Elastic limit in mechanics is defined as?

• A. The maximum stress a material can withstand without any deformation.
• B. Maximum stress or force per unit area within a solid material that can arise before the onset of permanent deformation.
• C. The stress at which a material yields a rigid plastic deformation.
• D. The ratio of stress to strain in the elastic region.

Answer: (B)

The elastic limit is the maximum stress a material can experience and still return to its original shape when the load is removed. Up to this point, deformation is elastic and reversible; beyond it, permanent (plastic) deformation begins. This boundary helps distinguish the elastic region (where Hooke’s law applies and the material is effectively stiff) from the plastic region (where shape changes remain even after unloading).

The correct description captures this idea: it states the highest stress before permanent deformation occurs. The other options mischaracterize the concept: one implies no deformation at all, which isn’t true in the elastic range; another mixes yield with a rigid plastic deformation, which isn’t how the elastic limit is defined; and the last describes the ratio of stress to strain in the elastic region (Young’s modulus), not the point at which irreversible changes start.