Mechanics, the science of forces and motions, with its numerous engineering applications has been rendering valuable service to the mankind since the very beginning of our civilization. These applications have been achieved through a proper blending of the principles of mechanics with certain postulates and assumptions based on experiments and experience. The popular name of this is Applied Mechanics and has various branches, viz. Solid mechanics, Fluid mechanics etc. Mechanics of Solids deals with the mechanical behavior of the deformable bodies (bars, plates, cylinder, disc, shell etc.) subjected to various types of external forces and goes by a variety of names, such as strength of materials, mechanics of deformable solids etc. Thermal stresses problems in mechanical engineering has been solved my B.R. Seth's Theory. Application of these problems are useful in Mechanical Engineering and Structural engineering.