Fiber bragg grating inclination sensor

A fiber Bragg grating inclination sensor, including a semicircular substrate and a packaged fiber Bragg grating. The semicircular substrate is fixed on a first structural member. One endpoint of the semicircular substrate is bonded with one end of the packaged fiber Bragg grating, and the other end of the packaged fiber Bragg grating is connected to a second structural member. The first structural member is fixed to the second structural member perpendicular to the first structural member. The packaged fiber Bragg grating is arranged on a tangent to the semicircular substrate. The fiber Bragg grating sensor of the present invention has the advantages of anti-electromagnetic interference and high sensitiveness. The present invention has a simple structure, high measurement accuracy, good stability, thereby having broad application prospects.

TECHNICAL FIELD

The present application relates to fiber Bragg grating sensing and monitoring, and more particular to a fiber Bragg grating inclination sensor.

BACKGROUND OF THE INVENTION

Differential settlement of foundations will severely and adversely affect house structures, which may cause global or local inclination of the structure, and structural cracking may occur as the result of a large local inclination. Therefore, monitoring the inclination of structural members is of great importance. The conventional inclination sensors are mainly electrical sensors, and the signal is susceptible to interference, thereby causing low accuracy.

SUMMARY OF THE INVENTION

The present application relates to a fiber Bragg grating inclination sensor.

The technical solutions of the present invention are as follows.

A fiber Bragg grating inclination sensor comprises a first structural member, a second structural member, a semicircular substrate, and a packaged fiber Bragg grating.

The semicircular substrate is fixed on the first structural member, and one endpoint of the semicircular substrate is bonded with one end of the packaged fiber Bragg grating.

The other end of the packaged fiber Bragg grating is connected to the second structural member. The first structural member is fixed to the second structural member perpendicular to the first structural member.

The packaged fiber Bragg grating is arranged on a tangent to the semicircular substrate.

The present invention has the following benefits.

1. The fiber Bragg grating sensor of the present invention has the advantages of anti-electromagnetic interference, high sensitiveness and high accuracy.

2. The present invention has a simple structure, high measurement accuracy, good stability, thereby having broad application prospects.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention will be further described in detail below with reference to the accompanying drawings.

A fiber Bragg grating inclination sensor, comprising a first structural member3, a second structural member4, a semicircular substrate1, and a packaged fiber Bragg grating2.

The semicircular substrate1is fixed on the first structural member3, and one endpoint of the semicircular substrate1is bonded with one end of the packaged fiber Bragg grating2.

The other end of the packaged fiber Bragg grating2is connected to the second structural member4. The first structural member3is fixed to the second structural member4perpendicular to the first structural member3.

The packaged fiber Bragg grating2is arranged on a tangent to the semicircular substrate1.

A lower portion of the semicircular substrate1is provided with a fixing flange11; the first structural member3is provided with a recess31to fix the fixing flange.

The semicircular substrate is made of Q235 steel.

An adhesive for the packaged fiber Bragg grating is 353ND.

A bottom surface of the semicircular substrate is bonded onto a surface of the first structural member.

Working principle of the present invention is as follows.

When the semicircular substrate1is rotated, θ is the inclination angle, and R is the radius of the semicircular structure. Referring toFIG. 2,
LAM=L1(1)

where LAMand L1each are the initial length of a sensor of the packaged fiber Bragg grating2;

where LAM′is the changed length of the packaged fiber Bragg grating2;
θ=2α  (3)

θ is the central angle, and α is the circumferential angle;

According to the law of cosines,

where R is the radius;

and plug (1) and (2) into (7),

This equation gives a theoretical relationship between the inclination angle θ and the wavelength change ΔλB. By demodulating the wavelength change of the sensor of the packaged fiber Bragg grating2, a change value of the inclination angle of the semicircular substrate1is obtained, realizing a real-time online monitoring of the structural inclination.