Strain Energy MCQ with answer and solution

Concept

Toughness and impact energy absorption

Formula

Modulus of Toughness = Area under stress-strain curve

Step-by-step solution

1. Absorbing energy and withstanding shock or impact without catastrophic fracture requires a material to be both strong and ductile. 2. Toughness quantifies the total work required to deform and fracture a specimen, measured as the total area beneath the stress-strain curve. 3. High yield strength alone is insufficient if the material fractures abruptly upon reaching its elastic limit. 4. Therefore, toughness defines the capability to absorb energy and withstand impact without fracture. Answer: B

Explanation

Toughness is the mechanical property that measures the total energy per unit volume a material can absorb before fracturing. In structural steel, high toughness ensures that sudden impact or shock loads are dissipated through plastic deformation rather than brittle failure. It is represented by the entire area under the tensile stress-strain diagram.

Why the other options are wrong

A) Hardness evaluates localized surface resistance to indentation, scratch, and wear. C) Elastic modulus reflects elastic stiffness, not energy absorbed up to fracture. D) Yield strength is the stress where plastic yielding begins, irrespective of total rupture energy.

Shortcut

Impact energy absorption = Toughness; Elastic energy absorption = Resilience.

Common mistake

Selecting hardness or yield strength instead of toughness when evaluating impact shock absorption.