CN115900524A - Bidirectional strain intelligent aggregate based on patch antenna, monitoring sensing system and method - Google Patents
Bidirectional strain intelligent aggregate based on patch antenna, monitoring sensing system and method Download PDFInfo
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Abstract
The invention relates to a bidirectional strain intelligent aggregate based on a patch antenna, a monitoring and sensing system and a method, wherein the whole structure of the intelligent aggregate is packaged by a cement-based protective layer, and the system also comprises a radiation patch component, a movable radiation patch component, a coupling radiation patch component, a transmission rod and a radio frequency identification chip carrying intelligent aggregate codes and position information; the radiation patch component is tightly attached to the movable radiation patch component and is overlapped up and down to form short circuits which are staggered with each other; an elastomer is filled between the radiation patch component and the coupling radiation patch component; one end of the transmission rod is fixed on the movable radiation patch component, and the other end of the transmission rod extends out of the protective layer and is fixed on the cement-based protective layer; the radio frequency identification chip is connected with the radiation patch component through a microstrip feeder line, and is used for activating the resonance of the radiation patch in two planar directions and the vertical coupling resonance. Compared with the prior art, the passive wireless monitoring system can realize passive wireless monitoring of bidirectional strain and temperature in concrete.
Description
Technical Field
The invention relates to the field of structural health monitoring, in particular to bidirectional strain intelligent aggregate based on a patch antenna, a monitoring sensing system and a monitoring sensing method.
Background
Concrete has been widely used in the field of civil engineering as an important building material. Concrete is a building material with good durability, but in the long-term use process, due to the action of factors such as external environment, load and the like, the concrete material can be degraded, and hidden troubles are buried for safe and reliable operation of the structure. Therefore, in the whole life cycle of the concrete structure, the deformation state of the concrete structure and the environmental factors influencing the durability need to be sensed, so that the potential safety hazard of the structure can be found in time, and necessary measures are taken to ensure the safe and reliable use of the structure.
In recent years, the intelligent concrete aggregate with the advantages of locality and distributivity is gradually applied to monitoring damage inside concrete. The intelligent aggregate is used for packaging a sensing unit for monitoring the concrete, so that the sensing unit becomes an intelligent element which can be implanted into the concrete, has the function of common aggregate, and can realize the information perception inside the concrete.
However, the current intelligent aggregate still needs continuous power supply and cable for signal transmission, and synchronous sensing of multiple parameters in concrete is difficult to realize, so that the application of the aggregate in practical engineering is limited to a certain extent.
Therefore, a passive wireless intelligent aggregate suitable for multi-directional strain and multi-parameter sensing in concrete needs to be designed, so that dependence on cables and power supplies is overcome, and wireless monitoring of multi-parameters in concrete is realized.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a bidirectional strain intelligent aggregate based on a patch antenna, a monitoring sensing system and a method, so as to realize passive wireless monitoring of bidirectional strain and temperature in concrete.
The purpose of the invention can be realized by the following technical scheme:
according to a first aspect of the invention, a bidirectional strain intelligent aggregate based on a patch antenna is provided, the whole structure is packaged by a cement-based protective layer, and the intelligent aggregate further comprises a radiation patch component, a movable radiation patch component, a coupling radiation patch component, a transmission rod and a radio frequency identification chip carrying intelligent aggregate codes and position information;
the radiation patch component is tightly attached to the movable radiation patch component, and the radiation patch component and the movable radiation patch component are partially overlapped to form short circuits which are staggered with each other; an elastic body is filled between the radiation patch component and the coupling radiation patch component and is used for being compressed or stretched when the intelligent aggregate generates vertical deformation so as to change the distance between the radiation patch component and the coupling radiation patch component, and therefore the corresponding resonance frequency is changed to carry out vertical strain monitoring; wherein, the vertical direction is the direction vertical to the plane of the radiation patch component;
the radiation patch component, the movable radiation patch component, the coupling radiation patch component and the radio frequency identification chip are wrapped with protective layers; one end of the transmission rod is fixed on the movable radiation patch component, and the other end of the transmission rod extends out of the protective layer and is fixed on the cement-based protective layer, so that when the intelligent aggregate deforms in a horizontal direction under stress, the two ends of the intelligent aggregate are compressed and deformed to transfer the horizontal direction stress to cause the mutual dislocation between the movable radiation patch and the radiation patch; wherein, the horizontal direction is the direction parallel to the transmission rod;
the radio frequency identification chip is connected with the radiation patch assembly through a microstrip feeder line, and is used for activating resonance and vertical coupling resonance in two directions of the plane of the radiation patch.
Preferably, radiation patch subassembly includes base plate and radiation patch, it includes removal radiation patch and removal base plate to remove radiation patch subassembly, coupling radiation patch subassembly includes coupling radiation patch and coupling base plate, radiation patch, removal base plate, coupling radiation patch, coupling base plate place wherein in proper order:
the radio frequency identification chip is welded on the upper surface of the substrate and is connected with the radiation patch through a micro-strip feeder line; the lower surface of the substrate is electroplated with a completely covered copper layer, and the upper surface of the substrate is electroplated and attached to the radiation patch; the lower surface of the movable substrate is electroplated and attached to the movable radiation patch, and the upper surface of the movable radiation patch is closely attached to the radiation patch and is overlapped up and down to form short circuits which are staggered with each other; the lower surface of the coupling substrate is electroplated and attached to the combined radiation patch, the upper surface of the coupling substrate is fixed to the lower surface of the protective layer, and an elastomer is filled between the coupling radiation patch and the radiation patch and is used for being compressed or stretched to change the distance between the coupling radiation patch and the radiation patch when the intelligent aggregate is vertically deformed;
one end of the transmission rod is fixed on the movable base plate, and the other end of the transmission rod extends out of the protective layer and is fixed on the cement-based protective layer, so that when the intelligent aggregate horizontally deforms towards stress, compression deformation transmission at two ends is carried out to cause mutual dislocation between the movable radiation patch and the radiation patch.
Preferably, the microstrip feed line is disposed at a set distance from a center line of the radiation patch to activate resonant modes of the radiation patch in two planar directions and a coupling resonant mode of the coupling radiation patch.
Preferably, filling particles are filled between the middle part of the transmission rod and the cement-based protective layer to bear part of vertical stress and enable the transmission rod to move along the horizontal direction.
Preferably, the intelligent aggregate is further provided with a waterproof coating layer arranged on the inner wall of the cement-based protective layer.
Preferably, the radiation patch, the mobile radiation patch, the coupling radiation patch and the microstrip feed line are all made of copper.
Preferably, the substrate, the moving substrate and the coupling substrate are all RT5880 dielectric plates.
According to a second aspect of the invention, a bidirectional strain intelligent aggregate sensing system based on a patch antenna is provided, and the system comprises intelligent aggregate embedded in a concrete structure and a reader for reading information of a radio frequency identification chip in the intelligent aggregate and processing data; the intelligent aggregate is any one of the bidirectional strain intelligent aggregates based on the patch antenna;
the reader includes:
the wireless transceiver module is used for receiving a multi-order resonant frequency shift signal sent by the intelligent aggregate;
the modulation and demodulation module is used for demodulating the signals received by the wireless receiving and transmitting module;
the digital processing module is used for decoupling and calculating the structural horizontal and vertical strain and temperature change of the intelligent aggregate embedding position in the concrete structure according to the corresponding relation;
and the control module is used for transmitting modulated electromagnetic wave signals with different frequencies to the intelligent aggregate embedded in the concrete structure so as to activate the radio frequency identification chip in the intelligent aggregate.
According to a third aspect of the present invention, there is provided a monitoring method for the intelligent aggregate sensing system, the method comprising the steps of:
1) The control module transmits modulated electromagnetic wave signals with different frequencies to intelligent aggregate embedded in the concrete structure; when the power of the signal received by the intelligent aggregate reaches a set threshold value, the radio frequency identification chip is activated;
2) After the radio frequency identification chip is activated, the antenna of the coupling patch generates current and emits an electromagnetic wave signal with a label number and measuring point position information, and the signal is received by the wireless transceiver module and processed by the modulation and demodulation module to obtain the label number and the position information corresponding to the intelligent aggregate;
3) The digital processing module determines each order of resonant frequency of the coupled patch antenna by searching the transmitting frequency of the reader electromagnetic wave of which the signal transmitting power reaches each order of minimum value when the radio frequency identification chip is activated;
4) When the intelligent aggregate embedded in the concrete generates horizontal strain, vertical strain and environmental temperature change, the size of the radiation patches in the intelligent aggregate and the dielectric constant of the substrate are changed, the distance between the radiation patches is changed, and the resonant frequency of each order of the intelligent aggregate is shifted; by calculating the offset of each order of resonant frequency of the intelligent aggregate, decoupling to obtain the bidirectional strain and temperature variation of the concrete at the embedding position of the intelligent aggregate, and synchronously monitoring the bidirectional strain and temperature in the concrete.
Preferably, in step 4), when the intelligent aggregate embedded in the concrete generates horizontal strain, vertical strain, and ambient temperature change, the size of the radiation patches inside the intelligent aggregate and the dielectric constant of the substrate change, the distance between the radiation patches changes, and the resonance frequency of each order of the intelligent aggregate shifts, specifically:
when the intelligent aggregate is deformed horizontally, the movable radiation patch and the radiation patch generate relative displacement, so that the longitudinal length of the combined radiation patch is changed, and the longitudinal resonant frequency of the combined radiation patch is changed;
when the internal temperature of the concrete changes, the dielectric constants of the base plate and the movable base plate change, and the lengths and widths of the radiation patches and the movable radiation patches change, so that the transverse resonant frequency and the longitudinal resonant frequency of the combined radiation patches change;
when the intelligent aggregate is vertically deformed, the elastic body is correspondingly deformed, so that the distance between the coupling radiation patch and the radiation patch is changed, and the resonant frequency of the coupling radiation patch is correspondingly changed.
Compared with the prior art, the invention has the following advantages:
1) The radio frequency identification sensing technology with the advantage of passive wireless is combined with the concrete sensor embedding form of the intelligent aggregate, the coupling patch antenna sensing unit is packaged into a passive wireless intelligent element which can be embedded in concrete for monitoring, energy input is not required to be carried out through a pre-installed battery or an electric wire, energy input is carried out through receiving electromagnetic waves of a transmitting antenna, energy is provided through the electromagnetic waves, a power supply wire or a battery is not required to provide energy for a sensing system, the sensing system is simpler and more flexible to arrange, the labor force for installing the intelligent aggregate and the cost of the sensing system are greatly reduced, and failure is less prone to occurring under natural disasters;
2) The sensing of the bidirectional strain in the concrete is realized through the stress transmission of the horizontal transmission rod and the vertical elastic body based on the resonance frequency change among the radiation patches, the movable radiation patches and the coupling patches;
3) When the concrete structure at the intelligent aggregate embedding position is subjected to bidirectional strain or temperature change, the multistage resonant frequency of the coupling patch antenna in the intelligent aggregate is changed, and synchronous monitoring of parameters such as bidirectional strain and temperature in the concrete is realized according to the influence of the bidirectional strain in the concrete and the embedding environment temperature on the multistage resonant frequency of the coupling antenna, so that the intelligent aggregate sensor has a temperature compensation function;
4) By utilizing the resonance characteristic of the coupling patch antenna, the micro-strip line eccentric feed is adopted to excite the multi-order resonance frequency of the radiation patch, the mobile radiation patch and the coupling radiation patch, and the sensing of horizontal strain, vertical strain and temperature change in the concrete can be realized by measuring and decoupling the multi-order resonance frequency;
5) The intelligent aggregate can be effectively protected from the influence of corrosive environment and the like in concrete by adopting a protection layer, a waterproof coating, a cement-based protection layer and other packaging protection structures, and the intelligent aggregate has good stress performance;
6) A macromolecule elastic material with a certain elastic modulus is adopted as a support between the radiation patch and the coupling radiation patch, so that the distance between the radiation patch and the coupling radiation patch can be changed under the condition that the intelligent aggregate is stressed, and the coupling resonance frequency of the radiation patch and the coupling radiation patch can be further changed;
7) The intelligent aggregate number and the information such as the embedded position in the concrete are stored through the radio frequency identification chip, and the information can be captured by a reader, so that the intelligent aggregate can be quickly positioned;
8) Based on the corresponding relation between the deviation of the multi-order resonant frequency of the coupled patch antenna and multiple monitoring variables in a fixed range, the monitoring of multiple different variables in the concrete by a single sensing unit can be realized, and the method is particularly suitable for monitoring the strain in different directions in the concrete and has strong applicability.
Drawings
FIG. 1 is a schematic diagram of a bidirectional strain intelligent aggregate structure based on a patch antenna according to the present invention;
FIG. 2 is a schematic diagram of a radiation patch feeding manner;
FIG. 3 is a schematic structural diagram of a bidirectional strain intelligent aggregate monitoring and sensing system based on a patch antenna according to the present invention;
reference numerals: the antenna comprises a substrate 1, a radiation patch 2, a radiation patch 3, a radiation patch 4, a radiation patch 5, a radiation patch 6, an elastomer 7, a protective layer 8, a waterproof coating 9, a cement-based protective layer 10, a transmission rod 11, a filling particle 12, a microstrip feeder 13, a radio frequency identification chip 14, a reader 15, a wireless transceiver 1501, a modem 1502, a digital processing module 1503 and a control module 1504.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.
Examples
As shown in fig. 1 and fig. 2, the present embodiment provides an intelligent aggregate based on bidirectional strain and temperature sensing, which includes a substrate 1, a radiation patch 2, a mobile radiation patch 3, a mobile substrate 4, a coupling radiation patch 5, a coupling substrate 6, an elastomer 7, a protective layer 8, a waterproof coating 9, a cement-based protective layer 10, a transmission rod 11, filler particles 12, a microstrip feed line 13, and a radio frequency identification chip 14 carrying intelligent aggregate codes and position information.
The lower surface of the substrate 1 is plated with copper and completely covers the lower surface of the substrate 1, and the radiation patch 2 is electroplated and attached to the upper surface of the substrate 1. The movable radiation patch 3 is electroplated and attached to the lower surface of the movable substrate 4, the movable radiation patch 3 is arranged on the upper radiation patch 2, the movable radiation patch 3 is closely attached to the radiation patch 2, the upper radiation patch and the lower radiation patch are overlapped to form a short circuit, and the movable radiation patch 3 and the radiation patch 2 can be staggered mutually.
The coupling radiation patch 5 is electroplated and attached to the lower surface of the coupling substrate 6, the upper surface of the coupling substrate 6 is fixed to the lower surface of the protective layer 8, and a space between the coupling radiation patch 5 and the radiation patch 2 is filled with a high polymer material elastomer 7 with a certain elastic modulus. When the intelligent aggregate is vertically deformed, the elastic body 7 can be compressed or stretched, and the distance between the coupling radiation patch 5 and the radiation patch 2 is changed.
The protective layer 8 is made of high-strength carbon fiber materials, plays a role in supporting stress and protects the internal patch antenna. The waterproof coating 9 uses epoxy resin to avoid the influence of moisture and aggressive media inside the concrete. The cement-based protective layer 10 is made of UHPC ultra-high performance concrete material, and the intelligent aggregate is integrally packaged, so that the intelligent aggregate is embedded in the concrete and has good stress performance.
One end of the transmission rod 11 is fixed on the movable base plate 4, the other end of the transmission rod is fixed on the cement-based protective layer 10, and when the intelligent aggregate is deformed due to horizontal stress, compression deformation at two ends can be transmitted through the transmission rod 11, so that the movable radiation patches 3 and the radiation patches 2 are staggered. The space between the middle part of the transmission rod 11 and the cement-based protective layer 10 is filled with filling particles 12 to bear part of the vertical stress and enable the transmission rod 11 to move along the horizontal direction.
The radio frequency identification chip 14 is soldered on the upper surface of the substrate 1 and connected to the radiating patch 2 through the microstrip feed line 13. The microstrip feed line 13 is not located at the center line of the radiating patch 2 but is offset by a distance to excite the resonant modes of the radiating patch 2 in both planar directions and the coupled resonant mode of the coupled radiating patch 5.
The radiating patch 2 has a lateral direction corresponding to one resonant mode and a longitudinal direction corresponding to the other resonant mode, the resonant frequencies of the two resonant modes being related to the combined radiating patch size and the substrate dielectric constant. When the intelligent aggregate is deformed horizontally, the movable radiation patches 3 and the radiation patches 2 are displaced relatively, so that the longitudinal length of the combined radiation patches is changed, and the longitudinal resonant frequency of the combined radiation patches is changed.
When the internal temperature of the concrete changes, the dielectric constants of the base plate 1 and the moving base plate 4 change, and the lengths and the widths of the radiation patches 2 and the moving radiation patches 3 also change, so that the transverse resonant frequency and the longitudinal resonant frequency of the combined radiation patches change.
When the intelligent aggregate is vertically deformed, the elastic body 7 is correspondingly deformed, so that the distance between the coupling radiation patch 5 and the radiation patch 2 is changed, and the resonant frequency of the coupling radiation patch 5 is correspondingly changed.
Through the measurement of multistage resonant frequency of two-way intelligent aggregate that meets an emergency based on patch antenna, can decouple and realize the inside level of concrete to meeting an emergency, vertical strain, the synchronous perception and the monitoring of temperature parameter to make this intelligent aggregate sensor have the temperature compensation function.
In this embodiment, the radiation patch 2, the mobile radiation patch 3, the coupling radiation patch 5, and the microstrip feed line 13 are made of copper, and the substrate 1, the mobile substrate 4, and the coupling substrate 6 are made of RT5880 dielectric plates.
The intelligent aggregate is embedded in the position of a monitoring point in the concrete structure, and the internal coupling patch antenna feeds power in a mode that the radio frequency identification chip 14 is connected with the eccentric microstrip feed line 13 so as to excite the multi-order resonance mode of the coupling patch antenna.
The intelligent aggregate packaging protection structures such as the protection layer 8, the waterproof coating 9 and the cement-based protection layer 10 can effectively protect the sensing antenna inside the intelligent aggregate from being influenced by the corrosive environment inside concrete and the like, and the intelligent aggregate has good stress performance.
In the strain monitoring of the concrete in the horizontal direction, the transmission rod 11 plays a role in transmitting strain, and when the measuring point position deforms horizontally, the transmission rod 11 transmits the relative displacement of two ends of the intelligent aggregate to the movable substrate 4 and the movable radiation patch 3, so that relative dislocation occurs between the transmission rod and the substrate 1 and between the transmission rod and the radiation patch 2. The mobile radiation patch 3 and the radiation patch 2 are tightly attached to form a combined patch antenna, and the longitudinal resonant frequency of the combined patch antenna is related to the overlapping length between the two radiation patches.
In the concrete internal vertical strain monitoring, the elastic body 7 and the protective layer 8 play a role in transferring vertical strain. When the position of the measuring point is vertically deformed, the intelligent aggregate is vertically stressed, so that the elastic body 7 is stretched or compressed, the distance between the radiation patch 2 and the coupling radiation patch 5 connected with the elastic body is changed, and the high-order resonant frequency of the coupling patch antenna is changed. The change amount of the resonant frequency is related to the vertical strain of the intelligent aggregate embedding position.
In the monitoring of the internal environment temperature of concrete, the change of temperature can cause the change of dielectric constants of the base plate 1, the moving base plate 4 and the coupling base plate 6. And under the influence of temperature change, the substrate 1 and the radiation patch 2, the moving substrate 3 and the moving radiation patch 4, and the coupling radiation patch 5 and the coupling substrate 6 are deformed cooperatively, so that the multi-order resonant frequency of the coupling patch antenna is changed.
It is emphasized that the horizontal direction and the vertical direction in the present invention are respectively the parallel direction of the transmission rod 11 and the vertical direction of the transmission rod 11 (i.e. the plane of the vertical radiation patch 2). And not the horizontal direction and the vertical direction in the traditional sense. In an actual monitoring application scene, the bidirectional strain intelligent aggregate device is embedded according to the direction of monitoring and sensing the stress as required.
Next, an embodiment of the system of the present invention is given, in which an intelligent aggregate sensing system, as shown in fig. 3, includes an intelligent aggregate embedded in a monitoring point inside a concrete structure, and a reader 15 for wirelessly measuring multi-stage resonant frequencies of a coupled patch antenna inside the intelligent aggregate. The reader 15 includes:
the wireless transceiver module 1501 is used for receiving multi-order resonant frequency shift signals sent by the intelligent aggregate;
a modulation/demodulation module 1502 configured to demodulate a signal received by the wireless transceiver module 1501;
the digital processing module 1503 is used for decoupling and calculating the structural horizontal and vertical strain and temperature change of the intelligent aggregate embedding position in the concrete structure according to the corresponding relation;
the control module 1504 is used for transmitting modulated electromagnetic wave signals with different frequencies to the intelligent aggregate embedded in the concrete structure so as to activate the radio frequency identification chip 14 in the intelligent aggregate.
Next, an embodiment of the method of the present invention is given, in which the monitoring method for the intelligent aggregate monitoring and sensing system includes the following steps:
1) The control module 1504 transmits modulated electromagnetic wave signals with different frequencies to intelligent aggregates embedded in the concrete structure; when the power of the signal received by the intelligent aggregate reaches a set threshold value, the radio frequency identification chip 14 is activated;
2) After the radio frequency identification chip 14 is activated, the antenna of the coupling patch generates current and emits an electromagnetic wave signal with a label number and measuring point position information, and the signal is received by the wireless transceiver module 1501 and processed by the modem module (1502) to obtain the label number and the position information corresponding to the intelligent aggregate;
3) The digital processing module 1503 determines each order of resonant frequency of the coupled patch antenna by searching for the transmission frequency of the electromagnetic wave of the reader 15, of which the signal transmission power reaches each order of minimum value when the radio frequency identification chip 14 is activated;
4) When the intelligent aggregate embedded in the concrete generates horizontal strain, vertical strain and environmental temperature change, the size of the radiation patches in the intelligent aggregate and the dielectric constant of the substrate are changed, the distance between the radiation patches is changed, and the resonant frequency of each order of the intelligent aggregate is shifted; by calculating the offset of each order of resonant frequency of the intelligent aggregate, decoupling to obtain the bidirectional strain and temperature variation of the concrete at the embedding position of the intelligent aggregate, and synchronously monitoring the bidirectional strain and temperature in the concrete.
Wherein, step 4) when the intelligent aggregate of embedding in the concrete inside produces horizontal strain, vertical strain, ambient temperature change, the size of the inside radiation paster of intelligent aggregate and the dielectric constant of base plate change, and the distance between the radiation paster changes, and each order resonant frequency of intelligence aggregate shifts, specifically is:
when intelligent aggregate produces the level to warping, produce relative displacement between removal radiation paster 3 and the radiation paster 2, and then lead to the combination radiation paster longitudinal length change, make its longitudinal resonance frequency change.
When the internal temperature of the concrete changes, the dielectric constants of the base plate 1 and the movable base plate 4 change, and the lengths and the widths of the radiation patches 2 and the movable radiation patches 3 change, so that the transverse resonant frequency and the longitudinal resonant frequency of the combined radiation patches change.
When the intelligent aggregate is vertically deformed, the elastic body 7 is correspondingly deformed, so that the distance between the coupling radiation patch 5 and the radiation patch 2 is changed, and the resonant frequency of the coupling radiation patch 5 is correspondingly changed.
The coupling patch antenna in the intelligent aggregate is fed in a mode that the radio frequency identification chip 14 is connected with the eccentric microstrip feed line 13, so that a multi-order resonance mode of the coupling patch antenna is excited.
The reader 15 transmits the modulated electromagnetic wave signals to the smart aggregate at different frequencies, and when the reader 15 transmits signals at a certain order of resonant frequency of the coupled patch antenna, the transmission power required to activate the rfid chip 14 is significantly reduced. The multi-order resonant frequency of the intelligent aggregate internal coupling patch antenna can be determined by searching the electromagnetic wave transmitting frequency which enables the threshold transmitting power to reach the minimum value.
Decoupling is carried out according to the multi-order resonant frequency of the intelligent aggregate internal coupling patch antenna measured by the reader, the horizontal and vertical strain of the concrete structure at the intelligent aggregate embedding position can be measured, and the temperature of a monitoring point can be synchronously measured, so that the temperature compensation is carried out on the bidirectional strain monitoring value in the concrete.
The code and the position information of the intelligent aggregate carried in the radio frequency identification chip 14 can identify the code of the intelligent aggregate and the embedding position in the concrete structure by transmitting a modulated electromagnetic wave signal to the intelligent aggregate by using the reader 15, and when the reader 15 scans a plurality of intelligent aggregates embedded in the range of the concrete structure, the reader 15 can mark the bidirectional strain and the temperature value at each monitoring point in the concrete structure according to the code of each intelligent aggregate for monitoring.
Temperature self-compensation principle:
the intelligent aggregate has two resonance modes of a longitudinal resonance mode and a transverse resonance mode, and also has a coupling resonance mode of a coupling radiation patch 5. The corresponding resonant frequency formula is expressed as follows:
wherein Δ T represents the amount of change in the internal temperature of the concrete, and Δ L Strain in horizontal direction ,ΔL Vertical strain Respectively showing the relative displacement generated between the moving radiation patch 3 and the radiation patch 2 and the relative displacement generated between the radiation patch 2 and the coupling radiation patch 5 due to the internal strain of the concrete;
and/or>
Respectively is a coefficient of longitudinal resonance frequency changing with temperature, a coefficient of transverse resonance frequency changing with temperature, a coefficient of coupling resonance frequency changing with temperature, and/or `>
Is a coefficient of the longitudinal resonance frequency changing with the concrete horizontal strain>
The coefficients are coefficients of the coupling resonance frequency changing along with the vertical strain of the concrete, and all the coefficients can be obtained by theoretical calculation.
Through the measurement of the multi-order resonant frequency (longitudinal resonant frequency, transverse resonant frequency and coupling resonant frequency) of the passive wireless intelligent aggregate, the synchronous sensing and monitoring of the horizontal strain, vertical strain and temperature parameters in the concrete can be realized in a decoupling mode, the intelligent aggregate sensor has a temperature compensation function, and the temperature deviation of the longitudinal resonant frequency and the coupling resonant frequency is corrected without an additional temperature sensor.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The bidirectional strain intelligent aggregate based on the patch antenna is characterized in that the whole structure is packaged by a cement-based protective layer (10), and the intelligent aggregate further comprises a radiation patch component, a movable radiation patch component, a coupling radiation patch component, a transmission rod (11) and a radio frequency identification chip (14) carrying intelligent aggregate codes and position information;
the radiation patch component is tightly attached to the movable radiation patch component, and the radiation patch component and the movable radiation patch component are partially overlapped to form short circuits which are staggered with each other; an elastic body (7) is filled between the radiation patch component and the coupling radiation patch component and is used for being compressed or stretched when the intelligent aggregate generates vertical deformation so as to change the distance between the radiation patch component and the coupling radiation patch component, and therefore the corresponding resonant frequency is changed to carry out vertical strain monitoring; wherein, the vertical direction is the direction vertical to the plane of the radiation patch component;
the radiation patch component, the movable radiation patch component, the coupling radiation patch component and the radio frequency identification chip (14) are wrapped with a protective layer (8); one end of the transmission rod (11) is fixed on the movable radiation patch component, and the other end of the transmission rod extends out of the protective layer (8) and is fixed on the cement-based protective layer (10) and is used for carrying out compression deformation transmission at two ends when the intelligent aggregate horizontally deforms in the direction of stress so as to cause mutual dislocation between the movable radiation patch (3) and the radiation patch (2); wherein the horizontal direction is a direction parallel to the transmission rod (11);
the radio frequency identification chip (14) is connected with the radiation patch assembly through an arranged microstrip feeder line (13) and is used for activating resonance in two directions of the plane of the radiation patch and vertical coupling resonance.
2. The bidirectional strain smart aggregate based on the patch antenna is characterized in that the radiating patch assembly comprises a substrate (1) and a radiating patch (2), the mobile radiating patch assembly comprises a mobile radiating patch (3) and a mobile substrate (4), the coupled radiating patch assembly comprises a coupled radiating patch (5) and a coupled substrate (6), the substrate (1), the radiating patch (2), the mobile radiating patch (3), the mobile substrate (4), the coupled radiating patch (5), and the coupled substrate (6) are sequentially arranged, wherein:
the radio frequency identification chip (14) is welded on the upper surface of the substrate (1) and is connected with the radiation patch (2) through a micro-strip feeder line (13); the lower surface of the substrate (1) is electroplated with a completely covered copper layer, and the upper surface of the substrate (1) is electroplated and attached to the radiation patch (2); the lower surface of the movable substrate (4) is electroplated and attached to the movable radiation patch (3), the upper surface of the movable radiation patch (3) is closely attached to the radiation patch (2), and the upper surface and the lower surface are overlapped to form short circuits which are staggered with each other; the lower surface of the coupling substrate (6) is electroplated and attached to the radiation combining patch (5), the upper surface of the coupling substrate (6) is fixed to the lower surface of the protective layer (8), and an elastic body (7) is filled between the coupling radiation patch (5) and the radiation patch (2) and used for being compressed or stretched to change the distance between the coupling radiation patch (5) and the radiation patch (2) when the intelligent aggregate is vertically deformed;
one end of the transmission rod (11) is fixed on the movable base plate (4), and the other end of the transmission rod extends out of the protective layer (8) and is fixed on the cement-based protective layer (10) and is used for carrying out compression deformation at two ends when the intelligent aggregate horizontally deforms towards stress to transfer the horizontal stress to cause mutual dislocation between the movable radiation patch (3) and the radiation patch (2).
3. A patch antenna based bi-directional strain smart aggregate according to claim 2, characterized in that the microstrip feed line (13) is provided at a set distance from the center line of the radiating patch (2) to activate the resonant modes of the radiating patch (2) in both planar directions and the coupled resonant mode of the coupled radiating patch (5).
4. The bidirectional strain intelligent aggregate based on the patch antenna is characterized in that filling particles (12) are filled between the middle part of the transmission rod (11) and the cement-based protective layer (10) to bear part of vertical stress and enable the transmission rod (11) to move horizontally.
5. The bidirectional strain intelligent aggregate based on the patch antenna is characterized in that the intelligent aggregate is further provided with a waterproof coating (9) arranged on the inner wall of the cement-based protective layer (10).
6. The bidirectional strain intelligent aggregate based on the patch antenna is characterized in that the radiation patch (2), the mobile radiation patch (3), the coupling radiation patch (5) and the microstrip feed line (13) are all made of copper.
7. The bidirectional strain intelligent aggregate based on the patch antenna as claimed in claim 2, wherein the substrate (1), the moving substrate (4) and the coupling substrate (6) are all RT5880 dielectric plates.
8. A bidirectional strain intelligent aggregate monitoring and sensing system based on a patch antenna is characterized by comprising intelligent aggregate embedded in a concrete structure and a reader (15) for reading information of a radio frequency identification chip (14) in the intelligent aggregate and performing data processing; the intelligent aggregate is the bidirectional strain intelligent aggregate based on the patch antenna, which is disclosed by any one of claims 1-7; the reader (15) comprises:
the wireless transceiving module (1501) is used for receiving multi-order resonant frequency offset signals sent by the intelligent aggregate;
a modulation and demodulation module (1502) for demodulating the signal received by the wireless transceiver module (1501);
the digital processing module (1503) is used for decoupling and calculating the structural horizontal and vertical strain and temperature change of the intelligent aggregate embedding position in the concrete structure according to the corresponding relation;
and the control module (1504) is used for transmitting modulated electromagnetic wave signals with different frequencies to the intelligent aggregate embedded in the concrete structure so as to activate the radio frequency identification chip (14) in the intelligent aggregate.
9. A method for the patch antenna based bi-directional strain smart aggregate monitoring sensing system of claim 8, the method comprising the steps of:
1) The control module (1504) transmits modulated electromagnetic wave signals with different frequencies to intelligent aggregate embedded in the concrete structure; when the power of the signal received by the intelligent aggregate reaches a set threshold value, the radio frequency identification chip (14) is activated;
2) After the radio frequency identification chip (14) is activated, the antenna of the coupling patch generates current and emits an electromagnetic wave signal with a label number and measuring point position information, and the signal is received by the wireless transceiver module (1501) and processed by the modem module (1502) to obtain the label number and the position information corresponding to the intelligent aggregate;
3) The digital processing module (1503) determines each order of resonant frequency of the coupling patch antenna by searching the transmission frequency of the electromagnetic wave of the reader (15) of which the signal transmission power reaches each order of minimum value when the radio frequency identification chip (14) is activated;
4) When the intelligent aggregate embedded in the concrete generates horizontal strain, vertical strain and environmental temperature change, the size of the radiation patches in the intelligent aggregate and the dielectric constant of the substrate are changed, the distance between the radiation patches is changed, and the resonant frequency of each order of the intelligent aggregate is shifted; by calculating the offset of each order of resonant frequency of the intelligent aggregate, decoupling to obtain the bidirectional strain and temperature variation of the concrete at the embedding position of the intelligent aggregate, and synchronously monitoring the bidirectional strain and temperature in the concrete.
10. The method according to claim 9, wherein in the step 4), when the intelligent aggregate embedded in the concrete generates horizontal strain, vertical strain and environmental temperature change, the size of the radiation patches and the dielectric constant of the substrate in the intelligent aggregate change, the distance between the radiation patches changes, and the resonant frequency of each order of the intelligent aggregate shifts, specifically:
when the intelligent aggregate is deformed horizontally, the movable radiation patch (3) and the radiation patch (2) generate relative displacement, so that the longitudinal length of the combined radiation patch is changed, and the longitudinal resonant frequency of the combined radiation patch is changed;
when the internal temperature of the concrete changes, the dielectric constants of the base plate (1) and the movable base plate (4) change, and the lengths and the widths of the radiation patches (2) and the movable radiation patches (3) change, so that the transverse resonant frequency and the longitudinal resonant frequency of the combined radiation patches change;
when the intelligent aggregate is vertically deformed, the elastic body (7) is correspondingly deformed, so that the distance between the coupling radiation patch (5) and the radiation patch (2) is changed, and the resonant frequency of the coupling radiation patch (5) is correspondingly changed.
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