A magnetostrictive system in bridges converts structural vibrations into electrical power through the principle of magnetostriction. Magnetostriction is a phenomenon where certain materials change their shape under the influence of a magnetic field. In this context, the system involves utilizing magnetostrictive materials to generate electrical energy from the vibrations and deformations that occur in a bridge due to traffic loads, wind, or other dynamic forces.
Here's a basic overview of how the process works:
Magnetostrictive Material: Magnetostrictive materials are chosen for their ability to change shape under the influence of a magnetic field. These materials experience mechanical strain when subjected to a magnetic field, causing them to deform slightly.
Setup: The magnetostrictive material is typically integrated into the structural elements of the bridge that experience significant vibrations and deformations. Common materials used for this purpose include Terfenol-D and Galfenol.
Magnetic Coils: Magnetic coils or solenoids are placed near the magnetostrictive material. When an electric current passes through these coils, they generate a magnetic field around the magnetostrictive material.
Vibrations and Deformations: As the bridge experiences vibrations and deformations from various sources like passing vehicles or wind, the magnetostrictive material embedded in the structure undergoes slight changes in shape.
Magnetostriction Effect: The mechanical strains caused by the vibrations and deformations lead to changes in the magnetostrictive material's magnetic properties. This, in turn, alters its magnetic susceptibility and the way it interacts with the nearby magnetic field generated by the coils.
Induced Voltage: The changes in the magnetic properties of the magnetostrictive material induce fluctuations in the magnetic field generated by the coils. These fluctuations result in an induced voltage across the coils according to Faraday's law of electromagnetic induction.
Electrical Output: The induced voltage generated across the coils can be captured and harnessed as electrical energy. This voltage can be rectified and stored in batteries or capacitors, or it can be directly fed into the electrical grid or used to power local devices.
It's important to note that magnetostrictive energy harvesting systems are most effective when the structural vibrations and deformations are consistent and repetitive, as this allows for a consistent generation of electrical energy. However, the energy harvested from this method might be relatively low compared to more conventional energy sources. These systems are often used as supplementary power sources in places where consistent structural vibrations are available, such as in bridges, buildings, or other infrastructure.