Hanmin Lee

Parameter study and optimization for piezoelectric energy harvester for TPMS considering speed variation

In this paper, we perform design parameter study and design optimization for a piezoelectric energy harvester considering vehicle speed variation. Initially, a FEM model using ANSYS is developed to appraise the performance of a piezoelectric harvester in a rotating tire. The energy harvester proposed here uses the vertical deformation at contact patch area from the car weight and centrifugal acceleration. This harvester is composed of a beam which is clamped at both ends and a piezoelectric material is attached on the top of that. The piezoelectric material possesses the 31 mode of transduction in which the direction of applied field is perpendicular to that of the electric field. To optimize the harvester performance, we would change the geometrical parameters of the harvester to obtain the maximum power. One of the main challenges in the design process is obtaining the required power while considering the constraints for harvester weight and volume. These two concerns are addressed in this paper. Since the final goal of this study is the development of an energy harvester with a wireless sensor system installed in a real car, the real time data for varied velocity of a vehicle are taken into account for power measurements. This study concludes that the proposed design is applicable to wireless tire sensor systems.

Design Optimization Process for Electromagnetic Vibration Energy Harvesters Using Finite Element Analysis

This paper presents a systematic optimization process for designing an electromagnetic vibration energy harvester using FEA(finite element analysis) to improve computational accuracy and efficiency. A static FEA is used in the optimization process where trend analysis in a short period of time is rather important than precise computation, while a dynamic FEA is used in the verification step for the final result where precise computation is more important. An electromechanical transduction factor can be calculated efficiently by using an approach to use the radial component of magnetic flux density directly instead of an approach to compute the flux density gradient. The proposed optimization process was verified through a case study where simulation and experiment results were compared.

Computer-Aided Bicycle Design and Analysis System

This paper introduces the development of a three-dimensional bicycle design and analysis system. Recently, three-dimensional CAD systems have been introduced in bicycle design, but it is essential to automate many routines and difficult work to reduce design time and cost. To accomplish this object, we first analyzed design activities and main design parameters of bicycle frame and crank assembly, and then built a standard part library. We developed a design automation system that allows users to get three-dimensional bicycle models simply by changing pre-defined dimensions. We also developed a bicycle structural analysis system that guides users to structural performance evaluation step-by-step. By using these systems, design can be performed more intuitively, and verification and simulation of design results can be done more easily.