Normal strain under axial loading is an important concept in the field of mechanics of materials. Axial loading implies the application of a force along the axis of a material, like a column or bar. This force can either compress or stretch the material. In the context of axial loading, normal strain is the deformation experienced by the material in the direction of the loading force. It's calculated as the change in length divided by the original length of the material. This unitless ratio provides a measure of the material's deformation under load.

When a material is subjected to axial load, it experiences stress, which is the applied load divided by the cross-sectional area of the material. The stress and strain relationship is defined by the material's modulus of elasticity, also known as Young's Modulus. However, the behavior of materials under axial load is only sometimes linear. As the load increases, the material might deform elastically up to a certain point, beyond which the deformation becomes plastic. This transition point is called the yield point. In practical applications, understanding the normal strain under axial loading is crucial in designing and analyzing structures, ensuring they can safely withstand the forces they're subjected to without deforming excessively or failing.