Abstract
The vibration characteristics of bolted structures are crucially affected by the pre-tightening torque. An approach for identifying the pre-tightening torque dependent stiffness parameters of bolted joints is proposed in this paper. Firstly, the interface of the bolted joint is characterized by the thin layer element with the isotropic material property, and the parameter value of the property is assigned relative to the distance from the center of the bolt; the influence of the bolt is ignored. Secondly, the model updating method is adopted to identify the parameters of thin layer elements using experimental data, and modal data under different values of pre-tightening torque in the range of 2 N·m~22 N·m are obtained; the torque wrench is used to determine the pre-tightening torque in the modal test. Finally, after identifying the material parameters using partial experimental data on pre-tightening torque range, the empirical equation of the interface parameters with the pre-tightening torque parameter is obtained by curve fitting and the rest of the experimental data are used to verify the accuracy of the fitted empirical equations. It is concluded that this method can obtain all the parameters of the equivalent thin layer elements within a certain range of pre-tightening torque, which can provide a reference for the empirical modeling of bolted structures, improve modeling efficiency and reflect the characteristic performance of real structural dynamics.
Highlights
Published: 30 September 2021Bolt connection has been widely used in mechanical structures; the vibration behavior of the assembly structure is closely related to the mechanical performance of the contact interface of the bolted joints [1,2,3,4]
We assuming that the normal dynamic stiffness Kn and tangential dynamic stiffness Kτ of the joint surface per unit area under uniform pressure are shown in Equations (22)
On the the basis basis of of the the thin thin layer layer element element with with isotropic isotropic constitutive constitutive relation, relation, this this paper paper presents method to tosimulate simulatethe thestiffness stiffness joint surface of the connection presents aa method ofof thethe joint surface of the boltbolt connection considering the variability of pre-tightening torque
Summary
Bolt connection has been widely used in mechanical structures; the vibration behavior of the assembly structure is closely related to the mechanical performance of the contact interface of the bolted joints [1,2,3,4]. Yao et al [11] proved that the material parameters of the partitioned thin-layer elements can be expressed for modeling aeroengine bolted joints These methods can provide the deformation and stress results in good agreement with experimental results, and the effects of surface slip and contact clearance on the mechanical properties of the bolted structure can be fully considered. Zhao et al [14] represented interface contact stiffness by implementing thin layer elements into the FE model and obtained the regularity of the contact stiffness in bolted interface changes with bolt preload These studies establish the viewpoint that the element method is better for simulating the pre-tightening force. The resulting curves can provide guidance for the accurate modeling of the same type of bolt connections in engineering
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