Stress is force per unit area by definition. Stress calculation in only possible, if area of material & force coming on that material is known. While strain is the deformation in material because of stress in the material. Young’s modulus is the ratio of normal stress to normal strain within the range of elastic limits. It can also be tensile stress to tensile strain or compressive stress to compressive strain.
Stress, strain & young’s modulus of elastictcity calculation can be easily explain through example.
Consider a tie bar of 3 meters long which is 8cm wide and 16cm deep. It is subjected to a pulling force of 4000 KN. As a result change in length of material is 2.5 cm. Find the stress, strain & young’s modulus of elasticity of the material.
From calculations it can be seen that total stress in the material is 31.25KN per centimeter square. Strain as a result of pulling force is 0.00833. And young’s modulus of the material is 3750 KN per centimeter square.