A magnetostrictive harvester is a device that converts mechanical vibrations or strain into electrical energy using a phenomenon known as magnetostriction. Magnetostriction refers to the property of certain materials to change their shape or dimensions when subjected to a magnetic field. This effect can be harnessed to create a mechanical-to-electrical energy conversion process in a magnetostrictive harvester. Here's how it works:
Material Selection: Magnetostrictive harvesters typically use materials known as magnetostrictive alloys, which exhibit the magnetostrictive effect. One common example is Terfenol-D, a compound composed of terbium, iron, and dysprosium.
Device Construction: The harvester is constructed with the magnetostrictive material as a core component. This material is often in the form of a rod or a strip within the device.
Mechanical Vibrations: When the magnetostrictive harvester is subjected to mechanical vibrations or strains, the magnetostrictive material within the device experiences these vibrations and undergoes changes in its shape or dimensions.
Magnetic Field: The harvester includes a permanent magnet or an electromagnet positioned near the magnetostrictive material. This magnetic field interacts with the magnetostrictive material and induces changes in its magnetization in response to the mechanical vibrations.
Induced Voltage: The changing magnetization of the magnetostrictive material generates fluctuations in the magnetic flux passing through the material. According to Faraday's law of electromagnetic induction, a changing magnetic flux induces an electromotive force (EMF) or voltage in nearby conductive coils or windings.
Coil Setup: The magnetostrictive harvester is equipped with a coil or coils of wire wound around the magnetostrictive material. These coils are connected to an external circuit and can transfer the induced voltage as an electrical signal.
Electrical Output: As the magnetostrictive material undergoes changes in shape due to mechanical vibrations, it causes the magnetic field around it to change. This change in the magnetic field induces voltage in the coils, which can be collected and used as electrical energy.
Conversion and Storage: The induced electrical voltage can be used to power electronic devices directly or can be stored in batteries or capacitors for later use.
In summary, a magnetostrictive harvester converts mechanical vibrations into electrical energy by utilizing the magnetostrictive effect in certain materials. The mechanical vibrations cause the magnetostrictive material to change its shape, which in turn induces changes in the surrounding magnetic field. This changing magnetic field induces voltage in nearby coils, which is then collected and used as electrical energy. This technology has applications in energy harvesting from various sources of mechanical vibrations, such as vibrations from machinery, vehicles, or even natural sources like wind and ocean waves.