During a tensile test, the time-dependent slow elongation where stress increases at a constant load is termed_____________?
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Answer: A. creeping
Explanation
Creep is defined as the slow, progressive, time-dependent plastic elongation of engineering materials under a constant mechanical load. This phenomenon occurs predominantly when metallic or polymeric components are subjected to sustained mechanical stresses over long periods. Unlike instantaneous elastic or plastic deformation, creep accumulates gradually through microscopic dislocation movements within the material structure. Material creep behavior becomes extremely pronounced when engineering components operate at elevated temperatures exceeding roughly forty percent of melting point. Standard creep curves typically exhibit primary, secondary, and tertiary stages leading eventually to material rupture under constant stress. Designing high-temperature machinery requires careful accounting of allowable creep rates to prevent unexpected operational component distortion.
Yielding refers to the rapid onset of plastic deformation occurring promptly when stress exceeds the proportional elastic limit. Breaking describes the final catastrophic fracture event rather than the slow, time-dependent elongation process characteristic of creep. Plasticity is the general material property describing permanent deformation capability rather than the specific time-dependent phenomenon.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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