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Functionally Graded Materials (FGMs) possess continuous variation of material properties and are characterized
by spatially varying microstructures. Recently, the FGM concept has been explored in piezoelectric materials
to improve properties and to increase the lifetime of piezoelectric actuators. Elastic, piezoelectric, and dielectric
properties are graded along the thickness of a piezoceramic FGM. Thus, the gradation of piezoceramic properties
can influence the performance of piezoactuators, and an optimum gradation can be sought through optimization
techniques. However, the design of these FGM piezoceramics are usually limited to simple shapes. An interesting
approach to be investigated is the design of FGM piezoelectric mechanisms which essentially can be defined as a
FGM structure with complex topology made of piezoelectric and non-piezoelectric material that must generate
output displacement and force at a certain specified point of the domain and direction. This can be achieved by
using topology optimization method. Thus, in this work, a topology optimization formulation that allows the
simultaneous distribution of void and FGM piezoelectric material (made of piezoelectric and non-piezoelectric
material) in the design domain, to achieve certain specified actuation movements, will be presented. The method
is implemented based on the SIMP material model where fictitious densities are interpolated in each finite element,
providing a continuum material distribution in the domain. The optimization algorithm employed is based on
sequential linear programming (SLP) and the finite element method is based on the graded finite element concept
where the properties change smoothly inside the element. This approach provides a continuum approximation
of material distribution, which is appropriate to model FGMs. Some FGM piezoelectric mechanisms were
designed to demonstrate the usefulness of the proposed method. Examples are limited to two-dimensional models,
due to FGM manufacturing constraints and the fact that most of the applications for such FGM piezoelectric
mechanisms are planar devices. An one-dimensional constraint of the material gradation is imposed to provide
more realistic designs.
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