A corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure
The fiber optic grating corrosion monitoring device based on a lever structure solves the problem of difficult corrosion monitoring of reinforced concrete structures, realizes long-term real-time and accurate corrosion monitoring, has sensitivity and stability, adapts to different environments, and reduces costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANSHAN UNIV
- Filing Date
- 2023-10-12
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies are insufficient for long-term, real-time, and accurate monitoring of corrosion in reinforced concrete structures. In particular, the presence of the concrete protective layer makes detection difficult, and existing monitoring methods are costly, environmentally dependent, and lack sensitivity, making it impossible to detect corrosion in its early stages.
A fiber optic grating corrosion monitoring device based on a lever structure is adopted. By combining the lever rotating arm and the sensitivity-enhancing twisted wire, the monitoring sensitivity is enhanced. The corrosion strain is amplified by the lever structure. Combined with the temperature compensation of the fiber optic grating and the differential method, high sensitivity and stability monitoring are achieved.
It enables long-term real-time monitoring of reinforced concrete structures, accurately detects early corrosion changes, and possesses sensitivity and stability. It is also low-cost, adaptable to different environmental needs, and provides important monitoring data support.
Smart Images
Figure CN117347360B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fiber optic sensing technology, specifically relating to a corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure. Background Technology
[0002] Reinforced concrete structures are widely used in modern construction, and their safety and stability are crucial to the overall lifespan of a building. Reinforced concrete structures suffer from some common inherent problems, particularly steel corrosion, which is often difficult to detect due to the concrete cover. This poses a threat to building safety, as steel corrosion leads to concrete cracking, severely impacting structural performance and potentially causing building collapse. Currently, many monitoring technologies exist for steel corrosion, such as electrochemical methods, acoustic emission technology, and electromagnetic wave detection. However, these methods require complex equipment and technology and have limitations, such as strong dependence on environmental conditions, inability to achieve long-term, continuous monitoring, and inability to accurately detect early corrosion. Fiber Bragg grating sensors, due to their high measurement accuracy, resistance to electromagnetic interference and corrosion, and ability to perform long-term continuous monitoring, are an ideal means of monitoring steel corrosion. Therefore, there is an urgent need for a fiber Bragg grating monitoring device for monitoring the degree of corrosion in reinforced concrete. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to provide a fiber optic grating corrosion monitoring device for reinforced concrete based on a lever structure, which can simultaneously meet the requirements of long-term real-time monitoring of reinforced concrete castings, has high stability and sensitivity, and adjustable sensitivity. It can also perform temperature compensation to distinguish the subtle changes when the steel bars are corroded. While saving the cost of the device, it can accurately provide more important data support for the maintenance and monitoring of reinforced concrete structures.
[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0005] A fiber optic grating corrosion monitoring device for reinforced concrete based on a lever structure includes a base, a support beam at the bottom of the base, a lever rotating arm on the support beam, one end of the lever rotating arm extending out of the base body, and a claw assembly slot connected to the other end of the lever rotating arm extending out of the base body. The claw assembly slot is connected to a measuring contact claw. A sensitivity-enhancing twisted wire and a fiber optic grating bonded to the sensitivity-enhancing twisted wire are fixed on the base. The other end of the lever rotating arm contacts the fiber optic grating. The fiber optic grating pigtail extends out of the base body and is connected to a demodulator. The measuring contact claw tightly wraps around the reinforcing bar to be measured.
[0006] A further improvement of the technical solution of the present invention is that: two lever rotating arms are arranged side by side, and two fiber optic gratings are arranged on the upper and lower sides of the base, with the lever rotating arms contacting the upper and lower fiber optic gratings respectively.
[0007] A further improvement of the technical solution of the present invention is that: the lever rotating arm has an L-shaped structure, including a long arm and a short arm, the long arms of the two lever rotating arms extend outward from the base body, and the two short arms face opposite directions and contact the fiber optic gratings on the upper and lower sides respectively.
[0008] A further improvement of the technical solution of the present invention is that: a lever arm fixing shaft and a fixing screw are respectively provided on the support beam, the lever arm fixing shaft and the fixing screw cooperate with each other, and the lever arm fixing shaft and the fixing screw are on the same horizontal line as the center hole of the support beam.
[0009] A further improvement of the technical solution of the present invention is that: one end of the long arm of the lever rotating arm is provided with a mating slot for the insertion claw assembly slot, a fixed shaft is provided on the long arm of the lever rotating arm, and the lever arm fixed shaft passes through the fixed shaft and the center hole of the support beam to hinge the two lever rotating arms to both sides of the support beam.
[0010] A further improvement of the technical solution of the present invention is that: two fixed platforms are set on the top and bottom of the base, and a knob for fixing the sensitivity-enhancing twisted wire is set on the fixed platform. A grating fixing groove for fixing the fiber Bragg grating is opened below the knob. The fiber Bragg grating fiber head and fiber tail are respectively bonded to the grating fixing grooves of the two fixed platforms on the same side. The grating area of the fiber Bragg grating is bonded to the sensitivity-enhancing twisted wire. The short arm of the lever rotating arm is directly opposite the middle of the two fixed platforms on the same side.
[0011] A further improvement of the technical solution of the present invention is that: the base is a box structure, and fixed slide rails for fixing dustproof plates are opened on both sides of the base. The dustproof plates are inserted into the fixed slide rails. One end of the lever rotating arm extends out of the base body through a window opened on one side of the base. An optical fiber through hole is opened on the side of the base on the same side as the fixed platform. The pigtail of the fiber optic grating extends out of the base body through the optical fiber through hole and is connected to the demodulator.
[0012] A further improvement of the technical solution of the present invention is that: a sliding groove for fixing the lever balance counterweight is provided on the outer side of one end of the short arm of the lever rotating arm; a fixed plate connected to the support beam is provided on one side of the fixed axis; and a grating pressing groove is provided below the sliding groove, which is in contact with the fiber optic grating.
[0013] A further improvement of the technical solution of the present invention is that: the measuring contact claw is provided with a claw head that fits tightly with the steel bar to be measured, and a spring-type stop pin is provided at the lower part of the claw head, and a pin through hole is provided on the spring-type stop pin.
[0014] A further improvement of the technical solution of the present invention is that: the claw assembly slot is provided with a cylindrical groove, and a pin through hole corresponding to the spring-type stop pin is opened on the cylindrical groove. The measuring contact claw and the claw assembly slot are fixedly connected by the pin and the pin through hole. The lower end of the claw assembly slot is provided with anti-slip texture and insertion groove. The claw assembly slot and the measuring contact claw can be separated and disassembled.
[0015] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:
[0016] This invention enables long-term real-time monitoring of the surface and internal corrosion status of reinforced concrete structures.
[0017] Because a two-stage sensitization method is used to enhance the sensitivity of the device structure, the device structure is sensitized by lever rotating arms and sensitizing twisted wires respectively. The lever structure can amplify the strain caused by corrosion. By bonding the grating to the sensitizing twisted wire, not only is the service life of the fiber Bragg grating guaranteed, but the sensitizing twisted wire can also be tightened by turning the knob on the base fixing platform, thereby increasing the pre-stretch of the fiber Bragg grating and improving the sensitivity.
[0018] Depending on the environment to be monitored, the lever rotation arm can be adjusted to increase the magnification factor by changing the ratio of the power arm and resistance arm in the lever structure, thereby achieving higher sensitivity for specific environments. Simultaneously, the limiting measurement range and corresponding sensitivity of the device can be altered by changing the tightness of the sensitive-enhancing strand; a tighter strand results in higher sensitivity and a smaller measurement range.
[0019] Because the frictional force and the weight of the structure itself significantly affect the measurement using a lever-rotating arm, a counterweight is added to balance the external force on the lever-rotating arm. This reduces the impact of other factors on the invention and ensures the stability of the monitoring process. The measuring contact claws fit snugly around the steel sample being measured, and the remaining core components are encased inside the base, making them less prone to damage. Therefore, this invention achieves stable and reliable monitoring.
[0020] Provided that the measuring contact claw is in contact with the steel bar to be measured, the rest of the device structure can be fixed to the surface of the structure to be measured by adhesive bonding or integral casting, making the installation simple and convenient. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the assembly structure of the present invention;
[0022] Figure 2 This is an exploded view of the assembly structure of the present invention during installation;
[0023] Figure 3 This is a schematic diagram of the fixing base of the present invention;
[0024] Figure 4 This is a schematic diagram of the dustproof plate of the present invention;
[0025] Figure 5 This is a schematic diagram of the overall external structure of the present invention;
[0026] Figure 6 This is a schematic diagram of the lever rotating arm of the present invention;
[0027] Figure 7 This is a schematic diagram of the claw engagement of the present invention;
[0028] Figure 8 This is a schematic diagram of the measuring contact claw of the present invention;
[0029] Figure 9 This is a schematic diagram of the claw assembly slot of the present invention;
[0030] Figure 10 This is a schematic diagram of the lever balance counterweight of the present invention;
[0031] The components include: 1. Base; 2. Dustproof plate; 3. Lever rotating arm; 4. Measuring contact claw; 5. Claw assembly slot; 6. Lever counterweight; 7. Sensitizing twisted wire; 8. Fiber optic grating; 9. Lever arm fixing shaft; 10. Fixing screw; 11. Pin; 1-1. Through window; 1-2. Support beam; 1-3. Fixing slide rail; 1-4. Grating fixing groove; 1-5. Knob; 1-6. Fiber optic through hole; 1-7. Fixing platform; 3-1. Fixing shaft; 3-2. Mating slot; 3-3. Fixing plate; 3-4. Sliding groove; 3-5. Grating pressing groove; 4-1. Claw head; 4-2. Spring-type stop pin; 4-3. Pin through hole; 5-1. Pin through hole; 5-2. Cylindrical groove; 5-3. Anti-slip texture; 5-4. Insertion groove. Detailed Implementation
[0032] The present invention will be further described in detail below with reference to embodiments:
[0033] like Figures 1 to 5As shown, the base 1 is a box structure with fixed slide rails 1-3 on both sides for fixing dustproof plates 2. Two parallel lever rotating arms 3 are fixed to the support beam 1-2 in the center of the base 1 through lever arm fixing shafts 9 and fixing screws 10, and extend out of the main body of the base 1 through a window 1-1 on the left side of the base 1. The lever arm fixing shafts 9 and fixing screws 10 are on the same horizontal line as the center hole of the support beam 1-2. Two fixing platforms 1-7 are respectively set at the top and bottom of the base 1 for fixing the fiber optic gratings 8 on the upper and lower sides. The fixing platform 1-7 is equipped with a knob 1-5 for fixing the sensitivity-enhancing twisted wire 7, which can adjust the tension of the sensitivity-enhancing twisted wire 7 as needed. A grating fixing slot 1-4 for fixing the fiber optic grating 8 is opened directly below the knob 1-5. The two fiber optic gratings 8 located on the upper and lower sides of the base 1 can achieve temperature mutual compensation. By separating temperature and strain factors through differential method, a more accurate measurement effect is achieved. Two corresponding fiber optic vias 1-6 are provided on the right side of the base 1. The pigtails of the two fiber optic gratings 8 extend out of the device through the fiber optic vias 1-6 and are connected to the demodulator.
[0034] like Figure 1 , Figure 2 , Figure 3 , Figure 6 , Figure 10 As shown, in the non-measuring state, the two lever rotating arms 3 maintain balance at both ends with the lever arm fixed shaft 9 as the fulcrum. The lever rotating arms 3 have a parallel L-shaped structure, including a long arm and a short arm. The end of each long arm is provided with a mating slot 3-2 for connecting with the claw assembly slot 5. The short arms of the two lever rotating arms 3 face opposite directions and, in the non-measuring state, are in contact with the upper and lower fiber optic gratings 8 respectively, without deforming them. The long arm of the lever rotating arm 3 is provided with a fixed shaft 3-1, the position of which can be adjusted according to the required magnification ratio. Different ratio coefficients of the power arm and the resistance arm can obtain different sensitization effects. A fixed plate 3-3 is provided on one side of the fixed shaft 3-1, which fits into the center hole of the support beam 1-2. The lever arm fixed shaft 9 passes through the fixed shaft 3-1 and the center hole of the support beam 1-2, hinged to both sides of the support beam 1-2. Due to the friction between the structures, the overall assembly structure of the measuring contact claw 4 and the claw mounting slot 5 is relatively heavy. A sliding groove 3-4 is provided on the outer side of the short arm of the lever rotating arm 3 to fix the lever balance weight 6, so as to balance the influence of external forces and keep the two ends of the lever rotating arm 3 balanced before the measurement begins. Below the sliding groove 3-4, a grating pressing groove 3-5 is provided, which contacts the fiber optic grating 8. It is coated with an elastic adhesive coating to protect the fiber optic grating 8 from damage during monitoring.
[0035] like Figure 1 , Figure 2 , Figure 3 , Figure 7, Figure 8 , Figure 9 As shown, the two measuring contact claws 4 adopt a claw head 4-1 structure that fits tightly against the rebar to be measured. The two claw heads 4-1 face each other, wrapping the rebar 360° to achieve accurate capture of corrosion products. Due to the surface contact measurement method, the problem of missed detection and false detection caused by point measurement is effectively avoided. The tail of the measuring contact claw 4 is equipped with a spring-type stop pin 4-2 for easy fixation in the cylindrical groove 5-2 of the claw assembly slot 5. The spring-type stop pin 4-2 and the cylindrical groove 5-2 have pin through holes at the same position. The use of pins 11 can more firmly fix the measuring contact claw 4 to the claw assembly slot 5, preventing the measuring contact claw 4 from shaking and affecting the measurement accuracy. The lower end of the claw assembly slot 5 is equipped with anti-slip texture 5-3 and insertion groove 5-4, which can fix the overall assembly structure of the measuring contact claw 4 and the claw assembly slot 5 to the lever rotating arm 3. The measuring contact claw 4 and the claw assembly slot 5 can be separated and disassembled. According to different sizes of rebar to be monitored, different materials and sizes of claw structures can be replaced to cope with different application scenarios and save equipment costs.
[0036] like Figures 1 to 3 As shown, the sensitivity-enhancing twisted wire 7 is fixed to the knob 1-5 on the base 1. By turning the knob 1-5, the tension of the sensitivity-enhancing twisted wire 7 can be adjusted to apply different prestresses and achieve different sensitivity enhancement effects. The fiber head and fiber tail of the fiber grating 8 are respectively bonded to the grating fixing groove 1-4 on the fixing platform 1-7 with epoxy resin. The grating area of the fiber grating 8 and the sensitivity-enhancing twisted wire 7 are tightly bonded with epoxy resin, ensuring the service life of the fiber grating 8. At the same time, by adjusting the tension of the knob, the sensitivity-enhancing twisted wire 7 can be stretched. As the sensitivity-enhancing twisted wire 7 is stretched, the pre-stretch value of the fiber grating 8 can be adjusted. The larger the pre-stretch value, the higher the measurement accuracy and the stronger the sensitivity.
[0037] The base 1 can be directly cast onto the surface of the structure to be measured using molds and concrete as needed, thereby reducing costs. The lever rotating arm 3 can be made of lightweight materials, the measuring contact claw 4 can be made of corrosion-resistant materials such as nickel alloys and titanium alloys, and the sensitive stranded wire 7 can be made of high-toughness materials such as carbon wire.
[0038] When the steel bar under test corrodes, the volume of the corrosion products is larger than the original volume of the steel bar, causing the steel bar to expand. This expansion drives the measuring contact claw 4 to move, which in turn causes the sensitive-enhancing stranded wire 7 and the fiber optic grating 8 to deform via the lever rotating arm 3. This causes a change in the center wavelength of the fiber optic grating 8, thereby monitoring the corrosion status of the steel bar under test. By modifying the ratio coefficients of different power arms and resistance arms of the lever rotating arm 3, different amplification ratios can be achieved to obtain different sensitivity enhancement effects. High sensitivity corresponds to a low measurement range, therefore, the device structure needs to be modified according to different monitoring requirements.
[0039] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure, characterized in that: Includes a base (1), a support beam (1-2) is provided at the bottom of the base (1), a lever rotating arm (3) is provided on the support beam (1-2), one end of the lever rotating arm (3) extends out of the main body of the base (1), and the other end of the lever rotating arm (3) extending out of the main body of the base (1) is inserted into a claw assembly slot (5), the claw assembly slot (5) is connected to a measuring contact claw (4), a sensitivity-enhancing twisted wire (7) and a fiber optic grating (8) bonded together with the sensitivity-enhancing twisted wire (7) are fixed on the base (1), the other end of the lever rotating arm (3) is in contact with the fiber optic grating (8), the pigtail of the fiber optic grating (8) extends out of the main body of the base (1) and is connected to a demodulator, and the measuring contact claw (4) tightly wraps the steel bar to be measured; The lever rotating arm (3) has a mating slot (3-2) for the insertion claw assembly slot (5) at one end of its long arm. A fixed shaft (3-1) is provided on the long arm of the lever rotating arm (3). The lever arm fixed shaft (9) passes through the fixed shaft (3-1) and the center hole of the support beam (1-2) to hinge the two lever rotating arms (3) to both sides of the support beam (1-2). The base (1) has two fixed platforms (1-7) separated at the top and bottom. The fixed platform (1-7) is provided with a knob (1-5) for fixing the sensitivity-enhancing twisted wire (7). The knob (1-5) is provided with a grating fixing groove (1-4) for fixing the fiber grating (8) below it. The fiber head and fiber tail of the fiber grating (8) are respectively bonded to the grating fixing groove (1-4) of the two fixed platforms (1-7) on the same side. The grating area of the fiber grating (8) is bonded to the sensitivity-enhancing twisted wire (7). The short arm of the lever rotating arm (3) is directly opposite the middle of the two fixed platforms (1-7) on the same side. The measuring contact claw (4) is provided with a claw head (4-1) that fits tightly with the steel bar to be measured. A spring-type stop pin (4-2) is provided at the lower part of the claw head (4-1). A pin through hole (4-3) is provided on the spring-type stop pin (4-2).
2. The corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure according to claim 1, characterized in that: Two lever rotating arms (3) are arranged side by side, and two fiber optic gratings (8) are arranged on the upper and lower sides of the base (1). The lever rotating arms (3) are in contact with the upper and lower fiber optic gratings (8) respectively.
3. The corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure according to claim 2, characterized in that: The lever rotating arm (3) has an L-shaped structure, including a long arm and a short arm. The long arms of the two lever rotating arms (3) extend out of the main body of the base (1), and the two short arms face opposite directions and contact the fiber optic gratings (8) on the upper and lower sides respectively.
4. A reinforced concrete fiber optic grating corrosion monitoring device based on a lever structure according to any one of claims 1-3, characterized in that: The support beam (1-2) is provided with a lever arm fixing shaft (9) and a fixing screw (10). The lever arm fixing shaft (9) and the fixing screw (10) cooperate with each other, and the lever arm fixing shaft (9) and the fixing screw (10) are on the same horizontal line as the center hole of the support beam (1-2).
5. The corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure according to claim 1, characterized in that: The base (1) is a box structure. Fixed slide rails (1-3) for fixing dustproof plates (2) are provided on both sides of the base (1). The dustproof plates (2) are inserted into the fixed slide rails (1-3). One end of the lever rotating arm (3) extends out of the main body of the base (1) through a window (1-1) opened on one side of the base (1). Fiber optic vias (1-6) are provided on the side of the base (1) on the same side as the fixed platform (1-7). The pigtail of the fiber optic grating (8) extends out of the main body of the base (1) through the fiber optic vias (1-6) and is connected to the demodulator.
6. The corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure according to claim 1, characterized in that: The lever rotating arm (3) has a sliding groove (3-4) on the outer side of one end of the short arm for fixing the lever balance counterweight (6). The fixed shaft (3-1) has a fixed plate (3-3) connected to the support beam (1-2) on one side. The sliding groove (3-4) has a grating pressing groove (3-5) below it, and the grating pressing groove (3-5) is in contact with the fiber optic grating (8).
7. The corrosion monitoring device for reinforced concrete fiber optic gratings based on a lever structure according to claim 1, characterized in that: The claw assembly slot (5) is provided with a cylindrical groove (5-2), and a pin through hole (5-1) corresponding to the spring-type stop pin (4-2) is provided on the cylindrical groove (5-2). The measuring contact claw (4) and the claw assembly slot (5) are fixedly connected by the pin (11) and the pin through hole. The lower end of the claw assembly slot (5) is provided with anti-slip texture (5-3) and insertion groove (5-4). The claw assembly slot (5) and the measuring contact claw (4) can be separated and disassembled.