CN101285846A - Fiber Bragg Grating Accelerometer Based on Cantilever Beam Deflection - Google Patents

Abstract

The present invention relates to the technical field of optical fiber sensors, and discloses a fiber grating accelerometer based on the deflection of a cantilever beam. Side wall n, third side wall p, and fourth side wall q; a fiber grating 2 for measuring acceleration, one end of the fiber grating 2 is fixedly connected to the proof mass 5, and the other end is parallel to the first side wall m and passes through the The hole 6 on the second side wall n of the fiber grating accelerometer extends to the outside of the fiber grating accelerometer; one end is horizontally fixed on the cantilever beam 3 on the third side wall p of the fiber grating accelerometer, for The vibration signal is transmitted to the fiber grating 2; the mass block 5 fixed at the other end of the cantilever beam 3 is used to adjust the sensitivity and natural frequency of the fiber grating accelerometer. The invention improves the sensitivity of the fiber grating accelerometer and improves the packaging process of the fiber grating accelerometer.

Description

Fiber Bragg Grating Accelerometer Based on Cantilever Beam Deflection

technical field

The invention relates to the technical field of optical fiber sensors, in particular to an optical fiber grating accelerometer based on the deflection of a cantilever beam.

Background technique

Compared with the corresponding conventional sensors, optical fiber sensors also have obvious advantages in terms of sensitivity, dynamic range, and reliability. They are particularly prominent in the fields of national defense and military applications, and are listed as key national defense technologies by many countries.

Optical fiber accelerometer is an instrument that uses the light transmission characteristics of optical fiber and various modulation effects generated by its interaction with the surrounding environment to detect vibrations on the ground, in the air or on the seabed. Compared with the traditional piezoelectric accelerometer, it has the following main advantages: wide frequency range, high sound pressure sensitivity, no electromagnetic interference, light weight, can be designed into any shape, and has both information sensing and optical information transmission in One suit and other advantages.

In view of the above technical advantages of the fiber optic accelerometer, it can meet the requirements of various developed countries in the fields of petroleum and military affairs, and research has been actively carried out in this area.

Among the common intensity-modulated, digital, and FBG-based fiber accelerometers, FBG-based accelerometers have attracted widespread attention due to their small size and easy reusability.

Yu Youlong and others reported a kind of fiber grating accelerometer, which adopts the method of bonding the fiber grating on the surface of the cantilever beam. When the cantilever beam vibrates, there will be periodic compressive and tensile strains on its surface, and the fiber grating can measure the vibration by detecting the strain on the cantilever beam surface. In this technical solution, on the one hand, the gate region of the fiber grating is directly encapsulated by glue, which is easy to cause chirp of the fiber grating; sensitivity.

Therefore, how to improve the packaging form of the FBG accelerometer and improve the sensitivity of the FBG accelerometer is an important technical problem that must be solved for the large-scale application of the FBG accelerometer.

Contents of the invention

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide a fiber grating accelerometer based on the deflection of the cantilever beam, so as to improve the sensitivity of the fiber grating accelerometer and improve the packaging process of the fiber grating accelerometer.

(2) Technical solution

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A fiber grating accelerometer based on the deflection of a cantilever beam, the fiber grating accelerometer comprising:

As the housing 1 of the fiber grating accelerometer supporting structure, it has a first side wall m, a second side wall n, a third side wall p and a fourth side wall q;

A fiber grating 2 for measuring acceleration, one end of the fiber grating 2 is fixedly connected to the mass block 5, and the other end is parallel to the first side wall m and passes through the hole 6 on the second side wall n of the fiber grating accelerometer and extends to the exterior of the fiber grating accelerometer;

One end is horizontally fixed to the cantilever beam 3 on the third side wall p of the FBG accelerometer, which is used to transmit the vibration signal to the FBG 2;

The mass block 5 fixed at the other end of the cantilever beam 3 is used to adjust the sensitivity and natural frequency of the fiber grating accelerometer.

In the above solution, the hole 6 is located on the second side wall n of the FBG accelerometer, and is used to lead out and fix the pigtail of the FBG 2 .

In the above solution, the fiber grating 2 is perpendicular to the cantilever beam 3 and has a certain initial stress.

In the above solution, the mass of the mass block 5 is much larger than that of the cantilever beam 3, so as to reduce the nonlinear effect of the fiber grating accelerometer.

In the above scheme, when the fiber grating vibration sensor is excited by vibration, the cantilever beam 3 and the mass block 5 form a spring-mass system, and the mass block 5 vibrates in a direction perpendicular to the cantilever beam 3, driving the cantilever beam 3 A certain deflection is generated, and the vibration of the cantilever 3 causes the axial stress in the fiber grating 2 to change periodically in accordance with the vibration frequency.

In the above solution, the cantilever beam 3 is horizontally fixed on the third side wall p of the fiber grating accelerometer through the support 4 .

In the above solution, the sensitivity and natural frequency of the fiber grating accelerometer can be changed by adjusting the mass of the mass block 5 or changing the material and structural parameters of the cantilever beam 3 .

(3) Beneficial effects

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. The fiber Bragg grating accelerometer based on the deflection of the cantilever provided by the present invention converts the deflection of the cantilever into the axial displacement of the fiber grating. A greater strain is generated, which makes the FBG accelerometer have higher sensitivity.

2. The fiber grating accelerometer based on the deflection of the cantilever beam provided by the present invention is fixed at both ends of the fiber grating, which simplifies the packaging process while avoiding the chirp of the fiber grating, and the manufacturing process is simple.

3. The fiber grating accelerometer based on the deflection of the cantilever beam provided by the present invention can easily change the sensitivity and natural frequency of the sensor by adjusting the quality of the mass block 5 or changing the material and structural parameters of the cantilever beam 3. The vibration frequency is easy to adjust.

Description of drawings

Fig. 1 is a top view of the structure of the fiber grating accelerometer based on the deflection of the cantilever provided by the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

As shown in FIG. 1 , FIG. 1 is a top view of the structure of the fiber grating accelerometer based on the deflection of the cantilever beam provided by the present invention. The fiber grating accelerometer includes: a housing 1 as the supporting structure of the fiber grating accelerometer, which has a first side wall m, a second side wall n, a third side wall p and a fourth side wall q; an optical fiber for measuring acceleration A grating 2, one end of the fiber grating 2 is fixedly connected to the mass block 5, and the other end is parallel to the first side wall m and passes through the hole 6 on the second side wall n of the fiber grating accelerometer and extends to the fiber grating accelerometer The outside of the meter; one end is horizontally fixed on the cantilever beam 3 on the third side wall p of the fiber grating accelerometer, which is used to transmit the vibration signal to the fiber grating 2; the quality block 5 fixed on the other end of the cantilever beam 3, Used to adjust the sensitivity and natural frequency of the fiber grating accelerometer.

The hole 6 is located on the second side wall n of the FBG accelerometer, and is used to lead out and fix the pigtail of the FBG 2 .

The fiber grating 2 is perpendicular to the cantilever beam 3 and has a certain initial stress.

The mass of the mass block 5 is much larger than that of the cantilever beam 3, and the mass of the cantilever beam 3 is relatively small compared to the mass block 5 and can be ignored, which is used to reduce the nonlinear effect of the fiber grating accelerometer.

When the fiber grating accelerometer is excited by vibration in the direction shown in Figure 1, the cantilever beam 3 and the mass block 5 form a spring-mass system, and the mass block 5 vibrates in a direction perpendicular to the cantilever beam 3, driving the cantilever beam 3 produce some deflection. Since one end of the fiber grating 2 is fixed on the mass block 5, the vibration of the cantilever 3 causes the axial stress in the fiber grating to produce periodic changes consistent with the vibration frequency. For fiber gratings, the variation of the reflected wavelength is proportional to the axial stress, so the external vibration acceleration can be obtained by detecting the variation of the wavelength.

The above-mentioned cantilever beam 3 is horizontally fixed on the third side wall p of the fiber grating accelerometer through the support 4 .

In addition, since the quality of the mass block 5 will have a significant impact on the sensitivity and natural frequency of the accelerometer, the sensitivity and natural frequency of the accelerometer can be changed by adjusting the mass of the mass block 5 . The stiffness of the cantilever beam 3 can also determine the sensitivity and natural frequency of the accelerometer, so changing the material and structural parameters of the cantilever beam 3 can also change the sensitivity and natural frequency of the accelerometer.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A fiber grating accelerometer based on the deflection of a cantilever beam, characterized in that the fiber grating accelerometer comprises: As the housing (1) of the fiber grating accelerometer supporting structure, it has a first side wall (m), a second side wall (n), a third side wall (p) and a fourth side wall (q); A fiber grating (2) for measuring acceleration, one end of the fiber grating (2) is fixedly connected to the mass block (5), and the other end is parallel to the first side wall (m) and passes through the second side of the fiber grating accelerometer a hole (6) on the wall (n) and extending to the outside of said fiber grating accelerometer; One end is horizontally fixed to the cantilever beam (3) on the third side wall (p) of the fiber grating accelerometer, which is used to transmit the vibration signal to the fiber grating (2); The quality block (5) fixed on the other end of the cantilever beam (3) is used to adjust the sensitivity and natural frequency of the fiber grating accelerometer. 2. The fiber grating accelerometer based on the deflection of the cantilever beam according to claim 1, wherein the hole (6) is located on the second side wall (n) of the fiber grating accelerometer for leading out and fixing the optical fiber Pigtail for grating (2). 3. The fiber grating accelerometer based on the deflection of the cantilever beam according to claim 1, wherein the fiber grating (2) is perpendicular to the cantilever beam (3) and has a certain initial stress. 4. The fiber grating accelerometer based on the deflection of the cantilever beam according to claim 1, wherein the quality of the mass block (5) is much greater than the quality of the cantilever beam (3), for reducing the fiber grating accelerometer non-linear effect. 5. The fiber grating accelerometer based on the deflection of the cantilever beam according to claim 1, wherein when the fiber grating vibration sensor is excited by vibration, the cantilever beam (3) and the mass block (5) constitute a In the spring-mass system, the mass block (5) vibrates in the direction perpendicular to the cantilever beam (3), which drives the cantilever beam (3) to produce a certain deflection, and the vibration of the cantilever mass (3) makes the fiber Bragg grating (2) produce and Periodically varying axial stress with consistent vibration frequency. 6. The fiber grating accelerometer based on the deflection of the cantilever beam according to claim 1, wherein the cantilever beam (3) is horizontally fixed to the third side wall (p) of the fiber grating accelerometer by the support (4) )superior. 7. The fiber grating accelerometer based on the deflection of the cantilever beam according to claim 1, wherein the fiber grating accelerometer adjusts the mass of the mass (5) or changes the material and structural parameters of the cantilever beam (3) To change the sensitivity and natural frequency of the FBG accelerometer.