Three types of high-strength bolt connections in fasteners

High-strength bolts in fasteners can be roughly divided into: friction connection, connection considering friction and bolt shear and bearing pressure, and connection of bolts under axial tension.

(1) Friction connection (friction type)

This is a connection method that uses the strong pretension of high-strength bolts to clamp the connected plate bundles, and transfers the edge stress by the friction between the contact surfaces of the joint plates. The stress flow through the contact surface is the biggest feature of this connection method.

The stress flow of friction connection, rivet connection and fillet welding. Therefore, friction connection is a method of using high-strength bolts to apply pressure to the connected steel plates to generate friction between the contact surfaces of the steel plates. At present in Japan, the so-called high-strength bolt connection generally refers to this kind of friction connection. (Guide: Explain how to reduce the chance of fastener locking)

(2) Considering friction, bolt shear, and pressure-bearing connection (pressure-bearing)

In the friction connection, once the friction fails, sliding occurs, and the bolt rod is pressed against the hole wall to generate the bearing pressure, so that the stress is transmitted through the pressure bearing and the shear force of the bolt rod. At this time, the effects of friction, pressure and shear can be considered for the connection at the same time. However, at this time, it is considered that the pressure-bearing effect is caused by the sliding of the connection. Therefore, the structure will inevitably produce deformation that is compatible with the sliding of the connection, which will cause problems in actual use. Therefore, in this case, drive-in bolts should be used to thicken the bolt shaft so that there is no gap between the hole walls.

(3) Bolt tension connection (tension type)

In the two forms of (1) and (2) above, the direction of force acting is perpendicular to the bolt axis, and sometimes there are cases where additional force acts on the bolt uranium direction. But for the connection of the bolt under tension, the force acts in the direction of the bolt axis, and the stress is transferred according to the change of the pressure between the connected steel plates.

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