Array type fiber bragg grating strain gauge, and die and method for preparing array type fiber bragg grating strain gauge

Abstract

The invention relates to the technical field of optical fiber sensors, and discloses an array type fiber bragg grating strain gauge, and a mold and a method for preparing the array type fiber bragg grating strain gauge. The array fiber bragg grating strain gauge comprises an optical fiber, and the optical fiber is provided with a temperature compensation accessory and a plurality of strain measurement accessories. The strain measurement accessory is used for measuring strain; the temperature compensation accessory isolates strain and is used for temperature compensation. The advantages of the grating fiber sensor and the electronic strain gauge are combined to manufacture the array fiber grating strain gauge, the high sensitivity and multi-point monitoring capability of the grating fiber are combined with the mechanical protection performance and waterproof and anticorrosion performance of the electronic strain gauge, the decoupling problem between the temperature and the strain is solved, and the optical fiber grating strain gauge has the advantages of being high in sensitivity, high in sensitivity and high in multi-point monitoring capability. And the stability and durability of the fiber bragg grating strain gauge are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensors, and in particular to an arrayed optical fiber Bragg grating strain gauge, and a mold and a method for preparing the arrayed optical fiber Bragg grating strain gauge. Background Art

[0002] Fiber Bragg grating strain gauge is a sensor based on the periodic structure inside the optical fiber, which can realize high-sensitivity and real-time monitoring of parameters such as strain and temperature. Compared with traditional sensors such as resistance strain gauges and strain gauges, fiber Bragg grating sensors have the advantages of small size, light weight, strong anti-interference, and easy remote monitoring. At the same time, arrayed fiber Bragg grating sensors can realize large-capacity multiplexing and multi-point monitoring at the same time, making them very valuable in the fields of engineering and science.

[0003] However, in actual engineering applications, the packaging and protection of fiber Bragg grating sensors is still a challenge that needs to be solved. In engineering environments, fiber Bragg grating sensors need to have good mechanical protection, waterproof and anti-corrosion, high temperature resistance and other characteristics to ensure their stability and reliability under extreme conditions.

[0004] At present, the packaging technology of fiber Bragg grating mainly includes two aspects: fixation and protection. The traditional packaging method mainly adopts organic glue packaging, among which epoxy adhesive is the most common. However, this glue packaging method has the problems of long-term creep, aging, and performance degradation under high temperature environment. In addition, the parameters such as the length and thickness of the fiber Bragg grating adhesive will affect the sensitivity of the fiber Bragg grating to temperature and strain response. The above packaging method is difficult to ensure the consistency of the sensitivity of the fiber Bragg grating after packaging. Another packaging method is the metallization treatment of the grating surface. This treatment method attaches a layer of metal material coating on the grating surface through chemical plating, chemical vapor deposition, plasma deposition, magnetron sputtering, etc., and then fixes it to the surface of the metal specimen to be tested by welding and other means. However, although the metallization of the grating surface eliminates the dependence on adhesives, it still faces the following problems: First, the formed metal film may have microscopic defects, holes, particles, etc., which may cause the fiber Bragg grating to be affected by uneven stress and may cause waveform deformation; second, the local temperature of the welding point is too high, resulting in uneven distribution of welding stress, affecting performance; third, the metal film is easily corroded by air and acid and alkali, and it is difficult to effectively protect the fiber Bragg grating for a long time. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of traditional grating optical fiber packaging methods, provide an arrayed optical fiber Bragg grating strain gauge, a mold and a method for preparing an arrayed optical fiber Bragg grating strain gauge, and combine the advantages of grating optical fiber sensors with electronic strain gauges to produce an arrayed optical fiber Bragg grating strain gauge, and combine the high sensitivity and multi-point monitoring capabilities of grating optical fibers with the mechanical protection performance and waterproof and anti-corrosion performance of electronic strain gauges, while solving the decoupling problem between temperature and strain, and improving the stability and durability of the optical fiber Bragg grating strain gauge.

[0006] In order to achieve the above-mentioned object, the present invention provides an arrayed fiber Bragg grating strain gauge, wherein the arrayed fiber Bragg grating strain gauge comprises an optical fiber, and a temperature compensation accessory and a plurality of strain measurement accessories are arranged on the optical fiber;

[0007] The strain measurement accessory is used to measure strain; the temperature compensation accessory isolates strain and is used for temperature compensation.

[0008] The second aspect of the present invention provides a mold for preparing the above-mentioned array fiber Bragg grating strain gauge, wherein the mold includes a plurality of template blocks and a fixture;

[0009] A rectangular groove penetrating the template block is formed on the top of each template block;

[0010] The clamp is used to clamp several template blocks at the same time.

[0011] A third aspect of the present invention provides a method for preparing an arrayed fiber Bragg grating strain gauge using the above mold, the method comprising the following steps:

[0012] A clamp is used to clamp several template blocks at the same time, polyamic acid is applied on the surface of the substrate, and then the substrate with the surface applied with polyamic acid is placed in the rectangular groove of each template block, and the optical fiber is placed in the rectangular groove of the template block, and the grating of the optical fiber is located in the rectangular groove, and polyamic acid is dripped into the gap in the rectangular groove, and the polyamic acid is wrapped around the optical fiber located in the rectangular groove, and then a heat shrink polymerization reaction is performed to obtain a semi-finished product of an arrayed fiber grating strain gauge;

[0013] Adhesive is applied on the surface of the polyimide packaging block to form an adhesive layer, a glass fiber cover plate is covered on the adhesive layer, a capillary is sheathed on the outside of the remaining gratings, and both ends are sealed with glue to obtain an arrayed fiber Bragg grating strain gauge.

[0014] Beneficial effects of the present invention:

[0015] 1. The use of molds can effectively control variables, facilitate packaging consistency and allow for batch production.

[0016] 2. The use of tight-packed optical fiber for packaging significantly improves the bending and tensile properties of the non-grid part. The non-glue packaging of the grid area does not have the problem of uneven stress, and can effectively protect and bond the optical fiber sensor.

[0017] 3. Using another grating on the same optical fiber as a temperature compensation grating maintains the advantages of splicing connection and reduces the occupation of signal channels. One optical fiber can achieve accurate measurement of strain. At the same time, the arrayed fiber grating strain gauge can achieve large-capacity multiplexing and multi-point monitoring at the same time.

[0018] 4. Reduced installation cost, shortened installation time, no need for special optical tools or professional technicians.

[0019] 5. It solves the problems faced by fiber Bragg grating packaging, such as complex operation, intolerance to high and low temperatures, and inability to achieve temperature and strain decoupling. It also solves the problem that fiber Bragg grating strain gauges cannot measure at multiple points and cannot be adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the top view of the arrayed fiber grating strain gauge of the present invention;

[0021] Figure 2 is a schematic diagram of an arrayed fiber Bragg grating strain gauge of the present invention;

[0022] Figure 3 is a schematic cross-sectional view of a strain measurement accessory of an array fiber Bragg grating strain gauge of the present invention;

[0023] Figure 4 It is a structural schematic diagram of the template block of the present invention;

[0024] Figure 5 It is a schematic structural diagram of the clamp of the present invention;

[0025] Figure 6 The present invention is a flow chart of a method for preparing an array type fiber grating strain gauge using the mold of the present invention.

[0026] Description of Reference Numerals

[0027] 1. Optical fiber; 11. Grating; 2. Temperature compensation accessories; 3. Strain measurement accessories;

[0028] 31. substrate; 311. bonding layer; 32. polyimide encapsulation block; 33. glass fiber cover plate; 331. adhesive layer;

[0029] 4. Template block; 41. Rectangular groove; 5. Clamp; 51. First clamp; 52. Second clamp; 53. Back plate; 54. Screws. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0032] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments provided by the present invention can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] The present invention will be described in detail below through examples.

[0035] Example 1

[0036] like Figure 1 and Figure 2 The arrayed fiber Bragg grating strain gauge ( Figure 1 This is a top view of the arrayed fiber Bragg grating strain gauge. Figure 2 Schematic diagram of an array fiber Bragg grating strain gauge), the array fiber Bragg grating strain gauge comprises an optical fiber 1 (the optical fiber 1 used in the present invention is a tightly wrapped optical fiber prepared by an optical fiber tight wrapping machine, and the use of the tightly wrapped optical fiber can enhance the bending and tensile properties of the non-grating area), and a temperature compensation accessory 2 and a plurality of strain measurement accessories 3 are arranged on the optical fiber 1;

[0037] The strain measurement accessory 3 is used to measure strain; the temperature compensation accessory 2 isolates strain and is used for temperature compensation.

[0038] In the arrayed fiber Bragg grating strain gauge of the present invention, the number of gratings 11 on the optical fiber 1 is at least three, the number of temperature compensation accessories 2 is one, and the number of strain measurement accessories 3 is at least two (the number of strain measurement accessories 3 is related to the number of gratings 11, that is, it is ensured that a temperature compensation accessory 2 is provided at one grating 11 on the optical fiber 1, and the remaining gratings 11 are respectively provided with strain measurement accessories 3; for example, when there are five gratings 11 on the optical fiber 1, one temperature compensation accessory 2 and four strain measurement accessories 3 are provided on the optical fiber 1; when there are three gratings 11 on the optical fiber 1, one temperature compensation accessory 2 and two strain measurement accessories 3 are provided on the optical fiber 1).

[0039] In the present invention, the temperature compensation accessory 2 is a capillary tube sleeved on the outside of the optical fiber 1 , and is further a stainless steel capillary tube, and the sleeved optical fiber 1 is provided with a grating 11 .

[0040] The length of the capillary is greater than or equal to twice the length of the grating 11 sleeved in the capillary; and the inner diameter of the capillary is 0.15-0.25 mm, and the outer diameter is 0.4-0.6 mm.

[0041] Furthermore, in this embodiment, the length of the capillary is twice the length of the grating 11 sleeved in the capillary; and the inner diameter of the capillary is 0.2 mm, and the outer diameter is 0.5 mm.

[0042] In the present invention, the grating 11 is affected by temperature and strain during measurement, which will cause changes in wavelength. The grating 11 encapsulated by the capillary is not affected by changes in strain (the strain measurement accessory 3 is pasted on the surface of the object to be measured when measuring strain, and the temperature compensation accessory 2 does not need to be pasted and fixed on the surface of the object to be measured, and is not affected by strain itself), but is only affected by temperature. In this way, the error of the wavelength change caused by temperature in the remaining grating 11 used to measure strain can be eliminated, making the result more accurate.

[0043] In the present invention, the cross section of the strain measuring accessory 3 is as follows: Figure 3 As shown, each strain measurement accessory 3 includes a substrate 31 and an adhesive layer 311 arranged on the upper surface of the substrate 31, a polyimide packaging block 32 is arranged on the upper surface of the adhesive layer 311, the polyimide packaging block 32 covers the upper surface of the adhesive layer 311, the polyimide packaging block 32 is wrapped around the outside of the optical fiber 1, and the wrapped optical fiber 1 is provided with a grating 11; an adhesive layer 331 is arranged on the upper surface of the polyimide packaging block 32, and a glass fiber cover plate 33 is also covered on the upper surface of the adhesive layer 331.

[0044] The strain measurement accessory 3 in the present invention is in the shape of a rectangular parallelepiped as a whole, and its specific size is related to the size required in actual use, wherein the thickness of the substrate 31 is determined according to the transfer coefficient required by the specifically prepared array fiber grating strain gauge.

[0045] In the present invention, the material of the substrate 31 is selected from aluminum, aluminum alloy, stainless steel, copper or polyimide, and in this embodiment, it is further polyimide.

[0046] Because the elastic modulus of the material of the substrate 31 will affect the strain transfer coefficient, that is, the sufficiency of the strain transfer of the measured object, when the shear modulus of the material of the substrate 31 is less than 400Mpa, a small change in the shear modulus will have a greater impact on the strain transfer coefficient. Therefore, different materials are selected here. On the one hand, the influence of the shear modulus on strain transfer is avoided. On the other hand, different materials can be used to prepare arrayed fiber grating strain gauges with different strain transfer coefficients to meet the sensitivity requirements under different working conditions. Therefore, in terms of material selection, materials with large shear modulus are selected. The thickness of the substrate 31 will affect the strain transfer coefficient. The thicker the substrate, the less sufficient the strain transfer. The thinner the substrate that meets the requirements, the higher the preparation cost. Therefore, under the condition of meeting different working conditions, a substrate 31 of appropriate thickness can be selected.

[0047] In the present invention, the bonding layer 311 and the polyimide encapsulation block 32 are both obtained by curing polyamic acid after a heat shrink polymerization reaction; the adhesive layer 331 is formed by applying adhesive on the upper surface of the polyimide encapsulation block 32 .

[0048] Example 2

[0049] like Figure 4 and 5 The mold for preparing the array fiber grating strain gauge of Example 1 shown in FIG. 1 includes several Figure 4 The template block 4 shown and Figure 5 The clamp 5 shown;

[0050] A rectangular groove 41 is formed on the top of each template block 4 and passes through the template block 4 (the template block 4 is made of glass);

[0051] The clamp 5 is used to clamp several template blocks 4 at the same time.

[0052] In the present invention, the length of the rectangular groove 41 is the axial direction of the rectangular groove 41, and the specific size of the rectangular groove 41 is related to the size of the prepared strain measurement accessory 3, wherein the length and width of the rectangular groove 41 are the same as the length and width of the strain measurement accessory 3 of the fiber grating strain gauge finally obtained, and the depth of the rectangular groove 41 is equal to the sum of the thickness of the substrate 31 and the diameter of the optical fiber (the diameter of the optical fiber is generally 125um).

[0053] Furthermore, in the present invention, the clamp 5 simultaneously clamps one side of the rectangular groove 41 of each template block 4 (there is no special requirement for the specific clamping position, as long as it can clamp one side of the rectangular groove 41 of several template blocks 4 at the same time and clamp and fix several template blocks 4).

[0054] In the present invention, the clamp 5 includes a first clamping plate 51 , a second clamping plate 52 , and a back plate 53 connecting the first clamping plate 51 and the second clamping plate 52 .

[0055] In the present invention, the clamp 5 further includes a screw 54 (the screw 54 passes through the first clamping plate 51 and the second clamping plate 52 ), and the distance between the first clamping plate 51 and the second clamping plate 52 is controlled by adjusting the screw 54 to achieve clamping of the template block 4 .

[0056] Furthermore, one side of the first clamping plate 51 and the second clamping plate 52 are connected by a back plate 53 , and the other side is controlled by screws 54 to be close to each other to form a clamping opening to clamp the template block 4 .

[0057] In actual use, the clamp 5 is required to clamp multiple template blocks 4 at the same time (the number of template blocks 4 used in actual use is the same as the number of strain measurement accessories 3 finally obtained), so the clamp length of the clamp 5 (the clamp length of the clamp 5 is the same as the length of the first clamp 51 and the second clamp 52) needs to be greater than or equal to twice the length of the template block 4.

[0058] Example 3

[0059] like Figure 6 The method for preparing an arrayed fiber grating strain gauge using the mold of Example 2 shown in the figure comprises the following steps:

[0060] (1) Use a clamp 5 to clamp several template blocks 4 at the same time (adjust the screw 54 to control the distance between the first clamping plate 51 and the second clamping plate 52 so that a clamping opening is formed between the first clamping plate 51 and the second clamping plate 52 to clamp and fix several template blocks 4 at the same time; the number of template blocks 4 used is the same as the number of strain measurement accessories 3 to be set, and the spacing between the template blocks 4 is adjusted according to the spacing between the gratings 11 on the optical fiber 1), apply polyamic acid on the surface of the substrate 31, and then place the substrate 31 with the surface coated with polyamic acid in the rectangular groove 41 of each template block 4 (the substrate 31 is a rectangular parallelepiped, and the length of the substrate 31 is equal to the length of the rectangular groove 41, The width of the substrate 31 is equal to the width of the rectangular groove 41), the optical fiber 1 is placed in the rectangular groove 41 of each template block 4, and the remaining gratings 11 on the optical fiber 1 except for one grating 11 (this grating 11 is used to set the temperature compensation accessory 2) are all located in their respective rectangular grooves 41 (one grating 11 corresponds to one rectangular groove 41; the spacing between the template blocks 4 is adjusted according to the spacing between the gratings 11 placed in the rectangular grooves 41), polyamic acid is dripped into the gap in the rectangular groove 41, and the polyamic acid is wrapped around the optical fiber 1 located in the rectangular groove 41, and then a heat shrink polymerization reaction is carried out. After the heat shrink polymerization reaction is completed, a semi-finished product of an arrayed optical fiber Bragg grating strain gauge is obtained;

[0061] (2) The arrayed fiber Bragg grating strain gauge semi-finished product is separated from the rectangular groove 41, and adhesive is applied on the surface of the polyimide packaging block 32 to form an adhesive layer 331. The adhesive layer 331 is covered with a glass fiber cover plate 33, and then a capillary is sleeved on the outer side of the remaining grating 11 without the strain measurement accessory 3, and the two ends are sealed with glue to obtain an arrayed fiber Bragg grating strain gauge.

[0062] Furthermore, in step (1) of the present invention, the purpose of applying polyamic acid on the surface of substrate 31 is to degrease and roughen the surface of substrate 31 (degreasing is to remove grease, dust, sweat and other substances on the surface of substrate 31, and roughening makes the surface of substrate 31 microscopically rough, which can ensure that the subsequently dropped polyamic acid has good bonding with the surface of substrate 31) to ensure good wettability and adhesion. At the same time, after the subsequent heat shrinkage polymerization reaction, the polyamic acid on the surface of substrate 31 will solidify to form a corresponding bonding layer 311 (the material of bonding layer 311 is polyimide) on the surface of substrate 31, which further plays a bonding role.

[0063] In the present invention, the amount of polyamic acid applied on the surface of the substrate 31 is sufficient as long as it can play a role in degreasing, roughening and bonding. Therefore, the depth of the rectangular groove 41 in the present invention is equal to the sum of the diameter of the optical fiber 1, the thickness of the substrate 31 and the thickness of the bonding layer 311. However, in actual operation, the amount of polyamic acid applied on the surface of the substrate 31 is relatively small, so the thickness of the bonding layer 331 can be ignored.

[0064] In the present invention, the optical fiber 1 is placed in the rectangular groove 41, and the two ends of the optical fiber 1 are fixed in turn with a high-temperature tape of polyimide, and at the same time, the corresponding grating 11 on the optical fiber 1 (the grating 11 is engraved in turn using an excimer laser and a phase mask plate, the optical fiber is placed behind the phase mask plate (the fiber stripping part is opposite to the phase mask plate), and the excimer laser is used to emit laser, which is irradiated to the phase mask plate after passing through the beam expander and the focusing lens. After passing through the phase mask plate, a diffraction beam is formed, which is irradiated to the optical fiber core, and the hydrogen molecules in the irradiated part of the core immediately react chemically with germanium to form Ge-OH bonds and Ge-H bonds, thereby causing a permanent increase in the refractive index of this part. The above steps are the grating writing process) is located in the rectangular groove 41 (the coating layer and the tight cladding layer at the grating 11 are stripped off, which can reduce the transfer layer and make the measurement result more accurate).

[0065] Furthermore, the length of the rectangular groove 41 in the present invention is 2-3 times the length of the grating 11 encapsulated in the polyimide packaging block 32. In this embodiment, the length of the rectangular groove 41 is twice the length of the grating 11 encapsulated in the polyimide packaging block 32, and the grating 11 is located in the middle of the rectangular groove 41.

[0066] In the present invention, after the grating 11 is placed in the rectangular groove 41, polyamic acid is dripped into the gap in the rectangular groove 41, and the dripped polyamic acid fills the gap in the rectangular groove 41 and wraps the optical fiber 1 located at the rectangular groove 41 (polyamic acid has low fluidity and is a viscous liquid at room temperature with a certain surface tension, so it can completely fill the gap in the rectangular groove 41), and then placed in a hot oven for a heat shrinkage polymerization reaction (including two processes of dehydration and imidization), the conditions of the heat shrinkage polymerization reaction include: keeping warm at 80-100°C for 0.5-1.5h, then heating to 150-200°C for 0.5-1.5h, and finally heating to 200-220°C for 1-3h; in the present embodiment, the conditions of the heat shrinkage polymerization reaction include: keeping warm at 100°C for 1h, then heating to 160°C for 1h, and finally heating to 220°C for 2h.

[0067] After the heat shrink polymerization reaction in the present invention is completed, the hot oven is closed and allowed to cool naturally. When the temperature drops to 150° C., the mold is taken out, the high-temperature tape of polyimide is peeled off, and the rectangular groove 41 and the array fiber grating strain gauge semi-finished product are separated using a utility knife (at this time, the polyamic acid filled in the gap of the rectangular groove 41 undergoes a heat shrink polymerization reaction and solidifies to form a polyimide packaging block 32, the length of the polyimide packaging block 32 is equal to the length of the rectangular groove 41, the height is equal to the diameter of the optical fiber 1, and the width is equal to the width of the rectangular groove 41; at the same time, the polyamic acid applied on the surface of the substrate 31 is solidified to form a corresponding bonding layer 311 on the upper surface of the substrate 31.

[0068] In the present invention, a semi-finished fiber grating strain gauge array is taken, and adhesive is applied on the upper surface of the polyimide packaging block 32 to form an adhesive layer 31. Then, a glass fiber cover plate 33 is covered on the upper surface of the adhesive layer 31. Then, a capillary is sleeved on the outer side of the remaining grating 11 without the strain measurement accessory 3, and both ends of the capillary are sealed with glue to finally obtain an array fiber grating strain gauge.

[0069] Furthermore, the amount of glue (the glue is a conventional adhesive type glue, further, the glue is selected from epoxy resin glue and / or UV curing glue, and in this embodiment, the glue is selected from UV curing glue) is sufficient to form an adhesive layer 31 to stick the fiberglass cover 33. Furthermore, the length of the fiberglass cover 33 is equal to the length of the rectangular groove 41, and the width of the fiberglass cover 33 is equal to the width of the rectangular groove 41.

[0070] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0071] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An array fiber Bragg grating strain gauge, characterized in that: The arrayed fiber grating strain gauge comprises an optical fiber (1), on which a temperature compensation accessory (2) and a plurality of strain measurement accessories (3) are arranged; The strain measurement accessory (3) is used to measure strain; the temperature compensation accessory (2) isolates strain and is used for temperature compensation.

2. The arrayed fiber Bragg grating strain gauge according to claim 1, characterized in that: The temperature compensation accessory (2) is a capillary tube sleeved on the outside of the optical fiber (1), and the sleeved optical fiber (1) is provided with a grating (11); The length of the capillary is greater than or equal to twice the length of the grating (11); The inner diameter of the capillary is 0.15-0.25 mm, and the outer diameter is 0.4-0.6 mm.

3. The arrayed fiber Bragg grating strain gauge according to claim 1 or 2, characterized in that: Each strain measurement accessory (3) comprises a substrate (31) and an adhesive layer (311) arranged on the upper surface of the substrate (31); a polyimide packaging block (32) is arranged on the upper surface of the adhesive layer (311); the polyimide packaging block (32) covers the entire upper surface of the adhesive layer (311); the polyimide packaging block (32) is wrapped around the outer side of the optical fiber (1); and the wrapped optical fiber (1) is provided with a grating (11); an adhesive layer (331) is arranged on the upper surface of the polyimide packaging block (32); and a glass fiber cover plate (33) is also covered on the upper surface of the adhesive layer (331); The material of the substrate (31) is selected from aluminum, aluminum alloy, stainless steel, copper or polyimide.

4. A mold for preparing the arrayed fiber Bragg grating strain gauge according to any one of claims 1 to 3, characterized in that: The mold comprises a plurality of template blocks (4) and a clamp (5); A rectangular groove (41) penetrating the template block (4) is provided on the top of each template block (4); The clamp (5) is used to clamp a plurality of template blocks (4) at the same time.

5. The mold for preparing an arrayed fiber Bragg grating strain gauge according to claim 4, characterized in that: The clamp (5) simultaneously clamps one side of the rectangular groove (41) of each template block (4).

6. The mold for preparing an arrayed fiber Bragg grating strain gauge according to claim 4 or 5, characterized in that: The clamp (5) comprises a first clamping plate (51), a second clamping plate (52), and a back plate (53) connecting the first clamping plate (51) and the second clamping plate (52); The clamp (5) further comprises a screw (54), through which the distance between the first clamping plate (51) and the second clamping plate (52) is controlled, so as to clamp the template block (4).

7. The mold for preparing an arrayed fiber Bragg grating strain gauge according to claim 6, characterized in that: The clamping length of the clamp (5) is greater than or equal to twice the length of the template block (4).

8. A method for preparing an arrayed fiber Bragg grating strain gauge using the mold according to any one of claims 4 to 7, characterized in that: The method comprises the following steps: A clamp (5) is used to clamp a plurality of template blocks (4) at the same time, polyamic acid is applied on the surface of the substrate (31), and then the substrate (31) with the surface applied with polyamic acid is placed in the rectangular groove (41) of each template block (4), and the optical fiber (1) is placed in the rectangular groove (41) of the template block (4), and the grating (11) of the optical fiber (1) is located in the rectangular groove (41), and polyamic acid is dripped into the gap in the rectangular groove (41), and the polyamic acid is wrapped around the optical fiber (1) located in the rectangular groove (41), and then a heat shrink polymerization reaction is performed to obtain a semi-finished product of an array type optical fiber grating strain gauge; Adhesive is applied on the surface of the polyimide packaging block (32) to form an adhesive layer (331), a glass fiber cover plate (33) is covered on the adhesive layer (331), a capillary is sheathed on the outer side of the remaining gratings (11), and both ends are sealed with glue to obtain an array-type fiber Bragg grating strain gauge.

9. The method for preparing an arrayed fiber Bragg grating strain gauge using a mold according to claim 8, characterized in that: The length of the rectangular groove (41) is 2-3 times the length of the grating (11).

10. The method for preparing an arrayed fiber Bragg grating strain gauge using a mold according to claim 8 or 9, characterized in that: The conditions of the heat shrink polymerization reaction include: keeping the temperature at 80-100° C. for 0.5-1.5 hours, then heating to 150-200° C. for 0.5-1.5 hours, and finally heating to 200-220° C. for 1-3 hours.

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