Rod type six-component optical fiber balance and FBG grating installation method

Abstract

The invention discloses a rod type six-component optical fiber balance and an FBG grating installation method, and belongs to the technical field of optical fiber balances. The problems that an existing optical fiber balance is low in sensitivity, the measuring capacity of the existing optical fiber balance is affected, and wiring is not convenient are solved. A first group of four-column strain beams, a resistance element supporting sheet, a second group of four-column strain beams and an equal straight section are sequentially arranged between a model end conical surface and a fixed end conical surface, a resistance element elastic element is arranged on the resistance element supporting sheet, and the equal straight section is connected with the fixed end conical surface through an M42 left-hand thread; the first set of four-column strain beams, the second set of four-column strain beams and the resistance element supporting piece are all provided with optical fiber wiring grooves machined along the centers of the beams, and optical fibers are arranged in the optical fiber wiring grooves. According to the rod type six-component optical fiber balance and the FBG grating installation method, the measurement capability of the optical fiber balance and the wiring convenience are improved, on the other hand, a sensitization structure is optimized to a certain degree, and the sensitivity of the optical fiber balance is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber balances, and in particular relates to a rod-type six-component optical fiber balance and an FBG grating installation method. Background Art

[0002] Strain balance is a main measuring instrument in wind tunnel force test, used to measure the force and torque of air on the aircraft model. The rod structure is the most commonly used structural form of strain balance. Its appearance is generally cylindrical, one end is connected to the model, and the other end is connected to the support rod. It has the advantages of strong applicability, small size, and simple processing. If strain gauges are used as measuring elements, it is usually necessary to form a Wheatstone bridge to convert the strain into an electrical signal under a certain power supply voltage. Since the output voltage signal of the strain balance is relatively small, usually at the millivolt or microvolt level, when the electromagnetic interference in the use environment is strong, it will have a greater impact on the measurement signal of the resistance balance. The fiber optic balance is a new measuring instrument developed in recent years. It installs fiber optic Bragg grating strain gauges on each measuring beam of the balance as a measuring element to sense aerodynamic force. The aerodynamic output value of the balance is obtained by converting the strain into the change in the central wavelength. The current fiber optic balance measurement capacity is usually three-component or five-component. On the one hand, its structure needs to be improved and optimized to enhance the measurement capability and facilitate wiring. On the other hand, the sensitivity enhancement structure should also be studied to improve the sensitivity of the balance.

[0003] Therefore, the present application proposes a rod-type six-component fiber optic balance and an FBG grating installation method to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing fiber optic balance has low sensitivity, affects its measurement ability and is inconvenient for wiring. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0005] The technical solution of the present invention: Solution 1: A rod-type six-component fiber optic balance, comprising a model end cone, a first group of four-column strain beams, a resistance element support plate, a second group of four-column strain beams, an equal straight section and a fixed end cone, wherein the first group of four-column strain beams, a resistance element support plate, a second group of four-column strain beams and an equal straight section are sequentially arranged between the model end cone and the fixed end cone, a resistance element support plate is provided with a resistance element elastic element, and the equal straight section is connected to the fixed end cone via an M42 left-handed thread; the first group of four-column strain beams, the second group of four-column strain beams and the resistance element support plate are all machined with a fiber optic routing groove machined along the center of the beam, and the optical fiber is arranged in the fiber optic routing groove.

[0006] Furthermore, a calibration plane is provided on the resistance element support sheet, and a cutting groove is also processed on the resistance element support sheet.

[0007] Furthermore, a central groove is processed on the support plate of the resistance element, and the elastic element of the resistance element is arranged in the central groove.

[0008] Furthermore, the first group of four-column strain beams and the second group of four-column strain beams are combined measurement elements of normal force, lateral force, yaw moment, pitch moment and roll moment.

[0009] Solution 2: A method for installing an FBG grating of a rod-type six-component fiber optic balance, which is based on the rod-type six-component fiber optic balance described in Solution 1 and includes the following steps: Step 1: Screen FBG grating strain gauges with stable spectral characteristics, test the linearity and sensitivity of the preliminarily screened FBG grating strain gauges one by one, and select FBG grating strain gauges with consistent sensitivity characteristics as the spare strain gauges for pasting; Step 2: Use gasoline to clean the balance surface and grooves to remove impurities and metal debris. Use No. 100 and No. 400 gauze to clean the surface of the first and second four-column strain beams. Grind them crosswise at 45 degrees along the axis of the balance until the lines are clear and the depth is consistent. Use an absorbent cotton ball soaked in ethanol to scrub the surface of the first and second four-column strain beams in one direction until the absorbent cotton does not change its original white color. Step 3: Press and fix the fiber core of the FBG grating strain gauge in the cutting groove according to the position of the balance line, and use high-temperature transparent tape to initially stick the optical fiber and its packaging in the optical fiber routing groove, so that the FBG grating strain gauge and the optical fiber do not move, and the curvature radius of the optical fiber is less than 5mm during installation; dip and apply epoxy resin glue at 2mm from the front and rear ends of the optical fiber core, apply appropriate pre-tightening force to straighten the optical fiber, compact the gap between the optical fiber and the optical fiber routing groove, make the FBG grating strain gauge and the optical fiber fit tightly, and let it stand at room temperature for one hour to allow the epoxy resin glue layer to dry completely; Step 4: Place the balance body in an oven for heating. Take it out and apply adhesive on the balance surface. Determine the number of times to apply the adhesive according to the type of adhesive and perform the curing process according to the selected adhesive curing procedure.

[0010] The present invention has the following beneficial effects: The rod-type six-component fiber optic balance of the present invention improves the existing three-component fiber optic balance or five-component fiber optic balance in structure, thereby improving the measurement capability and wiring convenience of the fiber optic balance. On the other hand, the sensitivity enhancement structure is also optimized to a certain extent, thereby improving the sensitivity of the fiber optic balance. The optical fiber routing groove designed for the rod-type six-component optical fiber balance of the present invention can improve the fit between the optical fiber strain gauge and the balance, increase the resolution of the balance and protect the optical fiber from displacement and damage by external forces. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the overall structure of a rod-type six-component optical fiber balance; Figure 2 It is a front view of a rod-type six-component fiber optic balance; Figure 3 This is a schematic diagram of the position relationship of the center wiring trough.

[0012] Figure 4 It is a partial cross-sectional view of a rod-type six-component fiber optic balance; Figure 5 This is a schematic diagram of optical fiber installation and laying.

[0013] In the figure: 1-conical surface of model end, 2-first group of four-column strain beams, 3-support plate of resistance element, 4-second group of four-column strain beams, 5-equal straight section, 6-M42 left-handed thread, 7-fixed end conical surface, 8-elastic element of resistance element, 9-calibration plane, 10-cutting groove, 11-center groove, 12-optical fiber routing groove, 13-optical fiber. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0015] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection (i.e., non-detachable connection) includes but is not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but is not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and hinge connection is selected for detachable connection.

[0016] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an 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, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0017] Embodiment 1, combination Figure 1-Figure 5 The present embodiment is described. A rod-type six-component fiber optic balance of the present embodiment comprises a model end cone surface 1, a first group of four-column strain beams 2, a resistance element support sheet 3, a second group of four-column strain beams 4, an equal straight section 5 and a fixed end cone surface 7. The first group of four-column strain beams 2, the resistance element support sheet 3, the second group of four-column strain beams 4 and the equal straight section 5 are sequentially arranged between the model end cone surface 1 and the fixed end cone surface 7. A resistance element elastic element 8 is arranged on the resistance element support sheet 3. The equal straight section 5 is connected to the fixed end cone surface 7 through an M42 left-handed thread 6. The first group of four-column strain beams 2, the second group of four-column strain beams 4 and the resistance element support sheet 3 are all processed with an optical fiber routing groove 12 processed along the center of the beam, and the optical fiber 13 is arranged in the optical fiber routing groove 12; A calibration plane 9 is arranged on the resistance element support plate 3. The calibration plane 9 is a plane machining reference for machining the balance body, and the angle of attack and the roll angle of the balance body are measured with this plane as a reference. The measuring beam of the resistance element support plate 3 is arranged at the design center of the balance body, and is in an I-shape. Its upper end is connected to the upper part of the balance body cut off by the cutting groove 10, and its lower end is connected to the lower part cut off by the cutting groove. The resistance measuring element is symmetrical front and back.

[0018] The resistance element support sheet 3 is also processed with a cutting groove 10, which is a slit-like physical structure that starts from the center plane of the balance and cuts the balance body part in a certain geometric shape. The preferred process is wire cutting. The balance body after cutting can be divided into two upper and lower frames, which are connected by the resistance element elastic element 8 and the resistance element support sheet 3. The purpose is to reduce the rigidity of the balance resistance direction and amplify the micro-deformation of the resistance element elastic element 8.

[0019] A central groove 11 is processed on the resistance element support sheet 3, and the resistance element elastic element 8 is arranged in the central groove 11. The central groove 11 starts from the design center of the balance body and is in a set geometric shape, preferably a rectangular shape. A longitudinally penetrating groove is formed by removing materials. The function of the central groove 11 is to increase the available space in the middle part of the balance body, so that the longitudinal length of the resistance element elastic element 8 reaches the maximum, so as to facilitate the subsequent pasting of the FBG optical fiber strain gauge. The height of the upper and lower edges of the central groove is consistent with the height of the resistance element elastic element 8. The optical fiber 13 is laid on the balance through the optical fiber wiring groove 12, as shown in the attached Figure 5 As shown, the middle section of the optical fiber 13 is etched to form an FBG grating, which acts as a strain gauge.

[0020] The first group of four-column strain beams 2 and the second group of four-column strain beams 4 are combined measuring elements for normal force, lateral force, yaw moment, pitch moment and roll moment. The first group of four-column strain beams 2, the second group of four-column strain beams 4 and the resistance element support plate 3 are all processed with an optical fiber routing groove 12 processed along the center of the beam. The optical fiber routing groove 12 is a shallow semicircular groove processed by removing material at the corresponding position where the optical fiber line of the balance body passes through. The preferred depth is 2 mm. The corresponding layout position can be changed according to different measurement requirements. The optical fiber routing groove 12 can improve the fit between the optical fiber strain gauge and the balance body, increase the balance resolution, and protect the optical fiber from displacement and damage by external forces.

[0021] Embodiment 2, combined Figure 1-Figure 5 This embodiment is described. The FBG grating installation method of a rod-type six-component fiber optic balance of this embodiment includes the following steps: Step 1: Screen FBG grating strain gauges with stable spectral characteristics, test the linearity and sensitivity of the preliminarily screened FBG grating strain gauges one by one, and select FBG grating strain gauges with consistent sensitivity characteristics as the spare strain gauges for pasting; Step 2: Use gasoline to clean the balance surface and grooves to remove impurities and metal debris, use No. 100 and No. 400 gauze to clean the surface of the first group of four-column strain beams 2 and the second group of four-column strain beams 4, and polish them crosswise along the axis of the balance at 45 degrees until the lines are clear and the depth is consistent, soak ethanol with an absorbent cotton ball, and scrub the surface of the first group of four-column strain beams 2 and the second group of four-column strain beams 4 in one direction until the absorbent cotton does not change its original white color; Step 3: Press and fix the core of the FBG grating strain gauge in the cutting groove 10 according to the position of the balance mark, and use high-temperature transparent tape to initially stick the optical fiber 13 and its packaging material in the optical fiber routing groove 12, so that the FBG grating strain gauge and the optical fiber 13 do not move, and the curvature radius of the optical fiber 13 is less than 5mm during installation; Dip and apply epoxy resin glue at 2mm from the front and rear ends of the optical fiber 13 core, apply appropriate pre-tightening force to straighten the optical fiber 13, compact the gap between the optical fiber 13 and the optical fiber routing groove 12, make the FBG grating strain gauge and the optical fiber 13 fit tightly, and let it stand at room temperature for one hour to allow the epoxy resin glue layer to completely dry; Step 4: Place the balance body in an oven for heating. Take it out and apply adhesive on the balance surface. Determine the number of times to apply the adhesive according to the type of adhesive and perform the curing process according to the selected adhesive curing procedure.

[0022] This embodiment is only an exemplary description of the present invention and does not limit its protection scope. Those skilled in the art may also make partial changes thereto. As long as they do not exceed the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. A rod-type six-component optical fiber balance, characterized in that: The invention comprises a model end cone surface (1), a first group of four-column strain beams (2), a resistance element support sheet (3), a second group of four-column strain beams (4), an equal straight section (5) and a fixed end cone surface (7); the first group of four-column strain beams (2), a resistance element support sheet (3), a second group of four-column strain beams (4) and an equal straight section (5) are arranged in sequence between the model end cone surface (1) and the fixed end cone surface (7); a resistance element elastic element (8) is arranged on the resistance element support sheet (3); the equal straight section (5) and the fixed end cone surface (7) are connected via an M42 left-handed thread (6); the first group of four-column strain beams (2), the second group of four-column strain beams (4) and the resistance element support sheet (3) are all processed with an optical fiber routing groove (12) processed along the center of the beam, and the optical fiber (13) is arranged in the optical fiber routing groove (12).

2. A rod-type six-component optical fiber balance according to claim 1, characterized in that: The resistance element support sheet (3) is provided with a calibration plane (9), and a cutting groove (10) is also machined on the resistance element support sheet (3).

3. A rod-type six-component optical fiber balance according to claim 2, characterized in that: A central groove (11) is machined on the resistance element support plate (3), and the resistance element elastic element (8) is arranged in the central groove (11).

4. A rod-type six-component optical fiber balance according to claim 3, characterized in that: The first group of four-column strain beams (2) and the second group of four-column strain beams (4) are combined measurement elements for normal force, lateral force, yaw moment, pitch moment and roll moment.

5. A method for installing an FBG grating of a rod-type six-component fiber optic balance, the method being implemented by the rod-type six-component fiber optic balance according to claim 4, characterized in that: The following steps are involved: Step 1: Screen FBG grating strain gauges with stable spectral characteristics, test the linearity and sensitivity of the preliminarily screened FBG grating strain gauges one by one, and select FBG grating strain gauges with consistent sensitivity characteristics as the spare strain gauges for pasting; Step 2: Use gasoline to clean the surface and grooves of the balance to remove impurities and metal debris, use No. 100 and No. 400 gauze to clean the surface of the first group of four-column strain beams (2) and the second group of four-column strain beams (4), and polish them crosswise along the axis of the balance at a 45-degree angle until the lines are clear and the depth is consistent, and use an absorbent cotton ball soaked in ethanol to wipe the surface of the first group of four-column strain beams (2) and the second group of four-column strain beams (4) in one direction until the absorbent cotton does not change its original white color; Step 3: Press and fix the fiber core of the FBG grating strain gauge into the cutting groove (10) according to the position of the balance mark, and use high-temperature transparent tape to initially stick the optical fiber (13) and its packaging into the optical fiber routing groove (12), so that the FBG grating strain gauge and the optical fiber (13) do not move, and at the same time, the curvature radius of the optical fiber (13) is less than 5mm during installation; Dip and apply epoxy resin glue at 2mm from the front and rear ends of the optical fiber (13) core, apply appropriate pre-tightening force to straighten the optical fiber (13), compact the gap between the optical fiber (13) and the optical fiber routing groove (12), so that the FBG grating strain gauge and the optical fiber (13) are closely attached, and stand at room temperature for one hour to allow the epoxy resin glue layer to completely dry; Step 4: Place the balance body in an oven for heating. Take it out and apply adhesive on the balance surface. Determine the number of times to apply the adhesive according to the type of adhesive and perform the curing process according to the selected adhesive curing procedure.

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