Which fiber is typically chosen for its high toughness and impact resistance?

• A. Carbon fiber: high stiffness and strength.
• B. Aramid fiber: high toughness and impact resistance.
• C. Glass fiber: minimal cost.
• D. Natural fiber: highest strength.

Answer: (B)

Toughness and impact resistance come from a material’s ability to absorb energy and resist crack growth under sudden loads. Aramid fibers excel here because they combine high energy absorption with the ability to deform and dissipate energy through mechanisms like fiber pull-out and matrix deformation. This makes them especially effective at stopping cracks from propagating when hit or impacted, which is why they’re a staple in protective gear and impact-resistant composites.

Carbon fiber, in contrast, offers outstanding stiffness and strength but can be brittle, meaning it can fail with limited deformation under impact. Glass fiber is cost-effective and strong, yet it tends to be more brittle than aramids and doesn’t absorb as much impact energy. Natural fibers also show wide property variation and generally lower, less reliable toughness, making them less suitable where high impact resistance is critical.

So, for applications requiring high toughness and impact resistance, aramid fiber is the best choice.