Determination of Nonlinear Joint Forces and Nonlinear Identification of Jointed Connections Using FRFs


Soleimani H., CİĞEROĞLU E., ÖZGÜVEN H. N.

40th IMAC, A Conference and Exposition on Structural Dynamics, 2022, Florida, United States Of America, 7 - 10 February 2022, pp.57-61 identifier

  • Publication Type: Conference Paper / Full Text
  • Doi Number: 10.1007/978-3-031-05405-1_7
  • City: Florida
  • Country: United States Of America
  • Page Numbers: pp.57-61
  • Keywords: Friction, Joint identification, Nonlinear dynamics
  • Middle East Technical University Affiliated: Yes

Abstract

© 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.Identification and modeling of joint dynamics is an important issue in the dynamic modeling of structures with joints. Moreover, structures connected by joints may show nonlinear behavior due to the existence of dry friction between the connected elements, especially at higher levels of vibration. Therefore, nonlinear identification of joints and parameterization of them is a necessary step in the dynamic analysis of structures. In this study, a new method is proposed for the identification of nonlinear joint forces as functions of relative responses in the frequency domain, which are used to model joint dynamics. In the proposed method, nonlinear joint forces are calculated by using both the measured nonlinear frequency responses of the system, and the calculated or measured linear frequency response functions (FRFs) of the substructures or calculated linear FRFs of the coupled structure at certain points by using estimated values for linear joint parameters. It is important to note that the proposed method does not require measurements at the connection DOFs, which is an advantage since it is generally not practical to make measurements at joints. To demonstrate the performance of the identification method proposed, as well as its sensitivity to measurement errors, two lumped parameter systems connected to each other by nonlinear elements are considered. In these case studies, simulated results representing experimental measurements are used. It is observed that the proposed method is robust to measurement noise, and nonlinear parameters of the connection can be identified accurately.