The basic function of the nut is to produce and maintain the clamp load on the assembly. As the fastener elongates, it starts to apply a compressive load to the nut. The first engaged thread of the bolt experiences
an enormous amount of tension from the entire body. Some of this load is transferred to the nut causing less tension in the bolt at the second engaged thread. Then, this thread transfers part of this load to the third thread, and so on. The threads of the bolt will stretch. At the same time, the compressive forces acting on the bearing surface of the nut squeeze the bottom threads of the nut together. Due to this deformation causing an uneven load distribution, the first few threads may plastically deform
