Question 37 3AE02 - Third Assistant Engineer (Alt)

The Correct Answer is D **Why Option D is Correct:** Toughness, in materials science, is defined as the ability of a material to absorb energy and plastically deform before fracturing. A key manifestation of this property is a material's resistance to crack propagation and catastrophic failure under dynamic or cyclic loading conditions. The application and release of force repeatedly (cyclic loading) tests the material's fatigue resistance and energy absorption capability, which are central components of toughness. Materials with high toughness can absorb significant energy from repeated impacts or stress cycles without failing immediately, making "the ability to resist repeated application and release of force" an excellent practical description of material toughness. **Why Other Options are Incorrect:** * **A) The ability to resist continuous compression.** This describes compressive strength or bearing strength. While related to general mechanical properties, it is not the specific definition of toughness, which emphasizes energy absorption and resistance to fracture propagation (often under tensile or cyclic stresses). * **B) The ability to resist penetration.** This property is primarily defined as **hardness**. Hardness is the material's resistance to localized plastic deformation, such as indentation or scratching, which is distinct from toughness (energy absorption before fracture). * **C) The ability to resist continuous tension.** This property is known as **tensile strength** (the maximum stress a material can endure under tension before breaking) or creep resistance (resistance to deformation over time under continuous stress). While toughness is measured on a stress-strain curve that includes tension, the ability to resist continuous tension alone does not capture the dynamic, energy-absorbing nature that defines toughness.