阅读说明：本技术 测校一体的船用光纤光栅应变传感器系统 (Marine fiber grating strain sensor system integrating measurement and calibration ) 是由 李涛 林杰俊 吴承勇 苑翼飞 于 2019-10-21 设计创作，主要内容包括：本发明涉及一种测校一体的船用光纤光栅应变传感器系统,由光纤光栅应变传感器和传感器校准装置组成,光纤光栅两端分别固定连接在传感器固定端和传感器活动端,传感器固定端通过固定端焊接底座固定连接在定位板上,传感器活动端通过活动端焊接底座与定位板连接,活动端焊接底座可沿定位板前后移动,使光纤光栅两固定点间的距离为有效应变长度L；高精度微分螺杆通过螺杆安装座固定连接在定位板上,螺杆安装座与活动端焊接底座之间通过回位弹簧连接,由高精度微分螺杆配合回位弹簧可以控制传感器活动端前后方向滑动,并可精确控制传感器活动端滑动的位移量ΔL,从而对光纤光栅应变传感器施加标准应变量ε＝ΔL/L,实现光纤光栅应变传感器的安装或校准。(The invention relates to a marine fiber grating strain sensor system with integrated measurement and calibration, which consists of a fiber grating strain sensor and a sensor calibration device, wherein two ends of the fiber grating are respectively and fixedly connected to a fixed end of the sensor and a movable end of the sensor; high accuracy differential screw rod passes through screw rod mount pad fixed connection on the locating plate, is connected through return spring between screw rod mount pad and the expansion end welding base, can control the sensor expansion end fore-and-aft direction by high accuracy differential screw rod cooperation return spring and slide to can the gliding displacement volume delta L of accurate control sensor expansion end, thereby exert standard dependent variable epsilon for fiber grating strain sensor delta L, realize fiber grating strain sensor's installation or calibration.)

1. A marine fiber grating strain sensor system integrating measurement and calibration comprises a fiber grating strain sensor and a sensor calibration device, wherein the fiber grating strain sensor is provided with a fiber grating, two ends of the fiber grating are respectively and fixedly connected to a fixed end of the sensor and a movable end of the sensor, the fixed end of the sensor is fixedly connected to a positioning plate through a fixed end welding base, the movable end of the sensor is connected with the positioning plate through a movable end welding base, and the movable end welding base can be adjusted and moved back and forth along the positioning plate, so that the distance between two fixed points of the fiber grating is the effective strain length L; sensor calibrating device has a high accuracy differential screw rod and return spring, high accuracy differential screw rod passes through screw rod mount pad fixed connection on the locating plate, be connected through return spring between screw rod mount pad and the expansion end welding base, make the top of high accuracy differential screw rod be connected with expansion end welding base contact all the time, can control the sensor expansion end fore-and-aft direction by high accuracy differential screw rod cooperation return spring and slide to but the gliding displacement volume DeltaL of accurate control sensor expansion end, thereby exert standard dependent variable epsilon ═ DeltaL to fiber grating strain sensor, realize fiber grating strain sensor's installation or calibration.

2. The calibration and measurement integrated marine fiber grating strain sensor system of claim 1, wherein: the fiber grating middle protection steel pipe is used for protection, the protection steel pipe is fixedly connected with the sensor fixed end in a thread mode and is connected with the sensor movable end in an oil seal mode, so that the sensor movable end can freely slide along the axial direction of the protection steel pipe, and deformation between the sensor fixed end and the sensor movable end is transmitted to the fiber grating.

3. The calibration and measurement integrated marine fiber grating strain sensor system of claim 1, wherein: the sensor fixed end and the sensor movable end are respectively installed together with the fixed end welding base and the movable end welding base through fastening screws, and the fixed end welding base and the movable end welding base are installed on the surface to be measured through a welding mode.

4. The calibration and measurement integrated marine fiber grating strain sensor system of claim 1, wherein: the sensor stiff end is placed in the stiff end trench of locating plate, stiff end trench both sides restriction sensor stiff end remove to use stop screw to make the sensor stiff end slide around unable, the sensor expansion end is placed in the expansion end trench of locating plate, the expansion end trench both sides restriction sensor expansion end remove.

5. A method for installing and calibrating a measurement and calibration integrated marine fiber grating strain sensor system according to any one of claims 1 to 4, which comprises an initial installation and calibration method and a method for calibrating and replacing the fiber grating strain sensor during use:

(1) initial installation calibration method

Firstly, the primary welding fixation of the fixed end of the sensor on the measured surface is used for calibrating the fiber grating strain sensor: the high-precision differential screw is used for propping against the movable end of the sensor to enable the fiber grating to be in a relaxed state, a return spring is installed, the high-precision differential screw is loosened to enable the fiber grating to be stretched, when the central wavelength begins to increase and change, the initial position of the high-precision differential screw is recorded, the fiber grating is continuously stretched, the standard strain epsilon is applied to the fiber grating strain sensor, the variation of the central wavelength of the fiber grating is delta lambda at the moment, and the sensitivity coefficient of the fiber grating strain sensor is k_εAnd (2) primarily welding and fixing the movable end of the sensor on the surface to be measured, taking down the sensor calibration device and the positioning plate, and further welding and fixing the fixed end of the sensor and the movable end of the sensor.

(2) Method for calibrating and replacing fiber grating strain sensor in use process

Firstly, a sensor calibration device, a fixed end welding base, a movable end welding base and a positioning plate are installed, a fastening screw between a movable end of the sensor and the welding base is dismounted, so that the movable end of the sensor can freely slide in a groove position of the movable end, and then the fiber bragg grating strain sensor is calibrated by adopting a calibration fiber bragg grating strain sensor in an initial installation calibration method; after calibration, if the sensitivity coefficient of the fiber grating strain sensor changes in a rated range, the movable end of the sensor is fastened on the welding base again, the original state is recovered, and the sensitivity coefficient is reset in software.

Technical Field

The invention relates to a fiber grating strain sensor system which is mainly suitable for measuring the overall deformation of a ship body or monitoring the overall deformation of the ship body for a long time.

Background

The fiber grating strain sensor has the advantages of electromagnetic interference resistance, corrosion resistance, light weight, small size and the like, and plays a great role in a ship structure health monitoring system. On one hand, the stress condition, fatigue damage and the like of key parts of the ship body can be monitored in real time in the navigation process of the ship, and early warning can be given when a dangerous condition is met, so that the safe navigation of the ship is ensured; on the other hand, the design of the large ship is continuously optimized by using the collected monitoring data, the structure is improved, the shipbuilding capacity is improved, and the ship is safer and more reliable. It can be seen that the accuracy of the fiber grating strain sensor measurement is of great importance.

However, the existing traceability system of the sensors is not perfect, most sensors do not have the function of being installed and calibrated for many times, and the calibration device of a few calibrated sensors can only be used in a laboratory, which brings great inconvenience for strain sensors which are in service on ships for a long time. Therefore, the development of the integrated fiber grating strain sensor system for measurement and calibration for field calibration has very important significance for ensuring the accurate and uniform magnitude of the ship structure health monitoring system.

Disclosure of Invention

In order to improve the reliability and accuracy of the data of the ship structure health monitoring system, the invention aims to provide a marine fiber grating strain sensor system integrating measurement and calibration.

In order to achieve the purpose, the technical scheme of the invention is as follows: a marine fiber grating strain sensor system integrating measurement and calibration comprises a fiber grating strain sensor and a sensor calibration device, wherein the fiber grating strain sensor is provided with a fiber grating, two ends of the fiber grating are respectively and fixedly connected to a fixed end of the sensor and a movable end of the sensor, the fixed end of the sensor is fixedly connected to a positioning plate through a fixed end welding base, the movable end of the sensor is connected with the positioning plate through a movable end welding base, and the movable end welding base can be adjusted and moved back and forth along the positioning plate, so that the distance between two fixed points of the fiber grating is the effective strain length L; sensor calibrating device has a high accuracy differential screw rod and return spring, high accuracy differential screw rod passes through screw rod mount pad fixed connection on the locating plate, be connected through return spring between screw rod mount pad and the expansion end welding base, make the top of high accuracy differential screw rod be connected with expansion end welding base contact all the time, can control the sensor expansion end fore-and-aft direction by high accuracy differential screw rod cooperation return spring and slide to but the gliding displacement volume DeltaL of accurate control sensor expansion end, thereby exert standard dependent variable epsilon ═ DeltaL to fiber grating strain sensor, realize fiber grating strain sensor's installation or calibration.

Further, protect with the protection steel pipe in the middle of the fiber grating, protection steel pipe and sensor stiff end adopt screw thread mode fixed connection, are connected with the mode that the sensor expansion end adopted the oil blanket, make the sensor expansion end can follow protection steel pipe axial free slip to transmit the deflection between sensor stiff end and the sensor expansion end to fiber grating.

Further, sensor stiff end and sensor expansion end are in the same place through fastening screw and stiff end welding base and expansion end welding pedestal mounting respectively, stiff end welding base and expansion end welding base are installed at the surface of being surveyed through the welded mode.

Further, the sensor stiff end is placed in the stiff end trench of locating plate, stiff end trench both sides restriction sensor stiff end remove to use stop screw to make the sensor stiff end slide around unable, the sensor expansion end is placed in the activity end trench of locating plate, the activity end trench both sides restriction sensor expansion end remove.

A method for installing and calibrating a marine fiber grating strain sensor system integrating measurement and calibration comprises an initial installation and calibration method and a method for calibrating and replacing the fiber grating strain sensor in the using process,

(1) initial installation calibration method

Firstly, the primary welding fixation of the fixed end of the sensor on the measured surface is used for calibrating the fiber grating strain sensor: pressing the movable end of the sensor with a high-precision differential screw to make the fiber grating in a relaxed state, installing a return spring, and loosening the high-precision differential screw to make the fiber grating stretched until the central wavelength begins to increase and change, recording the high-precision differential screwContinuously stretching the fiber grating at the initial position of the differential screw rod, applying a standard strain epsilon to the fiber grating strain sensor, wherein the central wavelength variation of the fiber grating is delta lambda, and the sensitivity coefficient of the fiber grating strain sensor is k_εAnd (2) primarily welding and fixing the movable end of the sensor on the surface to be measured, taking down the sensor calibration device and the positioning plate, and further welding and fixing the fixed end of the sensor and the movable end of the sensor.

(2) Method for calibrating and replacing fiber grating strain sensor in use process

Firstly, a sensor calibration device, a fixed end welding base, a movable end welding base and a positioning plate are installed, a fastening screw between a movable end of the sensor and the welding base is dismounted, so that the movable end of the sensor can freely slide in a groove position of the movable end, and then the fiber bragg grating strain sensor is calibrated by adopting a calibration fiber bragg grating strain sensor in an initial installation calibration method; after calibration, if the sensitivity coefficient of the fiber grating strain sensor changes in a rated range, the movable end of the sensor is fastened on the welding base again, the original state is recovered, and the sensitivity coefficient is reset in software.

The invention has the beneficial effects that:

1. the fiber grating strain sensor system is accurate and reliable after the system value is calibrated;

2. the fiber grating strain sensor mounting tool and the calibration device are the same set of assembly, can be used for on-site calibration, are convenient to use, and can ensure the state consistency during sensor mounting.

3. The fiber grating strain sensor system can be calibrated before installation and in the using process, and can ensure the stability of the sensor in long-term use.

Drawings

FIG. 1 is a schematic structural diagram of a fiber grating strain sensor and a calibration device thereof according to the present invention.

FIG. 2 is a schematic structural diagram of a fiber grating strain sensor according to the present invention.

Detailed Description

The invention is further illustrated by the following figures and examples.

As shown in figures 1 and 2, the marine fiber grating strain sensor system integrating measurement and calibration comprises a fiber grating strain sensor and a sensor mounting tool (calibration device), wherein the fiber grating strain sensor comprises a sensor fixed end 1, a sensor movable end 2, a protection steel pipe 3, a fiber grating 4, a fixed end welding base 8 and a movable end welding base 9, and the mounting tool (calibration device) comprises a positioning plate 5, a high-precision differential screw rod 6 and a return spring 7.

One end of a tail fiber of the fiber bragg grating 4 is fixed on the fixed end 1 of the sensor, the other end of the tail fiber of the fiber bragg grating is fixed on the movable end 2 of the sensor, the distance between two points of the fixed fiber bragg grating 4 is the effective strain length L, the middle of the fiber bragg grating 4 is protected by a protective steel pipe 3, the protective steel pipe 3 is fixedly connected with the fixed end 1 in a threaded mode and is connected with the movable end 2 in an oil seal mode, so that the movable end 2 can freely slide along the axial direction of the protective steel pipe 3, the deformation between the fixed end 1 and the movable end 2 of the sensor is transmitted to the fiber bragg grating 4, the fixed end 1, the movable end 2 and respective welding bases are installed together through fastening screws, and the two welding bases;

sensor stiff end 1 is placed in the stiff end trench of locating plate 5, this stiff end trench both sides restriction stiff end 1 removes, use stop screw to make sensor stiff end 1 unable fore-and-aft slip, sensor expansion end 2 is placed in the expansion end trench of locating plate 5, sensor expansion end 2 can't remove about in this expansion end trench, adopt 6 cooperation return springs 7 of high accuracy differential screw rod to control 2 fore-and-aft directions of sensor expansion end and slide, and its gliding displacement volume delta L of accurate control, thereby apply standard dependent variable epsilon ═ delta L/L to the variable transducer, realize fiber grating strain transducer's installation or calibration.

The general technical idea of the invention is as follows: the strain sensor sensing unit is a fiber grating, the strain measurement is directly realized by stretching or compressing the fiber grating, and the structural part of the sensor is mainly used for protecting, sealing, installing and fixing the sensor. The two ends of the fiber bragg grating for sensing the overall deformation of the ship body are respectively fixed at the fixed end of the sensor and the movable end of the sensor, the periphery of the fiber bragg grating is protected by a stainless steel pipe, one end of the steel pipe is fixedly connected with the fixed end of the sensor in a sealing mode, the other end of the steel pipe is connected with the movable end of the sensor in a sliding mode in a sealing mode, and the distance between the two points for fixing the fiber bragg.

And establishing a corresponding relation between the strain amount and the length variation and the effective strain length according to the strain physical definition. The high-precision spiral micrometer head mechanism is adopted to generate standard displacement variation, and strain calibration is realized by utilizing the corresponding relation between strain and length, so that the strain is traced to the length standard.

The invention relates to a calibration and installation method of a marine fiber grating strain sensor system integrating measurement and calibration, which comprises the following steps:

(1) method for calibrating fiber grating strain sensor

The fixed end 1 of the sensor is placed in a fixed end groove position of a positioning plate 5, the fixed end 1 cannot slide back and forth by using a limiting screw, the movable end 2 of the sensor is placed in a movable end groove position of the positioning plate 5, the movable end 2 of the sensor is propped against a high-precision differential screw 6, the fiber grating 4 is in a loose state, a return spring is installed, the fiber grating 4 is stretched by loosening the differential screw 6, when the central wavelength begins to change (increase), the initial position of the differential screw is recorded, the fiber grating is continuously stretched, a standard strain epsilon is applied to the sensor, the central wavelength variation of the fiber grating is delta lambda at the moment, and the sensitivity coefficient of the fiber grating strain sensor is k_εIf several calibration points are measured more, performance indexes such as linearity of the sensor can be obtained.

(2) Method for installing fiber grating strain sensor

The installation tool is placed at the installation position of the sensor, the surface of the installation position needs to be pretreated, the fixed end 1 of the sensor (installed together with the welding base) is placed in a fixed end groove position of a positioning plate 5, a limiting screw is used for preventing the fixed end 1 from sliding back and forth, the movable end 2 (installed together with the welding base) is placed in a movable end groove position of the positioning plate 5, the fixed end 1 of the sensor is preliminarily welded and fixed on the surface of the installation position, a high-precision differential screw 6 is used for propping against the movable end 2 to enable the fiber grating 4 to be in a loose state, a return spring is installed, the fiber grating 4 is stretched by loosening the differential screw 6, when the central wavelength begins to change (increase), the initial position of the differential screw is recorded, the fiber grating is continuously stretched, a standard strain epsilon is applied to the sensor, the size of the epsilon is determined by the measurement range of the sensor (for example, the, e ═ 2000 mu e), the movable end 2 is initially welded to the mounting surface, the mounting tool is removed, and the fixed end 1 and the movable end 2 are further welded.

(3) Method for calibrating and replacing fiber grating strain sensor in use process

The calibration device is mounted on the sensor in the manner described above, and the movable end 2 of the sensor can slide freely in the slot by removing the fastening screw between the movable end 2 of the sensor and the welding base, so that the sensor can be calibrated in the manner described above.

After calibration, if the change of the sensitivity coefficient of the sensor is not large, the movable end 2 of the sensor is fastened on the welding base again to restore the original state, and the sensitivity coefficient is reset in software.

The invention utilizes the high-precision differential screw to measure the deformation of the fiber grating strain sensor, designs a proper structure to apply a standard strain signal to the sensor, traces the strain quantity to a length reference, and realizes the calibration of the fiber grating strain sensor.

The technology ensures the reliability of the magnitude of the marine fiber grating strain sensor, perfects a ship structure health monitoring system to a certain extent, and ensures the reliability and accuracy of monitoring data.