The discussion focuses on calculating the radial stress gradient in a thick-walled tube due to temperature variations. The stress depends on whether the tube can expand; if constrained, maximum stress is calculated using thermal strain and Hooke's law. However, the tube in question is free to expand, leading to differential expansion between hot and cold walls, resulting in hoop and radial stress. For detailed calculations, Roark's Formulas for Stress & Strain provides relevant equations for maximum stress on surfaces with differing temperatures. The goal is to derive stress as a function of radial position based on the temperature gradient.
