The stress performance and calculation methods of ordin […]
The stress performance and calculation methods of ordinary bolts and high-strength rivet nuts are different. The force of high-strength rivet nuts is first applied by pre-tensioning inside it, and then frictional resistance is generated on the contact surface between the connected parts to bear the external load, while the ordinary bolts directly bear the external load.
The high-strength rivet nut connection has the advantages of simple construction, good stress performance, detachability, fatigue resistance, and no loosening under dynamic load. It is a very promising connection method.
In the high-strength bolt connection, the friction coefficient has a great influence on the bearing capacity. Tests show that the friction coefficient 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, methods such as sandblasting and wire brush cleaning are often used to treat the contact surface of the components in the connection range.
High-strength rivet nut connections rely on the friction between the contact surfaces of the connectors to prevent them from sliding. In order to have sufficient friction on the contact surfaces, it is necessary to increase the clamping force of the component and increase the friction coefficient of the component contact surface . The clamping force between the components is achieved by applying pretension to the bolts, so the bolts must be made of high-strength steel, which is why it is called a high-strength bolt connection.
The high-strength rivet nut uses a special wrench to tighten the nut, so that the bolt generates a huge and controlled pretension. Through the nut and the backing plate, the same amount of prestress is also generated on the connected parts. Under the action of pre-pressure, a relatively large friction force will be generated along the surface of the connected part. Obviously, as long as the axial force is less than this friction force, the component will not slip and the connection will not be damaged. This is a high-strength bolt connection. The principle.
There are actually two types of high-strength rivet nuts: friction type and pressure-bearing type. The criterion for friction-type high-strength bolts to withstand the shear force is that the shear force caused by the design load does not exceed the friction force. Pressure-bearing high-strength bolts are designed based on the fact that the shaft is not damaged by shearing or the plates are not crushed. In addition, high-strength bolts cannot be reused.