Topology Optimization of Piezoelectric Energy Harvesting Strap Buckle

In the past decades, the stagnant growth of battery technology becomes the bottle-neck of new generation of portable and wearable electronics which ask for longer work time and higher power consumption. Energy harvesting device based on the direct piezoelectric effect that converts ambient mechanical energy to usable electric energy is a very attractive energy source for portable and wearable electronics. This paper discusses the design of piezoelectric energy harvesting strap buckle that can generate as much as possible electric energy from the differential forces applying on the buckle. Topology optimization method is employed to improve the efficiency of piezoelectric energy harvesting strap buckle in a limited design space. A stiffness or displacement constraint is introduced to substitute material volume constraint in this problem formulation to avoid useless optimum result with nearly zero material volume. The sensitivities of both objective function and design constraint are derived from the adjoint method. A design example of piezoelectric energy harvesting strap buckle using the proposed topology optimization method is presented and the result is discussed.