New contributions in the analysis and identification of mechanical systems with hysteresis

Author(s)

Rafael de Oliveira Teloli

• Document type: Doctoral Thesis
• Press: Ilha Solteira. 2021-08-10.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Ilha Solteira
• Defense date: 2021-07-31
• Advisor: Samuel da Silva

Abstract

Structures exhibiting hysteresis behavior may present complex dynamic effects that restrict the application of conventional identification techniques. Among several systems in which these effects are present, structures assembled by bolted joints stand out. Thus, focusing on this subject, the dissertation presents new contributions in analyzing and identifying mechanical systems with hysteresis. Firstly, it is proposed a smoothing process to be applied on systems with hysteresis. For an equivalent system composed by a smooth nonlinear operator, the harmonic probing algorithm is then used to derive the higherorder frequency response functions (FRFs) computed by the Volterra series. To illustrate the applicability of the proposed approach, a Bouc-Wen model is simulated through a numerical integration scheme. Based on the smoothing process of the Bouc-Wen oscillator’s restoring force, some practical regards on applying the harmonic balance method (HBM) for predicting the hysteresis behavior of such a model are also addressed. Then, through the analytical formulation of the higher-order FRFs for systems with hysteresis, an identification procedure formulated into a white-box Bayesian modeling framework is proposed to calibrate a stochastic Bouc-Wen model for predicting the dynamics of a BoltEd strRucTure (BERT) benchmark. The dissertation then introduces the proposition of a new lap-joint configuration, the so-called Orion beam. The new setup comprises two thin beams connected by three bolted joints with contact patches on each connecting bolt, in which there are bolts dedicated to ‘‘static’’ functions to guarantee structural integrity and those that perform ‘‘damping’’ functions to increase energy dissipation due to frictional contact. Additionally, a Duffing-Van der Pol oscillator is proposed to evaluate, through its calibrated parameters, the impact of several tightening torque conditions and multiple excitation amplitudes on the structural stiffness and damping. Finally, the dissertation introduces the use of the GP-NARX model to approximate dynamic systems with hysteresis. Initially, the proposed model’s predictive applicability is evaluated on a numerical application involving the Bouc-Wen oscillator with hysteretic damping. Then, the GP-NARX model is proposed to describe the dynamics of the BERT benchmark. (AU)

• FAPESP's process: 16/21973-5 - New contribuitions on the analysis and identification of hysteretic mechanical systems: applications on Bouc-Wen oscillator
• Grantee: Rafael de Oliveira Teloli
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)