Design Scalability Study of the Γ-Shaped Piezoelectric Harvester Based on Generalized Classical Ritz Method and Optimization

• Main Authors: Sinwoo Jeong, Soobum Lee, Honghee Yoo
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Electronics
• Subjects: piezoelectric energy harvester; generalized classical Ritz method; shape optimization; differential evolution; normalized power density; design scalability
• Online Access: https://www.mdpi.com/2079-9292/10/16/1887

This paper studies the design scalability of a <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Γ</mi></semantics></math></inline-formula>-shaped piezoelectric energy harvester (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Γ</mi></semantics></math></inline-formula>EH) using the generalized classical Ritz method (GCRM) and differential evolution algorithm. The generalized classical Ritz method (GCRM) is the advanced version of the classical Ritz method (CRM) that can handle a multibody system by assembling its equations of motion interconnected by the constraint equations. In this study, the GCRM is extended for analysis of the piezoelectric energy harvesters with material and/or orientation discontinuity between members. The electromechanical equations of motion are derived for the PE harvester using GCRM, and the accuracy of the numerical simulation is experimentally validated by comparing frequency response functions for voltage and power output. Then the GCRM is used in the power maximization design study that considers four different total masses—15 g, 30 g, 45 g, 60 g—to understand design scalability. The optimized <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="sans-serif">Γ</mi></semantics></math></inline-formula>EH has the maximum normalized power density of 23.1 × 10³ kg·s·m⁻³ which is the highest among the reviewed PE harvesters. We discuss how the design parameters need to be determined at different harvester scales.