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Dynamic strain measured by Mach-Zehnder interferometric optical fiber sensors.

Her SC, Yang CM - Sensors (Basel) (2012)

Bottom Line: Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent.A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer.The experimental results are validated with the strain gauge.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan. mesch@saturn.yzu.edu.tw

ABSTRACT
Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge.

No MeSH data available.


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Cantilever beam mounted on a shaker.
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f6-sensors-12-03314: Cantilever beam mounted on a shaker.

Mentions: A cantilever beam subjected to base excitation is considered in the experimental test. The beam of length L = 285 mm, width b = 20 mm, thickness h = 1 mm is made of copper with elastic modulus E = 120 GPa, density ρ = 8,740 kg/m3. An optical fiber is surface bonded to the middle of the cantilever beam as the sensing fiber of the Mach-Zehnder interferometer. The percentage of the strain in the test specimen actually transferred to the optical fiber is dependent on the bonding length [20]. The bonding length is Lf = 60 mm in this work. The material properties for the optical fiber are [21]: elastic modulus Ef = 72 GPa, Poisson’s ratio vf = 0.17, index of refraction n0 = 1.45, pockel’s constants p11 = 0.12, p12 = 0.27, radius rf = 62.5 μm. An electric resistance strain gauge is adhered to the cantilever beam near by the optical fiber. The optical fiber sensing system is a Mach-Zehnder interferometer with a 3 × 3 coupler as shown in Figure 2, operating at the wavelength of λ = 1,547.28 nm. The cantilever beam is mounted on a shaker as shown in Figure 6. The shaker is capable of providing maximum of four different frequencies in the same test. The natural frequency of a cantilever beam can be calculated using the following equations:(14a)1+cosβLcoshβL=0(14b)ωi=βi2EIρAwhere βi is the root of Equation (14a); E, ρ, L, A, and I are the Young’s modulus, density, length, cross section area and moment of inertia of the cantilever beam, respectively.


Dynamic strain measured by Mach-Zehnder interferometric optical fiber sensors.

Her SC, Yang CM - Sensors (Basel) (2012)

Cantilever beam mounted on a shaker.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376560&req=5

f6-sensors-12-03314: Cantilever beam mounted on a shaker.
Mentions: A cantilever beam subjected to base excitation is considered in the experimental test. The beam of length L = 285 mm, width b = 20 mm, thickness h = 1 mm is made of copper with elastic modulus E = 120 GPa, density ρ = 8,740 kg/m3. An optical fiber is surface bonded to the middle of the cantilever beam as the sensing fiber of the Mach-Zehnder interferometer. The percentage of the strain in the test specimen actually transferred to the optical fiber is dependent on the bonding length [20]. The bonding length is Lf = 60 mm in this work. The material properties for the optical fiber are [21]: elastic modulus Ef = 72 GPa, Poisson’s ratio vf = 0.17, index of refraction n0 = 1.45, pockel’s constants p11 = 0.12, p12 = 0.27, radius rf = 62.5 μm. An electric resistance strain gauge is adhered to the cantilever beam near by the optical fiber. The optical fiber sensing system is a Mach-Zehnder interferometer with a 3 × 3 coupler as shown in Figure 2, operating at the wavelength of λ = 1,547.28 nm. The cantilever beam is mounted on a shaker as shown in Figure 6. The shaker is capable of providing maximum of four different frequencies in the same test. The natural frequency of a cantilever beam can be calculated using the following equations:(14a)1+cosβLcoshβL=0(14b)ωi=βi2EIρAwhere βi is the root of Equation (14a); E, ρ, L, A, and I are the Young’s modulus, density, length, cross section area and moment of inertia of the cantilever beam, respectively.

Bottom Line: Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent.A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer.The experimental results are validated with the strain gauge.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan. mesch@saturn.yzu.edu.tw

ABSTRACT
Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge.

No MeSH data available.


Related in: MedlinePlus