Engineering application-oriented temperature compensation integrated patch type fiber grating strain sensor

Abstract

The utility model relates to an engineering application oriented temperature compensation integrated patch type fiber bragg grating strain sensor, which comprises a substrate, an optical fiber, a connecting table, an armored sheath and a protective cover, the substrate is made of a deformable heat conduction metal material, one end of the substrate is a strain sensitive area, and the other end of the substrate is a temperature compensation area. A strain grating and a temperature compensation grating which are arranged at an interval are etched on the optical fiber, the strain grating is fixed in a strain sensitive area, the temperature compensation grating is fixed in a temperature compensation area, the optical fiber in the strain sensitive area is wired in a straight line, and the optical fiber in the temperature compensation area is wired in an arc shape. According to the utility model, the strain grating and the temperature grating are packaged into a whole, so that the temperature response real-time performance of the double gratings is ensured, and temperature compensation is carried out in time; and the fiber outlet end is protected by the armored optical cable and can be in hard connection with a protective cover, so that damage is prevented in the transportation and construction process, the yield is improved, and the strain monitoring device is suitable for strain monitoring of outdoor large building structures.

Description

Technical field:

[0001] The utility model belongs to the technical field of sensors, and in particular relates to a temperature-compensated integrated patch-type optical fiber Bragg grating strain sensor for engineering applications. Background technology:

[0002] With the development of optical fiber technology, fiber grating strain sensors have been widely used due to their high sensitivity, electromagnetic insulation, strong corrosion resistance, long transmission distance and other advantages. Among them, patch strain sensors are selected as a suitable choice for stress monitoring of various large structures such as energy and chemical industry, aerospace, civil engineering, etc. due to their small size and simple installation.

[0003] However, the temperature sensitivity of fiber Bragg grating strain sensors is much greater than their strain sensitivity, resulting in a greater impact of temperature on strain sensors. The timeliness of temperature compensation has become one of the important factors affecting the accuracy of strain sensors.

[0004] Traditional fiber Bragg grating patch strain sensors are designed with only strain sensitive units, and then connected in series with other temperature sensors for temperature compensation. However, due to the inconsistent temperature response time of the two sensors, the temperature compensation is delayed, resulting in strain monitoring errors. At the same time, traditional fiber Bragg grating patch strain sensors are thin and only use plastic sheaths to protect the optical fiber, which is easily damaged during transportation and construction, and cannot be used outdoors for a long time. Utility model content:

[0005] The technical problem to be solved by the utility model is to provide a temperature-compensated integrated patch-type fiber grating strain sensor for engineering applications. The strain sensor ensures the real-time temperature response of the dual gratings and timely temperature compensation by encapsulating the strain and temperature gratings in one. The fiber outlet end is protected by an armored optical cable and can be hard-connected to a protective cover to prevent damage during transportation and construction, thereby improving the yield rate and being suitable for strain monitoring of large outdoor building structures.

[0006] The technical solution of the utility model is to provide a temperature-compensated integrated patch-type fiber grating strain sensor for engineering applications, comprising a base, an optical fiber, a boss, an armored sheath and a protective cover, wherein the base is made of metal material, one end of the base is a strain sensitive area, the strain sensitive area is a structure that can be deformed under tension, the other end of the base is a temperature compensation area, strain gratings and temperature compensation gratings arranged at intervals are etched on the optical fiber, wherein the strain grating is welded to the strain sensitive area, the temperature compensation grating is fixed to the temperature compensation area, the optical fiber located in the strain sensitive area is arranged in a straight line, and the optical fiber located in the temperature compensation area is arranged in an arc; bosses are also provided at both ends of the base, and a through hole for the optical fiber to pass through is opened on the boss, one end of the armored sheath is passed through the through hole of the boss and fixedly connected to it, the other end of the armored sheath extends in a direction away from the boss, the two ends of the optical fiber are respectively passed through the armored sheaths at both ends of the base, and the protective cover is provided on the base and connected and fixed through the boss.

[0007] The base of the utility model is made of metal material with good elasticity, corrosion resistance and thermal conductivity, so as to ensure the rapid response of strain and temperature of the sensor and the service life.

[0008] As a preferred method, the strain grating is welded to the strain sensitive area, and the strain grating has a pre-tension during welding. Increasing the pre-tension during welding of the strain grating can ensure the accuracy of the strain coefficient.

[0009] As a preferred embodiment, the fiber section where the temperature compensation grating is located is arranged in an arc shape, and the temperature compensation grating is freely bent and pasted in the temperature compensation area, so that a certain amount of fiber redundancy can be left to ensure the accuracy of the temperature compensation grating.

[0010] Preferably, one end of the armored sheath is inserted into the through hole of the boss and is flush with the inner side of the boss, and the armored sheath is bonded and fixed to the boss. The bonding method can be fixed with glue to ensure the safety of the sensor fiber output, which is suitable for engineering applications.

[0011] Preferably, the protective cover is fixedly connected to the boss by screws. The boss is welded to the base, and the top of the boss and the protective cover have symmetrical threaded holes. During the transportation and installation of the sensor, the sensor and the protective cover are hard-connected to protect the patch strain sensor.

[0012] Preferably, the base is made of stainless steel.

[0013] Preferably, the protective cover is made of UV-resistant material to protect the sensor for long-term outdoor use.

[0014] Preferably, the protective cover is made of polyvinyl chloride.

[0015] Compared with the prior art, the utility model has the following advantages:

[0016] 1. Fast temperature response rate and high real-time performance: The sensor is designed to encapsulate strain and temperature gratings in one, ensuring the real-time temperature response of the dual gratings;

[0017] 2. High accuracy of strain and temperature testing: Pre-tension should be added when welding the strain grating to ensure the accuracy of strain measurement; the temperature compensation grating can not only be used as a temperature sensor, but also provide real-time temperature compensation for the strain grating, and a certain amount of redundancy is left when pasting to ensure the accuracy of temperature measurement;

[0018] 3. For engineering applications: The welded bosses on both sides of the base can be used to fix the armored optical cable and protect the sensor fiber output; the bosses can be hard-connected with the protective cover to protect the sensor during transportation and construction. Description of the drawings:

[0019] Figure 1 This is an optical fiber routing diagram of a temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications of the utility model.

[0020] Figure 2 This is a simulation diagram of a temperature-compensated integrated patch-type fiber grating strain sensor base for engineering applications of the utility model.

[0021] Figure 3 This is a simulation diagram of a protective cover for a temperature-compensated integrated patch-type fiber grating strain sensor for engineering applications according to the utility model.

[0022] In the figure, 1. strain grating; 2. temperature compensation grating; 3. threaded hole; 4. boss; 5. armored sheath; 6. base; 7. protective cover. Specific implementation method:

[0023] The present invention will be further described below with reference to the accompanying drawings:

[0024] like Figure 1-3As shown, a temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications includes a base 6, an optical fiber, a boss 4, an armored sheath 5 and a protective cover 7. The base 6 is made of a deformable heat-conducting metal material. One end of the base 6 is a strain sensitive area. The base area where the strain sensitive area is located can be stretched and easily deformed. The other end of the base 6 is a temperature compensation area. The base area where the temperature compensation area is located has a stable structure and is not easily affected by stress. A strain grating 1 and a temperature compensation grating 2 are etched on the optical fiber. The strain grating 1 and the temperature compensation grating 2 are arranged at intervals. 1 is fixed in the strain sensitive area, and the temperature compensation grating 2 is fixed in the temperature compensation area; there are two bosses 4, which are respectively fixed at both ends of the base 1, and the boss 4 is provided with a through hole along the long base axial direction 4. One end of the armored sheath 5 is passed through the through hole of the boss and is fixed thereto by glue, and the other end of the armored sheath 5 extends in a direction away from the boss. The two ends of the optical fiber are respectively passed through the armored sheath 5 at both ends of the base to protect the optical fiber output, which is suitable for engineering applications. In addition, the protective cover 7 is covered on the base 6 and is connected and fixed through the boss 4.

[0025] In this embodiment, the main body at one end of the base 6 is linear, so it is easily deformed by stress. This part is designed as a strain sensitive area, and in order to facilitate the connection between the boss 4 and the strain grating 1, the corresponding connection position can be horizontally integrated with a hollow wing plate. The other end of the base 6 is rectangular and not easily affected by stress. This part is designed as a temperature compensation area. Correspondingly, the optical fiber located in the strain sensitive area is arranged in a straight line, and the optical fiber located in the temperature compensation area is arranged in an arc. The base 6 is made of stainless steel with good elasticity, corrosion resistance and good thermal conductivity. This design encapsulates the temperature strain in one body, and physically isolates the monitoring of temperature and strain, ensuring the simultaneity of the temperature response of the dual gratings and the accuracy of the temperature compensation of the strain grating 1 to the temperature compensation grating 2.

[0026] As an implementation method, the strain grating 1 is welded to the strain sensitive area, and a pre-tension is applied to the strain grating 1 during welding. A certain pre-tension is added during welding to ensure high accuracy of strain monitoring within the measuring range.

[0027] As an implementation method, the fiber section where the temperature compensation grating 2 is located is arranged in an arc shape, which is an arc shape in this embodiment, and the temperature compensation grating 2 is freely bent and pasted in the temperature compensation area. In this way, a certain amount of fiber redundancy can be left, ensuring the high accuracy of the temperature compensation grating 2 as a temperature sensor to monitor temperature changes, and also providing timely temperature compensation for the strain grating 2.

[0028] In addition, one end of the armored sheath 5 is inserted into the through hole of the boss 4 and is flush with the inner side of the boss 4, and the armored sheath 5 is fixed to the boss 4 by glue, thereby ensuring the safety of the sensor output fiber and being suitable for engineering applications.

[0029] Preferably, the protective cover 7 is fixedly connected to the boss by screws. The boss is welded to the base, and the top of the boss and the protective cover have symmetrical threaded holes 3. During the transportation and installation of the sensor, the sensor and the protective cover 7 are hard-connected to protect the patch strain sensor.

[0030] As an implementation method, the protective cover 7 is made of an anti-ultraviolet material, so that the sensor can be protected for long-term outdoor use. In this embodiment, the protective cover 7 is made of polyvinyl chloride.

[0031] After experimental testing, the strain grating 1 and the temperature compensation grating 2 have the same and fast temperature response, which ensures the high accuracy of temperature monitoring and the reliability of strain monitoring; at the same time, in engineering applications, the integrated design of the sensor and the protective cover 7 and the fiber output of the armored sheath 5 prevent the sensor from being damaged.

[0032] The above is only an explanation of the preferred embodiments of the utility model, which cannot be understood as a limitation of the claims. All equivalent process changes made using the utility model specification are included in the patent protection scope of the utility model.

Claims

1. A temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications, characterized by: It includes a base, an optical fiber, a boss, an armored sheath and a protective cover. The base is made of metal material. One end of the base is a strain sensitive area, which is a structure that can be deformed under tension. The other end of the base is a temperature compensation area. Strain gratings and temperature compensation gratings are etched on the optical fiber with intervals. The strain grating is welded to the strain sensitive area, and the temperature compensation grating is fixed to the temperature compensation area. The optical fiber located in the strain sensitive area is arranged in a straight line, and the optical fiber located in the temperature compensation area is arranged in an arc. Bosses are also provided at both ends of the base, and through holes are opened on the bosses for the optical fiber to pass through. One end of the armored sheath is inserted into the through hole of the boss and fixedly connected to it, and the other end of the armored sheath extends in a direction away from the boss. The two ends of the optical fiber are respectively inserted from the armored sheaths at both ends of the base. The protective cover is set on the base and connected and fixed through the bosses.

2. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 1, characterized in that: Strain gratings have pre-tension when welded.

3. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 1, characterized in that: The temperature compensation grating is freely bent and pasted in the temperature compensation area.

4. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 1, characterized in that: One end of the armored sheath is inserted into the through hole of the boss and is flush with the inner side of the boss, and the armored sheath is bonded and fixed to the boss.

5. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 1, characterized in that: The protective cover is fixedly connected to the boss by screws.

6. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 1, characterized in that: The base is made of stainless steel.

7. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 1, characterized in that: The protective cover is made of UV-resistant material.

8. The temperature-compensated integrated patch-type fiber Bragg grating strain sensor for engineering applications according to claim 7, characterized in that: The protective cover is made of polyvinyl chloride.

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