Mechanics of Solids & Fluids notes for mechanical engineering students. Mechanics of solids & fluids app almost covers topics chapter wise. Chapter 1. Concept of Stress and Strain. 1. Stress and Strain. 2. Working stress. 3. Ultimate stress. 4. Stress - strain relations. 5. Poisson's ratio. 6. Two dimensional state of strain. 7. Principal Stresses and Principal Planes.