Strength of Materials/Axial Deformation of Bars

Examples
The analysis presented in this section is valid when the length of the object under analysis, say L, is much larger than other dimensions and when the applied load is in the direction of L. An example of such a case is a pin jointed truss. When a load is applied to a truss, its members carry compressive (or tensile) loads acting so as to shorten (or increase) the length of the truss member.

Let us consider a bar of length L, cross sectional area A and an elastic modulus E. It is fixed on one of its end and is acted upon a force P along its length.