Determining Deformations of Parts when Tightening Bolted Joints

Connecting parts of machines by bolts is widely used in various technical devices. Strict requirements to the efficiency of modern machines stimulate the development of accurate methods of calculating and assembling bolted joints. The problem of bolt tightening accuracy is related to the determination of deformation of the connected parts. Due to the tightening force, the bolt is stretched and twisted, and the parts are compressed. The tightening force is calculated so that the connection of the parts is tight and withstands external loads, and the bolt is not destroyed. The tightening is controlled by the moment of screwing or by the angle of rotation of the nut. For this purpose, electronic torque wrenches and ultrasonic devices are used that measure the torque and the angle with high accuracy. However, up until now, when calculating bolt tightening, approximate expressions have been used that do not consider the axial and torsional deformations of the bolt and the connected parts. As a result, the tightening accuracy of bolted connection decreases. The calculation formulae for the angle of rotation of the nut and the moment of screwing when tightening the bolt are clarified in the paper.

References

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