ABSTRACT
In general most the Lamb wave based SHM systems rely on a transducer network with permanently installed transducers, such as surface bonded or embedded transducers, to cover a pre-defined inspection area on a structure (Sohn et al. 2004; Su & Ye 2004; Ng 2015a). Each of the transducers can act as both actuator and sensor for excitation and measurement of Lamb waves. The damage detection is usually carried out by comparing the current measurements with the Lamb wave signals measured at pristine condition of the structure (baseline measurements). One of the commonly used approaches to extract the scattered wave information from the measured Lamb wave signals is to subtract the current measurements from the baseline measurements, i.e. baseline subtraction (Lee et al. 2011; Ng 2015a).
