Elastic waves in quasiperiodic structures

We study the transverse and sagittal elastic waves in different quasiperiod ic structures by means of the full transfer-matrix technique and surface Gr een-function matching method. The quasiperiodic structures follow Fibonacci , Thue-Morse and Rudin-Shapiro sequences, respectively. We consider finite structures having stress-free bounding surfaces and different generation or ders, including up to more than 1000 interfaces. We obtain the dispersion r elations for elastic waves and spatial localization of the different modes. The fragmentation of the spectrum for different sequences is evident for i ntermediate generation orders, in the case of transverse elastic waves, whe reas, for sagittal elastic waves, higher generation orders are needed to sh ow clearly the spectrum fragmentation. The results of Fibonacci and Thue-Mo rse sequences exhibit similarities not present in the results of Rudin-Shap iro sequences. (C) 2001 Elsevier Science Ltd. All rights reserved.