An improved version of conditioned time and frequency domain reverse path methods for nonlinear parameter estimation of MDOF systems

Abstract

The nonlinearities present in engineering structures are generally local in nature. Hence for system identification, it is required first to identify the spatial location and then the nonlinearities are characterized. Once the nonlinearity is characterized, the system identification involves identifying coefficient of nonlinear terms. In the present work, an improved version of traditional conditioned time and frequency domain reverse path method for nonlinear parameter estimation of multiple-degree-of-freedom structures is presented. Both numerical and experimental studies have been carried out to investigate the effectiveness of the proposed improved time and frequency domain parameter estimation techniques over the traditional ones. The comparisons between the time and frequency domain reverse path approaches are also carried out to highlight the strengths and weaknesses of each of these approaches. Numerical and experimental investigations reveal that both the time and frequency domain approaches proposed in this paper overcomes the major limitations of their traditional counterparts and are capable of estimating the nonlinear coefficients of multiple nonlinear attachments either grounded or attached between the masses.

Keywords:

• Nonlinear systems
• frequency response function
• reverse path method
• conditioning

Acknowledgements

This paper is being published with the permission of the Director, CSIR-Structural Engineering Research Centre (SERC), Chennai.