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.
Keywords: Operational conditions, health monitoring, transmissibility
