Effect of bolt connection on structural vibration modes and transfer characteristics

Bolt stiffness and pre-tightening force have great impact on structural vibration modes and transfer functions, which is often ignored in actual assembling because of the difficulty in treatment. By comparing the finite element calculation data and test data of three kinds of bolts with different stiffness under different pre-tightening force, the changes of structure modes and transfer function were analyzed. By using the ANSYS software, the vibration modes and harmonic responses under prestressed condition were investigated. Then the tests reguarding three kinds of bolts with different stiffness under the same pre-tightening force were carried out, and as to the steel bolt the tests were performed under six groups of pre-tightening forces. Finally, the differences between the calculation data and the test data were studied. The results show that the calculation results differ about 15% from the test data due to the ignorance of contact damping. Under the same pre-tightening force, natural frequencies increase with the increase of the bolt stiffness, and the maximum distortion also increases. The transfer function will be easier to be clearly expressed as the pre-tightening force increases.