Fiber-Reinforced Composites Worksheet

What is the typical function of the matrix in a fiber-reinforced composite?

• Carry the entire load

• Prevent crack initiation

• Bind and transfer stress to fibers

• Act as thermal insulation

Which property is most improved by using high-modulus carbon fibers?

• Fracture toughness

• Stiffness

• Density

• Damping ratio

Which manufacturing method is most common for making aerospace-grade prepregs?

• Hand lay-up

• Resin infusion

• Hot-melt impregnation

• Injection molding

The "critical fiber length" in short-fiber composites depends on:

• Fiber modulus

• Matrix viscosity

• Interfacial shear strength

• Fiber orientation angle

Which reinforcement offers highest toughness?

• E-glass

• Aramid (Kevlar)

• Carbon

• Basalt

What type of failure does the “double cantilever beam” test evaluate?

• Matrix cracking

• Delamination (Mode I)

• Fiber pull-out

• Bending fracture

The stiffness of a composite increases with:

• Decreased fiber aspect ratio

• Decreased matrix viscosity

• Increased fiber volume fraction

• Increased cure time

Which fiber orientation provides isotropic in-plane properties?

• 0°

• 90°

• ±45°

• Quasi-isotropic layup

Which of the following is a thermoset resin commonly used in composites?

• Nylon

• Epoxy

• ABS

• Polycarbonate

Voids in composite laminates mostly affect:

• Color

• Density

• Interlaminar strength

• Fiber stiffness