A decentralized procedure for structural health monitoring of uncertain nonlinear systems provided with dense active sensor arrays

Abstract

A numerical simulation study is conducted to evaluate the feasibility of a proposed algorithm for testing and analyzing the vibration signature of complex, nonlinear and uncertain structural systems provided with dense, active sensor arrays that have the capability to generate local probing signals. The proposed algorithm for 'decentralized' identification of the parameters of a highly reduced-order model can be easily embedded in simple processors that are incorporated in modern wireless sensors, without the need for demanding computational resources or inter-sensor communications. It is shown that the proposed estimation approach, in which a reduced-order equivalent single-degree-of-freedom linear system is identified to match the observed response of a specific sensor/actuator pair, is capable of detecting relatively small changes in the estimated system parameters. These parameters can be directly correlated with physically meaningful measures of the structural dynamic properties of the system being monitored. A parametric study is conducted to determine the robustness of the proposed approach with regard to variation in 'damage' location relative to the sensor location, 'damage' magnitude, scatter in the estimated system parameters due to the stochastic nature of the nonlinear system and variability (uncertainty) in the reference system parameters. It is shown that the proposed approach is viable for implementations involving sensor 'motes' with limited storage and computational resources.

Finite Element Model Updating Using Evolutionary Strategy for Damage Detection

“…Finite element model updating is inherently a time‐consuming process which makes it impractical for on‐line prediction of system parameters. On the other hand, change‐detection in modal properties (i.e., frequencies, mode shapes, and system damping) is quite well known as an easily quantifiable structural damage index in the field of SHM (Masri et al, 2008). Hence, a preliminary damage tracking technique that relies on detection of any shift in these quantities to trigger the model updating procedure may drastically increase its efficacy.…”

“…Hence, a preliminary damage tracking technique that relies on detection of any shift in these quantities to trigger the model updating procedure may drastically increase its efficacy. Notice that, actual damage in real structures manifests itself in different complex forms (Masri et al, 2008) and therefore, one of the practical challenges in conjunction with damage detection in physical systems is the monitoring indicators. For example, it is well recognized in the structural dynamics community that, solely detecting frequency shifts is a poor precursor of damage in realistic systems, due to its relative insensitivity to small changes (Nayeri et al, 2008).…”