Real Life Application Finding out stresses in cylinders due to high pressure fluids inside them is very important in designing boilers and other type of pressure vessels. The boilers etc. are used extensively in thermal power plants.
Explanation In the analysis of thin cylinders, we assume that the material along thickness in radial direction is negligible so we take the radial stress to be negligible as well. The pressure inside the cylinder causes stress in circumferential and longitudinal direction. The stress in circumferential direction is called as circumferential stress or hoop stress and the stress in axial stress is called as axial stress or longitudinal stress. As the stresses are there in only two directions, the state of stress is a plane stress condition.