ABSTRACT
Structural health monitoring (SHM) is aimed to determine health of a structure exposed to varying environmental and operational conditions as well as instrumentation noise (i.e., “real-world” conditions) while eliminating false indications. The basic premise of an SHM system is that damages alter stiffness, mass, or damping of a structure, and in turn cause changes in its dynamic response. The complete health state of a structure can be determined based on the presence, location, type and severity of damages (diagnostics), and estimation of remaining useful life (prognostics). The existing practice for ensuring structural safety (i.e., schedule-based maintenance) leads to expensive inspections, unnecessary downtime and retirement, and sometimes catastrophic failures without any warning. A reliable SHM system can inspect the structure continuously or periodically and provide the operator with up-to-date information about its health, which would provide tremendous benefits in terms of life-cycle costs by detecting damages early and allowing a much more efficient maintenance schedule (condition-based maintenance). Such a system would allow designers to relax the conservative designs and take full advantage of the benefits of advanced materials for engineered structures. Although SHM has experienced significantly increased research during the last decade, a damage detection method that can provide quantitative damage information anywhere in a complex structure, such as aircraft wings, wind turbine blades, or bridges, is still under development. Health monitoring of engineering structures is being pursued vigorously as evidenced by the proceedings of various conferences, journal publications, and recent books in the area.
