Strength of materials is a branch of applied mechanics that deals with the behavior of solid bodies subjected to various types of loading. The main objective of this subject is to determine the stresses, strains and deflections produced by loads. In general a body can be subjected to three different types of loads, known as tensile, compressive and shear loads. The stress acts in a direction perpendicular to the cut surface, it is referred to as normal stress. Thus normal stresses may be tensile or compressive stresses. Shearing stress differs from both tensile and compressive stresses in that it is caused by forces acting along or parallel to the area of resisting the forces, whereas tensile or compressive stresses are caused by forces perpendicular to the areas on which they act. For this reason tensile and compressive stresses are called normal stresses whereas shearing stress may called a tangential stress.