Strain sensor device

Abstract

The embodiment of the application provides a kind of strain sensor device, comprising: fiber grating strain gauge, fiber grating strain gauge includes optical fiber and encapsulation jig of encapsulation optical fiber;Fixing jig is used to accommodate fiber grating strain gauge, fixing jig includes first accommodating piece and second accommodating piece, first accommodating piece has first end and second end, second accommodating piece has third end and fourth end, the first end and tail end of fiber grating strain gauge are fixed with first end and fourth end respectively, and second end and third end cooperate with each other and can make second end and third end relative movement when fiber grating strain gauge is stressed to stretch out and contract.The strain sensor device provided by the embodiment of the application reduces the risk of physical damage of fiber grating during installation, also improves the accuracy and repeatability of strain measurement by optimizing mechanical coupling and stress transmission path, and also improves the detection accuracy of sensor.

Description

Technical Field

[0001] This application relates to the fields of fiber optic technology and measurement technology, and in particular to a strain sensor device. Background Technology

[0002] Fiber Bragg grating strain sensors are commonly used in harsh environments such as bridges and roadbeds, requiring protection of the fiber gratings to extend their lifespan. The fiber grating is encapsulated in a housing, which is fixed to the substrate being measured. When the substrate deforms, it pulls on the fiber grating within the housing, generating axial strain. Existing housings are inconvenient to install, resulting in low installation efficiency. Summary of the Invention

[0003] This application provides a strain sensor device to solve or alleviate one or more technical problems in the prior art.

[0004] This application provides a strain sensor device, including:

[0005] Fiber Bragg grating strain gauge, which includes optical fiber and a packaging fixture for encapsulating the optical fiber; A fixing fixture is used to accommodate a fiber Bragg grating strain gauge. The fixing fixture includes a first accommodating member and a second accommodating member. The first accommodating member has a first end and a second end, and the second accommodating member has a third end and a fourth end. The first end and the last end of the fiber Bragg grating strain gauge are fixed to the first end and the fourth end, respectively. The second end and the third end cooperate with each other and can move relative to each other when the fiber Bragg grating strain gauge is subjected to stress expansion and contraction.

[0006] In one embodiment, the second end and the third end are configured to have a clearance fit, and the second end and the third end can move relative to each other along the axial direction of the first receiving member and the second receiving member.

[0007] In one embodiment, the second end and the third end are optionally provided with an inner part and an outer part, the inner part being able to extend into the outer part and cooperate with the outer part.

[0008] In one embodiment, the outer end of the inner part is provided with a notch, and the inner end of the outer part is provided with a protrusion. When the inner part is engaged with the outer part, the protrusion and the notch cooperate.

[0009] In one embodiment, the outer wall of the inner part is provided with at least one first concave ring, the first concave ring is disposed at the end of the inner part away from the recess, and a washer is sleeved inside the first concave ring.

[0010] In one embodiment, the outer wall of the inner part is further provided with a second concave ring, which is disposed between the first concave ring and the notch. An elastic soft ring is sleeved inside the second concave ring, wherein the elastic soft ring is a ring spring or made of a conductive adhesive material with elastic restoring force, and the ring spring is a conductive material.

[0011] In one embodiment, there are two first concave rings and two second concave rings, with the two first concave rings spaced apart along the mating direction of the first receiving member and the second receiving member, and the two second concave rings spaced apart along the mating direction of the first receiving member and the second receiving member and located between the two first concave rings.

[0012] In one embodiment, the first receiving member has two first protrusions extending axially on the inner side of the first end, and a first opening groove is formed between the two first protrusions for inserting the head end of the fiber optic strain gauge; the second receiving member has two opposing second protrusions on the inner side of the fourth end, and a second opening groove is formed between the two second protrusions for inserting the tail end of the fiber optic strain gauge.

[0013] In one embodiment, the packaging fixture includes a base plate and a top cover, which cooperate with each other. The target side of the base plate is provided with a transverse groove for holding the optical fiber. The transverse groove extends from the first end of the target side to the last end of the target side. The target side is the side opposite to the base plate or the top cover. The transverse groove includes a central region for holding the fiber Bragg grating. The target side is provided with two first adhesive positions spaced apart along the length of the base plate for fixing the optical fiber. The two first adhesive positions are both provided on the transverse groove and are respectively provided on both sides of the central region near the central region.

[0014] In one embodiment, the target side of the base plate is further provided with a pair of first longitudinal grooves, the first longitudinal grooves being located between two first adhesive positions and the two pairs of first longitudinal grooves being located on opposite sides of the transverse groove; and / or, the top cover is provided with a pair of second longitudinal grooves, the second longitudinal grooves being located at the position of the top cover corresponding to the first adhesive position and the two pairs of first longitudinal grooves being located on opposite sides of the centerline of the top cover in its length direction.

[0015] In one embodiment, a first fixing seat is connected to the first end for fixing to the substrate under test, and a second fixing seat is connected to the fourth end for fixing to the substrate under test. The height distance between the bottom surface of the first fixing seat and the substrate under test and the fiber optic strain gauge is 5-10 mm.

[0016] In one embodiment, both the first fixing seat and the second fixing seat are provided with a receiving cavity. The first end and the fourth end are each provided with a first through hole that communicates with the receiving cavity and the transverse groove respectively for optical fiber to pass through. The receiving cavity is provided with a winding coil for winding optical fiber, and / or, the end of the first fixing seat away from the first end is provided with a second through hole for optical fiber to pass through, and the end of the second fixing seat away from the fourth end is provided with a fixing seat for fixing the optical fiber adapter.

[0017] The strain sensor device provided in this application reduces the risk of physical damage to the fiber Bragg grating during installation. It also improves the accuracy and repeatability of strain measurement and enhances the detection precision of the sensor through optimized mechanical coupling and stress transfer path.

[0018] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0019] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0020] Figure 1 An exploded view of an optical fiber packaging fixture in a strain sensor device according to an embodiment of this application is shown.

[0021] Figure 2 An exploded view of another fiber optic encapsulation fixture in a strain sensor device according to an embodiment of this application is shown.

[0022] Figure 3 This diagram illustrates the structure of a strain sensor device according to an embodiment of the present application, after the optical fiber is encapsulated in another optical fiber encapsulation fixture.

[0023] Figure 4 An exploded structural diagram of a strain sensor device according to an embodiment of this application is shown.

[0024] Figure 5 A schematic diagram of a strain sensor device according to an embodiment of this application is shown.

[0025] Figure 6 A schematic diagram of the structure of a second receiving member according to an embodiment of this application is shown.

[0026] Figure 7 A cross-sectional structural schematic diagram of a second receiving member according to an embodiment of this application is shown.

[0027] Figure 8 A cross-sectional structural schematic diagram of the first receiving member according to another embodiment of this application is shown. Detailed Implementation

[0028] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0029] This application provides a strain sensor device, such as... Figures 1 to 8 As shown in the figure, this application provides a strain sensor device, including: a fiber optic strain gauge and a fixing fixture.

[0030] The fiber optic strain gauge includes an optical fiber and a packaging fixture 600 for encapsulating the optical fiber to ensure that the fiber optic grating maintains its structural integrity in complex environments.

[0031] The fixture is used to accommodate the fiber Bragg grating strain gauge. The fixture includes a first accommodating member 700 and a second accommodating member 800. The first accommodating member 700 has a first end and a second end, and the second accommodating member 800 has a third end and a fourth end. The first end and the last end of the fiber Bragg grating strain gauge are fixed to the first end and the fourth end, respectively. The second end and the third end cooperate with each other and can move relative to each other when the fiber Bragg grating strain gauge is subjected to stress expansion and contraction.

[0032] When strain occurs in the substrate under test, the fiber Bragg grating strain gauge undergoes axial expansion and contraction, causing relative displacement between the first and second receiving components 700 and 800 at their second and third ends. This configuration, by fixing both ends of the strain gauge to two relatively movable receiving components, achieves continuous and smooth stress transmission from the substrate under test to the fiber Bragg grating. This avoids fiber breakage or grating chirping caused by localized stress concentration in traditional rigid fixing methods, significantly reducing the risk of physical damage to the fiber Bragg grating during installation and service. Simultaneously, the free expansion and contraction mechanism between the receiving components optimizes the mechanical coupling path, allowing strain to act more precisely on the grating region, thereby greatly improving the accuracy and repeatability of strain measurement and laying the foundation for high-precision detection.

[0033] In one embodiment, the second end and the third end are configured to have a clearance fit, and the second end and the third end can move relative to each other along the axial direction of the first receiving member 700 and the second receiving member 800.

[0034] The second end of the first receiving member 700 and the third end of the second receiving member 800 maintain a certain radial gap, neither excessively tight nor completely disengaged, forming a sliding fit interface. This gap fit design allows the receiving members to slide axially without obstruction when the fiber Bragg grating strain gauge expands and contracts, eliminating additional friction or jamming caused by excessive tightness. This unrestrained axial movement ensures the linearity and immediacy of strain transfer, avoids interference of non-axial force components on the grating wavelength, and thus improves the repeatability of strain measurement. At the same time, the gap fit avoids mechanical wear and secondary damage to the fiber caused by hard contact, further reducing the risk of physical damage during installation and long-term use.

[0035] In one embodiment, the second end and the third end are optionally provided with an inner portion 710 and an outer portion 840, wherein the inner portion 710 can extend into the outer portion 840 and cooperate with the outer portion 840.

[0036] For example, the second end of the first receiving member 700 can be designed as an inner connection 710, and the third end of the second receiving member 800 can be designed as an outer connection 840. The inner connection 710 is inserted into the inner cavity of the outer connection 840 to form a nested structure. This nested mating method allows for relative axial movement while effectively constraining radial displacement, ensuring that the two receiving members remain coaxial at all times. This arrangement optimizes the straightness of the stress transmission path, ensuring that the fiber optic strain gauge only bears axial tensile and compressive stress, avoiding interference from bending or shear stress on measurement accuracy. At the same time, the guiding effect of the inner connection 710 and the outer connection 840 makes it easy for the two receiving members to align during installation, reducing assembly difficulty and the risk of fiber twisting introduced by it, thus reducing physical damage from the source.

[0037] In one embodiment, the outer end of the inner part 710 is provided with a notch 790, and the inner end of the outer part 840 is provided with a protrusion. When the inner part 710 is engaged with the outer part 840, the protrusion and the notch 790 cooperate.

[0038] In one example, the notch 790 can be designed as an arc-shaped groove or radial hole distributed along the circumference of the outer end of the inner part 710, while the protrusion is an elastic protrusion or pin corresponding to the inner wall of the outer part 840. This concave-convex mating structure restricts the relative rotation between the two receiving parts while allowing axial relative movement. This anti-rotation design ensures that the fiber optic strain gauge does not twist during long-term service, avoiding grating region distortion or wavelength drift caused by twisting, significantly improving the stability and repeatability of strain measurement; at the same time, by preventing unexpected rotation, it eliminates the risk of fiber breakage due to torsional load, further enhancing the structural reliability of the sensor.

[0039] In one embodiment, the outer side wall of the inner connection portion 710 is provided with at least one first concave ring 750, the first concave ring 750 is disposed at one end of the inner connection portion 710 away from the recess 790, and a washer 730 is sleeved inside the first concave ring 750.

[0040] The gasket 730 can be made of wear-resistant materials such as PTFE, rubber, or metal spiral wound gaskets. This gasket 730 provides flexible support and cushioning when the inner part 710 and the outer part 840 slide relative to each other, while simultaneously filling the mating gap. The introduction of the gasket changes the sliding contact interface from rigid contact to elastic contact, effectively absorbing minor vibrations and impacts during installation and strain transfer, preventing the fiber Bragg grating strain gauge from breaking due to instantaneous overload. Furthermore, the gasket can compensate for machining tolerances, ensuring the fit is always at the optimal tightness, guaranteeing smooth sliding while preventing radial wobble, thereby optimizing the linearity and repeatability of stress transfer and improving detection accuracy. In addition, the gasket also achieves a seal between the first and second receiving parts, preventing rainwater, impurities, and dust from seeping into the fixture and corroding the fiber Bragg grating strain gauge.

[0041] In one embodiment, the outer wall of the inner portion 710 is further provided with a second concave ring 760, which is disposed between the first concave ring 750 and the notch 790. An elastic soft ring 740 is sleeved inside the second concave ring 760, wherein the elastic soft ring 740 is a ring spring or made of a conductive adhesive material with elastic restoring force, and the ring spring is a conductive material.

[0042] In one example, the ring spring can be a wave spring or a helical spring, and the conductive adhesive material can be silicone rubber doped with silver powder.

[0043] The flexible ring 740 provides radial elastic support while forming a two-stage buffer system with the washer 730: the washer focuses on sliding guidance and wear resistance, while the flexible ring 740 focuses on dynamic stress absorption and reset. The conductivity of the annular spring or conductive adhesive ensures a reliable electrical connection between the inner part 710 and the outer part 840, that is, between the first and second receiving parts, avoiding potential differences between them. At the same time, it grounds the sensor structure, effectively shields electromagnetic interference, and further improves the signal-to-noise ratio and detection accuracy of the strain signal. Meanwhile, the elastic restoring force ensures that the two receiving parts can automatically return to their original positions after relative movement, enhancing the measurement repeatability of the sensor under cyclic loads.

[0044] In one embodiment, there are two first concave rings 750 and two second concave rings 760. The two first concave rings 750 are spaced apart along the mating direction of the first receiving member 700 and the second receiving member 800, and the two second concave rings 760 are spaced apart along the mating direction of the first receiving member 700 and the second receiving member 800 and located between the two first concave rings 750.

[0045] The multi-point distribution of washers and elastic rings increases the sliding support points, resulting in more uniform force distribution and avoiding excessive wear or stress concentration at a single point. The two first concave rings 750 provide stable guidance at both ends and achieve double sealing, while the two second concave rings 760 enhance the elastic centering capability in the middle, ensuring that the inner part 710 remains coaxial with the outer part 840 at any extension or retraction position, thereby minimizing the nonlinear error of strain transmission. This design also improves fault tolerance; even if a single washer 730 or elastic ring 740 fails, the other component can still maintain basic functionality, thus extending the sensor's lifespan and ensuring long-term measurement accuracy.

[0046] In one embodiment, the first receiving member 700 has two first protrusions 770 extending axially on the inner side of the first end, and a first opening groove is formed between the two first protrusions 770 for inserting the head end of the fiber optic strain gauge; the second receiving member 800 has two opposing second protrusions 810 on the inner side of the fourth end, and a second opening groove 830 is formed between the two second protrusions 810 for inserting the tail end of the fiber optic strain gauge.

[0047] The first and second opening slots 830 are fixedly set within the first receiving member 700 and the second receiving member 800, respectively. The first receiving member 700 and the second receiving member 800 are fixed based on the cooperation of the aforementioned inner part 710 and outer part 840. The relative positions of the first and second opening slots 830 are fixed. When the fiber optic strain gauge is inserted into the first and second opening slots 830, its shape will not be twisted, and its axis will automatically align with the axis of the fixing fixture, ensuring that the strain is transmitted along the ideal axial direction, thus improving the repeatability and accuracy of the measurement from a mechanical structure perspective. In order to reliably fix the fiber optic strain gauge, the first and second ends of the fiber optic strain gauge can also be fixed to the first and second bosses, respectively, by fasteners such as screws.

[0048] In one implementation, such as Figures 1 to 3As shown, the fiber optic packaging fixture 600 includes a base plate 200 and a top cover 100, which cooperate with each other. The target side of the base plate 200 has a transverse groove 300 for securing the fiber optic cable, extending from the first end to the last end of the target side. The target side is the side opposite to the top cover 100. The transverse groove 300 includes a central region for securing a fiber optic grating. The target side has two first adhesive positions 210 spaced apart along the length of the base plate for fixing the fiber optic cable. Both first adhesive positions 210 are located on the transverse groove 300 and are positioned on either side of the central region near the central region. The two first adhesive positions 210 are used to adhesively attach the fiber optic grating, which is the strain-sensing part of the fiber optic cable 500. By attaching the fiber optic grating to both ends of the fiber optic grating within the transverse groove 300 through the two first adhesive positions 210, the fiber optic grating can be further secured, improving the stability of the fiber optic grating in receiving strain. Because the two first adhesive bonding positions 210 are close to the central region, when the optical fiber is subjected to external stress, only the fiber grating between the two first adhesive bonding positions 210 will change with the stress, thereby improving the sensitivity of the fiber grating during the detection process. The base plate 200 and the top cover 100 cooperate with each other, meaning that when the top cover 100 is placed on the base plate 200, the corresponding components are aligned or adapted. The base plate 200 and the top cover 100 can be connected by, for example, a snap-fit ​​connection or a bolt connection, as long as they can be fixed together as an integrated structure.

[0049] The fiber optic encapsulation fixture 600 provided in this embodiment covers the fiber optic cable 500 with a base plate 200 and a top cover 100, encapsulating the fiber optic grating within a closed housing, thus achieving all-around protection for the fiber optic grating. The cooperation between the base plate 200 and the top cover 100 enables rapid and precise positioning and encapsulation of the fiber optic grating. Specifically, the fiber optic cable 500 is snapped and fixed in a transverse groove 300 on the target side of the base plate 200. The transverse groove 300 extends from the first end to the last end of the target side, allowing the fiber optic cable 500 to be laid along the transverse groove 300. Silicone is used to fill the gap between the fiber optic cable 500 and the transverse groove 300, thereby ensuring the stable position of the fiber optic cable 500 within the encapsulation fixture 600 and enabling it to sensitively detect changes in strain. The fiber optic encapsulation fixture 600 of this embodiment also improves the consistency and stability of the fiber optic cable 500 encapsulation, ensuring the long-term reliability of the fiber optic grating in complex environments.

[0050] In one example, when the base plate 200 is attached to the substrate to be tested, a transverse groove 300 can be provided on the target side of the base plate 200 opposite to the top cover 100, so that the light grating on the base plate 200 can sensitively and accurately receive strain, thereby improving the test sensitivity.

[0051] In one example, such as Figure 1As shown, multiple pairs of first longitudinal grooves 400 are provided on the target side of the base plate 200, which has a transverse groove 300. Along the length of the base plate, the two pairs of first longitudinal grooves 400 are located on opposite sides of the transverse groove 300, and the multiple pairs of first longitudinal grooves 400 are all located close to the middle of the transverse groove 300, specifically between two first adhesive positions 210.

[0052] The fiber optic grating encapsulated within the fiber optic packaging fixture 600 needs to receive strain. The fiber optic cable 500 transmits a waveform corresponding to this strain, and the strain condition is determined based on this waveform. To ensure the sensitivity of the fiber optic grating in receiving strain, a first longitudinal groove 400 is provided near the fiber optic grating, which can more sensitively sense the strain condition on the side of the target.

[0053] In this embodiment, by providing a first longitudinal groove 400 on the base plate 200, the base plate 200 has a certain amount of expansion and contraction. When the optical fiber is stretched due to the strain of the object being tested during detection, the base plate 200 is also stretched accordingly, making the optical fiber more sensitive and improving the strain transmission efficiency and sensing sensitivity.

[0054] In one embodiment, the first longitudinal groove 400 extends from the first edge of the target side toward the transverse groove 300, or extends from the transverse groove 300 toward the first edge of the target side, wherein the first edge is a side opposite to the transverse groove 300 in the width direction of the base plate.

[0055] This application provides two types of first longitudinal grooves 400, which can be used selectively or in combination. Each side of the transverse groove 300 includes two edges: a first edge located at the edge of the target side and a second edge located at the edge of the transverse groove 300. One or more first longitudinal grooves 400 extend from the first edge toward the second edge, or from the second edge toward the first edge. The first longitudinal grooves 400 originating from the edge make the base plate easier to stretch.

[0056] In one embodiment, the paired first longitudinal grooves 400 include two first sub-grooves 420 extending from a first edge of the target side toward the transverse groove 300; and the paired first longitudinal grooves 400 include a second sub-grooves 410 extending from a first edge of the transverse groove 300 toward the target side. In this embodiment, multiple pairs of first longitudinal grooves 400 are provided on the base plate 200, wherein multiple first sub-grooves 420 and multiple second sub-grooves 410 are staggered.

[0057] The embodiments of this application, by staggering multiple first sub-grooves 420 and multiple second sub-grooves 410, can further improve strain sensitivity while ensuring the stability and service life of the encapsulation fixture 600.

[0058] In other embodiments, the paired first longitudinal grooves 400 may also include only two first sub-grooves 420 or only two second sub-grooves 410.

[0059] In one embodiment, the first sub-groove 420 and / or the second sub-groove 410 penetrate the base plate 200 along the thickness direction of the base plate; that is, the groove extends from the target side to the lower surface of the base plate 200, forming a through groove structure.

[0060] In one embodiment, the two opposing second sub-grooves 410 are interconnected. This interconnection is achieved without affecting the structural stability or service life of the packaging fixture 600, and features a relatively long first longitudinal groove 400, allowing the base plate 200 to have better flexibility at the interconnected second sub-grooves 410.

[0061] In one embodiment, multiple first longitudinal grooves 400 are disposed in the middle region of the transverse groove 300 and are located between two first adhesive positions 210.

[0062] In one embodiment, the transverse groove 300 is correspondingly disposed on the center line of the base plate 200 along its length direction. The length of the first longitudinal groove 400, or the length of the first sub-groove 420 extending from the first edge toward the transverse groove 300 or the length of the second sub-groove 410 extending from the transverse groove 300 toward the first edge, is less than or equal to 1 / 3 of the width of the target side.

[0063] Since all the first longitudinal grooves 400 extend through the width of the target side, they could easily affect the stability of the base plate 200 and increase the risk of breakage. In this embodiment, the length of the first longitudinal groove 400 is less than or equal to one-third of the width of the target side, i.e., less than half the width of the target side. This allows the first longitudinal grooves 400 to be positioned opposite each other on both sides of the transverse groove 300, resulting in a more balanced strain distribution and more accurate strain sensing by the fiber optic grating within the transverse groove 300.

[0064] In another embodiment, the width of the first longitudinal groove 400 is 0.5mm-2mm; the spacing between two adjacent first longitudinal grooves 400 is 2-5 times the width of the first longitudinal groove 400.

[0065] The width of the first longitudinal groove 400 does not need to be too wide, as an excessively wide groove can easily affect the robustness and service life of the packaging fixture 600; conversely, an excessively narrow width of the first longitudinal groove 400 results in greater strain sensitivity. Therefore, in this embodiment, the width of the first longitudinal groove 400 is limited to 0.5mm-2mm, for example, 0.5mm, 0.8mm, 1.2mm, 1.5mm, 1.7mm, or 2mm.

[0066] If the spacing between two adjacent first longitudinal grooves 400 is too narrow, that is, if the first longitudinal grooves 400 are set too close together, it will easily affect the firmness and service life of the packaging fixture 600. Therefore, under the condition of having appropriate sensitivity, the spacing between adjacent first longitudinal grooves 400 can be reasonably set.

[0067] In one embodiment, the spacing between the two first adhesive positions 210 is 1 / 4 to 1 / 3 of the length of the base plate 200, for example, 1 / 4, 7 / 24, or 1 / 3. This spacing range ensures that the fiber grating region has sufficient length to produce a significant strain response, thereby improving the sensor's ability to detect minute strains.

[0068] In one implementation, such as Figure 3 As shown, in this embodiment of the application, a pair of second longitudinal grooves 130 are provided on the upper cover 100. The second longitudinal grooves 130 are provided on the upper cover 100 at the position corresponding to the first adhesive position 210, and the two pairs of first longitudinal grooves 400 are respectively located on opposite sides of the center line of the upper cover 100 in its length direction.

[0069] A second longitudinal groove 130 is provided on the upper cover 100, allowing the upper cover to also have a certain amount of expansion and contraction. When the optical fiber is stretched due to the strain of the object being tested during detection, the upper cover 100 is also stretched accordingly, making the optical fiber more sensitive and improving strain transmission efficiency and sensing sensitivity. Compared to only providing a first longitudinal groove 400 on the base plate 200, which avoids the upper cover 100 being too rigid and hindering the strain of the optical fiber, the strain sensitivity of the optical fiber can be further improved.

[0070] In one embodiment, the second longitudinal groove 130 on the upper cover 100 is offset from the first longitudinal groove 400 on the base plate 200. For example, the first longitudinal groove 400 on the base plate 200 is located in the middle of the base plate 200, that is, between the two first adhesive positions 210. The second longitudinal groove 130 on the upper cover 100 can be corresponding to the two first adhesive positions 210, so as to balance the tension while ensuring the compressive strength of the fiber optic packaging fixture. At the same time, the number of second longitudinal grooves 130 on the upper cover 100 can be set to be the same as the number of first longitudinal grooves 400 on the base plate 200, thereby balancing the tension of the upper cover 100 and the base plate 200.

[0071] In another embodiment, the second longitudinal groove 130 of the upper cover 100 and the first longitudinal groove 400 of the base plate 200 form a mirror-symmetrical stress relief structure. When the upper cover 100 and the base plate 200 are pressed together, the symmetrical arrangement of the upper and lower grooves ensures the mechanical balance of the encapsulation structure, keeps the optical fiber in a centered position when subjected to strain, avoids off-center loading, and thus improves the consistency of strain transmission and sensing sensitivity.

[0072] Correspondingly, the second longitudinal groove 130 can be configured to have the same structure as the first longitudinal groove 400. The paired second longitudinal grooves 130 include two third sub-grooves 131 extending from the third edge of the cover toward the center line in its length direction; and the paired second longitudinal grooves 130 include two fourth sub-grooves 132 extending from the center line in the length direction of the cover toward its third edge, wherein the third edge refers to the side of the cover opposite to the center line in the length direction of the cover in the width direction.

[0073] In other embodiments, the paired second longitudinal grooves 130 may also include only two third sub-grooves 131 or only two fourth sub-grooves 132.

[0074] In one embodiment, the base plate 200 and / or the top cover 100 are provided with mounting holes 120 at both ends. The mounting holes 120 are used to connect the base plate 200 and the top cover 100 via fasteners and to connect with the external protective shell. Fasteners (such as screws, bolts, etc.) connect the base plate 200 and the top cover 100 within the mounting holes 120, achieving reliable pressing between the two. The same mounting hole 210 or a matching structure is also used to connect with the external protective shell, fixing the entire optical fiber encapsulation fixture inside the protective shell. In one example, the base plate 200 and / or the top cover 100 are respectively provided with protrusions 110 at both ends, and each protrusion 110 has at least one mounting hole 120.

[0075] The bump 110 can be used to conveniently fix the encapsulation fixture 600 so that the encapsulation fixture 600 can be installed on the substrate to be tested, thereby realizing strain measurement of the substrate to be tested.

[0076] In one example, a mounting hole 120 may be provided on the protrusion 110, which is offset from the transverse groove 300 to avoid interference with the optical fiber 500.

[0077] In one example, two or four mounting holes 120 can be provided on the protrusion 110, and the other upper cover 100 or base plate 200 opposite to the protrusion 110 is also provided with corresponding mounting holes 120. The upper cover 100 and the base plate 200 are then tightly fixed by screws.

[0078] To ensure the reliability of the connection between the top cover and the base plate, the fasteners are glued in place at the radial position where they contact the mounting holes. This setting can also further protect the optical fiber from corrosion by rainwater, impurities, etc.

[0079] In one example, after the optical fiber 500 emerges from the optical fiber encapsulation fixture 600, it is connected to an external optical fiber junction box via an adapter 510. The adapter 510 makes it easier to connect the optical fiber to the optical fiber junction box.

[0080] Other configurations of the fiber optic packaging fixture 600 in the above embodiments can be adopted from various technical solutions now and in the future known to those skilled in the art, and will not be described in detail here.

[0081] In this embodiment, the optical fiber 500 is embedded in the plate-shaped encapsulation fixture 600. This structural encapsulation enhances mechanical strength and environmental adaptability, reducing the risk of fiber breakage or grating damage due to improper operation, thus improving the long-term reliability of the fiber Bragg grating sensor from the source. The fixing fixture utilizes the modular cooperation of the first receiving member 700 and the second receiving member 800, and is provided with an output opening 780 to lead out the optical fiber. The encapsulation fixture 600 is installed as a whole within the first receiving member 700 and the second receiving member 800, achieving rapid positioning and pre-fixation of the fiber Bragg grating, reducing manual adjustments and repeated operations during installation, and improving installation efficiency. Furthermore, a fastening fixture including washers, elastic soft rings, and / or fastening rings is used to fasten the first receiving member 700 and the second receiving member 800. During the locking process, rotation of the first receiving member 700 or the second receiving member 800 is reduced, effectively avoiding localized stress concentration that could cause compression or micro-damage to the strain gauge, ensuring the fiber Bragg grating maintains good performance after installation.

[0082] The strain sensor device provided in this application reduces the risk of physical damage to the fiber Bragg grating during installation. It also improves the accuracy and repeatability of strain measurement and enhances the detection precision of the sensor through optimized mechanical coupling and stress transfer path.

[0083] In one example, such as Figures 4 to 7 As shown, both the first receiving member 700 and the second receiving member 800 are sleeve structures. The first receiving member 700 and the second receiving member 800 are optionally provided with an inner connection portion 710 and an outer connection portion 840, with the inner connection portion 710 snapped into the outer connection portion 840.

[0084] In one example, such as Figure 4As shown, the first end is connected to a first fixing seat 720 for fixing to the substrate under test, and the fourth end is connected to a second fixing seat 820 for fixing to the substrate under test. The height distance between the bottom surface of the first fixing seat 720 and the second fixing seat 820 and the fiber optic strain gauge is 5-10 mm, for example, 5 mm, 7 mm, 8 mm or 10 mm.

[0085] The mounting base can be fixed to the surface of the substrate under test by welding, bolting, or adhesive. In this embodiment, both the first mounting base 720 and the second mounting base 820 are provided with four bolt holes for fixing to the substrate under test. In other embodiments, the number of bolts can be increased or decreased according to actual needs; for example, two bolts can be used for fixing. A height difference of 5-10 mm raises the fiber optic strain gauge above the surface of the substrate under test, avoiding the squeezing of the packaging fixture 600 by unevenness, coatings, or debris on the surface of the substrate under test, while leaving space for bottom wiring or heat dissipation. This distance has been experimentally verified to achieve the best balance between strain transfer efficiency and anti-interference capability. Too low a distance is easily affected by surface conditions, while too high a distance leads to a longer strain transfer path and decreased sensitivity. This optimized height allows the strain on the surface of the substrate under test to be transferred to the grating area with almost no attenuation, while effectively isolating local stress concentrations, significantly improving measurement accuracy and repeatability.

[0086] In one embodiment, both the first fixing base 720 and the second fixing base 820 are provided with a receiving cavity 721. The first end and the fourth end are each provided with a first through hole 780 that communicates with the receiving cavity 721 and the transverse groove 300 respectively for optical fiber to pass through. The receiving cavity 721 is provided with a winding coil (not shown) for winding optical fiber. And / or, the end of the first fixing base away from the first end is provided with a second through hole 910 for optical fiber to pass through, and the end of the second fixing base away from the fourth end is provided with a mounting base 930 for fixing the optical fiber adapter 510.

[0087] For example, the winding coil is a cylindrical winding post or a toroidal winding coil, and the optical fiber is wound one or more turns inside the receiving cavity. The winding coil provides redundancy in the length of the optical fiber. When the sensor is subjected to extreme strain or thermal expansion and contraction, the redundant optical fiber can be passively released or absorbed, avoiding excessive tensile force on the grating area and reducing the risk of physical damage. The design of the second through hole 910, the optical fiber adapter 510, and the mounting base 930 allows the sensor to be quickly plugged and unplugged into the transmission optical cable, simplifying field wiring. The receiving cavity isolates the optical fiber connector, redundant optical fiber, and external environment, providing both protection and cleanliness. The sensor has high-precision strain detection capabilities while also possessing excellent engineering applicability and long-life reliability. Furthermore, the optical fiber 500 exits from the optical fiber packaging fixture 600, and the adapter 510 is located on the extension line of the optical fiber 500. The optical fiber exits from the second receiving member 800 and connects to the adapter 510. The mounting base 930 prevents the adapter 510 from shaking.

[0088] The first receiving member 700 is integrally formed with the first fixed base 720, and the second receiving member 800 is integrally formed with the second fixed base 820.

[0089] The first fixing seat 720 and the second fixing seat 820 are configured with a receiving cavity 721, and a winding coil is preset in the receiving cavity 721. After the optical fiber comes out of the sleeve, it can be wound on it as needed, so that the operator can quickly and flexibly adjust the excess length of the optical fiber on the installation site, avoiding damage caused by pulling or bending due to improper length. At the same time, it reduces the workload of accurately matching the length of the optical fiber in the early preparation and improves the installation efficiency.

[0090] Furthermore, since both ends of the housing are equipped with fixed bases with wound coils, optical fibers can be led out from both ends of the device, allowing the strain sensor device to be used independently as a single sensor, or multiple sensor devices can be conveniently combined into a distributed measurement network through the series or parallel connection of optical fibers, without the need for additional complex adapters or coupling components.

[0091] In the description of this specification, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0092] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0093] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0094] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0095] The foregoing disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described above. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0096] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A strain sensor device, characterized in that, include: A fiber optic strain gauge, comprising an optical fiber and a packaging fixture for encapsulating the optical fiber; A fixing fixture is used to accommodate the fiber Bragg grating strain gauge. The fixing fixture includes a first accommodating member and a second accommodating member. The first accommodating member has a first end and a second end, and the second accommodating member has a third end and a fourth end. The first end and the last end of the fiber Bragg grating strain gauge are fixed to the first end and the fourth end, respectively. The second end and the third end cooperate with each other and can move relative to each other when the fiber Bragg grating strain gauge is subjected to stress expansion and contraction.

2. The strain sensor device according to claim 1, characterized in that, The second end and the third end are configured to have a clearance fit, and the second end and the third end can move relative to each other along the axial direction of the first receiving member and the second receiving member.

3. The strain sensor device according to claim 2, characterized in that, The second end and the third end are optionally provided with an inner part and an outer part, the inner part can extend into the outer part and cooperate with the outer part.

4. The strain sensor device according to claim 3, characterized in that, The outer end of the inner part is provided with a notch, and the inner end of the outer part is provided with a protrusion. When the inner part is engaged with the outer part, the protrusion and the notch cooperate.

5. The strain sensor device according to claim 4, characterized in that, The outer wall of the inner part is provided with at least one first concave ring, the first concave ring is disposed at the end of the inner part away from the recess, and a washer is sleeved inside the first concave ring.

6. The strain sensor device according to claim 5, characterized in that, The outer wall of the inner part is also provided with a second concave ring, which is disposed between the first concave ring and the notch. An elastic soft ring is sleeved inside the second concave ring, wherein the elastic soft ring is a ring spring or made of a conductive adhesive material with elastic restoring force, and the ring spring is a conductive material.

7. The strain sensor device according to claim 6, characterized in that, There are two first concave rings and two second concave rings. The two first concave rings are spaced apart along the mating direction of the first receiving member and the second receiving member, and the two second concave rings are spaced apart along the mating direction of the first receiving member and the second receiving member and located between the two first concave rings.

8. The strain sensor device according to claim 1, characterized in that, The first receiving member has two first protrusions extending axially on the inner side of the first end, and a first opening groove is formed between the two first protrusions for the first end of the fiber optic strain gauge to be inserted; the second receiving member has two opposing second protrusions on the inner side of the fourth end, and a second opening groove is formed between the two second protrusions for the tail end of the fiber optic strain gauge to be inserted.

9. The strain sensor device according to any one of claims 1-8, characterized in that, The packaging fixture includes a base plate and a top cover, which cooperate with each other. The target side of the base plate is provided with a transverse groove for holding the optical fiber. The transverse groove extends from the first end of the target side to the last end of the target side. The target side is the side opposite to the base plate or the top cover. The transverse groove includes a central region for holding the fiber Bragg grating. The target side is provided with two first adhesive positions spaced apart along the length of the base plate for fixing the optical fiber. The two first adhesive positions are both provided on the transverse groove and are respectively located on both sides of the central region near the central region.

10. The strain sensor device according to claim 9, characterized in that, The target side of the base plate is also provided with a pair of first longitudinal grooves, the first longitudinal grooves being located between two first adhesive positions and the two pairs of first longitudinal grooves being located on opposite sides of the transverse groove; and / or, the top cover is provided with a pair of second longitudinal grooves, the second longitudinal grooves being located at the position of the top cover corresponding to the first adhesive position and the two pairs of first longitudinal grooves being located on opposite sides of the centerline of the top cover in its length direction.

11. The strain sensor device according to claim 9, characterized in that, The first end is connected to a first fixing seat for fixing to the substrate under test, and the fourth end is connected to a second fixing seat for fixing to the substrate under test. The height distance between the bottom surface of the first fixing seat and the second fixing seat and the substrate under test and the fiber optic strain gauge is 5-10 mm.

12. The strain sensor device according to claim 11, characterized in that, Both the first fixing base and the second fixing base are provided with a receiving cavity. The first end and the fourth end are each provided with a first through hole that communicates with the receiving cavity and the transverse groove respectively for optical fiber to pass through. The receiving cavity is provided with a winding coil for winding optical fiber. And / or, the end of the first fixing base away from the first end is provided with a second through hole for optical fiber to pass through, and the end of the second fixing base away from the fourth end is provided with a fixing base for fixing the optical fiber adapter.

Images