CN201945413U - Fiber bragg grating arch bridge pressure sensor - Google Patents

Abstract

The utility model discloses a fiber bragg grating arch bridge pressure sensor which comprises a combined metal case, an arch bridge elastic device, a metal wire and a fiber bragg grating. The two ends of the metal wire are connected with the central part of the arch bridge elastic device. The fiber bragg grating is attached to the metal wire. The combined metal case comprises an upper portion and a lower portion. The upper portion and the lower portion can move vertically and relatively. When the upper portion of the combined metal case bears pressure, the pressure impacts completely on the upper portion of the arch bridge elastic device. One end of the arch bridge elastic device is fixed at the bottom of the metal case. The other end of the arch bridge elastic device is a movable end. The pressure sensor based on an optical fiber sense is formed by the fiber bragg grating sensing technology and realizes the high accuracy test of the vertical stress.

Description

A fiber grating arch bridge pressure sensor

technical field

The utility model relates to the technical field of sensors, in particular to an optical fiber grating arch bridge pressure sensor.

Background technique

Sensor technology is a key technology of modern science and technology. Existing sensors mostly use electric sensors to measure stress, which are prone to problems such as low accuracy and failure due to external interference (especially the influence of water).

Fiber Bragg grating is a new kind of reflective filter passive sensitive element with wide application prospect and excellent performance in the world since the 1990s. It realizes on-line measurement of structures by sensing external micro-strain changes through the movement of Bragg grating reflection wavelength. The basic principle is: when the light wave in the fiber passes through the grating, the light that satisfies the wavelength condition of the grating is reflected back to become reflected light, and the rest of the light becomes transmitted light. Changes in external parameters will cause the wavelength of reflected light to drift, and through The detection of the wavelength drift can obtain the variation of the external parameter. Temperature and strain are the external parameters that can most directly change the reflected wavelength. The fiber grating structure is shown in Figure 1, where 01 is the fiber core, 02 is the cladding wrapped outside the fiber core, and Λ is the grating period; Figure 2 is the energy distribution diagram when light passes through the grating, and 2-1 is the incident spectrum , 2-2 is the reflection spectrum, 2-3 is the transmission (transmission) spectrum, the abscissa represents the wavelength, the ordinate represents the energy, and λ _b is the center wavelength of the reflected light.

Fiber Bragg grating has extremely high test accuracy and is free from external interference such as electromagnetic radiation. In addition, it also has many advantages such as easy layout and quasi-distributed measurement. In view of this, this technology has a wide range of applications in aerospace, composite materials, concrete It has been widely used in many fields such as structural engineering, electric power engineering and medicine.

Utility model content

The technical problem to be solved by the utility model is to provide an optical fiber grating arch bridge pressure sensor aiming at the deficiencies of the prior art.

The utility model adopts the following technical solutions:

An optical fiber grating arch bridge pressure sensor, comprising a combined metal box, an arch bridge elastic device, a metal wire and an optical fiber grating; two ends of the metal wire are connected to the middle of the arch bridge elastic device, and an optical fiber grating is pasted on the metal wire; The combined metal box includes an upper part and a lower part. The upper part and the lower part can move relative to each other up and down. When there is pressure on the upper part of the combined metal box, the pressure will all act on the upper part of the arch bridge-shaped elastic device. One end of the arch bridge-shaped elastic device is fixed on the bottom of the metal box. One end is a movable end.

In the fiber grating arch bridge pressure sensor, the arch bridge elastic device is a steel sheet.

In the fiber grating arch bridge pressure sensor, the metal wire is a steel wire.

In the fiber grating arch bridge pressure sensor, the combined metal box is a cuboid.

In the fiber grating arch bridge pressure sensor, the movable end is in contact with the lower part of the combined metal box, and there is a groove at the contact point, so that the movable end has sufficient space for movement.

A pressure sensor based on fiber optic sensing is formed through fiber grating sensing technology to achieve high-precision testing of vertical pressure.

Description of drawings

Fig. 1 Schematic diagram of fiber grating structure;

Figure 2 is an energy distribution diagram when light passes through the grating;

Fig. 3 structural schematic diagram of the utility model sensor

Figure 4 is a partially enlarged view of Figure 3;

Fig. 5 schematic diagram of circuit principle of testing process of the utility model.

Detailed ways

Below in conjunction with specific embodiment, the utility model is described in detail.

1. Sensor structure

The specific structure of the sensor of the utility model is shown in Figures 3 and 4. It includes a cuboid combined type (divided into upper and lower parts, and the upper and lower parts are movably connected) metal box 20 , high-strength steel sheet 10 , steel wire 50 and optical fiber grating 30 . The high-strength steel sheet 10 is folded into an arch bridge, the steel wire 50 is pulled in the middle of the arch bridge, and the fiber grating 30 is pasted on the steel wire 50 at the same time. One end 101 of the arch bridge is fixed at the bottom of the metal box, and the other end is a movable end 102 . The movable end 102 is in contact with the bottom of the metal box 20, and there is a groove 40 with a small slope at the contact point, so that there is sufficient room for movement. The upper and lower parts of the metal box 20 can move relative to each other up and down. When there is pressure on the upper part of the metal box 20, the upper part of the metal does not act as a support, so that the pressure can all act on the upper part of the arch bridge formed by the high-strength steel sheet 10.

2. The working principle of the sensor

The two ends of the arch bridge have a tendency to move outwards under the pressure of the upper part, which makes the steel wire in the middle part produce more obvious tensile stress, which in turn causes the fiber grating pasted on it to produce tensile strain, and the wavelength drift of reflected light occurs. Through the test of the reflected wavelength , data processing, the size of the upper stress can be obtained.

3. Test process

The fiber grating 30 is connected to the demodulator 40 through an external lead, and the demodulator 40 is connected to an external computer 42 through a network connection 41 . The demodulator 40 sends out an optical signal, and after reaching the fiber grating 30, the light that satisfies the reflection conditions is reflected back, and the reflected light returns to the demodulator 40, and the electrical signal is generated through the photoelectric conversion 21, and the data acquisition 22 produces a digital signal 32, and the digital signal 32 After wavelength calculation 23 and data analysis 24, the change information of the reflected wavelength can be obtained through this process, and then the change of the rotation angle can be obtained through data processing. The specific test process is shown in Figure 5.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present utility model.

Claims (5)

1. the arch-shaped pressure transducer of fiber grating is characterized in that, comprises combined can, arch-shaped elastic force apparatus, tinsel and fiber grating; The tinsel two ends are connected with the middle part of described arch-shaped elastic force apparatus, paste fiber grating on the tinsel; Described combined can comprises the upper and lower, upper and lower relative motion up and down, when pressure was arranged at combined can top, this pressure all acted on arch-shaped elastic force apparatus top, arch-shaped elastic force apparatus one end is fixed on the can bottom, and an other end is movable end.

2. the arch-shaped pressure transducer of fiber grating according to claim 1 is characterized in that described arch-shaped elastic force apparatus is a steel disc.

3. the arch-shaped pressure transducer of fiber grating according to claim 1 is characterized in that described tinsel is a steel wire.

4. the arch-shaped pressure transducer of fiber grating according to claim 1 is characterized in that described combined can is a rectangular parallelepiped.

5. the arch-shaped pressure transducer of fiber grating according to claim 1 is characterized in that described movable end contacts with the bottom of combined can, and there is a groove contact position, makes described movable end that abundant activity space be arranged.

Images