Spatial location identification of structural nonlinearities from random data

Document type: Journal Articles
Article type: Original article
Peer reviewed: Yes
Author(s): Andreas Josefsson, Martin Magnevall, Kjell Ahlin, Göran Broman
Title: Spatial location identification of structural nonlinearities from random data
Journal: Mechanical Systems and Signal Processing
Year: 2012
Volume: 27
Issue: 1
Pagination: 410-418
ISSN: 0888-3270
Publisher: Elsevier
URI/DOI: 10.1016/j.ymssp.2011.07.020
ISI number: 000298865300007
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Mechanical Engineering (Sektionen för ingenjörsvetenskap - avd. för maskinteknik)
School of Engineering S- 371 79 Karlskrona, School of Engineering S- 371 79 Karlskrona
+46 455 38 50 00
Language: English
Abstract: With growing demands on product performance and growing complexity of engineering structures, efficient tools for analyzing their dynamic behavior are essential. Linear techniques are well developed and often utilized. However, sometimes the errors due to linearization are too large to be acceptable, making it necessary to take nonlinear effects into account. In many practical applications it is common and reasonable to assume that the nonlinearities are highly local and thus only affect a limited set of spatial coordinates. The purpose of this paper is to present an approach to finding the spatial location of nonlinearities from measurement data, as this may not always be known beforehand. This information can be used to separate the underlying linear system from the nonlinear parts and create mathematical models for efficient parameter estimation and simulation. The presented approach builds on the reverse-path methodology and utilizes the coherence functions to determine the location of nonlinear elements. A systematic search with Multiple Input/Single Output models is conducted in order to find the nonlinear functions that best describe the nonlinear restoring forces. The obtained results indicate that the presented approach works well for identifying the location of local nonlinearities in structures. It is verified by simulation data from a cantilever beam model with two local nonlinearities and experimental data from a T-beam experimental set-up with a single local nonlinearity. A possible drawback is that a relatively large amount of data is needed. Advantages of the approach are that it only needs a single excitation point that response data at varying force amplitudes is not needed and that no prior information about the underlying linear system is needed.
Subject: Mechanical Engineering\General
Keywords: Location identification, Reverse-path, Structural nonlinearities, System identification