Fracture failure is defined as what?

• A. Permanent deformation under stress
• B. Separation into pieces under stress at low relative temperatures
• C. Time-dependent deformation
• D. Necking before fracture

Answer: (B)

Fracture is the material breaking apart into separate pieces when subjected to stress. It is about the final separation, not just how the material deforms or slowly changes shape over time. In many materials, this breakup is most characteristic at low temperatures where the material behaves in a brittle manner and cannot sustain significant plastic deformation.

That is why describing fracture as separation into pieces under stress at low temperatures best captures the essential idea: the body splits into pieces due to applied stress, especially in brittle conditions. The other options describe different phenomena—permanent deformation is plastic yielding, time-dependent deformation is creep, and necking is a stage in ductile failure that occurs before fracture but isn’t the definition of the fracture event itself.