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

Abstract

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.

System Identification and Dynamic Analysis of the Propulsion Shaft Systems Using Response Surface Optimization Technique

“…Figure 14 displays the response of the optimized model and the experimental model. The error between the two models is less than 10% in terms of the resonant frequency, and the maximum amplitude of vibration, which is considered an acceptable range for a complex problem with several unknown variables, and the accuracy of the results is close to those available in the existing literature [23,24]. It is worth noting that only three stiffness parameters of the bearing contributed to the transverse vibration problems in the chosen excitation frequency range.…”

“…Equation ( 7) can be solved by using the FE based harmonic analysis tools utilizing the frequency domain approach [23,24] or by using the numerical technique. In this paper ANSYS modal and harmonic analysis module are used to generate the response data.…”

Non-linear modeling and parameter identification of a bolted joint using substructure synthesis theory

“…The system related frequency and amplitude are both decreased in the existence of softening non linearity [1]. As a result of which when the bolt that has been fully tightened is relaxed, there are noticeable softening effects.…”