Dynamic characterization of bolted joints using FRF decoupling and optimization

Mechanical connections play a significant role in predicting dynamic characteristics of assembled structures. Therefore, equivalent dynamic models for joints are needed. Due to the complexity of joints, it is difficult to describe joint dynamics with analytical models. Reliable models are generally obtained using experimental measurements. In this paper an experimental identification method based on FRF decoupling and optimization algorithm is proposed for modeling joints. In the method the FRFs of two substructures connected with a joint are measured, while the FRFs of the substructures are obtained numerically or experimentally. Then the joint properties are calculated in terms of translational, rotational and cross-coupling stiffness and damping values by using FRF decoupling. In order to eliminate the numerical errors associated with matrix inversion an optimization algorithm is used to update the joint values obtained from FRF decoupling. The validity of the proposed method is demonstrated with experimental studies with bolted joints.


Dynamic modeling of structural joints
Tol, Şerife; Özgüven, Hasan Nevzat; Department of Mechanical Engineering (2012)
Complex systems composed of many substructures include various structural joints connecting the substructures together. These mechanical connections play a significant role in predicting the dynamic characteristics of the assembled systems accurately. Therefore, equivalent dynamic models of joints that consist of stiffness and damping elements should be developed and the joint parameters should be determined for an accurate vibration analysis. Since it is difficult to estimate joint parameters accurately by...
Analytical modeling of asymmetric multi-segment rotor - bearing systems with Timoshenko beam model including gyroscopic moments
Özşahin, Orkun; Özgüven, Hasan Nevzat (2014-11-01)
In this study, analytical modeling and an analysis approach for asymmetric multi-segment rotor bearing systems are presented. Timoshenko beam model which includes the effect of gyroscopic moments is employed for modeling rotor segments. Instead of applying FEM, sub-segment Frequency Response Functions (FRFs) are obtained analytically, and sub-segment FRFs obtained are coupled by using receptance coupling method. Bearing properties are included into system dynamics by employing structural modification techni...
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Tekin, Merve; Özgüven, H. Nevzat.; Department of Mechanical Engineering (2019)
For aviation applications, the noise and vibration cancellation is so important that there are many damping methods and applications used in the field. In military configurations the weight and the visual elegance is not so important that even a blanket may solve the problem. In civil configurations, on the other hand, there should be a lightweight solution for vibration damping. For this reason, since shell structures are widely used on aerospace applications, it is common to use surface damping solutions ...
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Design recommendations for reinforced concrete beam-column connections are based on limited experimental studies on the seismic behavior of eccentric connections. To supplement existing information, an experimental study was conducted that focused on the affect of eccentricity of spandrel beams with respect to the column. Specimens included a floor slab and transverse beams to evaluate the effect of slab participation. Test results indicated that including the floor system significantly reduced the negative...
Nonlinear vibration analysis of rotors supported by ball bearings
Bahan, Doğancan; Ciğeroğlu, Ender; Department of Mechanical Engineering (2019)
Performance of ball bearing-rotor systems is highly dependent on and often limited by characteristics of ball bearings. Ball bearings are nonlinear by their nature and this nonlinearity must be investigated rigorously to correctly predict vibration response of the system. The steady-state periodic response of rotor systems with nonlinear ball bearings is investigated. The rotor is modeled with the Finite Element Method. Nonlinear model for the bearings considers finite number of balls, bearing clearance and...
Citation Formats
S. Tol and H. N. Özgüven, “Dynamic characterization of bolted joints using FRF decoupling and optimization,” MECHANICAL SYSTEMS AND SIGNAL PROCESSING, pp. 124–138, 2015, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/39489.