Topology optimization of piezoelectric transducers considering functionally graded material: design, simulation, analysis and fabrication.

Piezoelectric materials generate displacements when they are excited by electrical potential and electrical potential when they are excited by force or pressure. These materials are widely applied in Precision Mechanics, Mechatronics, and Ultrasonic imaging areas. On the other hand, Functionally Graded Materials (FGM) are advanced materials, whose properties change continuously in a specified direction. These materials combine desirable features of their constituent phases; for instance, high temperature resistance typical of ceramics with mechanical strength of metals. Several works have shown the advantages of applying FGM concept to piezoelectric transducer design. These advantages are; for example: (i) flextensional actuators without interfaces (e.g. PZT and Aluminum); (ii) smoothing mechanical stresses; and (iii) increasing bandwidth and reducing reflected waves in ultrasonic transducers. However, in the literature, a lack of computational methods for modeling and systematic designing of Functionally Graded Piezoelectric Transducers (FGPT) is observed. According to above ideas, this work proposes the formulation and development of analytical models, finite element algorithms, and topology optimization algorithms to design novel Functionally Graded Piezoelectric Transducers (FGPT). In addition, FGPT samples are manufactured by using Spark Plasma Sintering SPS, where it is studied their dynamic behavior and their microstructural characteristics. Hence, by performing analysis, optimal designing, manufacturing and characterization, the FGM concept potential is explored for FGPTs; particularly, FGPTs can bring advantages in ultrasonic non-destructive testing and ultrasonic medical imaging, and increasing life-time of flextensional piezoelectric transducers. (AU)