Development of Resonators with Reversible Magnetostrictive Effect for Applications as Actuators and Energy Harvesters

Abstract

This chapter presents the methodology of designing and testing wideband actuators and energy harvesters which can be treated as one device called a mechanical resonator. In order to obtain described effects, the magnetostriction phenomenon was used. This effect enables the construction of resonators in selected frequency bands, including the ultrasonic range. Cores made of giant magnetostrictive materials (GMM) were used for the construction. Considerable attention was given to composite cores to reduce the weight of pure Terfenol-D. The influence of the volume fraction of Terfenol-D powder, the size of its grains, and the direction of polarization on the value of magnetostriction in a wide frequency band were investigated. The magnetostriction of composite cores and solid Terfenol-D samples was also compared. The structure and the use of magnetostrictive cores containing a combination of NdFeB magnets and pure Terfenol-D are also presented. An important issue was also the development of our own methodology of magnetostriction testing, including the use of fiber optic sensors (Fiber Bragg Grating sensors, FBGs), Hall's sensors, and the original measuring system for magnetic field visualization (Magscanner). The chapter also discusses several own designs of actuators and energy harvesters, including shock harvester, resonant harvester, and energy transmission system.

Multi-phase Magnetostrictive Actuator Dedicated to Close-Loop Vibration Control System

“…The number of core components (GMM rods, neodymium magnets, pressure mandrels) is of key significance for its construction, the fewer of them, the higher work frequencies are achieved. One of the solutions used in the core is a system made of alternately located neodymium magnets and Terfenol-D rods [3].…”

“…The authors have considerable experience in constructing actuators and magnetostrictive actuator harvesters [3], and their earlier research on the use of Terfenol-D have found a number of applications in exciters and vibration transducers [2,7,8].…”