Modulus of Elasticity:
In solid mechanics, Young’s modulus (E) is a measure of the stiffness of a material.It is defined as the ratio of stress over strain in the region in which Hooke’s Law is obeyed for the material.
Young’s modulus is the ratio of stress, which has units of pressure to strain, which is dimensionless; therefore Young’s modulus itself has units of pressure.
Proportional Limit :
The point up to which the stress and strain are linearly related is called the proportional limit.
Ultimate Stress :
The largest stress in the stress strain curve is called the ultimate stress.
Rupture Stress :
The stress at the point of rupture is called the fracture or rupture stress.