Which term describes the property that measures a material's ability to resist crack propagation?

• A. Thermal conductivity
• B. Volume
• C. Twisting
• D. Toughness

Answer: (D)

Toughness is the property that describes a material’s ability to resist crack propagation. It reflects how much energy the material can absorb as a crack grows before it finally fails. A tough material can blunt the crack tip and deform plastically around it, dissipating energy and slowing or stopping further crack growth, so it can carry load even with flaws. In practical terms, this means materials with higher toughness are less likely to fail suddenly when cracks are present.

Other terms don’t describe this resistance to crack growth. Thermal conductivity is about heat flow, volume is just the size of the material, and twisting refers to a kind of motion or deformation rather than a material property related to fracture resistance. For example, metals like steel tend to have higher toughness than brittle ceramics, which crack and propagate cracks more readily.