Propagation of nonlinear guided waves is a very attracting phenomenon for structural health\r\nmonitoring applications that has received a lot of attention in the last decades. They exhibit very\r\nlarge sensitivity to structural conditions when compared to traditional approaches based on linear\r\nwave features. On the other hand, the applicability of this technology is still limited because of\r\nthe lack of a solid understanding of the complex phenomena involved when dealing with real\r\nstructures. In fact the mathematical framework governing the nonlinear guided wave propagation\r\nbecomes extremely challenging in the case of waveguides that are complex in either materials\r\ndamping, anisotropy, heterogeneous, etc. or geometry multilayers, geometric periodicity, etc..\r\nThe present work focuses on the analysis of nonlinear second-harmonic generation in complex\r\nwaveguides by extending the classical Semianalytical Finite Element formulation to the nonlinear\r\nregime, and implementing it into a powerful commercial Finite Element package. Results are\r\npresented for the following cases: a railroad track and a viscoelastic plate. For these casestudies\r\noptimum combinations of primary wave modes and resonant double-harmonic nonlinear\r\nwave modes are identified. Knowledge of such combinations is critical to the implementation of\r\nstructural monitoring systems for these structures based on higher-harmonic wave generation.
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