Structural health monitoring

Compared to the relatively slow development of fixed wing aircraft loads monitoring, helicopters are possibly a step ahead. Helicopters today are only sold with a health and usage monitoring system (HUMS), which is mainly 

Active damage interrogation sensors placed around cargo door surround 

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Figure 1.6. Application of large-area embedded flexible control electronics includes structural health monitoring of large objects such as airframes.

Qing, X. P. Chan, H.-L. Beard, S. I Kumar, A. 2006. An active diagnostic system for structural health monitoring of rocket engines. /. Intelligent Material Systems and Struct. 17 619-628. 

While conductivities of nanocarbons dispersed in polymers fall short of those of metals, a variety of applications can be unlocked by turning an insulating matrix into a conductor, which requires only small volume fractions that can therefore keep the system viscosity at a level compatible with composite processing techniques. Of particular interest are novel functionalities of these conductive matrices that exploit the presence of a conductive network in them, such as structural health monitoring (SHM) based on changes in electrical resistance of the nanocarbon network as it is mechanically deformed [30]. 

In addition to mechanical reinforcement, the presence of nanocarbons in these hierarchical composites can also be used for piezoresistive structural health monitoring or damage evaluation by thermal imaging. Other functions of the nanocarbon, for example in structural supercapacitors, are likely to emerge in the near future. 

A newer class of materials called smart tagged composites has been developed for structural health monitoring applications. These composites consist of PZT-5A particles embedded into the matrix resin (unsaturated polyester) of the composite. 

Soutis C, Dm J-B. Design, analysis and structural health monitoring of bonded composite repair and substructure. In Boiler C, Chang F-K, Fujino Y, editors. Encyclopaedia of structural health monitoring. J. Wiley Sons Ltd. 2009, ISBN 978-0-470-05822-0. pp. 1923-40. 

Structural health monitoring (SHM) rehes on sensors that can be permanently placed on the stracture and monitored over time either in a passive or in an active way. These sensors should be affordable, hghtweight, and unobtrasive such as to not impose cost and weight penalty on the stmcture and to not interfere with the structural strength and airworthiness. Some of the sensor types that have been considered for SHM appUca-tions are ... 

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