CN110044287A - The combined long gauge length optical fibre grating strain transducer that prestressing force can be adjusted accurately - Google Patents

Abstract

The invention discloses a combined long gauge fiber grating strain sensor whose prestress can be precisely adjusted, relates to the technical field of sensors, and solves the problem to a certain extent between the elastic modulus of the packaging structural material of the existing strain sensor and the elasticity of the soil to be measured. If the modulus does not match, the encapsulation structure and the soil to be measured cannot be deformed cooperatively, resulting in technical problems of inaccurate monitoring accuracy. The prestressed and precisely adjustable combined long gauge fiber grating strain sensor of the present invention comprises: a fiber grating component, a first fixed chassis, a second fixed chassis, an adjustment component and a fiber grating demodulator; one end of the fiber grating component is arranged on the On the first fixed chassis, the other end of the fiber grating assembly is passed through and fixed on the second fixed chassis; the adjusting component is sleeved with the fiber grating component and fixed on the second fixed chassis, and the adjusting component is used to adjust the tension of the fiber grating; The fiber grating demodulator is connected with the fiber grating assembly and is close to the second fixed chassis.

Description

Combined long-gauge fiber grating strain sensor with precisely adjustable prestress

technical field

The invention relates to the technical field of sensors, in particular to a combined long gauge fiber grating strain sensor whose prestress can be precisely adjusted.

Background technique

As a passive optical fiber device, the detection of physical quantities is mainly caused by the change of the grating period and the change of the effective refractive index. The package form with prestress is of great significance for the effective measurement of physical quantities. Under the prestressed process specification, the fiber grating strain sensor not only has high compression linearity, but also improves the measurement compressive strain range, greatly improves the fiber grating sensing performance, improves the negative strain measurement accuracy and increases the sensitivity, which is helpful in high It is more advantageous in the measurement of frequency.

In highway structures, traditional strain gauges can no longer meet the current measurement requirements. Because the measuring device needs to be buried in the foundation, it is easy to be damaged during the rolling process of the foundation. In addition, in the long-term high temperature weather, the ordinary strain gauge will age, which will cause great difficulties to the measurement. The elastic modulus of the encapsulated structural material of most strain sensors does not match the elastic modulus of the soil to be measured, and the encapsulated structure and the soil to be measured cannot deform cooperatively, resulting in inaccurate monitoring accuracy. The use of materials such as polytetrafluoroethylene can withstand high temperature and have certain flexibility, so as to achieve the purpose of adjusting the prestress of the fiber grating.

Therefore, how to provide a combined long gauge length fiber grating strain sensor whose prestress can be precisely adjusted has become a technical problem that those skilled in the art need to solve urgently.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a combined long gauge length fiber grating strain sensor with precisely adjustable prestress and long gauge length, which can solve the problem of the elasticity of the packaging structure material of the existing strain sensor to a certain extent. The modulus does not match the elastic modulus of the soil to be measured, and the encapsulation structure and the soil to be measured cannot deform together, resulting in technical problems of inaccurate monitoring accuracy.

The invention provides a combined long gauge fiber grating strain sensor with precise prestress adjustment, comprising: a fiber grating component, a first fixed chassis, a second fixed chassis, an adjustment component and a fiber grating demodulator;

One end of the fiber grating component is set on the first fixed chassis, and the other end of the fiber grating component is penetrated and fixed on the second fixed chassis; the adjustment component is sleeved on the fiber grating component and fixed on the second fixed chassis. On the second fixed chassis, the adjustment component is used to adjust the tension of the fiber grating; the fiber grating demodulator is connected to the fiber grating component and is close to the second fixed chassis.

Further, the adjustment assembly includes: a fixed collar, a threaded pipe, a force-adjusting screw cap and a tension wire;

The threaded pipe is sleeved on the fixing collar; the force-adjusting screw cap is sleeved on the threaded pipe, and the threaded pipe is threadedly matched with the force-adjusting screw cap; One end is arranged on the fiber grating assembly, and the connection is located outside the second fixed chassis, and the other end of the tension wire passes through the gap between the fiber grating assembly and the fixed collar , which is fixed on the adjusting screw cap.

Further, the length of the fixing collar is greater than the length of the force-adjusting screw cap, and the length of the force-adjusting screw cap is greater than the length of the threaded pipe.

Further, the adjustment assembly further includes: a pointer 24; the pointer 24 is arranged on the outer side of the fixed collar, and is close to the top of the force-adjusting screw cap;

The top end of the adjusting screw cap is provided with a scale, and the pointer 24 is used to indicate the adjusting scale of the adjusting component.

Further, the second fixed chassis is provided with an inner annular groove and an outer annular groove on a side away from the first fixed chassis, and the inner annular groove is located inside the outer annular groove;

The fixing collar and the threaded pipe are arranged on the second fixing chassis through the inner annular groove.

Further, it also includes: a protection cover; the protection cover is disposed on the second fixed chassis through the outer annular groove, and the protection cover is used for sealing and protecting the adjustment assembly.

Further, the fiber grating assembly includes: a fiber grating and a protective layer; the protective layer is sleeved on the fiber grating, and the fiber grating is connected to the fiber grating demodulator.

Further, it also includes: a protective shell; the protective shell is sleeved on the fiber grating assembly, and one end of the protective shell is set on the first fixed chassis, and the other end of the protective shell is provided with the on the second fixed chassis.

Further, the protective layer is a sleeve made of polytetrafluoroethylene.

Compared with the prior art, the combined long gauge fiber grating strain sensor with precise prestress adjustment of the present invention has the following advantages:

The invention provides a combined long gauge fiber grating strain sensor with precise prestress adjustment, comprising: a fiber grating component, a first fixed chassis, a second fixed chassis, an adjustment component and a fiber grating demodulator;

One end of the fiber grating component is set on the first fixed chassis, and the other end of the fiber grating component is penetrated and fixed on the second fixed chassis; the adjustment component is sleeved on the fiber grating component and fixed on the second fixed chassis. On the second fixed chassis, the adjustment component is used to adjust the tension of the fiber grating; the fiber grating demodulator is connected to the fiber grating component and is close to the second fixed chassis. The combined long gauge fiber grating strain sensor with precise prestress adjustment provided by the present invention can solve the problem that the elastic modulus of the packaging structure material of the existing strain sensor does not match the elastic modulus of the soil to be measured to a certain extent, and the packaging structure It cannot co-deform with the soil to be measured, resulting in inaccurate monitoring accuracy.

When the first fixed chassis and the second fixed chassis are fixed, the middle adjustment assembly of the present invention can drive the tensioning wire to pull the fiber grating and the protective layer together with the second fixed chassis by rotating the force adjustment cap to stretch the direction of the second fixed chassis, changing the optical fiber The tension degree of the grating achieves the purpose of adjusting the size of the pre-stress; the pointer 24 set on the fixed collar and the scale set on the force-adjusting screw cover ensure the precision and accuracy of the adjustment of the adjustment components.

The invention also provides a sensor, which also solves the problem that the elastic modulus of the packaging structure material of the existing strain sensor does not match the elastic modulus of the soil to be measured, and the packaging structure and the soil to be measured cannot be deformed cooperatively, thereby causing Technical problems with inaccurate monitoring accuracy.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram in the length direction of a combined long gauge fiber grating strain sensor with precisely adjustable prestress provided by an embodiment of the present invention;

2 is a schematic structural diagram of an adjustment assembly provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a partial axial side structure of a combined long gauge length fiber grating strain sensor with precisely adjustable prestress provided by an embodiment of the present invention.

Reference numerals: 10-fiber grating; 11-protective layer; 20-fixed collar; 21-threaded pipe; 22-force adjustment screw cap; 23-tension wire; 24-pointer; 30-first fixed chassis; 40 -Second fixed chassis; 50-protective shell; 60-protective cover; 70-fiber grating demodulator.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Referring to FIGS. 1-3 , FIG. 1 is a schematic structural diagram of a combined long gauge fiber grating strain sensor with precisely adjustable prestress in the length direction provided by an embodiment of the present invention; FIG. 2 is a structure of an adjustment assembly provided by an embodiment of the present invention Schematic diagram; FIG. 3 is a schematic structural diagram of a partial axial side structure of a combined long gauge length fiber grating strain sensor with precisely adjustable prestress provided by an embodiment of the present invention.

The present invention provides a combined long gauge fiber grating strain sensor with precise prestress adjustment, comprising: a fiber grating component, a first fixed chassis 30, a second fixed chassis 40, an adjustment component, and a fiber grating demodulator 70;

One end of the fiber grating assembly is set on the first fixed chassis 30, and the other end of the fiber grating assembly is passed through and fixed on the second fixed chassis 40; the adjustment component is sleeved with the fiber grating component and fixed on the second fixed chassis 40, and the adjustment component Used to adjust the tension of the fiber grating 10 ; the fiber grating demodulator 70 is connected to the fiber grating assembly and is close to the second fixed chassis 40 .

To further illustrate, compared with the prior art, the combined long gauge fiber grating strain sensor with precisely adjustable prestress in the embodiment of the present invention has the following advantages:

The combined long gauge length fiber grating strain sensor provided by the embodiment of the present invention includes: a fiber grating component, a first fixed chassis 30, a second fixed chassis 40, an adjustment component, and a fiber grating demodulator 70;

One end of the fiber grating assembly is set on the first fixed chassis 30, and the other end of the fiber grating assembly is passed through and fixed on the second fixed chassis 40; the adjustment component is sleeved with the fiber grating component and fixed on the second fixed chassis 40, and the adjustment component Used to adjust the tension of the fiber grating 10 ; the fiber grating demodulator 70 is connected to the fiber grating assembly and is close to the second fixed chassis 40 . The combined long gauge length fiber grating strain sensor and sensor provided by the present invention can solve the problem to a certain extent that the elastic modulus of the packaging structure material of the existing strain sensor does not match the elastic modulus of the soil to be measured. The encapsulation structure and the soil to be tested cannot be deformed cooperatively, resulting in a technical problem of inaccurate monitoring accuracy.

Specifically, when the first fixed chassis 30 and the second fixed chassis 40 are fixed, the middle adjustment assembly of the present invention can drive the tension wire 23 to pull the fiber grating 10 and the protective layer 11 together by rotating the force adjustment screw cap 22. 2. The fixed chassis 40 is stretched in the direction to change the tension of the fiber grating 10, so as to achieve the purpose of adjusting the prestress; Adjustment precision and accuracy.

More specifically, one end of the fiber grating assembly is provided with a groove thread that fits and is fixed with the first fixing chassis 30, and a small hole is provided at the same plane as the disk of the second fixing chassis 40 at the collar end of the fiber grating assembly to fix the fiber grating. assembly, so that the fiber grating assembly measures the average strain between the first fixed chassis 30 and the second fixed chassis 40 .

Further, preferably, the fiber grating assembly is located away from the second fixed chassis 40 and is provided with an annular groove at a distance of 25 mm from the small hole, for the tension wire 23 to be clamped; the distance between the first fixed chassis 30 and the second fixed chassis 40 It is 150-500mm, and this distance is adjusted according to the measurement needs of the measured body.

Further, the inner diameter of the first fixed chassis 30 is 13mm, the inner wall of the side close to the second fixed chassis 40 is provided with groove threads, which fit the fiber grating assembly, the outer diameter is 60mm, and the thickness of the disc is 8mm. Adjust the size of the outer diameter according to the difficulty of measuring the deformation of the body.

In an embodiment of the present invention, in order to achieve the purpose of accurately adjusting the size of the prestress, see Figures 1-3; the adjusting assembly of the present invention includes: a fixed collar 20, a threaded pipe 21, a force-adjusting screw cap 22 and a pull tight wire 23;

The threaded tube 21 is sleeved on the fixed collar 20; the force adjusting screw cap 22 is sleeved on the threaded tube 21, and the threaded tube 21 is threadedly matched with the force adjusting screw cap 22; one end of the tension wire 23 is set on the fiber grating assembly , and this connection is located on the outside of the second fixed chassis 40 , the other end of the tension wire 23 protrudes through the gap between the fiber grating assembly and the fixed collar 20 , and is fixed on the force adjusting screw cap 22 .

Specifically, the threaded tube 21 is screwed with the force-adjusting cap 22, that is, when the force-adjusting cap 22 is rotated, the force-adjusting cap 22 moves along the length of the threaded tube 21, and one end of the tensioning wire 23 is linked to the fiber grating assembly , and the other is connected to the force-adjusting screw cap 22, so that the size of the pre-stress can be adjusted.

In an embodiment of the present invention, in order to ensure the stability of the adjustment assembly during adjustment, see FIGS. 1-3 ; the length of the fixing collar 20 of the present invention is greater than the length of the force-adjusting screw cap 22, and the force-adjusting screw cover 22 is greater than the length of the threaded pipe 21 .

Specifically, when the length of the fixed collar 20 is greater than the length of the force-adjusting screw cap 22, and the length of the force-adjusting screw cap 22 is greater than the length of the threaded pipe 21, the tension wire 23 is between the fiber grating assembly and the fixed collar 20. After the gap is pierced, it is tightly fitted with the top of the fixing collar 20, and then fixed with the adjusting screw cap 22, so that the tensioning wire 23 is V-shaped.

More specifically, when the force-adjusting cap 22 moves toward the direction close to the second fixed chassis 40, the tension wire 23 stretches the fiber grating assembly to increase the pre-stress. On the contrary, when the force-adjusting cap 22 moves away from the second When the direction of the fixed chassis 40 moves, the tension wire 23 does not stretch the fiber grating assembly, and the prestress is reduced.

Further, the pitch of the thread is set to 1.5mm, that is, when the force-adjusting screw cap 22 is in the initial position, the fiber grating assembly is elongated by 1.5mm for each rotation of the force-adjusting screw cap 22.

Further, the number of tensioning wires 23 in the present invention is preferably three, and one is arranged every 120° around the circumference of the fiber grating assembly, and three clamping grooves are evenly arranged at the top of the fixed collar 20 for pulling three tensioning wires. The wire 23 is passed through, and the upper end of the force-adjusting screw cap 22 is evenly provided with three small holes for the three tensioning wires 23 to pass through and fix; the three tensioning wires 23 are evenly distributed so that the fiber grating assembly is evenly stressed.

In an embodiment of the present invention, in order to accurately know the magnitude of the prestress, refer to FIGS. 2-3 ; the adjusting assembly of the present invention further includes: a pointer 24; the pointer 24 is arranged outside the fixed collar 20 and is close to the The top end of the adjusting screw cap 22;

The top end of the adjusting screw cap 22 is provided with a scale, and the pointer 24 is used to indicate the adjustment scale of the adjusting component.

Specifically, the pointer 24 is used to identify the size of the pre-stress. When the force-adjusting cap 22 is in the initial position, the pointer 24 is in a position where the pre-stress is zero. The top of the force-adjusting cap 22 is evenly provided with 72 scales. The force screw cap 22 drives the tension wire 23 to stretch the fiber grating assembly, changing the tension degree of the fiber grating assembly, and achieving the purpose of adjusting the prestress.

More specifically, the scale of the force-adjusting screw cap 22 can be appropriately decreased or increased according to the requirements of the prestressing accuracy.

In an embodiment of the present invention, in order to make the combined long gauge length fiber grating strain sensor with precise prestress adjustment more stable, see FIGS. 1 and 3 ; One side is provided with an inner annular groove and an outer annular groove, and the inner annular groove is located on the inner side of the outer annular groove;

The fixing collar 20 and the threaded pipe 21 are arranged on the second fixing chassis 40 through the inner annular groove.

Specifically, the cross section of the second fixed chassis 40 in the axial direction is E-shaped, and the two grooves of the E-shape are the inner annular groove and the outer annular groove.

In an embodiment of the present invention, it further includes: a protective cover 60; the protective cover 60 is disposed on the second fixed chassis 40 through the outer annular groove, and the protective cover 60 is used for sealing and protecting the adjustment assembly.

Specifically, the outer annular groove is provided with a thread, which cooperates with the protection cover 60 and acts as a sealing protection for the adjustment assembly.

In an embodiment of the present invention, in order to obtain accurate results, see Figures 1-3; the fiber grating assembly of the present invention includes: a fiber grating 10 and a protective layer 11; the protective layer 11 is sleeved on the fiber grating 10, and the fiber grating The grating 10 is connected to a fiber grating demodulator 70 .

Specifically, the protective layer 11 enhances the coordinated deformation ability and the high temperature and anti-aging ability of the combined long gauge fiber grating strain sensor with precisely adjustable prestress and the measured structure, and further protects the fiber grating 10 .

More specifically, the fiber grating 10 is a diffraction grating formed by periodically modulating the refractive index of the fiber core by a certain method, and is a passive filter element. Because grating fiber has the advantages of small size, low splice loss, full compatibility with optical fiber, and can be embedded in intelligent materials, and its resonant wavelength is sensitive to changes in external environment such as temperature, strain, refractive index, concentration, etc., it is widely used in optical fiber communication and The field of sensing has been widely used.

The fiber grating 10 uses the photosensitivity of the fiber material to write the coherent field pattern of the incident light into the fiber core by means of ultraviolet light exposure, and generates a periodic change in the refractive index along the axis of the fiber core in the fiber core, thereby forming a permanent space. The phase grating essentially acts as a narrow-band (transmissive or reflective) filter or mirror within the fiber core. When a beam of broad spectrum light passes through the fiber grating 10 , the wavelengths satisfying the Bragg condition of the fiber grating 10 will be reflected, and the remaining wavelengths will continue to transmit through the fiber grating 10 .

Further, the fiber grating demodulator 70 has a small size, high precision, and a large dynamic range fiber grating 10 sensor measurement capability and spectral analysis capability of accuracy. Mainly used in real-time monitoring of structural strain and temperature in bridges, dams, high-rise buildings, tunnels, highways, electric power, petrochemicals, fire protection, HVAC and other fields.

In an embodiment of the present invention, in order to protect the fiber grating assembly, see FIGS. 1-3 ; it also includes: a protective shell 50; the protective shell 50 is sleeved on the fiber grating assembly, and one end of the protective shell 50 is disposed on the first On a fixed chassis 30 , the other end of the protective shell 50 is disposed on a second fixed chassis 40 .

Specifically, the protective shell 50 is arranged between the first fixed chassis 30 and the second fixed chassis 40, which can fully protect the fiber grating assembly and prevent the impact of rolling in practical engineering applications. Prestress can be precisely adjusted combined long gauge length The normal operation of the fiber grating strain sensor.

More specifically, the protective case 50 of the present invention is preferably a protective case 50 made of stainless steel.

In an embodiment of the present invention, in order to better protect the fiber grating 10, see FIGS. 1-3 ; the protective layer 11 of the present invention is a sleeve made of polytetrafluoroethylene.

Specifically, the material selected for the protective layer 11 is polytetrafluoroethylene as the deformation member, which improves the resistance to high temperature aging and enhances the ability to coordinate deformation with the structure.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (9)

1. A combined long gauge fiber grating strain sensor with precise prestress adjustment is characterized in that, comprising: a fiber grating assembly, a first fixed chassis, a second fixed chassis, an adjustment component and a fiber grating demodulator; One end of the fiber grating component is set on the first fixed chassis, and the other end of the fiber grating component is passed through and fixed on the second fixed chassis; the adjustment component is sleeved on the fiber grating component and fixed On the second fixed chassis, the adjustment assembly is used to adjust the tension of the fiber grating; the fiber grating demodulator is connected to the fiber grating assembly and is close to the second fixed chassis. 2 . The combined long gauge fiber grating strain sensor with precise prestress adjustment according to claim 1 , wherein the adjustment component comprises: a fixed collar, a threaded pipe, a force adjustment screw cap and a tension wire. 3 . ; The threaded pipe is sleeved on the fixing collar; the force-adjusting screw cap is sleeved on the threaded pipe, and the threaded pipe is threadedly matched with the force-adjusting screw cap; One end is arranged on the fiber grating assembly, and the connection is located outside the second fixed chassis, and the other end of the tension wire passes through the gap between the fiber grating assembly and the fixed collar , which is fixed on the adjusting screw cap. 3 . The combined long gauge fiber grating strain sensor with precisely adjustable prestress according to claim 2 , wherein the length of the fixed collar is greater than the length of the force-adjusting screw cap, and the force-adjusting The length of the screw cap is greater than the length of the threaded pipe. 4 . The prestressed and precisely adjustable combined long gauge fiber grating strain sensor according to claim 2 , wherein the adjustment assembly further comprises: a pointer 24 ; the pointer 24 is arranged on the fixed collar. 5 . outside, and close to the top end of the adjusting screw cap; The top end of the adjusting screw cap is provided with a scale, and the pointer 24 is used to indicate the adjusting scale of the adjusting component. 5 . The combined long gauge length fiber grating strain sensor with precise prestress adjustment according to claim 2 , wherein the second fixed chassis is provided with an inner annular groove and a side away from the first fixed chassis. 6 . an outer annular groove, the inner annular groove is located inside the outer annular groove; The fixing collar and the threaded pipe are arranged on the second fixing chassis through the inner annular groove. 6 . The prestressed and precisely adjustable combined long gauge fiber grating strain sensor according to claim 5 , further comprising: a protective cover; the protective cover is disposed on the first section through the outer annular groove. 7 . On the two fixed chassis, the protection cover is used to seal and protect the adjustment assembly. 7 . The combined long gauge fiber grating strain sensor with precisely adjustable prestress according to claim 1 , wherein the fiber grating component comprises: a fiber grating and a protective layer; the protective layer is sleeved on the On the fiber grating, the fiber grating is connected with the fiber grating demodulator. 8 . The prestressed and precisely adjustable combined long gauge fiber grating strain sensor according to claim 1 , further comprising: a protective shell; the protective shell is sleeved on the fiber grating assembly, and One end of the protective shell is set on the first fixed chassis, and the other end of the protective shell is set on the second fixed chassis. 9 . The combined long gauge fiber grating strain sensor with precisely adjustable prestress according to claim 7 , wherein the protective layer is a sleeve made of polytetrafluoroethylene. 10 .