Guided wave SHM with a distributed sensor network

It has been shown by many researchers that guided wave structural health monitoring is capable of detecting the presence of damage in a structure. The requirements for grid spacing and sensitivity to temperature change have been established and can be used to specify an array with a given signal to noise ratio. What is not clear at this point is how, given that damage is detectable, its location should be found. This paper discusses two different imaging algorithms and investigates the relative merits of each. This is initially done on the smallest possible array of three transducers. This is then carried forward to larger sparse arrays to show how a larger structure with a distributed sensor network can be imaged with several "units" of transducers working together. It is shown that in general using more transducers is beneficial to the quality of imaging achieved. However it is still necessary to perform imaging using smaller arrays to ensure that in the event of multiple damage sites occurring simultaneously each can be detected.