This paper proposes a design for monitoring high temperature structures utilizing phased array waveguide transducers, where the active sensing elements work synthetically together to achieve damage detection. The waveguide transducer is comprised of a wave-generation piezo element and a waveguide bar conducting the wave energy into the host structure. A coupled-field local finite element model (FEM) is constructed to grasp an in-depth understanding of the wave generation behavior. Via the harmonic analysis, optimum wave generation frequency and mode type can be analyzed. Thereafter, an array of waveguide transducer elements are attached to the host structure to study their wave manipulating ability. The system works based on the principle of phased array theory; the excitation instant of each element is controlled to form an equiphasic surface. In this way, the wave propagation phenomenon such as focusing and directional steering can be realized. An ultrasonic radar for high temperature working condition can thus be realized. The proposed system possesses great application potential to enhance the performance of Lamb wave SHM and NDE systems for high temperature structures.

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