In this paper, two separate topology optimization MATLAB codes are proposed for a piezoelectric plate in actuation and energy harvesting. The codes are written for one-layer piezoelectric plate based on 2D finite element modeling. As such, all forces and displacements are confined in the plane of the piezoelectric plate. For the material interpolation scheme, the extension of solid isotropic material with penalization approach known as PEMAP-P (piezoelectric material with penalization and polarization) which considers the density and polarization direction as optimization variables is employed. The optimality criteria and method of moving asymptotes (MMA) are utilized as optimization algorithms to update the optimization variables in each iteration. To reduce the numerical instabilities during optimization iterations, finite element equations are normalized. The efficiencies of the codes are illustrated numerically by illustrating some basic examples of actuation and energy harvesting. It is straightforward to extend the codes for various problem formulations in actuation, energy harvesting and sensing. The finite element modeling, problem formulation and MATLAB codes are explained in detail to make them appropriate for newcomers and researchers in the field of topology optimization of piezoelectric material.

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Piezoelectric materials based actuators are highly recognized for the development of microrobotic systems thanks to their high bandwidth, high resolution and high force density. However, one of their main drawback is the low relative stroke (0.1% of actuator's size) that limits the actuator motion range. Overcoming this limitation is challenging but would increase the achievable working space of microrobots. In this paper, topology optimization method is used to maximize the actuator stroke. Instead of optimizing only the material density, we also consider the optimization of the electrodes polarity. This approach allows to combine both material expansion and compression in order to increase the actuator output displacement. To demonstrate this approach, two actuators were designed starting from a full domain considered as a basic reference piezoelectric actuator. The first design considered only the density optimization while the second one took into account the optimization of the topology of electrodes. Both simulation and experiment showed a good agreement between the obtained designs and the fabricated prototypes. The result revealed that the optimized design with polarization has an improved factors of 2.8 and 2.02 compared to full plate and actuator without electrodes optimization, respectively.