CN114076795B - Alternating induction type flexible vortex array sensor and crack monitoring method thereof - Google Patents
Alternating induction type flexible vortex array sensor and crack monitoring method thereof Download PDFInfo
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- CN114076795B CN114076795B CN202111354011.6A CN202111354011A CN114076795B CN 114076795 B CN114076795 B CN 114076795B CN 202111354011 A CN202111354011 A CN 202111354011A CN 114076795 B CN114076795 B CN 114076795B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
- G01N27/9046—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents by analysing electrical signals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
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Abstract
The invention discloses an alternating induction type flexible eddy current array sensor, which comprises exciting coils, wherein the exciting coils are spirally arranged from inside to outside in the same plane, and the exciting coils are in homodromous exciting layout; each alternating induction coil group is formed by sequentially connecting a plurality of induction coils in series, and the voltage polarity of the connecting end of the former induction coil is the same as that of the connecting end of the latter induction coil connected with the former induction coil; the induction coils of each alternating induction coil group are sequentially arranged between two adjacent turns of coils of the excitation coil from inside to outside along the spiral direction of the excitation coil, and the end parts of the first induction coil and the last induction coil of each alternating induction coil group are induction voltage output ends of the alternating induction coil group. All induction coils of each alternating induction coil group are placed at the middle left side or the middle right side of the adjacent two turns of exciting coils. The number of induction channels is greatly reduced, and the connecting circuit is simplified.
Description
Technical Field
The invention belongs to the field of nondestructive detection for structural health monitoring, and relates to an alternating induction type flexible vortex array sensor and a crack monitoring method thereof.
Background
The structural health monitoring technology is to arrange advanced sensors on the structure, collect parameters representing the structural health state in real time, judge the structural health state through the technologies of collection, data processing, damage identification and the like, and further make a maintenance plan of equipment.
The sensors commonly used for structural health monitoring at the present stage include strain sensors, optical fiber sensors, intelligent coating sensors, ultrasonic guided wave sensors, eddy current sensors and the like. But each sensor has its own advantages and disadvantages and application scenario. Strain sensors can monitor the strain state of a structure in real time, but the sensor is not very sensitive to the propagation of microcracks. The optical fiber sensor has the characteristic of large monitoring range, can monitor the strain state and the crack of the structure, but the sensor is greatly influenced by temperature, and the installation process is complex. The intelligent coating sensor can monitor the initiation and the expansion of surface cracks, but the sensitivity of crack identification is low, especially in the crack initiation stage, and meanwhile, the intelligent coating sensor is more complex to install structurally. The ultrasonic guided wave sensor can monitor composite materials and metal materials, but the sensor can not monitor complex structures, and equipment is greatly influenced by noise in the operation process. The eddy current sensor has the advantages of high sensitivity, mature technology, high crack detection rate and the like, and has wider application prospect in the field of structural health monitoring. Particularly, the flexible vortex array sensor has the characteristics of light weight, flexibility, bending and capability of monitoring cracks of a complex structure, and simultaneously, the sensing channels are arranged in an array manner, so that the crack length can be quantitatively monitored. However, because the flexible eddy current array sensor has more sensing channels, the signals of each channel need to be collected in the use process, which tends to cause the complicated connection circuit of the sensor and increases the weight of the whole sensor network. Meanwhile, as the number of sensing channels is large, the number of connected signal conditioning modules is large, so that the hardware cost of the signal conditioning modules is high, and the defects can increase the weight of the structural health monitoring system.
Disclosure of Invention
The embodiment of the invention aims to provide an alternate induction type flexible vortex array sensor so as to solve the problems of multiple induction channels, complex connecting lines and high hardware cost of a signal conditioning module of the conventional flexible vortex array sensor.
It is another object of an embodiment of the present invention to provide a crack monitoring method for an alternating induction type flexible eddy current array sensor.
The technical scheme adopted by the embodiment of the invention is as follows: an alternating induction type flexible eddy current array sensor comprises exciting coils which are spirally arranged from inside to outside in the same plane and are in same-direction exciting layout, and
at least one alternating induction coil group, each alternating induction coil group is formed by sequentially connecting a plurality of induction coils in series, wherein:
the induction coils of each alternating induction coil group are sequentially arranged between two adjacent turns of coils of the excitation coil from inside to outside along the spiral direction of the excitation coil, and the end parts of the first induction coil and the last induction coil of each alternating induction coil group are induction voltage output ends of the alternating induction coil group.
Further, all induction coils of each alternating induction coil group are placed at the position close to the left in the middle of two adjacent turns of excitation coils or at the position close to the right in the middle of two adjacent turns of excitation coils;
the distance between two adjacent turns of the exciting coils is equal to the required crack monitoring precision.
Further, when the induction coils of each alternating induction coil group are connected in series, the voltage polarity of the connecting end of the former induction coil is the same as the voltage polarity of the connecting end of the latter induction coil connected with the former induction coil, and the voltage polarity is positive or negative.
Further, two adjacent induction coils of each alternating induction coil group are connected through via holes arranged at the connecting ends of the adjacent induction coils, and connecting lines among the via holes are arranged on the top layer of the flexible substrate.
Further, a first bonding pad, a fourth bonding pad and an induced voltage output port bonding pad are further arranged on the top layer of the flexible substrate, the first bonding pad is connected with the fourth bonding pad, and two ends of each alternating induction coil group are connected with the corresponding induced voltage output port bonding pad through a through hole arranged at the connecting end of each alternating induction coil group.
Further, the exciting coil and all the alternating induction coil groups are arranged on the bottom layer of the flexible substrate, the bottom layer of the flexible substrate is one side which is in contact with the monitoring structure, the end part of one turn of exciting coil which is positioned at the outermost side of the exciting coil is provided with an exciting coil first through hole, the end part of one turn of exciting coil which is positioned at the innermost side of the exciting coil is provided with an exciting coil second through hole, the exciting coil is connected with a second bonding pad through the exciting coil first through hole, the exciting coil is connected with a third bonding pad through the exciting coil second through hole, and the second bonding pad and the third bonding pad are connected with an exciting source.
The technical scheme adopted by the embodiment of the invention is as follows: the monitoring method of the alternating induction type flexible eddy current array sensor comprises the following steps of:
s1, determining the shape of an alternate induction type flexible vortex array sensor according to the shape of a monitored structure, determining the number and layout of alternate induction coil groups according to the stress direction and crack propagation direction of the monitored structure, determining the distance between two adjacent turns of excitation coils of an excitation coil according to the required crack monitoring precision, and determining the number of turns of the excitation coil and the number of induction coils of each alternate induction coil group according to the required crack length monitoring range;
s2, analyzing the stress concentration part of the monitored structure according to the stress direction of the monitored structure, and determining the setting position of the alternating induction type flexible vortex array sensor;
s3, monitoring the induction voltage of each alternating induction coil group of the alternating induction type flexible vortex array sensor in real time, and drawing an induction voltage curve of each alternating induction coil group;
and S4, judging whether inflection points oscillating back and forth exist in the induction voltage curve of each alternating induction coil group, if so, determining the position of the alternating induction coil group as the crack initiation position, and multiplying the crack monitoring precision by the number of the inflection points oscillating back and forth in the voltage in the induction voltage curve of each alternating induction coil group to determine the crack length monitored by each alternating induction coil group.
Further, in the step S1, if the monitored hole structure is the hole structure, the shape of the alternate induction type flexible eddy current array sensor is set to be circular, and two alternate induction coil sets are set, so that the two alternate induction coil sets are correspondingly positioned at left and right sides of the monitored hole structure in the stress direction; if the stress direction of the monitored hole structure is uncertain, a plurality of alternating induction coil groups are arranged and uniformly distributed on the periphery of the monitored hole structure.
Further, in the step S1, if the weld structure is monitored, the alternate induction type flexible eddy current array sensor is set to have a rectangular shape, and at least one alternate induction coil set is set, where the at least one alternate induction coil set is set along the length direction of the weld.
Further, the device is used for carrying out crack monitoring on the porous structure, when carrying out crack monitoring on the porous structure, an empty corresponding sensor is arranged on an alternating induction type flexible vortex array sensor, and a plurality of alternating induction type flexible vortex array sensors corresponding to a plurality of holes are connected in series, specifically:
for the first alternate induction type flexible vortex array sensor, the fourth bonding pad is grounded, the third bonding pad is connected with the core wire of the radio frequency wire, the second bonding pad is connected with the third bonding pad of the next alternate induction type flexible vortex array sensor, and the first bonding pad is connected with the fourth bonding pad of the next alternate induction type flexible vortex array sensor; for the middle alternate induction type flexible vortex array sensor, connecting a third bonding pad with a second bonding pad of the previous alternate induction type flexible vortex array sensor, connecting the second bonding pad with a third bonding pad of the next alternate induction type flexible vortex array sensor, connecting the fourth bonding pad with a first bonding pad of the previous alternate induction type flexible vortex array sensor, and connecting the first bonding pad with a fourth bonding pad of the next alternate induction type flexible vortex array sensor; and for the last alternating induction type flexible vortex array sensor, connecting the second bonding pad with the first bonding pad of the last alternating induction type flexible vortex array sensor, and connecting the third bonding pad with the second bonding pad of the previous alternating induction type flexible vortex array sensor.
The embodiment of the invention has the beneficial effects that:
1. the induction coils are integrated into the alternating induction coil group, so that the induction coils are connected to form an induction channel on the premise of not changing the quantitative monitoring effect, the number of the induction channels is greatly reduced, the connecting circuit is simplified, the demand on the signal conditioning module is greatly reduced, the cost of the sensor network and the additional weight of the sensor network are reduced, and the problems that the existing flexible vortex array sensor induction channel is complex in connecting circuit and high in hardware cost of the signal conditioning module are effectively solved.
2. The quantitative monitoring of the crack length can be carried out according to the peak-to-valley value of the induction voltage output by the alternating induction coil group, namely the number of oscillating turns back and forth, and the quantitative crack monitoring method is simplified.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of the underlying structure of a circular alternating induction type flexible eddy current array sensor.
Fig. 2 is a schematic top layer structure of a circular alternating induction type flexible eddy current array sensor.
Fig. 3 is an enlarged schematic view of the structure of the alternating induction coil assembly.
Fig. 4 is a schematic structural view of a rectangular alternating induction type flexible eddy current array sensor.
Fig. 5 is an equivalent schematic diagram of an alternating induction coil assembly.
Fig. 6 is a graph of induced voltage versus crack length for an alternating induction coil assembly during crack monitoring.
In the figure, 1, 2, 3, 4, fourth, 5, fifth, 6, sixth, 7, seventh, 8, eighth, 9, first via, 10, second via, 11, first via of excitation coil, 12, second via of excitation coil, 13, first via of induction coil, 14, second via of first induction coil, 15, first via of second induction coil, 16, second via of second induction coil, 17, third via of induction coil, 18, third via of induction coil, 19, fourth via of induction coil, 20, fourth via of induction coil, 21, fifth via of induction coil, 22, fifth via of induction coil, 23, third via of pad, 24, fourth via of pad, 25, fifth via of induction coil, 26, first via of induction coil, 27, third via of induction coil, 29, sixth via of induction coil, 31, sixth via of induction coil, 33, sixth via of induction coil.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The embodiment of the invention provides an alternate induction type flexible eddy current array sensor for monitoring hole edge cracks, which is shown in fig. 1-3, and comprises an exciting coil 34, wherein the exciting coil 34 is spirally arranged outwards from a monitored hole edge in the same plane, and two alternate induction coil groups which are correspondingly positioned at the left side and the right side (stress concentration parts of a monitored structure) of a stress direction of a monitored hole structure and are bilaterally symmetrical relative to the stress direction of the monitored structure, and when a monitored hole is a bolt hole and the force applied to the bolt hole is an axial force, the two alternate induction coil groups are symmetrically arranged at the right side and the right side of the threaded hole Kong Bianzuo.
The number of turns of the exciting coil 34 is 6, and a first turn exciting coil, a second turn exciting coil, a third turn exciting coil, a fourth turn exciting coil, a fifth turn exciting coil and a sixth turn exciting coil are sequentially arranged from inside to outside on the monitored hole edge, exciting current flows in from the end part of the first turn exciting coil, and exciting current flows out from the end part of the sixth turn exciting coil; each of the alternating induction coil groups includes 5 induction coils, namely, a first induction coil 26, a second induction coil 27, a third induction coil 28, a fourth induction coil 29 and a fifth induction coil 30, the first induction coil 26 to the fifth induction coil 30 are sequentially connected in series from inside to outside along the aperture direction of the monitored threaded hole, and the first induction coil 26 is located between the first turn excitation coil and the second turn excitation coil of the excitation coil 34, the second induction coil 27 is located between the second turn excitation coil and the third turn excitation coil of the excitation coil 34, the third induction coil 28 is located between the third turn excitation coil and the fourth turn excitation coil of the excitation coil 34, the fourth induction coil 29 is located between the fourth turn excitation coil and the fifth turn excitation coil of the excitation coil 34, and the fifth induction coil 30 is located between the fifth turn excitation coil and the sixth turn excitation coil of the excitation coil 34.
Further, the excitation coil 34 and at least one alternate induction coil group are both disposed at the bottom layer of the flexible substrate, the end of the sixth turn of excitation coil, i.e. the one turn of excitation coil located at the outermost side, of the excitation coil 34 is provided with an excitation coil first via hole 11, the end of the first turn of excitation coil, i.e. the one turn of excitation coil located at the innermost side, of the excitation coil 34 is provided with an excitation coil second via hole 12, the excitation coil 34 is connected with a second bonding pad 2 located at the top layer of the flexible substrate through the excitation coil first via hole 11, the excitation coil 34 is connected with a third bonding pad 3 located at the top layer of the flexible substrate through the excitation coil second via hole 12, and the second bonding pad 2 and the third bonding pad 3 are connected with an excitation power supply through radio frequency wires.
All induction coils of each alternating induction coil group, namely a first induction coil 26-a fifth induction coil 30 are placed at the position close to the left side in the middle of two adjacent turns of excitation coils, so that the electric potential of each induction coil of each alternating induction coil group, namely the first induction coil 26-the fifth induction coil 30, is high on the left side and low on the right side; or all induction coils of each alternate induction coil group, namely the first induction coil 26-the fifth induction coil 30 are placed at the position close to the right in the middle of two adjacent turns of excitation coils, so that the electric potential of each induction coil of each alternate induction coil group, namely the first induction coil 26-the fifth induction coil 30, is high on the right and low on the left.
When the induction coils of each alternating induction coil group are connected in series, the voltage polarity of the connecting end of the former induction coil is the same as that of the connecting end of the latter induction coil connected with the former induction coil, and the voltage polarity is positive or negative. As shown in fig. 5, the positive electrode of the first induction coil 26 of the alternating induction coil set adopted in the present embodiment is an induced voltage positive electrode output port, the negative electrode thereof is connected with the negative electrode of the second induction coil 27, the positive electrode of the second induction coil 27 is connected with the positive electrode of the third induction coil 28 until the negative electrode of the last fifth induction coil is an induced voltage negative electrode output port.
Two adjacent induction coils of each alternating induction coil group are connected through the through holes arranged at the connecting ends of the adjacent induction coils, and connecting wires between the through holes are arranged on the top layer of the flexible substrate. In the alternating induction coil set of the present embodiment, the first induction coil 26 is correspondingly provided with a first induction coil first via hole 13 and a first induction coil second via hole 14 at two ends, the second induction coil 27 is correspondingly provided with a second induction coil first via hole 15 and a second induction coil second via hole 16 at two ends, the third induction coil 28 is correspondingly provided with a third induction coil first via hole 17 and a third induction coil second via hole 18 at two ends, the fourth induction coil 29 is correspondingly provided with a fourth induction coil first via hole 19 and a fourth induction coil second via hole 20 at two ends, and the fifth induction coil 30 is correspondingly provided with a fifth induction coil first via hole 21 and a fifth induction coil second via hole 22 at two ends; the voltage polarities at the first induction coil first through hole 13, the second induction coil first through hole 15, the third induction coil first through hole 17, the fourth induction coil first through hole 19 and the fifth induction coil first through hole 21 are consistent, the voltage polarities at the first induction coil second through hole 14, the second induction coil second through hole 16, the third induction coil second through hole 18, the fourth induction coil second through hole 20 and the fifth induction coil second through hole 22 are consistent, the voltage polarities are positive or negative, namely, when the induction coils of each alternating induction coil group are connected in series, the voltage polarities of the connecting end of the previous induction coil and the connecting end of the subsequent induction coil connected with the connecting end are the same. The first induction coil first via hole 13 is connected with the eighth bonding pad 8 positioned on the top layer of the flexible substrate, the first induction coil second via hole 14 is connected with the second induction coil second via hole 16, the second induction coil first via hole 15 is connected with the third induction coil first via hole 17, the third induction coil second via hole 18 is connected with the fourth induction coil second via hole 20, and the fourth induction coil first via hole 19 is connected with the fifth induction coil first via hole 21.
The flexible substrate is provided with a fifth bonding pad 5, a sixth bonding pad 6, a seventh bonding pad 7 and an eighth bonding pad 8, the fifth bonding pad 5 and the sixth bonding pad 6 are induction voltage output ports of the alternating induction coil groups positioned on the left side of the hole, the seventh bonding pad 7 and the eighth bonding pad 8 are induction voltage output ports of the alternating induction coil groups positioned on the right side of the hole, and therefore the fifth bonding pad 5-eighth bonding pad 8 are called induction voltage output port bonding pads. When the fifth pad 5 and the sixth pad 6 are disposed on the bottom layer of the flexible substrate, the other end of the first induction coil 26 of the alternating induction coil group located on the left side of the hole is directly connected to the sixth pad 6, and the other end of the fifth induction coil 30 is directly connected to the fifth pad 5. When the seventh pad 7 and the eighth pad 8 are disposed on the bottom layer of the flexible substrate, the other end of the first induction coil 26 of the alternating induction coil group located on the right side of the hole is directly connected to the eighth pad 8, and the other end of the fifth induction coil 30 is directly connected to the seventh pad 7. When the fifth bonding pad 5 and the sixth bonding pad 6 are arranged on the top layer of the flexible substrate, the first sensing coil 26 of the alternating sensing coil group positioned at the left side of the hole is connected with the sixth bonding pad 6 through the first sensing coil first via hole 13 on the first sensing coil, the fifth sensing coil 30 of the alternating sensing coil group is connected with the bonding pad third via hole 23 through the fifth sensing coil second via hole 22, the bonding pad third via hole 23 is arranged at the left outer side of the exciting coil 34, the bonding pad third via hole 23 is connected with the bonding pad fourth via hole 24, the bonding pad fourth via hole 24 is connected with the fifth bonding pad 5, the connecting line of the bonding pad third via hole 23 and the bonding pad fourth via hole 24 is positioned at the bottom layer of the flexible substrate, and the connecting line of the bonding pad fourth via hole 24 and the fifth bonding pad 5 is positioned at the top layer of the flexible substrate. When the seventh pad 7 and the eighth pad 8 are disposed on the top layer of the flexible substrate, the first inductor coil 26 of the alternating inductor coil group disposed on the right side of the hole is connected to the sixth pad 8 through the first inductor coil first via 13 thereon, the fifth inductor coil 30 of the alternating inductor coil group is connected to the pad third via 23 through the fifth inductor coil second via 22, the pad third via 23 is disposed on the right outer side of the excitation coil 34, the pad third via 23 is connected to the pad fifth via 25, the pad fifth via 25 is connected to the seventh pad 7, and the connection line of the pad third via 23 and the pad fifth via 25 is disposed on the bottom layer of the flexible substrate, and the connection line of the pad fifth via 25 and the seventh pad 7 is disposed on the top layer of the flexible substrate. Namely, when the induced voltage output port bonding pad is arranged on the top layer of the flexible substrate, two ends of each alternating induction coil group are respectively connected with the corresponding induced voltage output port bonding pad through the through hole.
Further, when two adjacent induction coils of each alternating induction coil group are connected by arranging via holes at the connection ends thereof, the connection line between the via holes is arranged on the top layer of the flexible substrate, in the embodiment of the invention, the connection line between the first induction coil second via hole 14 and the second induction coil second via hole 16, the connection line between the second induction coil first via hole 15 and the third induction coil first via hole 17, the connection line between the third induction coil second via hole 18 and the fourth induction coil second via hole 20, and the connection line between the fourth induction coil first via hole 19 and the fifth induction coil first via hole 21 are all positioned on the top layer of the flexible substrate.
The induction coils are integrated into the alternating induction coil groups, so that the number of induction channels is greatly reduced, each alternating induction coil group only comprises 1 induction channel, a connecting circuit is simplified, the demand on a signal conditioning module is greatly reduced, the cost of a sensor network and the additional weight of the sensor network are reduced, whether single-side cracks are generated or not and the lengths of the cracks can be monitored by collecting signals of one induction channel, and the quantitative crack monitoring method is simplified.
The distance between two adjacent turns of the exciting coils 34 is the crack monitoring precision required by the embodiment, for example, the distance between two adjacent turns of exciting coils can be 1mm, and the distance between two adjacent turns of exciting coils can be properly adjusted according to the structural form of the flexible eddy current array sensor and the required crack monitoring precision.
Because all induction coils of each alternate induction coil group are respectively positioned between two adjacent turns of the excitation coil 34, the number of turns of the excitation coil 34 is 1 more than that of the induction coils of the alternate induction coil group, and the number of the alternate induction coil groups and the induction coils contained therein can be set according to the crack propagation condition of the monitored structure, when the stress condition of the monitored structure is ambiguous, a plurality of alternate induction coil groups can be arranged on the periphery of the monitored structure, and all parts of the periphery can be monitored. The number of induction coils of each of the alternating induction coil sets may be increased or decreased according to the crack monitoring range, for example, the number of induction coils of each of the alternating induction coil sets may be increased or decreased on the basis that the alternating induction coil sets of the present embodiment include 5 induction coils. As in this embodiment, the distance between two adjacent turns of exciting coils is 1mm, and since the alternating induction coil group comprises 5 induction coils, the maximum crack length which can be monitored is 5mm; if it is known empirically that the crack propagation length of the monitored structure may exceed 5mm, the number of induction coils included in the alternating induction coil sets may be increased appropriately; the number of induction coils included in the alternating induction coil assembly may be suitably reduced as it is empirically known that the crack propagation length of the monitored structure may be much less than 5 mm.
The embodiment of the invention can print the exciting coil and the induction coil on the flexible substrate, and can also be printed on a common PCB hard board or other boards capable of printing coils. The exciting coil and the induction coil are prepared by adopting a circuit printing technology, and can also be wound by adopting a wire.
The shape of the alternate induction type flexible eddy current array sensor according to the embodiment of the invention can be not only annular, but also rectangular or other irregular shapes, as shown in fig. 4, and can be specifically set according to requirements. For example, when weld crack monitoring is performed, a rectangular alternate induction type flexible eddy current array sensor can be used, and at least 1 alternate induction coil set is arranged.
Further, in order to use the alternate induction type flexible eddy current array sensor of the present embodiment for monitoring the via structure, the line arrangement is facilitated, and the first bonding pad 1 and the fourth bonding pad 4 which are mutually communicated are arranged on the top layer of each alternate induction type flexible eddy current array sensor.
In order to facilitate wiring, the first bonding pad 1-the fourth bonding pad 4 on the top layer of the flexible substrate are arranged in the same area, so that the second bonding pad 2 and the third bonding pad 3 influence the connection of the first bonding pad 1 and the fourth bonding pad 4, in order to avoid the influence, a bonding pad first through hole 9 is arranged at the first bonding pad 1, a bonding pad second through hole 10 is arranged at the fourth bonding pad 4, and the bonding pad first through hole 9 and the bonding pad second through hole 10 are connected through a connecting wire positioned on the bottom layer of the flexible substrate.
Example 2
Taking the example that each alternating induction coil group comprises 6 induction coils as an example on the basis of the embodiment 1, namely, on the basis of the embodiment 1, the number of turns of the excitation coil 34 is 7, a sixth induction coil 31 is arranged between a sixth turn excitation coil and a seventh turn excitation coil, and an excitation coil second through hole 12 is arranged at the end part of the seventh turn excitation coil; and the two ends of the sixth induction coil 31 are correspondingly provided with a sixth induction coil first via hole 32 and a sixth induction coil second via hole 33, the voltage polarity at the position of the sixth induction coil first via hole 32 is consistent with that at the position of the fifth induction coil first via hole 21, the voltage polarity at the position of the sixth induction coil second via hole 33 and the fifth induction coil second via hole 22 is consistent, and the fifth induction coil second via hole 22 is connected with the sixth induction coil second via hole 33. The sixth inductor first via 32 of the alternating inductor group located to the left of the monitored hole is connected to the fifth bond pad 5 located on the top layer of the flexible substrate, and the sixth inductor first via 32 of the alternating inductor group located to the right of the monitored hole is connected to the seventh bond pad 7 located on the top layer of the flexible substrate. At this time, crack monitoring was performed by the following method:
step S1, determining the shape of an alternate induction type flexible vortex array sensor according to the shape of a monitored structure, determining the number and layout of alternate induction coil groups according to the stress direction and crack propagation direction of the monitored structure, determining the distance between two adjacent turns of the excitation coil 34 according to the required crack monitoring precision, and determining the number of turns of the excitation coil 34 and the number of induction coils of each alternate induction coil group according to the required crack length monitoring range. If the hole structure is monitored, arranging the shape of the alternating induction type flexible vortex array sensor to be round, and arranging two alternating induction coil groups, so that the two alternating induction coil groups are correspondingly positioned at the left side and the right side of the stress direction of the monitored hole structure; if the stress direction of the monitored hole structure is uncertain, a plurality of alternating induction coil groups are arranged and uniformly distributed on the periphery of the monitored hole structure. If the weld structure is monitored, the alternate induction type flexible eddy current array sensor is arranged to be rectangular in shape, at least one alternate induction coil set is arranged, and the at least one alternate induction coil set is arranged along the length direction of the weld.
And S2, analyzing the stress concentration part of the monitored structure according to the stress direction of the monitored structure, and determining the setting position of the alternating induction type flexible vortex array sensor. As in example 1, when the monitored structure is a hole structure, the stress concentration portion of the hole structure is analyzed to be Kong Bianzuo on the right side, so that the alternate induction type flexible vortex array sensor is arranged at the hole edge; if the weld structure is monitored, an alternating induction type flexible eddy current array sensor is stuck to the weld position.
S3, monitoring the induction voltage of each alternating induction coil group of the alternating induction type flexible vortex array sensor in real time, and drawing an induction voltage curve of each alternating induction coil group;
and S4, judging whether inflection points oscillating back and forth exist in the induction voltage curve of each alternating induction coil group, if so, determining the position of the alternating induction coil group as the crack initiation position, and multiplying the crack monitoring precision by the number of the inflection points oscillating back and forth in the voltage in the induction voltage curve of each alternating induction coil group to determine the crack length monitored by each alternating induction coil group.
Since the exciting coils 34 are in the same-direction exciting layout, the induction voltage directions of all the induction coils distributed between two adjacent exciting coils are identical for any one side, and the induction voltage directions are high-potential points at the left end and low-potential points at the right end (all the induction coils of each alternate type induction coil group are placed at the position close to the left side in the middle of the two adjacent exciting coils), or the induction voltage directions of all the induction coils of each alternate type induction coil group are low-potential points and high-potential points at the left end (all the induction coils of each alternate type induction coil group are placed at the position close to the right side in the middle of the two adjacent exciting coils).
When all induction coils of each alternating induction coil group are arranged at the middle of two adjacent turns of exciting coils and are close to the left side, the left end of all induction coils of each alternating induction coil group is a high potential point, the right side is a low potential point, potential differences of 6 induction coils are V1, V2, V3, V4, V5 and V6 correspondingly, and as shown in fig. 5, the connection modes among the induction coils are 13-14-16-15-17-18-20-19-21-22-33-32 from an endpoint m. According to the connection between 6 induction coils, there is a relation (1):
-V 1 +V 2 -V 3 +V 4 -V 5 +V 6 =V； （1）
since the potential of the left side of the 6 induction coils is higher than that of the right side, the voltage goes from the m end to the n end, and it can be seen that the potential of a is higher than that of b, the potential drops by V from a to b 1 Thus, is-V 1 The potential at point b is the same as that at point d, and the potential increases in the process from point d to point c, so that the potential is V 2 Thereby obtaining the potential difference between the m end and the n end as-V 1 +V 2 -V 3 +V 4 -V 5 +V 6 =V。
Similarly, when all induction coils of each alternating induction coil group are arranged at the middle of two adjacent turns of excitation coils and are close to the right, the left end of each induction coil of each alternating induction coil group is a low potential point, the right side is a high potential point, from an end point n, the connection modes among the induction coils are 32- & gt 33- & gt 22- & gt 21- & gt 19- & gt 20- & gt 18- & gt 17- & gt 15- & gt 16- & gt 14- & lt 13 & gt, and according to the connection modes among 6 induction coils, a relation (2) exists:
V 1 -V 2 +V 3 -V 4 +V 5 -V 6 =V； （2）
for example, the left end of all induction coils of each alternating induction coil group is a high potential point, and the right side of all induction coils of each alternating induction coil group is a low potential point, so that when a crack sequentially passes through each induction coil of each alternating induction coil group, the induction potential difference at two ends of each induction coil can be increased. For example, when a crack passes through the first induction coil 26, the difference in induced electric potential across the first induction coil 26 will be positiveTo increase, thus V 1 The induced potential difference of other induction coils is not changed, and the combined formula (1) shows that the overall induced potential difference V is reduced until the induced potential difference at two ends of the first induction coil 26 is not changed when the crack continues to propagate through the first induction coil 26 and enters the second induction coil 27; after the crack propagates into the second induction coil 27, the difference in induced electric potential across the second induction coil 27 will increase, and thus, V 2 The induced potential difference V of the whole coil will increase until the induced potential difference across the second induction coil 27 is no longer changed when the crack continues to propagate through the second induction coil 27 into the third induction coil 28; similarly, when entering the third induction coil 28, the induced potential difference V of the overall coil will decrease again until the induced potential difference across the third induction coil 28 is no longer changed as the crack continues to propagate through the third induction coil 28 into the fourth induction coil 29; when entering the fourth induction coil 29, the induced electric potential difference V of the whole coil will increase again until the induced electric potential difference at both ends of the fourth induction coil 29 is not changed when the crack continues to propagate through the fourth induction coil 29 into the fifth induction coil 30; when entering the fifth induction coil 30, the induced potential difference V of the whole coil will decrease again until the induced potential difference across the fifth induction coil 30 no longer changes when the crack continues to propagate through the fifth induction coil 30 into the sixth induction coil 31; when entering the sixth induction coil 31, the induced potential difference V of the whole coil will increase again until the induced potential difference across the sixth induction coil 31 is no longer changed as the crack continues to propagate completely through the sixth induction coil 31. It can be seen that with this arrangement, the induced potential difference of the overall coil tends to rise and fall as the crack propagates. Therefore, in the use process, the crack propagation condition can be monitored according to the number of inflection points of the back and forth oscillation of the induction potential difference V of the whole coil of the sensor.
In order to verify that the flexible eddy current array sensor adopting the alternating induction coil group has a crack quantitative monitoring effect, simulation research is carried out, 3 induction coils are adopted as verification in the simulation in order to improve the calculation efficiency, and the simulation result is shown in fig. 6. In fig. 6, the crack does not reach 1mm, and the curve appears to be a somewhat decreasing trend, because of the edge effect of the induction coil, that is, the signal of the first induction coil changes somewhat when the crack does not propagate below the exciting coil 34, but the amount of change of the change is small, which can be ignored, when the crack propagates to 1mm, and at this time the crack is just below the first turn exciting coil, the induced voltage of the first induction coil changes sharply as the crack continues to propagate, so that the crack propagation condition can be determined according to this point. The spacing between adjacent excitation coils in this simulation was 1mm, and it can be seen from the simulation result that when the crack propagates to 1mm, it enters the first induction coil 26, the induction voltage of the entire alternate induction coil group starts to decrease, when the crack tip starts to enter the second induction coil 27, the induction voltage of the entire alternate induction coil group starts to increase, and when the crack continues to propagate to 3mm, it starts to enter the third induction coil 28, and the induction voltage of the entire alternate induction coil group starts to decrease. It can be seen that the induced voltage across the alternating induction coil assembly appears to oscillate back and forth as the crack propagates. Quantitative monitoring of crack length is carried out through the inflection point number and the monitoring accuracy of the back and forth oscillation of the induction voltage of the alternating induction coil group, and according to simulation results, when the crack is expanded to 3mm, the induction voltage of the alternating induction coil group has 3 inflection points in total, and the monitoring accuracy is 1mm, so that the crack length at the moment is 3mm according to the inflection point number and the monitoring accuracy of the back and forth oscillation of the induction voltage of the alternating induction coil group and is consistent with the actual crack length.
The alternate induction type flexible eddy current array sensor of the embodiment of the invention can also be used for monitoring a porous structure, and when the porous structure is monitored, one alternate induction type flexible eddy current array sensor can be used for hole edge crack expansion monitoring of one hole, at the moment, a plurality of alternate induction type flexible eddy current array sensors corresponding to a plurality of holes are required to be connected in series, specifically, excitation coils 34 of the plurality of alternate induction type flexible eddy current array sensors are connected in series, specifically, the method comprises the following steps: for the first alternate induction type flexible vortex array sensor, the fourth bonding pad 4 is grounded, the third bonding pad 3 is connected with the core wire of the radio frequency wire, the second bonding pad 2 is connected with the third bonding pad 3 of the next alternate induction type flexible vortex array sensor, and the first bonding pad 1 is connected with the fourth bonding pad 4 of the next alternate induction type flexible vortex array sensor; for the middle alternate induction type flexible vortex array sensor, the third bonding pad 3 is connected with the second bonding pad 2 of the previous alternate induction type flexible vortex array sensor, the second bonding pad 2 is connected with the third bonding pad 3 of the next alternate induction type flexible vortex array sensor, the fourth bonding pad 4 is connected with the first bonding pad 1 of the previous alternate induction type flexible vortex array sensor, and the first bonding pad 1 is connected with the fourth bonding pad 4 of the next alternate induction type flexible vortex array sensor; for the last alternate induction type flexible eddy current array sensor, the second bonding pad 2 is connected with the first bonding pad 1 of the last alternate induction type flexible eddy current array sensor, and the third bonding pad 3 is connected with the second bonding pad 2 of the previous alternate induction type flexible eddy current array sensor.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims (10)
1. An alternating induction type flexible eddy current array sensor is characterized by comprising an exciting coil (34), wherein the exciting coil (34) is spirally arranged from inside to outside in the same plane, the exciting coil (34) is in a homodromous exciting layout, and
at least one alternating induction coil group, each alternating induction coil group is formed by sequentially connecting a plurality of induction coils in series, wherein:
the induction coils of each alternating induction coil group are sequentially arranged between two adjacent turns of coils of the excitation coil (34) from inside to outside along the spiral direction of the excitation coil (34), and the end parts of the first induction coil and the last induction coil of each alternating induction coil group are induction voltage output ends of the alternating induction coil group.
2. An alternating induction type flexible eddy current array sensor according to claim 1, wherein all induction coils of each alternating induction coil group are placed at a position on the left side of the middle of two adjacent turns of excitation coils or at a position on the right side of the middle of two adjacent turns of excitation coils;
the distance between two adjacent turns of the excitation coil (34) is equal to the required crack monitoring accuracy.
3. The sensor of claim 1, wherein when the induction coils of each of the alternating induction coil groups are connected in series, the voltage polarity of the connection end of the former induction coil is the same as the voltage polarity of the connection end of the latter induction coil connected with the former induction coil, and the voltage polarity refers to the positive electrode or the negative electrode.
4. An alternating induction type flexible eddy current array sensor according to claim 1, wherein two adjacent induction coils of each alternating induction coil group are connected by vias provided at connection ends thereof, and connection lines between the vias are provided at a top layer of the flexible substrate.
5. An alternating induction type flexible eddy current array sensor according to claim 4, wherein the top layer of the flexible substrate is further provided with a first bonding pad (1), a fourth bonding pad (4) and an induced voltage output port bonding pad, the first bonding pad (1) is connected with the fourth bonding pad (4), and two ends of each alternating induction coil group are respectively connected with the corresponding induced voltage output port bonding pad through a via hole arranged at the connecting end of each alternating induction coil group.
6. The alternating induction type flexible eddy current array sensor according to any one of claims 1 to 5, wherein the excitation coil (34) and all alternating induction coil groups are arranged on the bottom layer of the flexible substrate, the bottom layer of the flexible substrate refers to one side which is in contact with the monitoring structure, an excitation coil first through hole (11) is arranged at the end part of one turn of the excitation coil (34) located at the outermost side, an excitation coil second through hole (12) is arranged at the end part of one turn of the excitation coil (34) located at the innermost side, the excitation coil (34) is connected with the second bonding pad (2) through the excitation coil first through hole (11), the excitation coil (34) is connected with the third bonding pad (3) through the excitation coil second through hole (12), and the second bonding pad (2) and the third bonding pad (3) are connected with an excitation source.
7. The method for monitoring an alternating induction type flexible eddy current array sensor according to any one of claims 1 to 4, wherein the method comprises the following steps:
s1, determining the shape of an alternate induction type flexible vortex array sensor according to the shape of a monitored structure, determining the number and layout of alternate induction coil groups according to the stress direction and crack propagation direction of the monitored structure, determining the distance between two adjacent turns of an excitation coil (34) according to the required crack monitoring precision, and determining the number of turns of the excitation coil (34) and the number of induction coils of each alternate induction coil group according to the required crack length monitoring range;
s2, analyzing the stress concentration part of the monitored structure according to the stress direction of the monitored structure, and determining the setting position of the alternating induction type flexible vortex array sensor;
s3, monitoring the induction voltage of each alternating induction coil group of the alternating induction type flexible vortex array sensor in real time, and drawing an induction voltage curve of each alternating induction coil group;
and S4, judging whether inflection points oscillating back and forth exist in the induction voltage curve of each alternating induction coil group, if so, determining the position of the alternating induction coil group as the crack initiation position, and multiplying the crack monitoring precision by the number of the inflection points oscillating back and forth in the voltage in the induction voltage curve of each alternating induction coil group to determine the crack length monitored by each alternating induction coil group.
8. The method for monitoring an alternate induction type flexible eddy current array sensor according to claim 7, wherein in the step S1, if the hole structure is monitored, the alternate induction type flexible eddy current array sensor is configured to be circular, and two alternate induction coil sets are configured so that the two alternate induction coil sets are correspondingly positioned at left and right sides of the stress direction of the monitored hole structure; if the stress direction of the monitored hole structure is uncertain, a plurality of alternating induction coil groups are arranged and uniformly distributed on the periphery of the monitored hole structure.
9. The method according to claim 7, wherein in the step S1, if the weld structure is monitored, the alternate induction type flexible eddy current array sensor is rectangular in shape, and at least one alternate induction coil set is provided, and the at least one alternate induction coil set is provided along the length direction of the weld.
10. The method for monitoring the alternating induction type flexible eddy current array sensor according to claim 7, wherein the method is used for monitoring cracks of the porous structure, wherein when the crack is monitored on the porous structure, one alternating induction type flexible eddy current array sensor is correspondingly arranged in one hole, and a plurality of alternating induction type flexible eddy current array sensors corresponding to a plurality of holes are connected in series, specifically:
for the first alternate induction type flexible vortex array sensor, a fourth bonding pad (4) is grounded, a third bonding pad (3) is connected with a core wire of a radio frequency wire, a second bonding pad (2) is connected with a third bonding pad (3) of the next alternate induction type flexible vortex array sensor, and a first bonding pad (1) is connected with a fourth bonding pad (4) of the next alternate induction type flexible vortex array sensor; for the middle alternate induction type flexible vortex array sensor, connecting a third bonding pad (3) with a second bonding pad (2) of the previous alternate induction type flexible vortex array sensor, connecting the second bonding pad (2) with a third bonding pad (3) of the next alternate induction type flexible vortex array sensor, connecting a fourth bonding pad (4) with a first bonding pad (1) of the previous alternate induction type flexible vortex array sensor, and connecting the first bonding pad (1) with a fourth bonding pad (4) of the next alternate induction type flexible vortex array sensor; for the last alternate induction type flexible vortex array sensor, the second bonding pad (2) is connected with the first bonding pad (1) of the last alternate induction type flexible vortex array sensor, and the third bonding pad (3) is connected with the second bonding pad (2) of the previous alternate induction type flexible vortex array sensor.
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