Investigation of Nonlinear Effects in a Bolted Joint Beam Using the Base Excitation

Abstract

Abstract In this paper, the nonlinearity detection, characterization and identification of a bolted beam assembly is presented. The new approach based on the force reconstruction using the base excitation as an input is used for the identification of nonlinear parameters. 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.