The area under load v/s elongation diagram for a ductile material upto fracture indicates _____.
Toughness
When a specimen is pulled in a tensile test, the machine records load P against elongation δ. The area under a load–deformation curve is energy (force × distance), so the area under the P–δ diagram represents the total mechanical energy the specimen absorbs.
If that area is taken all the way to the point of fracture, it represents the total energy the material can absorb before it breaks — both the recoverable elastic energy and the much larger energy dissipated in plastic deformation. This total energy-absorbing capacity is called toughness. A ductile material, which yields and stretches considerably before rupturing, encloses a large area and is therefore tough.
It helps to separate the related terms carefully:
| Quantity | Region of the curve | Meaning |
|---|---|---|
| Resilience | Elastic region only | Energy absorbed elastically (fully recoverable) |
| Modulus of resilience | Up to the yield point | Elastic strain energy per unit volume at yield |
| Modulus of toughness | Up to fracture | Total strain energy per unit volume (from the stress–strain curve) |
| Toughness | Up to fracture | Total energy absorbed before fracture (from the load–elongation curve) |
The distinction between the two "toughness" answers is subtle but decisive. Modulus of toughness is defined as energy per unit volume and is the area under the stress–strain (σ–ε) diagram, not the load–elongation diagram. Resilience and modulus of resilience refer only to the elastic portion and therefore represent a much smaller area that stops at yield, so neither describes energy up to fracture. Since the question specifically names the load versus elongation curve taken up to fracture, the total area corresponds to toughness.
Similar Questions
A component in a high-impact environment requires resistance to fracture with minimal deformation. Which material property would be most critical to avoid premature failure?
Important Questions from Mechanical Properties
The materials having the same elastic properties in all directions are called:
The energy stored in a body when strained within elastic limit is known as
Strain energy stored in a material when it is strained within its elastic limit is termed as:
Property of material which enables it to absorb energy without rupture
The maximum strain energy which can be stored by a body without undergoing permanent deformation is known as ________.
