Composite Materials 50-Item Questionnaire PDF

Composite Materials Multiple-Choice Questionnaire 1. What is the defining characteristic of a composite material? A. It is formed by mixing multiple phases without a distinct interface B. It consists of multiple chemically distinct phases separated by an interface C. It has a...

Composite Materials Multiple-Choice Questionnaire 1. What is the defining characteristic of a composite material? A. It is formed by mixing multiple phases without a distinct interface B. It consists of multiple chemically distinct phases separated by an interface C. It has a single-phase microstructure D. It is naturally occurring without engineering modifications Answer: B 2. Why are composites considered advantageous for aerospace applications? A. High density and brittleness B. Low density and resistance to corrosion C. Ability to conduct electricity D. High temperature conductivity Answer: B 3. Which of the following industries is NOT a primary user of composite materials? A. Aerospace B. Bioengineering C. Textile manufacturing D. Underwater engineering Answer: C 4. What is the primary role of the matrix in a composite? A. It provides strength and stiffness B. It protects the dispersed phase and transfers stress C. It reacts chemically with the environment D. It reduces the weight of the material Answer: B 5. The dispersed phase in composites is responsible for: A. Providing elasticity B. Transferring stress C. Providing strength and stiffness D. Encasing the matrix Answer: C 6. Which of the following is NOT a classification of composites? A. Particle-reinforced B. Fiber-reinforced C. Natural composites D. Nanocomposites  Answer: C 7. In large-particle composites, the particulate phase typically: A. Provides corrosion resistance B. Enhances thermal insulation C. Restrains movement of the matrix phase D. Acts as the sole load-bearing component Answer: C 8. Which composite subclass relies on atomic or molecular-level strengthening? A. Large-particle composites B. Dispersion-strengthened composites C. Fiber-reinforced composites D. Structural composites Answer: B 9. What distinguishes continuous fibers in fiber-reinforced composites? A. Random orientation B. Short lengths C. High strength along their length D. Low manufacturing cost Answer: C 10. Which of the following is a common fiber material used in composites? A. Wood B. Nylon C. Glass D. Steel Answer: C 11. The rule-of-mixtures predicts which property in composites? A. Color B. Density C. Elastic modulus D. Electrical conductivity Answer: C 12. What type of composite is reinforced concrete? A. Fiber-reinforced B. Particle-reinforced C. Nanocomposite D. Natural composite Answer: B 13. The strength of a composite increases significantly with: A. Lower volume fraction of the dispersed phase B. Uniform distribution of particles or fibers C. Large void spaces within the matrix D. Use of brittle dispersed phases Answer: B 14. What is the most common application of cemented carbide composites? A. Aerospace structures B. Cutting tools C. Automotive panels D. Electrical circuits Answer: B 15. Which property is most improved by nanocomposites? A. Electrical insulation B. Gas permeability C. Tensile strength D. Optical clarity Answer: C 16. Why is carbon black commonly used in rubber composites? A. Increases stiffness B. Reduces cost C. Enhances tensile strength and toughness D. Improves heat resistance Answer: C 17. What is the primary feature of structural composites? A. High temperature resistance B. Multi-layered design with high structural integrity C. Molecular-level reinforcements D. Naturally occurring fibers Answer: B 18. The most common matrix material in polymer composites is: A. Epoxy resin B. Concrete C. Metal alloys D. Glass Answer: A 19. Kevlar is primarily valued for its: A. High cost B. Strength-to-weight ratio C. Brittleness under tension D. Susceptibility to acids Answer: B 20. Carbon fiber-reinforced composites are commonly used in: A. Food packaging B. Sporting equipment C. Fireproof insulation D. Road surfaces Answer: B 21. What is the critical fiber length required for effective reinforcement in fiber composites? A. 10 times the fiber diameter B. Equal to the fiber diameter C. Approximately 20–150 times the fiber diameter D. Independent of fiber diameter Answer: C 22. What is the primary benefit of aligned fibers in composites? A. Strength is uniform in all directions B. Maximum strength along the direction of alignment C. Reduced production cost D. Increased thermal expansion Answer: B 23. The effectiveness of load transfer between the matrix and fiber phases depends on: A. The length of the fibers B. The fiber–matrix bond strength C. The type of matrix material used D. All of the above Answer: D 24. Discontinuous fibers provide significant reinforcement only if: A. The fiber length is much shorter than the critical length B. The fiber length exceeds the critical length C. The fibers are aligned randomly D. The matrix is metallic Answer: B 25. Randomly oriented short fibers are typically used for applications requiring: A. Maximum tensile strength B. Isotropic properties C. High thermal conductivity D. Extreme corrosion resistance Answer: B 26. Large-particle composites typically involve: A. A molecular-level interaction between phases B. Particles significantly smaller than the matrix C. Reinforcing particles that are stiffer than the matrix D. Fibers as the dispersed phase Answer: C 27. Dispersion-strengthened composites derive their strength from: A. The plastic deformation of the matrix B. Hindered motion of dislocations C. Fiber alignment in the matrix D. Increased porosity of the matrix Answer: B 28. The most common material for dispersion strengthening in nickel alloys is: A. Carbon fibers B. Thoria (ThO₂) C. Silica nanoparticles D. Aluminum oxide Answer: B 29. The primary application of cemented carbides (e.g., WC-Co) is: A. Abrasion-resistant coatings B. Cutting tools C. High-temperature insulation D. Lightweight components Answer: B 30. Which type of particle reinforcement enhances tire durability? A. Silica particles B. Carbon black C. Ceramic particles D. Metallic powders Answer: B 31. Which polymer-matrix composite is the most widely produced? A. Carbon fiber–reinforced plastics B. Glass fiber–reinforced plastics (GFRP) C. Aramid fiber–reinforced plastics D. Boron fiber–reinforced plastics Answer: B 32. A limitation of glass fiber–reinforced composites is their: A. Low cost B. Rigidity C. High-temperature resistance D. Chemical reactivity Answer: B 33. Carbon fiber–reinforced composites are preferred in aerospace due to: A. Low thermal expansion and high specific modulus B. High reactivity and cost efficiency C. Ease of manufacturing D. Low specific strength Answer: A 34. Aramid fibers are best suited for: A. Electrical insulation B. Ballistic protection applications C. High-temperature resistance D. Abrasive tools Answer: B 35. The most commonly used matrix materials in polymer composites are: A. Concrete and epoxy B. Epoxy and polyester C. Nylon and carbon fibers D. Silicon and polycarbonate Answer: B 36. Ceramic-matrix composites primarily aim to improve: A. Electrical conductivity B. Fracture toughness C. Thermal expansion D. Cost efficiency Answer: B 37. Metal-matrix composites are commonly used for: A. Lightweight armor B. High-temperature structural applications C. Electrical insulators D. Water-resistant coatings Answer: B 38. The matrix material in metal-matrix composites must be: A. Brittle and strong B. Ductile and tough C. Lightweight and soft D. Corrosive and reactive Answer: B 39. An advantage of ceramic-matrix composites is their: A. Resistance to corrosion B. Ease of manufacturing C. Low density D. Improved ductility Answer: A 40. A limitation of metal-matrix composites is: A. High brittleness B. Difficulty in manufacturing C. Low thermal stability D. Susceptibility to moisture Answer: B 41. Which property is typically enhanced in composites used in marine applications? A. Electrical conductivity B. Corrosion resistance C. Thermal conductivity D. Magnetic properties Answer: B 42. What is the key advantage of sandwich composites? A. High density B. Lightweight design with high stiffness C. Uniform electrical conductivity D. Enhanced brittleness Answer: B 43. Portland cement concrete is reinforced with steel primarily to: A. Reduce weight B. Increase tensile strength C. Improve thermal insulation D. Reduce thermal expansion Answer: B 44. A common application of prestressed concrete is: A. Electrical transformers B. Highway bridges C. Lightweight vehicle panels D. Sporting goods Answer: B 45. The primary advantage of fiber reinforcement in composite applications is: A. Enhanced thermal conductivity B. High strength-to-weight ratio C. Lower cost compared to monolithic materials D. Uniform distribution of properties Answer: B 46. The primary disadvantage of composites is their: A. High strength B. High cost and recyclability challenges C. Poor corrosion resistance D. Limited design flexibility Answer: B 47. The strength of a composite under longitudinal loading is primarily determined by: A. Matrix strength B. Fiber strength and alignment C. Thermal properties D. Chemical reactivity Answer: B 48. Reinforcement efficiency in randomly oriented composites is generally: A. Zero B. Equal to continuous fibers C. Lower than aligned composites D. Higher than aligned composites Answer: C 49. The modulus of elasticity in the transverse direction for aligned composites is typically: A. Higher than in the longitudinal direction B. Lower than in the longitudinal direction C. Equal in all directions D. Independent of fiber orientation Answer: B 50. Composites achieve superior properties due to: A. Homogeneity of materials B. Combined action of multiple phases C. Use of single-phase materials D. Higher density than traditional materials Answer: B