A brittle and a ductile material both have similar yield stress, which of the following is true about their absorbed energy before fracture 4 Select one:
a. Less for ductile fracture
b. Same for both brittle and ductile fracture
c. Cannot be predicted
d. Less for brittle fracture
The correct answer and explanation is:
The correct answer is d. Less for brittle fracture.
Explanation:
When comparing brittle and ductile materials, both having similar yield stress, the amount of energy absorbed before fracture differs significantly due to the nature of the materials’ deformation mechanisms.
- Ductile Materials: Ductile materials, such as mild steel, undergo significant plastic deformation before fracture. When stress is applied, the material stretches and deforms, allowing it to absorb a considerable amount of energy. This plastic deformation is often visible as necking or stretching at the fracture site. Ductile materials can undergo large amounts of strain without breaking, which means they absorb much more energy before failure occurs.
- Brittle Materials: Brittle materials, such as glass or ceramics, do not undergo noticeable plastic deformation. Instead, they fracture almost immediately after reaching their yield stress, breaking with very little energy absorption. Brittle fracture tends to occur quickly and catastrophically, with little or no plastic deformation. These materials absorb much less energy compared to ductile materials before they fail.
In the context of the given options, brittle materials absorb less energy before fracture because they fracture without undergoing significant plastic deformation. On the other hand, ductile materials, which can undergo large plastic deformations, are able to absorb more energy before fracturing. This energy absorption ability is key in determining the toughness of the material. Toughness refers to the ability of a material to absorb energy and plastically deform without fracturing, which is much higher in ductile materials than brittle ones.
Thus, the answer is d. Less for brittle fracture, as brittle materials absorb significantly less energy before they break compared to ductile ones.