Elastic behavior terminology: the greatest stress that a material can withstand without any permanent set (so that it fully returns to its original shape after unloading) is known as what?

Introduction / Context:
Engineers must distinguish between several critical stress levels: proportional limit, elastic limit, yield stress, ultimate stress, and breaking stress. Each term captures a distinct point on a stress–strain response curve and has specific design implications.

Given Data / Assumptions:

• Standard tensile test behavior is assumed.
• Small-scale material nonlinearity may occur near limits.
• Definitions are based on conventional engineering usage.

Concept / Approach:
The elastic limit is the maximum stress a material can endure without leaving any residual (permanent) deformation after complete unloading. Below this limit, the strain is fully recoverable. Yield stress marks the onset of significant plastic flow. Ultimate stress is the peak stress prior to necking or fracture. Breaking stress is the stress at fracture.

Step-by-Step Solution:

Verification / Alternative check:
On a stress–strain diagram, unloading from any point below the elastic limit returns along (nearly) the same path to zero strain.

Why Other Options Are Wrong:
Yield stress: marks plastic flow; unloading leaves a permanent set.Ultimate and breaking stress: occur much later in the test and include plasticity.Proportional limit: where stress is strictly proportional to strain; it may be just below but not above the elastic limit for some materials.

Common Pitfalls:
Confusing proportional limit with elastic limit; while close, they are not identical for all materials.

Final Answer:

elastic limit