Event Title

Design of a Functionally Graded Terfenol-D Epoxy Composite for Electric Current Sensing

Mentor 1

Dr. Chiu Tai Law

Location

Union Wisconsin Room

Start Date

29-4-2016 1:30 PM

End Date

29-4-2016 3:30 PM

Description

One well known property of Fiber Bragg Grating (FBG) is that its spectrum of reflected light depends upon the strain and temperature dependant Bragg period. The magnetoelastic properties of composite materials composed of Terfenol-D (TD), a giant magnetostrictive alloy, in an epoxy matrix have been used to transform magnetic field intensity into strain upon an embedded FBG. By placing the embedded FBG into the magnetic field caused by an electric current it can be used to detect the current’s strength. One method which has been implemented in the past measures the spectral shift in the reflectivity caused by that strain to infer the magnitude of electric current. One obstacle to this method is differentiating the effects of temperature change from those of strain. For temperature compensation, one can use a non-magnetostrictive material with coefficient of thermal expansion matched sensing element, however this provides difficulties in construction of the device. Here we investigate a design method which properly deployed will not be based upon analysis of the spectral response on a wavelength basis, but will instead utilize measurement of spectral power. We will implement this method by creation of a similar composite, the difference being it will have functionally graded TD particle size across its length. Research has shown magnetostrictive strain in a TD/epoxy composite varies proportionally to particle size, therefore we believe this will create a linear gradient in the magnetostrictive strain when exposed to a magnetic field resulting a simplified distinction between magnetostrictive and thermal effects. By measuring the change in the power with respect to the magnetic field strength instead of spectral shift we will be able to reduce the complexity of the system as well as reduce thermal drift.

This document is currently not available here.

Share

COinS
 
Apr 29th, 1:30 PM Apr 29th, 3:30 PM

Design of a Functionally Graded Terfenol-D Epoxy Composite for Electric Current Sensing

Union Wisconsin Room

One well known property of Fiber Bragg Grating (FBG) is that its spectrum of reflected light depends upon the strain and temperature dependant Bragg period. The magnetoelastic properties of composite materials composed of Terfenol-D (TD), a giant magnetostrictive alloy, in an epoxy matrix have been used to transform magnetic field intensity into strain upon an embedded FBG. By placing the embedded FBG into the magnetic field caused by an electric current it can be used to detect the current’s strength. One method which has been implemented in the past measures the spectral shift in the reflectivity caused by that strain to infer the magnitude of electric current. One obstacle to this method is differentiating the effects of temperature change from those of strain. For temperature compensation, one can use a non-magnetostrictive material with coefficient of thermal expansion matched sensing element, however this provides difficulties in construction of the device. Here we investigate a design method which properly deployed will not be based upon analysis of the spectral response on a wavelength basis, but will instead utilize measurement of spectral power. We will implement this method by creation of a similar composite, the difference being it will have functionally graded TD particle size across its length. Research has shown magnetostrictive strain in a TD/epoxy composite varies proportionally to particle size, therefore we believe this will create a linear gradient in the magnetostrictive strain when exposed to a magnetic field resulting a simplified distinction between magnetostrictive and thermal effects. By measuring the change in the power with respect to the magnetic field strength instead of spectral shift we will be able to reduce the complexity of the system as well as reduce thermal drift.