Structural Health Monitoring in Changing Operational Conditions Using Tranmissibility Measurements

Abstract

Abstract. This article uses frequency domain transmissibility functions for detecting and locating damage in operational conditions. In recent articles numerical and experimental examples were presented and the possibility to use the transmissibility concept for damage detection seemed quite promising. In the work discussed so far, it was assumed that the operational conditions were constant, the structure was excited by a single input in a fixed location. Transmissibility functions, defined as a simple ratio between two measured responses, do depend on the amplitudes or locations of the operational forces. The current techniques fail in the case of changing operational conditions. A suitable operational damage detection method should however be able to detect damage in a very early stage even in the case of changing operational conditions. It will be demonstrated in this paper that, by using only a small frequency band around the resonance frequencies of the structure, the existing methods can still be used in a more robust way. The idea is based on the specific property that the transmissibility functions become independent of the loading condition in the system poles. A numerical and experimental validation will be given.

Generalized Transmissibility Damage Indicator With Application to Wind Turbine Component Condition Monitoring

“…However, in the literature [15], [21], it has been pointed that several important issues, such as the frequency range and the location of input, have to be considered first. In this section, detailed discussions on these issues are given as below.…”

“…A carefully chosen frequency range can improve the detection accuracy. In [21], it has been shown that damage in a cantilever beam can be more accurately detected using a small frequency band around resonance frequencies of the structure than that using the whole frequency range. However, in many practical applications, it is hard to determine a specific frequency band without knowing the frequency responses of all possible damage or faults.…”

Whys and Wherefores of Transmissibility

“…Other recent studies have applied the transmissibility to the problem of transfer path analysis in vibro-acoustics (Tcherniak & Schuhmacher, 2009) and for damage detection (Canales et al, 2009;Devriendt, Vanbrabant, et al, 2009;Urgueira et al, 2011).…”

Output-only structural damage detection based on transmissibility measurements and kernel principal component analysis

“…As an alternative, transmissibility measurements have been widely explored as features in damage detection for SHM [9]- [12], due to their output-only nature [13]- [15], which implies the need for measuring only the response signals, without any knowledge about the excitation forces.…”