The ball-and-bolt connection has the advantages of simple construction, good performance, detachability, fatigue resistance, and no looseness under dynamic load. It is a promising connection method. The ball studs are tightened with special wrenches to create a large and controlled pre-tension of the bolts. Through the nuts and pads, the same amount of pre-stress is applied to the connected parts. Under the pre-pressure, a large friction force will be generated along the surface of the connected member. Obviously, as long as the axial force is less than the frictional force, the member will not slip and the connection will not be damaged. This is the Round Head Bolt.
In the ball joint connection, the coefficient of friction has a great influence on the bearing capacity. Tests have shown that the coefficient of friction is mainly affected by the form of the contact surface and the material of the component. In order to increase the friction coefficient of the contact surface, the contact surface of the components in the connection range is often treated by sandblasting or wire brush cleaning during construction.