CN209877993U - Spoke type fiber bragg grating fatigue sensor with temperature self-compensation function - Google Patents
Spoke type fiber bragg grating fatigue sensor with temperature self-compensation function Download PDFInfo
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- CN209877993U CN209877993U CN201921033301.9U CN201921033301U CN209877993U CN 209877993 U CN209877993 U CN 209877993U CN 201921033301 U CN201921033301 U CN 201921033301U CN 209877993 U CN209877993 U CN 209877993U
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Abstract
A spoke type fiber bragg grating fatigue sensor with a temperature self-compensation function comprises an elastic body and a fiber bragg grating, wherein the elastic body is composed of a rim, a hub and spokes, the rim is concentrically sleeved on the outer side of the hub, and the rim is fixedly connected with the hub through four uniformly distributed spokes; peripheral screw through holes are uniformly distributed on the wheel rim; a central threaded through hole is formed in the center of the hub; the fiber grating comprises a first grating, a second grating and a third grating, and three gratings are connected in series in one fiber; the four spokes are arranged according to the sequence of the labels, wherein the phase angle between the No. one spoke and the No. three spoke is 180 degrees, and the phase angle between the No. two spoke and the No. four spoke is 180 degrees; firstly, adhering the grating to the front side surface of the spoke, and secondly, adhering the grating to the rear side surface of the spoke; the No. three grating is adhered to the middle part of the upper surface of the No. two or No. four spoke; the first grating and the second grating are adhered in the same direction and are in the tensile strain direction and form an angle of 45 degrees with the neutral layer; the pasting direction of the No. three grating is vertical to the length direction of the No. two or No. four spoke, and the pasting thickness is larger than 1 mm.
Description
Technical Field
The utility model belongs to the technical field of the sensor, especially, relate to a spoke formula fiber grating fatigue sensor with temperature self compensating function.
Background
In a fatigue testing machine, a commonly used fatigue sensor is mainly an electrical measurement sensor, the electrical measurement sensor mostly adopts a transformation principle of a resistance strain type, an elastic body of the sensor is deformed by applying a load, so that surface strain is generated, induction measurement is performed on the strain through a resistance strain gauge, and finally, the variation of the resistance strain gauge is converted into an electrical signal to be output.
Although the electric measurement sensor has the characteristics of good dynamic response and high sensitivity, the strain gauge bridging circuit is too complex and is easily influenced by electromagnetic interference, and after the sensor is used for a long time, the lead and the sensitive grid of the strain gauge are also easily subjected to fatigue damage, so that the long-term measurement stability of the sensor is poor.
The fiber grating is used as a novel passive sensor component, has the excellent characteristics of good insulativity, electrical passivity, strong anti-electromagnetic interference capability, good fatigue property, absolute wavelength coding and the like, and is widely applied to many fields. Although the fiber grating sensor can measure strain, temperature and other physical parameters, in the practical application process of the fiber grating sensor, the strain and the temperature can cause the central wavelength of the fiber grating to drift simultaneously, so that the measurement result cannot be distinguished, and the problem of temperature-strain cross sensitivity is caused, and the problem always influences the application of the fiber grating in the field of sensors.
Taking an existing spoke type optical fiber force transducer as an example, two gratings are generally used in the transducer, the pasting positions of the two gratings are distributed on the side face of the spoke of the elastic body relatively, the first grating is used for sensing tensile strain, and the second grating is used for sensing compressive strain, however, in the structural design of the traditional elastic body, the strain in the tensile direction can only be ensured to be relatively uniform, the strain uniformity in the compressive direction can not be ensured, and the non-uniformity of the strain can cause the reflection spectrum of the grating to generate fission, thereby seriously affecting the measurement precision of the transducer.
SUMMERY OF THE UTILITY MODEL
Problem to prior art existence, the utility model provides a spoke formula fiber grating fatigue sensor with temperature self-compensating function, simple structure need not extra temperature sensor and assists just can realize the self-compensating of temperature, can effectively solve temperature-strain cross sensitivity problem, can effectively improve the measurement accuracy of sensor.
In order to achieve the above purpose, the utility model adopts the following technical scheme: a spoke type fiber bragg grating fatigue sensor with a temperature self-compensation function comprises an elastic body and fiber bragg gratings, wherein the elastic body is composed of a rim, a hub and a spoke, the rim and the hub are both of circular structures, the rim is positioned on the outer side of the hub, and the rim and the hub are concentrically arranged; the number of the spokes is four, the four spokes are uniformly distributed between the wheel rim and the wheel hub, and the wheel rim and the wheel hub are fixedly connected through the spokes; a plurality of peripheral screw hole through holes are formed in the wheel rim, are uniformly distributed in a circumferential manner, each peripheral screw hole is matched with a fastening bolt, and the elastic body is fixedly connected with an installation base of the fatigue testing machine through the fastening bolt; a central threaded through hole is formed in the center of the hub, and a connector of the fatigue testing machine is connected with the central threaded through hole in a matched mode; the fiber grating comprises three gratings which are respectively marked as a No. I grating, a No. II grating and a No. III grating, and the three gratings are connected in series in one optical fiber; the four spokes are respectively marked as a spoke I, a spoke II, a spoke III and a spoke IV, the spoke I, the spoke II, the spoke III and the spoke IV are sequentially arranged, a phase angle of 180 degrees is formed between the spoke I and the spoke III, and a phase angle of 180 degrees is formed between the spoke II and the spoke IV; the grating is adhered to the front side surface of the spoke, and the grating is adhered to the rear side surface of the spoke; and the grating III is adhered to the middle part of the upper surface of the spoke III or the spoke IV.
The first grating and the second grating are adhered in the same direction, are in the tensile strain direction and form an angle of 45 degrees with the neutral layer.
The pasting direction of the No. three grating is perpendicular to the length direction of the No. two spoke or the No. four spoke, and the pasting thickness of the No. three grating is larger than 1 mm.
The central wavelength of the first grating is greater than that of the second grating, and the central wavelength difference between the first grating and the second grating is greater than or equal to 3nm and less than 20 nm; the central wavelength of the No. two gratings is greater than that of the No. three gratings, and the central wavelength difference between the No. two gratings is greater than or equal to 3nm and less than 20 nm.
The first grating, the second grating and the third grating all adopt optical fiber Bragg gratings.
The adhering modes between the grating and the spoke, and between the grating and the spoke or the spoke are all gluing modes.
The utility model has the advantages that:
the utility model provides a spoke formula fiber grating fatigue sensor with temperature self-compensating function, simple structure need not extra temperature sensor and assists just can realize the self-compensating of temperature, can effectively solve temperature-strain cross sensitivity problem, can effectively improve the measurement accuracy of sensor. The utility model discloses compare with traditional electricity class sensor, be difficult for receiving electromagnetic interference, and long-term stability is good.
Drawings
Fig. 1 is a schematic structural diagram of a spoke-type fiber grating fatigue sensor with a temperature self-compensation function according to the present invention;
FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;
in the figure, 1-wheel rim, 2-wheel hub, 3-wheel spoke, 4-peripheral screw hole through hole, 5-central screw hole through hole, 6-grating, 7-grating and 8-grating.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 and 2, a spoke type fiber bragg grating fatigue sensor with a temperature self-compensation function comprises an elastic body and a fiber bragg grating, wherein the elastic body is composed of a rim 1, a hub 2 and a spoke 3, the rim 1 and the hub 2 are both in a circular structure, the rim 1 is positioned on the outer side of the hub 2, and the rim 1 and the hub 2 are concentrically arranged; the number of the spokes 3 is four, the four spokes 3 are uniformly distributed between the rim 1 and the hub 2, and the rim 1 and the hub 2 are fixedly connected through the spokes 3; a plurality of peripheral screw hole through holes 4 are formed in the wheel rim 1, the peripheral screw hole through holes 4 are uniformly distributed in the circumferential direction, each peripheral screw hole through hole 4 is matched with a fastening bolt, and the elastic body is fixedly connected with a mounting base of the fatigue testing machine through the fastening bolt; a central threaded through hole 5 is formed in the center of the hub 2, and a connector of the fatigue testing machine is connected with the central threaded through hole 5 in a matched mode; the fiber grating comprises three gratings, wherein the three gratings are respectively marked as a No. 6 grating, a No. 7 grating and a No. 8 grating, and the three gratings are connected in series in one optical fiber; the four spokes 3 are respectively marked as a spoke I, a spoke II, a spoke III and a spoke IV, the spoke I, the spoke II, the spoke III and the spoke IV are sequentially arranged, a phase angle of 180 degrees is formed between the spoke I and the spoke III, and a phase angle of 180 degrees is formed between the spoke II and the spoke IV; the grating 6 is adhered to the front side surface of the spoke, and the grating 7 is adhered to the rear side surface of the spoke; and the No. three grating 8 is adhered to the middle part of the upper surface of the No. two spoke or the No. four spoke.
The first grating 6 and the second grating 7 are adhered in the same direction, are in the tensile strain direction and form an angle of 45 degrees with the neutral layer.
The pasting direction of the No. three grating 8 is perpendicular to the length direction of the No. two spoke or the No. four spoke, and the pasting thickness of the No. three grating 8 is larger than 1 mm.
The central wavelength of the grating 6 is greater than that of the grating 7, and the central wavelength difference between the grating 6 and the grating 7 is greater than or equal to 3nm and less than 20 nm; the central wavelength of the No. 7 grating is greater than that of the No. 8 grating, and the central wavelength difference between the No. 7 grating and the No. 8 grating is greater than or equal to 3nm and smaller than 20 nm.
The first grating 6, the second grating 7 and the third grating 8 all adopt optical fiber Bragg gratings.
The pasting modes between the grating 6 and the spoke 6, between the grating 7 and the spoke III, and between the grating 8 and the spoke II or the spoke IV are all gluing modes.
When the elastic body of the sensor is subjected to a load vertically applied, the No. 6 grating and the No. 7 grating are simultaneously influenced by strain and temperature, and the influence of an eccentric load is effectively eliminated by the symmetrical arrangement mode of the No. 6 grating and the No. 7 grating; for the No. 8 grating, the No. 8 grating is adhered to the middle part of the upper surface of the No. two spoke or the No. four spoke, and the adhering direction is perpendicular to the length direction of the No. two spoke or the No. four spoke, so that the strain generated in the middle part of the upper surface of the spoke 3 is extremely small through simulation analysis, the adhering thickness is larger than 1mm, the strain transfer rate is lower when the thickness is larger, and the No. 8 grating is insensitive to strain and only influenced by temperature.
When a beam of light enters the optical fiber, the beam of light enters the first grating 6, the second grating 7 and the third grating 8 along the optical fiber, and the following can be known according to the characteristics of the elastic body and the mode coupling theory of the optical fiber grating:
the grating 6 is affected by temperature and strain, and the drift amount of the central wavelength is as the formula (1):
the grating 7 is affected by temperature and strain at the same time, and the drift amount of the central wavelength is as shown in formula (2):
no. 8 grating is only affected by temperature, and the drift amount of the central wavelength is as follows (3):
in the formula: delta lambda1Is the drift amount of the central wavelength of the No. 6 grating, Delta lambda2Is the amount of drift of the center wavelength of the grating 7, Delta lambda3Is the drift amount, lambda, of the center wavelength of No. 8 grating1Is the central wavelength, lambda, of grating 62Is the central wavelength, lambda, of grating 73Is the central wavelength of No. three grating 8,the shift amount of the center wavelength of the # grating 6 caused by the strain,is the amount of shift of the center wavelength of the # grating 6 caused by temperature,the shift amount of the central wavelength of the grating 7 caused by the strain,the amount of central wavelength drift of the # grating 7 caused by temperature,is the central wavelength drift quantity of No. three grating 8 caused by temperature, and the delta T is the temperature variation quantity,are all constant and are all provided with the same power, Peis the effective elasto-optic coefficient;
formula (4) can be obtained by combining formulae (1), (2) and (3) and eliminating delta T:
the shear strain of the spoke side surface obtained by performing stress analysis on the spoke 3 is expressed by the following formula (5):
in the formula: delta epsilon is the shear strain of the side surface of the spoke, mu is the Poisson ratio of the elastomer material, F is the applied force, E is the elastic modulus, and A is the cross-sectional area of the spoke;
bringing formula (5) into formula (4) can obtain the relationship between the amount of center wavelength shift and the applied force, as shown in formula (6):
therefore, through the derivation process, the influence of the temperature change on the strain measurement can be easily eliminated.
The embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the scope of the present invention are intended to be included within the scope of the present invention.
Claims (6)
1. The utility model provides a spoke formula fiber grating fatigue sensor with temperature self compensating function which characterized in that: the elastic body is composed of a wheel rim, a wheel hub and a spoke, the wheel rim and the wheel hub are both of circular structures, the wheel rim is positioned on the outer side of the wheel hub, and the wheel rim and the wheel hub are arranged concentrically; the number of the spokes is four, the four spokes are uniformly distributed between the wheel rim and the wheel hub, and the wheel rim and the wheel hub are fixedly connected through the spokes; a plurality of peripheral screw hole through holes are formed in the wheel rim, are uniformly distributed in a circumferential manner, each peripheral screw hole is matched with a fastening bolt, and the elastic body is fixedly connected with an installation base of the fatigue testing machine through the fastening bolt; a central threaded through hole is formed in the center of the hub, and a connector of the fatigue testing machine is connected with the central threaded through hole in a matched mode; the fiber grating comprises three gratings which are respectively marked as a No. I grating, a No. II grating and a No. III grating, and the three gratings are connected in series in one optical fiber; the four spokes are respectively marked as a spoke I, a spoke II, a spoke III and a spoke IV, the spoke I, the spoke II, the spoke III and the spoke IV are sequentially arranged, a phase angle of 180 degrees is formed between the spoke I and the spoke III, and a phase angle of 180 degrees is formed between the spoke II and the spoke IV; the grating is adhered to the front side surface of the spoke, and the grating is adhered to the rear side surface of the spoke; and the grating III is adhered to the middle part of the upper surface of the spoke III or the spoke IV.
2. The spoke type fiber grating fatigue sensor with the temperature self-compensation function according to claim 1, wherein: the first grating and the second grating are adhered in the same direction, are in the tensile strain direction and form an angle of 45 degrees with the neutral layer.
3. The spoke type fiber grating fatigue sensor with the temperature self-compensation function according to claim 1, wherein: the pasting direction of the No. three grating is perpendicular to the length direction of the No. two spoke or the No. four spoke, and the pasting thickness of the No. three grating is larger than 1 mm.
4. The spoke type fiber grating fatigue sensor with the temperature self-compensation function according to claim 1, wherein: the central wavelength of the first grating is greater than that of the second grating, and the central wavelength difference between the first grating and the second grating is greater than or equal to 3nm and less than 20 nm; the central wavelength of the No. two gratings is greater than that of the No. three gratings, and the central wavelength difference between the No. two gratings is greater than or equal to 3nm and less than 20 nm.
5. The spoke type fiber grating fatigue sensor with the temperature self-compensation function according to claim 1, wherein: the first grating, the second grating and the third grating all adopt optical fiber Bragg gratings.
6. The spoke type fiber grating fatigue sensor with the temperature self-compensation function according to claim 1, wherein: the adhering modes between the grating and the spoke, and between the grating and the spoke or the spoke are all gluing modes.
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| CN110186490A (en) * | 2019-07-04 | 2019-08-30 | 东北大学 | A kind of spoke type fiber grating fatigue sensor with temperature self-compensation function |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110186490A (en) * | 2019-07-04 | 2019-08-30 | 东北大学 | A kind of spoke type fiber grating fatigue sensor with temperature self-compensation function |
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