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Vulture Technologies Project Update 1 15 February 2007. Vibration Harvesting Device. Magnet. Design: Geometric configuration transfer of vibrational energy from source to magnet Source: Donations from Prof. O'Handley and/or Prof. Ross Type: Powerful, probably rare earth (NdFeB).
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Magnet • Design: • Geometric configuration • transfer of vibrational energy from source to magnet • Source: Donations from Prof. O'Handley and/or Prof. Ross • Type: Powerful, probably rare earth (NdFeB)
Magnetostriction • “Deformation of a body in response to a change in its magnetization.” Engdahl, G. (2000). Handbook of Giant Magnetostrictive Materials. San Diego: Academic Press. • Arises from an imbalance in magnetic moments of electrons • Type: CoFe, TERFENOL-D, GALFANOL (FeGa) • Challenges: TERFENOL-D: eddy current loss, brittle
Piezoelectricity • Property of materials to convert between mechanical strain and voltage • Challenges: Stiffness, anisotropy, leads • Design: Geometry, ratio of piezo to magnetostrictive • Type: PZT, BaTi • Sources: Morgan, TRS
Lamination • Design question: How to connect magnetostrictive to piezoelectric to maximize transferred strain and minimize chance of failure? • Options: • Bulk: Conductive epoxy (Ag) • Composite: cold compression
Power Conditioning • Design question: How to most effectively normalize and store the electric energy produced by the device? • Challenges • Appropriate size capacitor/battery • Rectifying circuit • Appropriate resistance in circuit • Sources: EE students
Application • Sources: • Windows on busy street: 100 Hz at 1μm • The London Millenium Footbridge: 1.1 Hz. • Uses: • Small or non-constant powered devices • Existing devices <1 mW • LED ( ~30 mW) • Themocouple; wireless sensor; actuator
Next Research Steps • Evaluate kinetic energy of various sources • Ducts, motors, ground • Calculate energy loss through 2 transformations • mechanical→magnetic→electrical (DC↔AC) • Answer materials questions • Will magnetostrictive strain cause failure in piezo? • Ideal frequencies; ratio magnetostrictive/piezo • Bulk vs. Composite