rain erosion on fiberglass laminates can generally be repaired by applying

    • A.

      A piece of resin impregnated glass fabric facing.

    • B.

      One or more coats of suitable resin (room temperature catalyzed) to the surface.

    • C.

      A sheet of polyethylene over the abraded surface and one or more coats of resin cured with infrared heat lamps

    Correct Answer
    B. One or more coats of suitable resin (room temperature catalyzed) to the surface.
  • 15. 

    The classification for fiberglass reinforcement material that has high resistivity and is the most common is

    • A.

      E

    • B.

      G

    • C.

      S

    Correct Answer
    A. E
    Explanation
    The correct answer is E. Fiberglass reinforcement material with high resistivity is commonly classified as E.

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  • 16. 

    A potted compound repair on honeycomb can usually be made on damages less than

    • A.

      2 inches in diameter

    • B.

      1 inches in diameter

    • C.

      4 inches in diameter

    Correct Answer
    B. 1 inches in diameter
    Explanation
    A potted compound repair on honeycomb can usually be made on damages less than 1 inch in diameter. This means that if the damage to the honeycomb structure is smaller than 1 inch in diameter, it can be repaired using a potted compound method. This method involves filling the damaged area with a compound material to restore the structural integrity of the honeycomb. However, if the damage exceeds 1 inch in diameter, alternative repair methods may be required.

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  • 17. 

    Composite fabric material is considered to be the strongest in what direction?

    • A.

      Fill

    • B.

      Bias

    • C.

      Warp

    Correct Answer
    C. Warp
    Explanation
    Composite fabric material is considered to be the strongest in the warp direction. The warp direction refers to the lengthwise threads in the fabric that run parallel to the selvage. In composite fabrics, the warp threads are typically stronger and more tightly woven than the weft threads, which run perpendicular to the selvage. This design allows the fabric to have greater strength and resistance to stretching in the warp direction, making it the strongest direction for composite fabrics.

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  • 18. 

    The strength and stiffness of a properly constructed composite buildup depends primarily on

    • A.

      The orientation of the plies to the load direction.

    • B.

      The ability of the fibers to transfer stress to the matrix

    • C.

      A 60 percent matrix to 40 percent fiber ratio

    Correct Answer
    A. The orientation of the plies to the load direction.
    Explanation
    The strength and stiffness of a composite buildup depend primarily on the orientation of the plies to the load direction. This means that the arrangement of the layers of fibers in the composite material plays a crucial role in determining its mechanical properties. When the plies are properly aligned with the load direction, they can efficiently transfer stress and distribute it throughout the material, resulting in enhanced strength and stiffness. On the other hand, if the plies are misaligned, the load may not be effectively transferred, leading to reduced performance of the composite buildup.

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  • 19. 

    Which fiber to resin (percent) ratio for advanced composite wet lay-ups is generally considered the best for strength?

    • A.

      60:40

    • B.

      40:60

    • C.

      50:50

    Correct Answer
    A. 60:40
    Explanation
    A fiber to resin ratio of 60:40 is generally considered the best for strength in advanced composite wet lay-ups. This means that there is a higher percentage of fiber compared to resin in the composite. The higher fiber content provides better load-bearing capacity and stiffness, resulting in increased strength. The lower resin content also helps to reduce weight and improve overall performance.

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  • 20. 

    What is the material layer used within the vacuum bag pressure system to absorb excess resin during curing called?

    • A.

      Release

    • B.

      Bleeder

    • C.

      Breather

    Correct Answer
    B. Bleeder
    Explanation
    The material layer used within the vacuum bag pressure system to absorb excess resin during curing is called a bleeder. This layer helps to remove any excess resin from the laminate, allowing for a more efficient and controlled curing process. The bleeder acts as a pathway for the excess resin to escape, preventing it from causing any defects or inconsistencies in the final product.

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  • 21. 

    Proper pre-preg composite lay-up curing is generally accomplished by
    1. applying external heat
    2. room temperature exposure
    3. adding a catalyst or curing agent to the resin
    4. applying pressure

    • A.

      1 and 4

    • B.

      2 and 3

    • C.

      1, 3, and 4

    Correct Answer
    A. 1 and 4
    Explanation
    The proper pre-preg composite lay-up curing process involves applying external heat (1) and applying pressure (4). Applying external heat helps to cure the resin and bond the composite materials together, while applying pressure ensures proper consolidation and eliminates any voids or air bubbles. Adding a catalyst or curing agent to the resin (3) is not mentioned as a step in the given explanation. Therefore, the correct answer is 1 and 4.

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  • 22. 

    When repairing large, flat surfaces with polyester resins, warping of the surface is likely to occur. One method of reducing the amount of warpage is to

    • A.

      Use less catalyst than normal so the repair will be more flexible.

    • B.

      Add an extra amount of catalyst to the resin

    • C.

      Use short strips of fiberglass in the bonded repair

    Correct Answer
    C. Use short strips of fiberglass in the bonded repair
    Explanation
    Using short strips of fiberglass in the bonded repair helps to reduce warping of the surface when repairing large, flat surfaces with polyester resins. The fiberglass strips provide additional reinforcement and support to the repair, preventing excessive warpage.

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  • 23. 

    When making repairs to fiberglass, cleaning of the area to be repaired is essential for a good bond. The final cleaning should be made using

    • A.

      MEK (methyl ethyl ketone)

    • B.

      A thixotropic agent.

    • C.

      Soap, water, and a scrub brush

    Correct Answer
    A. MEK (methyl ethyl ketone)
    Explanation
    MEK (methyl ethyl ketone) is the correct answer because it is a solvent that is commonly used for cleaning and preparing surfaces before applying adhesives or making repairs. It is effective in removing dirt, grease, and other contaminants from the fiberglass surface, ensuring a clean and proper bond. The use of a thixotropic agent or soap, water, and a scrub brush may not be as effective in removing all the contaminants, resulting in a weaker bond.

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  • 24. 

    When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?

    • A.

      Water only

    • B.

      Water displacing oil

    • C.

      Water soluble oil

    Correct Answer
    A. Water only
    Explanation
    When machining composite laminates, water is usually the most acceptable type of cutting fluid. This is because water does not react with or damage the composite material. Water is also effective in cooling the cutting tool and reducing friction during the machining process. Additionally, using water as a cutting fluid helps to minimize any potential environmental and health hazards associated with other types of cutting fluids.

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  • 25. 

    Fiberglass laminate damage not exceeding the first layer or ply can be repaired by

    • A.

      Sanding the damaged area until aerodynamic smoothness is obtained

    • B.

      Trimming the rough edges and sealing with paint

    • C.

      Filling with a putty consisting of a compatible resin and clean, short glass fibers

    Correct Answer
    C. Filling with a putty consisting of a compatible resin and clean, short glass fibers
    Explanation
    When a fiberglass laminate is damaged, it can be repaired by filling the damaged area with a putty made of a compatible resin and clean, short glass fibers. This putty will help to restore the strength and integrity of the damaged laminate. Sanding the area until it is aerodynamically smooth and trimming the rough edges are also important steps in the repair process. However, these steps alone are not sufficient to fully repair the damage. Sealing the repaired area with paint is not mentioned in the explanation, so it is not necessary for this particular repair process.

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  • 26. 

    Fiberglass damage that extends completely through a laminated sandwich structrue

    • A.

      Must be filled with resin to eliminate dangerous stress concentrations

    • B.

      May be repaired

    • C.

      May be filled with putty which is compatible with resin

    Correct Answer
    B. May be repaired
    Explanation
    The given correct answer suggests that fiberglass damage that extends completely through a laminated sandwich structure can be repaired. This implies that the damage is not beyond repair and can be fixed using appropriate methods. It is important to fill the damaged area with resin to eliminate dangerous stress concentrations and ensure the structural integrity of the laminated sandwich structure. Additionally, the option of filling the damaged area with putty that is compatible with resin is also mentioned as a possible repair solution.

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  • 27. 

    Fiberglass laminate damage that extends completely through one facing and into the core

    • A.

      Requires the replacement of the damaged core and facing

    • B.

      Can be repaired by using a typical metal facing patch

    • C.

      Cannot be repaired

    Correct Answer
    A. Requires the replacement of the damaged core and facing
    Explanation
    When fiberglass laminate damage extends completely through one facing and into the core, it is necessary to replace both the damaged core and facing. This is because the damage has compromised the structural integrity of the laminate, and simply patching it with a metal facing would not adequately restore its strength. Therefore, the only solution is to replace the damaged components entirely to ensure the structural integrity of the laminate is restored.

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  • 28. 

    Repairing advanced composites using materials and techniques traditionally used for fiberglass repairs is likely to result in

    • A.

      An unairworthy repair

    • B.

      Improved wear resistance to the structure

    • C.

      Restored strength and flexibility

    Correct Answer
    A. An unairworthy repair
    Explanation
    Repairing advanced composites using materials and techniques traditionally used for fiberglass repairs is likely to result in an unairworthy repair. This is because advanced composites have different properties and require specialized materials and techniques for proper repair. Using materials and techniques meant for fiberglass repairs may not provide the necessary strength, flexibility, and durability required for advanced composites, leading to a repair that does not meet the standards for safe and reliable aircraft operation.

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  • 29. 

    The preferred way to make permanent repairs on composites is by

    • A.

      Bonding on metal or cured composite patches.

    • B.

      Riveting on metal or cured composite patches

    • C.

      Laminating on new repair plies

    Correct Answer
    C. Laminating on new repair plies
    Explanation
    Laminating on new repair plies is the preferred way to make permanent repairs on composites. This involves applying new layers of composite material to the damaged area, which helps restore the structural integrity of the composite. This method ensures a strong bond between the new repair plies and the existing composite, resulting in a durable and long-lasting repair. Bonding on metal or cured composite patches and riveting on metal or cured composite patches may also be used for repairs but are not the preferred method as they may not provide the same level of strength and durability as laminating on new repair plies.

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  • 30. 

    Which of the following, when added to wet resins, provide strength for the repair of damaged fastener holes in composite panels?
    1. Microballons
    2. Flox
    3. Chopped fibers

    • A.

      1 and 3

    • B.

      1, 2, and 3

    • C.

      2, and 3

    Correct Answer
    C. 2, and 3
  • 31. 

    The part of a replacement honeycomb core that must line up with the adjacent original is the

    • A.

      Cell edge

    • B.

      Cell side

    • C.

      Ribbon direction

    Correct Answer
    C. Ribbon direction
    Explanation
    The ribbon direction is the correct answer because when replacing a honeycomb core, it is important for the new core to align with the adjacent original core. The ribbon direction refers to the orientation of the honeycomb cells, and ensuring that the ribbon direction matches helps maintain the structural integrity and strength of the overall honeycomb structure.

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  • 32. 

    Which of the following are generally characteristic of aramid fiber (Kevlar) composites?
    1. High tensile strength
    2. Flexibility
    3. Stiffness
    4. Corrosive effect in contact with aluminum
    5. Ability to conduct electricity

    • A.

      1, 3, and 5

    • B.

      1, and 2

    • C.

      2, 3, and 4

    Correct Answer
    B. 1, and 2
    Explanation
    Aramid fiber composites, such as Kevlar, are known for their high tensile strength, making them suitable for applications where strength is crucial. They also exhibit flexibility, allowing them to bend and deform without breaking. However, aramid fibers are not stiff like other composite materials. The corrosive effect in contact with aluminum is not a characteristic of aramid fiber composites. Additionally, aramid fibers do not conduct electricity. Therefore, the correct answer is 1, and 2.

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  • 33. 

    Which of the following are generally characteristic of carbon/graphite fiber composites?
    1. Flexibility
    2. Stiffness
    3. High compressive strength
    4. Corrosive effect in contact with aluminium
    5. Ability to conduct electricity

    • A.

      1, 3, and 5

    • B.

      2, 3, and 4

    • C.

      1 and 3

    Correct Answer
    B. 2, 3, and 4
    Explanation
    Carbon/graphite fiber composites are known for their stiffness, high compressive strength, and the ability to corrode aluminum when in contact with it. They are not typically flexible and have the ability to conduct electricity. Therefore, the correct answer is 2, 3, and 4.

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  • 34. 

    Which is an identifying characteristic of acrylic plastics?

    • A.

      Zinc chloride will have no effect.

    • B.

      Acrylic has a yellowish tint when viewed from the edge.

    • C.

      Acetone will soften plastic, but will not change its color

    Correct Answer
    A. Zinc chloride will have no effect.
    Explanation
    Acrylic plastics are known for their resistance to chemicals, including zinc chloride. This means that when exposed to zinc chloride, acrylic plastics will not undergo any noticeable changes or reactions. Therefore, the fact that zinc chloride will have no effect on acrylic plastics is an identifying characteristic of this type of plastic.

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  • 35. 

    If an aircraft's transparent plastic enclosures exhibit fine cracks which may extend in a network over or under the surface or through the plastic, the plastic is said to be

    • A.

      Brinelling

    • B.

      Hazing

    • C.

      Crazing

    Correct Answer
    C. Crazing
    Explanation
    Crazing refers to the formation of fine cracks in transparent plastic enclosures of an aircraft. These cracks can extend in a network pattern over or under the surface or through the plastic. This condition is known as crazing.

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  • 36. 

    When installing transparent plastic enclosures which are retained by bolts extending through the plastic material and self-locking nuts, the nuts should be

    • A.

      Tightened to a firm fit, then backed off one full turn.

    • B.

      Tightened to a firm fit, plus one full turn

    • C.

      Tightened to a firm fit

    Correct Answer
    A. Tightened to a firm fit, then backed off one full turn.
    Explanation
    When installing transparent plastic enclosures, it is important to tighten the nuts to a firm fit. However, it is also necessary to back off the nuts one full turn after reaching the firm fit. This is because plastic materials can expand or contract due to temperature changes, and by backing off the nuts, it allows for any potential expansion or contraction without causing damage to the plastic or putting excessive pressure on the enclosure.

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  • 37. 

    Which is considered good practice concerning the installation of acrylic plastics?

    • A.

      When rivets are used, adequate spacer or other satisfactory means to prevent excessive tightening of the frame to the plastic should be provided

    • B.

      When rivets or nuts and bolts are used, slotted holes are not recommended

    • C.

      When nuts and bolts are used, the plastic should be installed hot and tightened to a firm fit before the plastic cools.

    Correct Answer
    A. When rivets are used, adequate spacer or other satisfactory means to prevent excessive tightening of the frame to the plastic should be provided
    Explanation
    In the installation of acrylic plastics, it is considered good practice to use adequate spacer or other satisfactory means when using rivets to prevent excessive tightening of the frame to the plastic. This is important because acrylic plastics are prone to cracking or breaking under excessive pressure or stress. By providing a spacer or other means, it helps distribute the pressure evenly and prevents damage to the plastic.

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  • 38. 

    The coefficient of expansion of most plastic enclosure materials is

    • A.

      Greater than steel but less than aluminum

    • B.

      Greater than both steel and aluminum

    • C.

      Less than either steel or aluminum

    Correct Answer
    B. Greater than both steel and aluminum
    Explanation
    Plastic enclosure materials have a higher coefficient of expansion compared to steel and aluminum. This means that when exposed to heat, plastic materials will expand more than steel and aluminum. Therefore, the statement "greater than both steel and aluminum" is correct.

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  • 39. 

    If no scratches are visible after transparent plastic enclosure materials have been cleaned, their surfaces should be

    • A.

      Covered with a thin coat of wax

    • B.

      Buffed with a clan, soft, dry cloth

    • C.

      Polished with rubbing compound applied with a damp cloth

    Correct Answer
    A. Covered with a thin coat of wax
    Explanation
    After cleaning transparent plastic enclosure materials, covering their surfaces with a thin coat of wax can help to prevent scratches from appearing. The wax creates a protective layer that adds an extra barrier between the plastic and any potential sources of damage. This ensures that the plastic remains in good condition and maintains its transparency.

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  • 40. 

    What is the most common method of cementing transparent plastics?

    • A.

      Bevel method

    • B.

      Soak method

    • C.

      Heat method

    Correct Answer
    B. Soak method
    Explanation
    The most common method of cementing transparent plastics is the soak method. This involves immersing the plastic parts in a solvent that can dissolve the surface of the plastic, creating a bond when the solvent evaporates. This method is commonly used because it allows for a strong and seamless bond between the plastic parts, without causing any damage or distortion to the transparency of the material. The bevel method involves creating a beveled edge on the plastic parts and joining them together, while the heat method involves using heat to melt the plastic parts and fuse them together. However, the soak method is the preferred choice for cementing transparent plastics.

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  • 41. 

    When holes are drilled completely through Plexiglas, a

    • A.

      Wood drill should be used

    • B.

      Standard twist drill should be used

    • C.

      Specially modified twist drill should be used

    Correct Answer
    C. Specially modified twist drill should be used
    Explanation
    Plexiglas is a type of acrylic plastic that is prone to cracking and chipping when drilled. Using a standard twist drill or a wood drill can cause damage to the material. Therefore, a specially modified twist drill should be used to drill holes completely through Plexiglas. This type of drill is designed to reduce the risk of cracking and produce clean and precise holes in the material.

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  • 42. 

    What is an individual fiber called?

    • A.

      Tape

    • B.

      Filament

    • C.

      Splice

    • D.

      Roving

    Correct Answer
    B. Filament
    Explanation
    An individual fiber is called a filament. Filaments are long, continuous strands of material, often used in textiles and manufacturing processes. They can be made from various materials such as silk, nylon, or carbon fiber. Filaments are known for their strength and flexibility, making them suitable for a wide range of applications including clothing, ropes, and industrial materials.

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  • 43. 

    Carbon fibers have a low potential for causing galvanic corrosion when used with metallic fasteners and structures

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Carbon fibers have a high potential for causing galvanic corrosion when used with metallic fasteners and structures. Galvanic corrosion occurs when two dissimilar metals come into contact in the presence of an electrolyte, causing one metal to corrode more rapidly than it would on its own. Carbon fibers, being electrically conductive, can act as a catalyst for galvanic corrosion when in contact with metals. Therefore, the statement that carbon fibers have a low potential for causing galvanic corrosion is false.

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  • 44. 

    Special scissors are needed to cut aramid fibers.

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Aramid fibers, also known as Kevlar fibers, are extremely strong and resistant to heat. Due to their unique properties, special scissors are required to cut aramid fibers effectively. Regular scissors may not be able to cut through the fibers or may cause damage to them. Therefore, it is true that special scissors are needed to cut aramid fibers.

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  • 45. 

    What do the structural properties such as stiffness, dimensional stability, and strength of a composite laminate depend on?

    • A.

      The size of the fibers.

    • B.

      The stacking sequence of the plies

    • C.

      The Matrix

    Correct Answer
    B. The stacking sequence of the plies
    Explanation
    The structural properties of a composite laminate, such as stiffness, dimensional stability, and strength, depend on the stacking sequence of the plies. The arrangement and order in which the plies are layered greatly affect the overall performance of the laminate. The stacking sequence determines the distribution of forces and load transfer within the material, impacting its mechanical properties. Therefore, selecting the appropriate stacking sequence is crucial in optimizing the desired characteristics of the composite laminate.

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  • 46. 

    What is the primary disadvantage of Aramid Fibers?

    • A.

      Weak in tension

    • B.

      Hygroscopic

    • C.

      Highly susceptible to impact damage

    Correct Answer
    B. Hygroscopic
    Explanation
    Aramid fibers are known to be hygroscopic, meaning they have a tendency to absorb moisture from the surrounding environment. This can be a disadvantage as the absorbed moisture can weaken the fibers and reduce their overall strength and performance. Additionally, the absorbed moisture can also lead to dimensional changes, causing the fibers to expand or shrink, which can further affect their structural integrity. Therefore, the primary disadvantage of aramid fibers is their hygroscopic nature.

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  • 47. 

    Unidirectional tapes products have which of the following physical properties?

    • A.

      High compressive strength across the fibers

    • B.

      High tensile strength in the fiber direction

    • C.

      High shear and compressive strength in the fiber direction

    • D.

      High shear strength perpendicular to the fiber direction.

    Correct Answer
    B. High tensile strength in the fiber direction
    Explanation
    Unidirectional tapes are designed to have high tensile strength in the fiber direction. This means that they are strong and resistant to stretching or breaking when force is applied along the length of the fibers. The other physical properties mentioned in the options, such as high compressive strength across the fibers and high shear strength, may also be present in unidirectional tapes to some extent, but the primary and most important property is the high tensile strength in the fiber direction.

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  • 48. 

    Kevlar is DuPont's trademark name for what type of fibers?

    • A.

      Thermoplastics

    • B.

      Polyester

    • C.

      Carbon

    • D.

      Aramid

    Correct Answer
    D. Aramid
    Explanation
    Kevlar is DuPont's trademark name for aramid fibers. Aramid fibers are a type of synthetic fibers that are known for their high strength and heat resistance. They are commonly used in applications that require protection against abrasion, impact, and heat, such as in bulletproof vests, helmets, and tires. Kevlar is one of the most well-known and widely used brands of aramid fibers.

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  • 49. 

    In this ply orientation, the plies are stacked in a 0, -45, 45, 90 degrees sequence. This type of ply orientation simulate the properties of an isotropic material.

    • A.

      Isotropic

    • B.

      Bi-directional

    • C.

      Quasi-isotropic

    • D.

      Unidirectional

    Correct Answer
    C. Quasi-isotropic
    Explanation
    The given correct answer is "Quasi-isotropic." In quasi-isotropic ply orientation, the plies are stacked in a specific sequence of 0, -45, 45, 90 degrees. This arrangement helps to simulate the properties of an isotropic material, which means that the material has similar properties in all directions. The term "quasi" is used because although it simulates isotropy, it is not truly isotropic. Instead, it is an approximation that provides balanced strength and stiffness properties in multiple directions.

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  • 50. 

    Satin Weaves have less crimp and are easier to distort than plain weave fabrics.

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Satin weaves have fewer crimps, which means the yarns are more spaced out and have longer floats compared to plain weave fabrics. This results in a smoother and more lustrous surface. However, this also makes satin weaves more prone to distortion as the longer floats are more susceptible to being pulled out of shape. Therefore, it is true that satin weaves have less crimp and are easier to distort than plain weave fabrics.

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Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 20, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Mar 12, 2015
    Quiz Created by
    Voicezzang83
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