The shear-bearing components are often seen in engineering. The common characteristics of this kind of rod force are: in the two sides of the component are equal, opposite, the action line is very close and perpendicular to the rod axis of the external forces. Under such an external force, the main deformation of the rod is: the M of the cross section between the two forces is the interface, and the two parts of the component are relatively dislocated along the surface. This form of deformation is called shear, and the section m is called shear surface, and the shearing plane is parallel to the direction of external force. When the external force is large enough, the component will be cut along the shearing plane. Only one shear surface, called a single shear, at the same time the component compression, both sides are also subjected to other components of the extrusion, this local surface pressure phenomenon called extrusion. If the pressure is greater, the local area of the contact surface will have a significant plastic deformation, causing the structure to not be used normally, this phenomenon is called crush damage. In addition to being cut and extruded, the mating parts are often accompanied by other forms of deformation. For example, bend or stretch deformation. However, since these deformations are secondary to shear and extrusion deformation, they are generally not considered. This kind of deformation is caused by the force of equal size, opposite direction, and parallel action lines, which appear to be relative dislocation between the two parts of the shear member along the external direction. The commonly used joints in machinery, such as keys, pins, bolts and so on, produce shear deformation.