Reinforcements

Which of the following is NOT a common fiber reinforcement in composites?

• Carbon fiber

• Glass fiber

• Copper fiber

• Aramid fiber

Which of the following best describes the purpose of the fiber-matrix interface in a composite?

• It acts as an insulator to prevent heat transfer

• It transfers load between fibers and prevents fiber pull-out

• It prevents moisture absorption in the composite

• It increases the density of the composite

What is the primary reason for using hybrid composites (e.g., carbon-glass hybrids)?

• To reduce costs while maintaining performance

• To make the composite electrically conductive

• To increase the density of the material

• To improve the material's biodegradability

Short fiber composites are generally stronger than continuous fiber composites

• True

• False

Unidirectional fiber composites exhibit the same mechanical properties in all directions.

• True

• False

The aspect ratio (length/diameter) of short fibers has no effect on the composite's mechanical properties.

• True

• False

Aramid fibers (e.g., Kevlar) are primarily known for their high impact resistance.

• True

• False

Which of the following is the primary function of reinforcement in a composite material?

• To act as a binder for the matrix

• To provide stiffness and strength

• To increase the composite’s density

• To improve electrical conductivity

Which of the following best describes the behavior of unidirectional fiber composites?

• They have the same mechanical properties in all directions

• They exhibit high strength only along the fiber direction

• They have lower strength in the fiber direction than in other directions

• They behave identically to isotropic materials

What is the main advantage of using discontinuous (short) fibers instead of continuous fibers?

• They provide higher stiffness

• They are easier to process and mold

• They have higher tensile strength