Study of nonlinear effects in a bolted joint using the base excitation as an input

• Main Authors: Sushil Doranga, Christine Wu
• Format: Article
• Language: English
• Published: JVE International 2021-05-01
• Series: Journal of Vibroengineering
• Subjects: nonlinear; base excitation; modal analysis; force reconstruction
• Online Access: https://www.jvejournals.com/article/21849

In this paper, the nonlinearity detection, characterization and identification of a bolted beam assembly is presented. The methodology utilized in this work is based on the force reconstruction using the base excitation as an input and the nonlinear system identification. The force reconstruction procedure was carried out by exciting the bolted beam assembly at very low excitation with fully tightened bolt condition. The nonlinear effect in the bolted beam assembly was induced by reducing the bolt clamping loads. A collection of frequency response functions (FRFs) are shown at different clamping loads to detect and characterize the nonlinearities. Once the nonlinearities are detected and characterized, the restoring force surface method using the reconstructed force was used to identify the nonlinear parameters in the modal space. Four different base excitation (energy) levels with three different tightening torques were considered in the tests in order to study the energy dependence of the damping nonlinearities. In all the cases, the nonlinear system identification methodology employed was successful in identifying the damping and stiffness nonlinearities.