Event Title

Magnetostrictive Electric Current Sensor

Mentor 1

Chiu Tai Law

Mentor 2

Rani El-Hajjar

Location

Union Wisconsin Room

Start Date

24-4-2015 10:30 AM

End Date

24-4-2015 11:45 AM

Description

Application of a magnetostrictive composite in an electric current Brett Sweeneya, Suha Mubarak Lasassmehb, Rani El-Hajjarc, and Chiu Tai Lawb a Dept of Mechanical Engineering b Dept of Electrical Engineering and Computer Science c Dept of Civil and Environmental Engineering University of Wisconsin – Milwaukee, 3200 N. Cramer St., Milwaukee WI 53211 Using Terfenol-D as a material for a fiber optical current sensor (FOCS) is a technology that hasjust been gaining attention of researchers. Coupling Terfenol-D with a fiber Bragg grating (FBG) is an excellent method of magnetic field sensing. However, Terfenol-D is a very brittle material and is difficult to handle. Here, a magnetostriction-based FOCS using a Terfenol-D/epoxy composite is investigated. It consists of an FBG embedded in the composite that converts magnetostrictive strain into frequency chirp of optical signal proportional to a magnetic field. This sensor would be applicable in any situation that requires closely monitoring of an electric current, e.g. the detection of fault current in power systems. The FOCS is based on applying magnetostrictive composite as a transducer that transform a magnetic field into a corresponding mechanical strain caused by the deformation of the composite under the magnetic field. Since Terfenol-D is a giant magnetostrictive material, it can maximize the FOCS response. Its composite is incorporated in the FOCS for increased durability, flexibility in shape, extended frequency response, and tensile strength compared to monolithic materials. For electromagnetic interference mitigation and optimal signal condition, an FBG, which can be easily integrated with an optical fiber network and reflect certain wavelengths based on grating periods, is used to encode strain information onto optical signal. Particularly, the return optical spectrum reflects the strain distribution. A magnetostrictive composite with certain engineered Terfenol-D particle distribution can exert various strain distributions according to different values of magnetic field. Here, the FBG is epoxied between two identical composites in rectangular shape with triangular distribution of Terfenol-D particles that produce an approximately linear strain distribution along the FBG. As a result, the optical signal reflected by the FBG has a spectral width proportional to the magnetic field. The two identical composites are constructed in piece-meal using Terfenol-D particles with sizes ranging from 250–300 μm and a two part epoxy. The mixture of Terfenol-D and epoxy is poured into two identical right angle triangular molds to produce two triangular magnetostrictive composites under a magnetic field that aligns particles along the longer leg of the right angle triangle. Two more pure epoxy triangular pieces are fabricated with the same molds. Each rectangular composite is composed of two right angle triangular pieces with only one of them being magnetostrictive. This setup can potentially allow greater flexibility in tailoring the sensitivity and dynamic range of the sensor.

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Apr 24th, 10:30 AM Apr 24th, 11:45 AM

Magnetostrictive Electric Current Sensor

Union Wisconsin Room

Application of a magnetostrictive composite in an electric current Brett Sweeneya, Suha Mubarak Lasassmehb, Rani El-Hajjarc, and Chiu Tai Lawb a Dept of Mechanical Engineering b Dept of Electrical Engineering and Computer Science c Dept of Civil and Environmental Engineering University of Wisconsin – Milwaukee, 3200 N. Cramer St., Milwaukee WI 53211 Using Terfenol-D as a material for a fiber optical current sensor (FOCS) is a technology that hasjust been gaining attention of researchers. Coupling Terfenol-D with a fiber Bragg grating (FBG) is an excellent method of magnetic field sensing. However, Terfenol-D is a very brittle material and is difficult to handle. Here, a magnetostriction-based FOCS using a Terfenol-D/epoxy composite is investigated. It consists of an FBG embedded in the composite that converts magnetostrictive strain into frequency chirp of optical signal proportional to a magnetic field. This sensor would be applicable in any situation that requires closely monitoring of an electric current, e.g. the detection of fault current in power systems. The FOCS is based on applying magnetostrictive composite as a transducer that transform a magnetic field into a corresponding mechanical strain caused by the deformation of the composite under the magnetic field. Since Terfenol-D is a giant magnetostrictive material, it can maximize the FOCS response. Its composite is incorporated in the FOCS for increased durability, flexibility in shape, extended frequency response, and tensile strength compared to monolithic materials. For electromagnetic interference mitigation and optimal signal condition, an FBG, which can be easily integrated with an optical fiber network and reflect certain wavelengths based on grating periods, is used to encode strain information onto optical signal. Particularly, the return optical spectrum reflects the strain distribution. A magnetostrictive composite with certain engineered Terfenol-D particle distribution can exert various strain distributions according to different values of magnetic field. Here, the FBG is epoxied between two identical composites in rectangular shape with triangular distribution of Terfenol-D particles that produce an approximately linear strain distribution along the FBG. As a result, the optical signal reflected by the FBG has a spectral width proportional to the magnetic field. The two identical composites are constructed in piece-meal using Terfenol-D particles with sizes ranging from 250–300 μm and a two part epoxy. The mixture of Terfenol-D and epoxy is poured into two identical right angle triangular molds to produce two triangular magnetostrictive composites under a magnetic field that aligns particles along the longer leg of the right angle triangle. Two more pure epoxy triangular pieces are fabricated with the same molds. Each rectangular composite is composed of two right angle triangular pieces with only one of them being magnetostrictive. This setup can potentially allow greater flexibility in tailoring the sensitivity and dynamic range of the sensor.