Question

What is the surface energy of a crack?

(a) ϒ

(b) 2 ϒ c

(c) 4 ϒ c

(d) 12 ϒ c

This question was addressed to me in my homework.

I'd like to ask this question from Types of Fracture in portion Imperfection in Metal Crystals, Fracture, Corrosion and Oxidation of Engineering Material & Metallurgy

Answer 1

The correct choice is (c) 4 ϒ c

To elaborate: Griffith suggested the norm for the formation and spreading of cracks in brittle materials. He found that the surface energy of the crack is 4 ϒ c. Here, ϒ is the surface energy per unit area of the material.