Q.Describe the behaviour of a wire under gradually increasing load.
You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
Start your 14-day free trial to unlock the full solution →A wire under gradually increasing load passes through elastic, yield, plastic, and fracture stages, traced out by its stress–strain curve.
When a wire is loaded gradually and its elongation (strain) is plotted against the applied load per unit area (stress), the curve obtained shows the following stages:
1. Proportional (Hooke's law) region — O to A. For small loads, stress is directly proportional to strain: the graph is a straight line through the origin, and Hooke's law (stress ∝ strain, i.e. stress/strain = Young's modulus Y) holds. Point A is the proportional limit.
2. Elastic region — A to B. Beyond A the curve deviates slightly from a straight line, but the wire still returns exactly to its original length when the load is removed, up to point B, the elastic limit (or yield point in some treatments). Within OB, deformation is fully reversible.
3. Yield point — B to C. Just beyond the elastic limit, at the yield point, a small increase in stress produces a relatively large increase in strain — the material starts to deform plastically, and if the load is removed the wire does not return to its original length (a permanent set remains).
4. Plastic region — C to D. Beyond yield, stress and strain are no longer proportional; the wire stretches substantially with further loading. Point D corresponds to the ultimate tensile strength — the maximum stress the wire can withstand.
…
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.