CN113835047A - Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method - Google Patents

Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method Download PDF

Info

Publication number
CN113835047A
CN113835047A CN202110976412.9A CN202110976412A CN113835047A CN 113835047 A CN113835047 A CN 113835047A CN 202110976412 A CN202110976412 A CN 202110976412A CN 113835047 A CN113835047 A CN 113835047A
Authority
CN
China
Prior art keywords
cabin
transducer
port
frequency
impedance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110976412.9A
Other languages
Chinese (zh)
Other versions
CN113835047B (en
Inventor
谢楷
郭云冲
刘艳
权磊
吴必成
宋江文
谷恺恒
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xidian University
Original Assignee
Xidian University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xidian University filed Critical Xidian University
Priority to CN202110976412.9A priority Critical patent/CN113835047B/en
Publication of CN113835047A publication Critical patent/CN113835047A/en
Application granted granted Critical
Publication of CN113835047B publication Critical patent/CN113835047B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/74—Testing of fuses
    • 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
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/54—Testing for continuity

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

The invention discloses a metal wall-crossing embedded single-port passive burning loss sensing device and a monitoring and manufacturing method, wherein the device comprises a passive sensing system and a circuit monitoring system; the passive sensing system comprises a bulkhead composite structure, and a group of cabin interior energy converters and a group of cabin exterior energy converters are respectively arranged on the inner side and the outer side of a metal bulkhead; and the circuit monitoring system is used for transmitting an alternating current signal for exciting the energy converter in the cabin, monitoring the electrical complex impedance of the cabin wall composite structure seen from two electrodes of the energy converter in the cabin, obtaining the resonant frequency value of the cabin wall composite structure through measuring the impedance, and judging the on-off condition of the fusible link according to the deviation condition of the resonant frequency value. The invention only adopts a pair of transducers across the metal wall, wherein the transducer outside the cabin is connected with a metal fuse wire for sensing, and the transducer inside the cabin simultaneously completes two functions of excitation and monitoring, thereby simplifying the structure, avoiding the problems of energy crosstalk and resonance matching, and simultaneously reducing the installation difficulty and the manufacturing cost of the sensor.

Description

Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method
Technical Field
The invention belongs to the technical field of aircraft monitoring, and relates to a metal wall-crossing embedded single-port passive burning loss sensing device, monitoring and preparation methods.
Background
The heat-proof layer is used as a protective umbrella of the aircraft, and plays a role in effectively isolating the pneumatic high temperature outside the aircraft body from the interior of the aircraft body. Particularly, the heat-proof layer of the reusable aircraft has the potential safety hazards of burning loss, cracking, even falling off and the like under the impact of high temperature and pneumatic stress repeated for a long time and many times. Therefore, the monitoring of the burning state of the heat-proof layer is very important, for example, once damage is found, disasters can be avoided by means of track change, reentry posture adjustment and the like in time.
The measurable area of the aircraft is limited by the weight and the size of the aircraft, and the measurable areas of the infrared thermal imaging, the active acoustic flaw detection and other means are very limited; various passive sensors such as optical fiber temperature sensors and thermocouple sensors are embedded in the heat-proof layer, which is an effective means for solving large-area coverage monitoring, but a signal cable needs to be transmitted back to the interior of the cabin through the cabin wall, and the integrity of the cabin wall can be damaged by a large number of perforated structures, so that additional hidden dangers in the aspects of structure, strength and the like are brought.
The wireless passive sensor is a development direction of physical quantity monitoring in a severe environment, for example, a passive electrical resonance structure based on inductance, capacitance and the like is proposed in documents of wireless passive patch type temperature sensor based on microwave (DOI: 10.13250/j. cnki. wndz.2018.02.006), patent publication No. CN103698060A, patent publication No. CN109342460A and patent publication No. CN112378424A, and the LC resonance frequency of the passive electrical resonance structure can respond to changes of physical quantities such as temperature, pressure and cracks, and can couple resonance characteristic information to a wireless receiving end in an electromagnetic coupling mode, and physical parameters in the severe environment are obtained through analysis of the resonance frequency. However, these methods are limited to electromagnetic coupling, and can only be applied to penetrate through non-metal (e.g. composite) wall surfaces, and cannot be applied to the inside of a closed metal cabin body for monitoring burning loss of the heat-proof layer outside the cabin.
The document "wireless passive burnout sensing technology across an aircraft metal bulkhead" (DOI: 10.13435/j.cnki.ttc.003142) discloses a method for enabling passive sensing across a metal bulkhead, which is based on a combination of acoustic energy coupling and circuit fusing, and a sensing structure of "electro-acoustic conversion-electric sensing-electro-acoustic conversion" is constructed by using two pairs of piezoelectric transducers and fuse wires together. One pair of transducers completes the excitation function, and the other pair completes the signal monitoring function, so that the on-off state of the thermal protection layer embedded fuse outside the metal bulkhead is monitored. When the structure has the hidden troubles of overheating, mechanical damage, peeling and the like, the embedded fuse wire is broken and sensed, and the burning loss of the heat-proof structure is monitored.
In the process of implementing the invention, the inventor finds that the prior art has at least the following defects:
(1) two pairs of piezoelectric transducers may have energy crosstalk in the horizontal direction of the metal wall. This determines that a large distance needs to be maintained between the two pairs of transducers, otherwise mutual crosstalk in close proximity would seriously affect the decision margin and therefore cannot be mounted on a wall with a small space.
(2) The problem of resonance matching of two pairs of piezoelectric transducer structures. Because the resonance frequency band of the acoustoelectric material is narrow, the composite structure of the two pairs of transducers needs to have a common resonance frequency point to form an effective energy path. In practice, factors such as adhesive thickness difference, wall thickness difference of special-shaped parts, batch difference of transducers and the like can cause resonance point deviation of an acoustic structure, so that smooth flowing of energy is influenced, and higher requirements are brought to assembly precision and process precision.
(3) Both pairs of transducers require strict alignment which exacerbates installation difficulties and manufacturing costs.
Disclosure of Invention
In order to solve the problems, the invention provides a cross-metal wall embedded single-port passive burning loss sensing device, which only adopts a pair of cross-metal wall transducers, wherein the transducer outside a cabin is connected with a metal fuse wire for sensing, and the transducer inside the cabin simultaneously completes two functions of excitation and monitoring, thereby simplifying the structure, avoiding the problems of energy crosstalk and resonance matching, and reducing the installation difficulty and the manufacturing cost of the sensor.
Another object of the present invention is to provide a method for monitoring a single-port passive burn-in sensor embedded across a metal wall.
Another object of the present invention is to provide a method for manufacturing a cross-metal-wall embedded single-port passive burn-out sensing device.
Because the ports of the transducer in the cabin are excited and monitored at the same time, the excitation signal and the monitoring signal are aliased and have the same frequency and cannot be separated, and the judgment by adopting the traditional signal monitoring means is difficult. To achieve the above object, the present invention utilizes a new monitoring principle: the on-off of the metal fuse wire changes the secondary piezoelectric effect of the piezoelectric material, so that the elasticity compliance constant of the piezoelectric material is changed, and the electrical impedance of the system is changed; and judging the state of the metal fuse wire by monitoring and analyzing the change relation between the complex impedance of the port and the frequency.
The invention adopts the technical scheme that a cross-metal wall embedded single-port passive burning loss sensing device comprises a passive sensing system and a circuit monitoring system;
the passive sensing system comprises a bulkhead composite structure, wherein the bulkhead composite structure consists of an in-cabin transducer, a metal bulkhead, an out-cabin transducer and a fusible wire embedded in a heat-proof layer; the group of the energy converters inside the cabin and the energy converters outside the cabin are respectively arranged on the inner side and the outer side of the metal cabin wall and used for transmitting energy to the outside of the cabin through sound waves and reflecting sound wave signals carrying the on-off state of the melting wire back to the cabin;
the circuit monitoring system is used for transmitting alternating current signals for exciting the energy converter in the cabin, monitoring electrical complex impedance of the cabin wall composite structure seen from two electrodes of the energy converter in the cabin, obtaining a resonant frequency value of the cabin wall composite structure through measuring the impedance, and judging the on-off condition of the fusible link according to the deviation condition of the resonant frequency value.
Furthermore, the cabin interior transducer and the cabin exterior transducer are coaxial and can generate axial longitudinal waves, and the cabin interior transducer and the cabin exterior transducer have the same resonance frequency; two electrodes of the transducer outside the cabin are connected to two ends of the fuse wire, the heat-proof layer is arranged on the outer wall of the metal cabin wall, and the transducer outside the cabin is provided with a free mechanical boundary;
two electrodes of the transducer in the cabin are connected with a measuring port of the impedance measuring unit, an output end of the sweep frequency signal source is connected with an input end of the impedance measuring unit, and an output end of the impedance measuring unit is connected with an input end of the damage judging unit.
Furthermore, the circuit monitoring system comprises a sweep frequency signal source, an impedance measuring unit and a damage judging unit;
the output end of the sweep frequency signal source is connected with two electrodes of the transducer in the cabin, and the sweep frequency signal source is used for generating an alternating current signal for exciting the transducer in the cabin and providing a local reference signal with adjustable frequency for the impedance measuring unit; the frequency scanning range of the frequency scanning signal source covers the resonance frequency band of the bulkhead composite structure;
the impedance measuring unit is used for measuring the electrical complex impedance of the composite structure of the cabin wall seen from the two electrodes of the transducer in the cabin;
and the damage judgment unit is used for analyzing the result of the impedance measurement unit and judging the damage condition of the heat-proof layer.
Further, the impedance measuring unit includes an impedance calculating module, a power divider, and a directional coupler; alternating current signals generated by the sweep frequency signal source are separated by the power divider, incoming and outgoing components are used as reference signals and are transmitted to the impedance calculation module, the rest alternating current signals are applied to the transducer in the cabin through the directional coupler, reflected signals of the transducer in the cabin are transmitted to the impedance calculation module through the directional coupler, the impedance calculation module calculates the reflection coefficient of a port of the transducer in the cabin under the frequency point according to the two received signals, and then the electrical complex impedance of the port of the transducer in the cabin under the frequency point is calculated.
Further, the impedance measuring unit comprises an impedance calculating module, a port voltage sampling module and an inlet voltage sampling module; the output end of the sweep frequency signal source is connected with two electrodes of the transducer in the cabin, a known constant value resistor is connected in series between the sweep frequency signal source and the transducer in the cabin, an inlet voltage sampling module is connected at an inlet of the sweep frequency signal source, port voltage sampling modules are connected at the two electrode ports of the transducer in the cabin, and the electrical complex impedance of the port of the transducer in the cabin under the frequency point is calculated according to the voltage division ratio and the phase delay relation of the constant value resistor and the port resistor of the transducer in the cabin.
Further, the impedance measuring unit comprises an impedance calculating module, a port voltage sampling module and a port current sampling module; the output end of the sweep frequency signal source is connected with two electrodes of the transducer in the cabin, an alternating current signal of the sweep frequency signal source is directly applied to a port of the transducer in the cabin, port voltage sampling modules are connected to the two electrode ports of the transducer in the cabin, a port current sampling module is connected to a circuit between the sweep frequency signal source and the transducer in the cabin, voltage and current waveforms of the port of the transducer in the cabin are sampled simultaneously, and the electrical complex impedance of the port of the transducer in the cabin at the frequency point is calculated according to the amplitude and the phase of the voltage and the current waveforms.
Furthermore, a strain isolation pad is arranged between the metal bulkhead and the heat-proof layer, a mechanical isolation cover is embedded in the strain isolation pad and covers the outside of the extravehicular transducer, a gap is kept between the mechanical isolation cover and the extravehicular transducer without mechanical contact, so that the outer side of the extravehicular transducer is provided with a free mechanical boundary, the top surface of the mechanical isolation cover is provided with an opening, and a fuse wire penetrates through the opening and is connected with two electrodes of the extravehicular transducer.
Furthermore, the circuit monitoring system further comprises an alarm output unit, wherein the input end of the alarm output unit is connected with the output end of the damage judgment unit, and the alarm output unit is in signal connection with the flight control computer and is used for converting the judgment result into a signal form which can be identified and received by the flight control computer.
A monitoring method based on a cross-metal-wall embedded single-port passive burning loss sensing device is specifically carried out according to the following steps:
step 1: sweeping frequency in a main resonance frequency point +/-10-20% of a bandwidth of an acoustic composite structure through a sweep frequency signal source in a circuit monitoring system, and recording the sweep frequency asf 1…f nAt a frequency interval off w，f wTaking 1/50-1/100 frequency sweep bandwidth; setting a frequency offset threshold value to be delta F, and taking 1/10-1/40 of the sweep frequency bandwidth;
step 2: in the frequency sweeping process, measuring the electrical complex impedance of the port of the transducer in the cabin at each frequency pointZ 1…Zn；
And step 3: finding a plurality of frequency points corresponding to the local minimum value of the absolute value of the argument of the complex impedance in the step 2, measuring for many times, and storing;
and 4, step 4: finding the peak frequency point of the complex impedance module value and the peak frequency point of the absolute value of the real part of the complex impedance, measuring for many times, and storing;
and 5: and (4) comparing the frequency point obtained in the step (3) or the peak frequency point obtained in the step (4) of the current measurement with the corresponding frequency points stored in previous measurements to obtain a difference absolute value, comparing the difference absolute value with a frequency deviation threshold value delta F, obtaining the current electrical state of the fuse wire according to the comparison result, and further judging the health or burning state of the heat-proof layer at the embedding part of the fuse wire.
A preparation method based on a cross-metal-wall embedded single-port passive burning loss sensing device is specifically carried out according to the following steps:
step A: selecting a conductive material to manufacture a fuse wire, embedding the fuse wire in a raw material for preparing a heat-proof layer in a snake-shaped bent configuration, covering the raw material in an area needing to be monitored, and simultaneously leading out two ends of the fuse wire;
and B: integrally processing the raw material of the heat-proof layer embedded with the fuse wire, forming a composite heat-proof layer, and exposing the leads at two ends of the fuse wire;
and C: an in-cabin transducer and an out-cabin transducer are respectively arranged on the inner side and the outer side of the metal bulkhead;
step D: assembling the metal cabin wall provided with the cabin interior transducer and the cabin exterior transducer and the heat-proof layer to form a cabin wall composite structure, wherein lead wires at two ends of the fuse wire are connected with a positive electrode and a negative electrode of the cabin exterior transducer;
step E: and manufacturing a circuit monitoring system with corresponding functions, and connecting a monitoring end of the circuit monitoring system with the transducer in the cabin to obtain the circuit monitoring system.
The invention has the beneficial effects that: according to the invention, holes do not need to be formed in the metal bulkhead of the aircraft, and the health states of structures such as the heat-proof layer on the outer side of the bulkhead are wirelessly and passively sensed, such as health hidden dangers of abnormal ablation, structural damage, peeling and the like of the heat-proof layer; the device has the advantages of real-time monitoring in a flying state, wireless passive monitoring across a metal wall, no monitoring dead angle for the abnormal-shaped convex structures such as flanges and control surfaces and the like, and also has the following advantages:
1. the problem of horizontal crosstalk is fundamentally eliminated; the decision margin is not affected by the energy crosstalk caused by the two pairs of piezoelectric transducers in the horizontal direction of the metal wall.
2. The problem of resonant frequency matching is avoided. The transmitting and receiving share the same pair of composite structures of transducer-metal wall-transducer, and the transmitting and receiving are carried out simultaneously in time without strict control of two pairs of resonant frequencies and strict correspondence of the thickness of an adhesive and the embedding depth of the transducer in the two pairs of composite structures.
3. The structure is simpler, and the installation difficulty and the preparation cost are reduced. A pair (two) of piezoelectric transducers is omitted, the cost is lower, and multi-point alignment is not needed.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural view of embodiment 1 of the present invention.
Fig. 2a is a schematic structural diagram of embodiment 2 of the present invention.
Fig. 2b is a schematic structural diagram of embodiment 3 of the present invention.
Fig. 2c is a schematic structural diagram of embodiment 3 of the present invention.
Fig. 3a is a diagram illustrating the operation of the fuse according to the embodiment of the present invention.
Fig. 3b illustrates the operation of fuse blowing according to an embodiment of the present invention.
Fig. 4 is a flow chart of the operation of an embodiment of the present invention.
FIG. 5 is a flow chart of a method of making an embodiment of the present invention.
In the figure, 1, a passive sensing system, 11, a metal bulkhead, 12, an in-cabin transducer, 13, a fusible link, 14, a heat protection layer, 15, a mechanical isolation cover, 16, an out-cabin transducer, 2, a circuit monitoring system, 21, an impedance measuring unit, 22, a damage judging unit, 23, a sweep frequency signal source, 24, an alarm output unit, 25, a flight control computer, 26, a strain isolation pad, 27, an impedance calculating module, 28, a power divider, 29, a directional coupler, 30, a port voltage sampling module, 31, an inlet voltage sampling module and 32, a port current sampling module are arranged.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the case of the example 1, the following examples are given,
a cross-metal-wall-embedded single-port-based passive burning loss sensing device is shown in figure 1 and comprises a passive sensing system 1 and a circuit monitoring system 2.
The passive sensing system 1 comprises a bulkhead composite structure, wherein the bulkhead composite structure consists of an in-cabin transducer 12, a metal bulkhead 11, an out-cabin transducer 16 and a fusible link 13 embedded in a heat-proof layer 14; a group of in-cabin transducers 12 and an out-cabin transducer 16 are respectively arranged on the inner side and the outer side of the metal cabin wall 11, and are used for transmitting energy to the outside of the cabin through the metal cabin wall 11 by sound waves and reflecting sound wave signals carrying the on-off state of the fusible link 13 back to the inside of the cabin.
The cabin interior transducer 12 is adhered to the inner side of the metal cabin wall 11, the cabin exterior transducer 16 is adhered to the outer side of the metal cabin wall 11, the cabin interior transducer 12 and the cabin exterior transducer 16 are coaxial and can generate axial longitudinal waves, and the cabin interior transducer 12 and the cabin exterior transducer 16 have the same resonance frequency; two electrodes of the outdoor transducer 16 are connected to two ends of the fusible link 13, the heat-proof layer 14 is arranged on the outer wall of the metal bulkhead 11, and the outdoor transducer 16 has a free mechanical boundary.
And the circuit monitoring system 2 is used for transmitting alternating current signals of the transducer 12 in the excitation cabin, monitoring electrical complex impedance of a composite structure of the cabin wall seen from two electrodes of the transducer 12 in the cabin, ensuring that the frequencies for transmitting and monitoring are the same at the same time, and realizing the separation of transmitted waves and reflected waves through impedance monitoring.
The circuit monitoring system 2 comprises a sweep frequency signal source 23, an impedance measuring unit 21, a damage judging unit 22 and an alarm output unit 24;
the output end of the sweep frequency signal source 23 is connected with two electrodes of the transducer 12 in the cabin, and the sweep frequency signal source 23 is used for generating an alternating current signal for exciting the transducer 12 in the cabin and providing a local reference signal with adjustable frequency for the impedance measuring unit 21; the frequency sweep range of the sweep signal source 23 covers the resonance frequency band of the bulkhead composite structure, and the sweep signal source 23 is composed of a direct frequency synthesizer (DDS), a Voltage Controlled Oscillator (VCO), a filter and a signal amplifier.
And an impedance measuring unit 21 for measuring the electrical complex impedance of the composite structure seen from the two electrodes of the cabin transducer 12 into the cabin wall.
A damage determination unit 22, configured to analyze a result of the impedance measurement unit 21, and determine a damage condition of the heat protection layer 14 according to the damage determination method described in embodiment 5; the function of the damage determination unit 22 may be performed by a separate microprocessor, or may be a part of the software function of the flight control computer 25.
The input end of the warning output unit 24 is connected with the output end of the damage judgment unit 22, and the warning output unit 24 is in signal connection with the flight control computer 25 and is used for converting the judgment result into a signal form which can be identified and received by the flight control computer 25; according to actual requirements, the output of the photoelectric coupler, the differential data bus interface, the 1553B bus interface or the relay dry contact can be adopted.
The positive electrode and the negative electrode of the output end of the sweep frequency signal source 23 are connected with two electrodes of the transducer 12 in the cabin through leads, and the sweep frequency signal source 23 is used for generating a high-frequency alternating current signal required by exciting the transducer 12 in the cabin and providing a local reference signal with adjustable frequency for the subsequent impedance measurement unit 21; two electrodes of the in-cabin transducer 12 are connected to a measurement port of the impedance measurement unit 21, an output end of the sweep frequency signal source 23 is connected to an input end of the impedance measurement unit 21, an output end of the impedance measurement unit 21 is connected to an input end of the damage judgment unit 22, and output information of the warning output unit 24 is connected to the flight control computer 25 in the form of switching value, data bus, and the like.
The impedance measuring unit 21 may be configured by, but not limited to, the following three schemes:
in the case of the example 2, the following examples are given,
as shown in fig. 2a, the impedance measuring unit 21 includes an impedance calculating module 27, a power divider 28, and a directional coupler 29; alternating current signals generated by the sweep frequency signal source 23 are separated by the power divider 28 into incident and outgoing components as reference signals and are transmitted to the impedance calculation module 27, the rest alternating current signals are applied to the transducer 12 in the cabin through the directional coupler 29, reflected signals of the transducer 12 in the cabin are transmitted to the impedance calculation module 27 through the directional coupler 29, the impedance calculation module 27 calculates the reflection coefficient S11 of the port of the transducer 12 in the cabin at the frequency point according to the two received signals, and then calculates the electrical complex impedance of the port of the transducer 12 in the cabin at the frequency pointZ 1I.e. the above-mentioned electrical complex impedance looking into the cabin wall composite structure from both electrodes of the in-cabin transducer 12.
The output of the signal by the sweep frequency signal source 23 and the impedance monitoring by the impedance measuring unit 21 are performed simultaneously, and the frequencies used by the two are the same, that is, the incident component and the reflected component are obtained simultaneously, and the port impedance can be calculated in real time according to the two components.
In the case of the example 3, the following examples are given,
as shown in FIG. 2b, the impedance measuring unit 21 comprises an impedance calculating module 27, a port voltage sampling module 30, and an inlet voltage sampling module31; the output end of a sweep frequency signal source 23 is connected with two electrodes of an in-cabin transducer 12, a known constant value resistor is connected in series between the sweep frequency signal source 23 and the in-cabin transducer 12, an inlet voltage sampling module 31 is connected at an inlet of the sweep frequency signal source 23, port ports of the two electrodes of the in-cabin transducer 12 are connected with a port voltage sampling module 30, and the electrical complex impedance of a port of the in-cabin transducer 12 at the frequency point is calculated according to the voltage division proportion and the phase delay relation of the constant value resistor and the port resistor of the in-cabin transducer 12Z 1。
In the case of the example 4, the following examples are given,
as shown in fig. 2c, the impedance measuring unit 21 includes an impedance calculating module 27, a port voltage sampling module 30, and a port current sampling module 32; the output end of the sweep frequency signal source 23 is connected with two electrodes of the transducer 12 in the cabin, the alternating current signal of the sweep frequency signal source 23 is directly applied to the port of the transducer 12 in the cabin, the port voltage sampling module 30 is connected with the two electrode ports of the transducer 12 in the cabin, the port current sampling module 32 is connected on the circuit between the sweep frequency signal source 23 and the transducer 12 in the cabin, the voltage and current waveforms of the port of the transducer 12 in the cabin are sampled at the same time, and the electrical complex impedance of the port of the transducer 12 in the cabin under the frequency point is calculated according to the amplitude and the phase of the voltage and the current waveformsZ 1。
The sampling and impedance calculations of embodiments 2-4 can be performed by separate ADCs and microprocessors, or by using spare analog channels and computational resources of flight control computer 25.
The circuit monitoring system 2 of the embodiment of the invention realizes simultaneous emission and monitoring, and the frequencies for emission and monitoring at the same time are the same.
In some embodiments, a strain isolation pad 26 is disposed between the metal bulkhead 11 and the heat-proof layer 14, a mechanical isolation cover 15 is embedded inside the strain isolation pad 26, the mechanical isolation cover 15 covers the outside of the outboard transducer 16, and a gap is maintained between the mechanical isolation cover 15 and the outboard transducer 16 without mechanical contact, so as to mechanically isolate the outboard transducer 16 from the heat-proof layer 14, so that the outside of the outboard transducer 16 has a free mechanical boundary, and prevent other materials from contacting the outboard transducer 16 to cause the resonance frequency to change; the mechanical isolation cover 15 has an opening on its top surface through which the fuse wire 13 passes to connect with the two electrodes of the extravehicular transducer 16.
In some embodiments, the cabin interior transducer 12 and the cabin exterior transducer 16 are piezoelectric transducers, such as lead zirconate titanate (PZT), lithium niobate, etc., and the two piezoelectric transducers are attached to the inner side and the outer side of the metal cabin wall 11 in a manner of overlapping the axes, so as to form a composite structure of electrical/acoustic energy conversion and cross-cabin transmission.
In some embodiments, lead zirconate titanate piezoelectric ceramic (PZT-8) with a diameter of 20mm, a thickness of 2mm and a resonant frequency of 1.7MHz is used for the in-cabin transducer 12 and the out-cabin transducer 16. The cabin interior transducer 12 and the cabin exterior transducer 16 are correspondingly adhered to the inner side and the outer side of the metal cabin wall 11 by means of epoxy resin AB glue axes to form a composite structure of electricity/sound energy conversion and cross-cabin transmission together, and the composite structure has the functions of transmitting energy to the outside of the cabin through metal crossing by sound waves and reflecting and transmitting sound wave signals carrying fuse wire states back to the inside of the cabin.
In some embodiments, the fuse wire 13 is connected between two electrodes of the extravehicular transducer 16, embedded in the heat-proof layer 14, for sensing damage of the heat-proof layer 14 caused by local aerodynamic high temperature, the fuse wire 13 being capable of conducting electricity and having a high melting point; the melting point is generally above 1000 ℃, and metal filaments such as copper wires and nickel wires are preferred, the melting point of copper is 1083 ℃, and the melting point of nickel is 1453 ℃; the melt wire 13 is arranged in a serpentine shape to cover the area to be monitored for burn-out. The heat-proof layer 14 is made of composite materials, the diameter of the fuse wire 13 is consistent with that of carbon fibers or quartz fibers used in the heat-proof layer 14 (about 0.03-0.1 mm), and the heat-proof layer has good process compatibility and material consistency.
The working principle and the monitoring process of the embodiment of the invention are as follows:
as shown in fig. 3a, when the heat protective layer 14 is not damaged: since the fusible link 13 is connected (intact), the extravehicular transducer 16 (a 2) is in an electrical short circuit state, although the extravehicular transducer 16 is excited by the vibration of the extravehicular transducer 12 (a 1), the extravehicular transducer 16 is short-circuited between two poles, and no charge can be accumulated on the surface, the internal electric field E is constantly equal to 0, at this time, the vibration excitation of the extravehicular transducer 12 only can make the extravehicular transducer 16 generate elastic deformation, and does not cause additional secondary piezoelectric effect through the internal electric field E, i.e. no additional piezoelectric deformation, and the equivalent elastic compliance constant of the extravehicular transducer 16 is higher in this state.
As shown in fig. 3b, if the heat shield 14 is damaged: external high-speed and high-temperature pneumatic heat flows into damaged gaps of the heat-proof layer 14, so that the fusible link 13 is broken (blown), the tail end of the outdoor transducer 16 (A2) is in an electrical open circuit state, charge accumulation generated between two electrodes of the outdoor transducer 16 under the vibration excitation of the indoor transducer 12 (A1) cannot be released, an electric field E is generated inside the outdoor transducer 16, the outdoor transducer 16 generates additional piezoelectric deformation due to a secondary piezoelectric effect caused by the electric field E, and the equivalent elastic compliance constant of the outdoor transducer 16 in the state is reduced.
Therefore, when the fuse wire 13 is blown from the connection, that is, the end of the outdoor transducer 16 is short-circuited to the open circuit, the compliance constant of the elasticity of the outdoor transducer 16 is instantaneously reduced, which causes an increase in the wave speed in the outdoor transducer 16, thereby causing a change in the overall resonance frequency, a change in the reflection impedance, a phase advance of the echo, and the like of the "transducer-metal wall-transducer" composite structure. Because the cabin interior transducer 12 and the cabin exterior transducer 16 are coaxial and can generate axial longitudinal waves, the cabin interior transducer 12 and the cabin exterior transducer 16 have the same resonance frequency and high mechanical coupling degree, and therefore, the change of the composite structure parameters can be reflected on the port of the cabin interior transducer 12. By monitoring and analyzing the change condition of the complex impedance between the two electrodes of the transducer 12 in the cabin, the state change before and after the thermal protection layer 14 is damaged can be effectively found, and a safety warning can be timely sent out after the thermal protection layer 14 is damaged.
In some embodiments, as shown in FIG. 4, the swept signal source 23 comprises a quartz crystal oscillator ECS-500-8-47Q-CES-TR, a high speed DAC chip DAC2932, an active filter LT1567CMS8, and an amplifier LT 1210R; the quartz crystal oscillator provides an accurate clock for the microcontroller STM32F765, the microcontroller and the DAC chip generate small-power step-shaped signals, the small-power step-shaped signals are filtered by the active filter to obtain smooth high-frequency alternating-current signals, the signals are amplified to high-power signals which are enough to excite the passive sensing system 1 through the amplifier, and meanwhile, local reference signals with adjustable frequency are provided for the impedance measuring unit 21.
The impedance measuring unit 21 includes a 50 Ω constant value resistor, a follower (made of LT 1210R), an amplifier (made of LT 1210R), and a high-speed ADC chip THS 10082; the 50 omega constant value resistor is connected with the transducer 12 in the cabin in series and used for dividing alternating current signals sent by the sweep frequency signal source 23, complex voltages at two ends of the 50 omega constant value resistor are completely extracted by the follower, are amplified by the amplifier and then enter the ADC chip for analog-to-digital conversion, and are transmitted to the microcontroller STM32F765, and the microcontroller measures complex impedances at two ends of the transducer 12 in the cabin by using the alternating current signals generated by the sweep frequency signal source 23 and the complex voltages at two ends of the 50 omega constant value resistor according to a resistance voltage division principle. The follower measures the voltage across the constant resistor, which is equal to the inlet voltage minus the port voltage, and the inlet voltage sampling module 31 is omitted from fig. 4.
The damage decision unit 22 is done internally by the microcontroller STM32F765 for analyzing the results of the impedance measurement unit 21 after each frequency sweep and impedance measurement.
The warning output unit 24 is internally completed by the microcontroller STM32F765, and is configured to output the decision result in the form of differential data.
The connection relationship of each part is as follows: the output end (amplifier LT 1210R) of the sweep frequency signal source 23 is connected with the input end (50 omega constant value resistance) of the impedance measuring unit 21; the measurement port of the impedance measurement unit 21 is connected with the cabin transducer 12 in the passive sensing system 1; the output end of the impedance measuring unit 21 is connected with the input end of the damage judging unit 22, and the connection between the output end of the damage judging unit 22 and the input end of the warning output unit 24 is performed inside the microcontroller STM32F 765.
The working flow of the whole device is as follows:
the microcontroller STM32F765 controls the sweep frequency signal source 23 to output a sweep frequency signal, the sweep frequency signal is applied to two electrodes of the transducer 12 in the cabin as an incident alternating current signal after power amplification, due to the existence of inverse piezoelectric effect, acoustic longitudinal waves in the normal direction are generated in the transducer 12 in the cabin, the acoustic longitudinal waves vibrate along the thickness direction of the transducer, the acoustic longitudinal waves penetrate through the metal cabin wall 11 and are transmitted to the interior of the transducer 16 outside the cabin and are reflected at the outer side boundary, reflected waves penetrate through the metal cabin wall 11 again and are transmitted to the interior of the transducer 12 in the cabin, reflected alternating current signals are generated on two sides of the transducer 12 in the cabin through positive piezoelectric effect, and the microcontroller STM32F765 calculates the electrical complex impedance of the passive sensing system 1 seen from the transducer 12 in the cabin according to the relationship between the incident alternating current signal and the reflected alternating current signal. If the heat-proof layer 14 is damaged, external high-speed and high-temperature aerodynamic heat flow can flow into a damaged gap of the heat-proof layer 14, so that the fuse wire 13 is broken, the two electrodes of the extravehicular transducer 16 are in an electrical open circuit state, charges begin to accumulate on the electrodes, an electric field E inside the extravehicular transducer 16 is changed from zero to nonzero, and the extravehicular transducer 16 generates additional piezoelectric deformation due to a secondary piezoelectric effect caused by the electric field E, so that the equivalent elastic compliance constant of the extravehicular transducer 16 is instantly reduced, the wave velocity in the extravehicular transducer 16 is increased, and the peak frequency point of the electrical complex impedance of the passive sensing system 1 seen between the two electrodes of the extravehicular transducer 12 is integrally raised. The phenomenon of the complex impedance peak frequency point rising is calculated by a judgment damage unit in the microcontroller. And finally, judging the burning degree and the burning position of the heat-proof layer by the microcontroller according to the position where the fuse wire is embedded, and outputting the burning degree and the burning position through a differential data bus.
The embodiment of the invention monitors the change of the electro-acoustic conversion characteristic by using the secondary piezoelectric effect, monitors the integral drift of the system resonance frequency point caused by the breakage of the metal wire, monitors the frequency, does not damage an energy reflection path, and only changes the energy transmission characteristic. Compared with the prior art for monitoring the voltage gain change caused by the breakage of the metal wire, the embodiment of the invention does not need to specially design the shape of the transducer, and the transducer is square, circular and triangular, and only needs to be flat at two ends and can generate longitudinal waves in the thickness direction.
In the case of the example 5, the following examples were conducted,
a monitoring method based on a metal wall-crossing embedded single-port passive burning loss sensing device obtains a resonant frequency value of a bulkhead composite structure through impedance measurement, judges the on-off condition of a fusible link line 13 according to the deviation condition of the resonant frequency value, and specifically comprises the following steps:
step 1: the frequency sweeping signal source 23 is used for sweeping frequency in the bandwidth near the main resonance frequency point (plus or minus 10-20%) of the acoustic composite structure, and the frequency sweeping frequency is recorded asf 1…f nAt a frequency interval off w，f wGenerally, about 1/50-1/100 of frequency sweep bandwidth is selected; setting a frequency offset threshold to Δ F (Δ F)>0) And delta F is generally selected from 1/10-1/40 of the sweep bandwidth.
Step 2: in the process of frequency sweeping, the impedance measurement unit 21 is used for measuring the electrical complex impedance of the port of the transducer 12 in the cabin at each frequency pointZ 1…Zn。
And step 3: finding a plurality of frequency points corresponding to the local minimum value of the absolute value of the argument of the complex impedance in the step 2, measuring for a plurality of times, and storing;
step 3.1: taking out each complex impedance argument phi in the step 2j=arctan[Im(Zj)/Re(Zj)]Is recorded as phi1… φn(ii) a Im is the imaginary symbol, Im (Z)j) Represents ZjRe is the imaginary sign, Re (Z)j) Represents ZjThe real part of (a);
step 3.2: taking the absolute value of the argument of the complex impedance in step 3.1 and recording the absolute value as | phi1|…| φn|；
Step 3.3: find all local minima points in step 3.2, i.e. satisfy | φj|<|φj-1I and i phij|<|φj+1|；
Step 3.4: find the minimum number m of points in step 3.3, and the corresponding frequencyf p1…f pm；
Step 3.5: storing the argument minimum frequency obtained in step 3.4, and recording asf p1k…f pmkK is the serial number of the measurement times,f p1k…f pmkindicating the k time of storagef p1…f pmEach measurement will result in a setf p1…f pm。
And 4, step 4: searching out a peak frequency point of a complex impedance module value and a peak frequency point of an absolute value of a real part of complex impedance, measuring for many times, and storing;
step 4.1: obtaining each complex impedance module value in the step 2 and recording as | Z1|…|Zn|；
Step 4.2: according to Rj=|Re(Zj) I, obtaining absolute values of real parts of the complex impedances in the step 2 and recording the absolute values as R1…Rn；
Step 4.3: finding out the peak values of the complex impedance module value in step 4.1, i.e. satisfying | Zj|>|Zj-1And Zj|>|Zj+1|；
Step 4.4: finding out each peak value of the absolute value of the real part of the complex impedance in step 4.2, namely, satisfying Rj>Rj-1And R isj>Rj+1；
Step 4.5: find out the number s of the peak values of each complex impedance modulus in step 4.3, and the corresponding frequencyf a1…f as；
Step 4.6: finding out the number h of the absolute value peaks of the real part of each complex impedance in step 4.4 and the corresponding frequencyf r1…f rh；
Step 4.7: storing the frequency corresponding to the peak value of the complex impedance modulus obtained in step 4.5, and recording the frequency asf a1k…f askK is the serial number of the measurement times,f a1k…f askindicating the k-th time of storagef a1…f asEach measurement will result in a setf a1…f as；
Step 4.8: storing the frequency corresponding to the absolute peak value of the real part of the complex impedance obtained in the step 4.6, and recording the frequency asf r1k…f rhkK is the serial number of the measurement times;f r1k…f rhkindicating the k-th time of storagef r1…f rhEach measurement will result in a setf r1…f rh。
And 5: the frequency point obtained from the step 3 in the current measurement (kth time)f p1k…f pmkAnd the frequency (frequency point) corresponding to the peak value of the complex impedance modulus obtained in step 4f a1k…f ask、f r1k…f rhkAnd comparing the current electrical state of the fuse wire 13 with the frequency points measured and stored in the previous times to obtain the current electrical state of the fuse wire 13, and further judging the health/burning state of the heat-proof layer 14 at the embedded part of the fuse wire 13.
Based on the decision result of step 5, the health/burn-out state of the heat-protective layer 14 is transmitted to the warning output unit 24, and the actions of step 1 to step 5 are repeated.
In the case of the example 6, it is shown,
step 5 was specifically performed according to the following steps, with the rest of the steps being the same as in example 5;
step 5.1: the frequency point corresponding to the local minimum value of the absolute value of the complex impedance argument obtained in the step 3f p1k…f pmkFrequency points respectively stored with previous g timesf p1k-1…f pmk-1、f p1k-2…f pmk-2、……、f p1k-g…f pmk-gDifference is made to obtain Deltaf p1k,k-1…Δf pmk,k-1、Δf p1k,k-2…Δf pmk,k-2、……、Δf p1k,k-g…Δf pmk,k-g；
Step 5.2: from the frequency difference obtained in step 5.1, the absolute value is calculated and recorded as | Δ |f p1k,k-1|…|Δf pmk,k-1|、|Δf p1k,k-2|…|Δf pmk,k-2|、……、|Δf p1k,k-g|…|Δf pmk,k-g|；
Step 5.3: absolute value | Δ of all frequency differences obtained in step 5.2f p1k,k-1|…|Δf pmk,k-1|、|Δf p1k,k-2|…|Δf pmk,k-2|、……、|Δf p1k,k-g|…|Δf pmk,k-gComparing the magnitude of | with a frequency offset threshold value delta F;
step 5.4: decision 5.3 of the comparison result, if | Δ |f p1k,k-1|…|Δf pmk,k-1|、|Δf p1k,k-2|…|Δf pmk,k-2|、……、|Δf p1k,k-g|…|Δf pmk,k-gIf the number of more than 60% in |, is more than the frequency deviation threshold value delta F, the fuse wire 13 is fused, the heat-proof layer 14 is burnt, and the step 5.5 is carried out; otherwise, the fuse wire 13 is normally communicated, and the heat-proof layer 14 is healthy;
step 5.5: and evaluating the burning loss of the heat-proof layer 14 according to the position and the depth of the embedded fuse wire 13 to obtain the serious condition and the position information of the burning loss of the heat-proof layer 14.
In the case of the example 7, the following examples are given,
step 5 was specifically performed according to the following steps, with the rest of the steps being the same as in example 5;
step 5.1: the peak value of the complex impedance modulus value obtained in the step 4 is subjected to frequency pointf a1k…f askFrequency points respectively stored with previous g timesf a1k-1…f ask-1、f a1k-2…f ask-2、……、f a1k-g…f ask-gDifference is made to obtain Deltaf a1k,k-1…Δf ask,k-1、Δf a1k,k-2…Δf ask,k-2、……、Δf a1k,k-g…Δf ask,k-g；
Step 5.2: from the frequency difference obtained in step 5.1, the absolute value is calculated and recorded as | Δ |f a1k,k-1|…|Δf ask,k-1|、|Δf a1k,k-2|…|Δf ask,k-2|、……、|Δf a1k,k-g|…|Δf ask,k-g|；
Step 5.3: absolute value | Δ of all frequency differences obtained in step 5.2f a1k,k-1|…|Δf ask,k-1|、|Δf a1k,k-2|…|Δf ask,k-2|、……、|Δf a1k,k-g|…|Δf ask,k-gComparing the magnitude of | with a frequency offset threshold value delta F;
step 5.4: decision 5.3 of the comparison result, if | Δ |f a1k,k-1|…|Δf ask,k-1|、|Δf a1k,k-2|…|Δf ask,k-2|、……、|Δf a1k,k-g|…|Δf ask,k-gIf the number of more than 60% in |, is more than the frequency deviation threshold value delta F, the fuse wire 13 is fused, the heat-proof layer 14 is burnt, and the step 5.5 is carried out; otherwise, the fuse wire 13 is normally communicated, and the heat-proof layer 14 is healthy;
step 5.5: and evaluating the burning loss of the heat-proof layer 14 according to the position and the depth of the embedded fuse wire 13 to obtain the serious condition and the position information of the burning loss of the heat-proof layer 14.
In the case of the example 8, the following examples are given,
step 5 was specifically performed according to the following steps, with the rest of the steps being the same as in example 5;
step 5.1: the peak frequency point of the absolute value of the real part of the complex impedance obtained in the step 4f r1k…f rhkFrequency points respectively stored with previous g timesf r1k-1…f rhk-1、f r1k-2…f rhk-2、……、f r1k-g…f rhk-gDifference is made to obtain Deltaf r1k,k-1…Δf rhk,k-1、Δf r1k,k-2…Δf rhk,k-2、……、Δf r1k,k-g…Δf rhk,k-g；
Step 5.2: from the frequency difference obtained in step 5.1, the absolute value is calculated and recorded as | Δ |f r1k,k-1|…|Δf rhk,k-1|、|Δf r1k,k-2|…|Δf rhk,k-2|、……、|Δf r1k,k-g|…|Δf rhk,k-g|；
Step 5.3: absolute value | Δ of all frequency differences obtained in step 5.2f r1k,k-1|…|Δf rhk,k-1|、|Δf r1k,k-2|…|Δf rhk,k-2|、……、|Δf r1k,k-g|…|Δf rhk,k-gComparing the magnitude of | with a frequency offset threshold value delta F;
step 5.4: decision 5.3 of the comparison result, if | Δ |f r1k,k-1|…|Δf rhk,k-1|、|Δf r1k,k-2|…|Δf rhk,k-2|、……、|Δf r1k,k-g|…|Δf rhk,k-gIf the number of more than 60% in |, is more than the frequency deviation threshold value delta F, the fuse wire 13 is fused, the heat-proof layer 14 is burnt, and the step 5.5 is carried out; otherwise, the fuse wire 13 is normally communicated, and the heat-proof layer 14 is healthy;
step 5.5: and evaluating the burning loss of the heat-proof layer 14 according to the position and the depth of the embedded fuse wire 13 to obtain the serious condition and the position information of the burning loss of the heat-proof layer 14.
In the case of the example 9, the following examples are given,
the specific steps of making the damage judgment inside the microcontroller STM32F765 are as follows:
step (1): sweeping frequency at the frequency interval of 4KHz between 1.7MHz and 2.1MHz by using a sweep frequency signal source; setting a frequency offset threshold value delta F =20 KHz;
step (2): in the frequency sweeping process, the electrical complex impedance of the port of the transducer 12 in the measuring cabin at each frequency point is measuredZ 1…Z100；
And (3): taking out each complex impedance module value in the step (2) and recording as | Z1|…|Z100|；
And (4): finding out each peak value of the complex impedance module value in the step (3), namely satisfying | Zj|>|Zj-1And Zj|>|Zj+1|；
And (5): finding out the number s of the peak values of each complex impedance module value in the step (4) and the corresponding frequencyf a1…f as
And (6): the frequency corresponding to the peak value of the complex impedance modulus obtained in the step (5)f a1…f asStore it asf a1k…f askK is the serial number of the measurement times;
and (7): will step withThe peak frequency point of the complex impedance modulus stored in the step (6)f a1k…f askFrequency points respectively stored with previous 3 timesf a1k-1…f ask-1、f a1k-2…f ask-2、f a1k-3…f ask-3Difference is made to obtain Deltaf a1k,k-1…Δf ask,k-1、Δf a1k,k-2…Δf ask,k-2、Δf a1k,k-3…Δf ask,k-3；
And (8): calculating the absolute value of the frequency difference obtained in the step (7) and recording the absolute value as | deltaf a1k,k-1|…|Δf ask,k-1|、|Δf a1k,k-2|…|Δf ask,k-2|、|Δf a1k,k-3|…|Δf ask,k-3|；
And (9): absolute value | Delta of all frequency differences acquired in step (8)f a1k,k-1|…|Δf ask,k-1|、|Δf a1k,k-2|…|Δf ask,k-2|、|Δf a1k,k-3|…|Δf ask,k-3Comparing the magnitude of | with a frequency offset threshold value delta F;
step (10): determining the comparison result of step (9) if | Δ |f a1k,k-1|…|Δf ask,k-1|、|Δf a1k,k-2|…|Δf ask,k-2|、|Δf a1k,k-3|…|Δf ask,k-3If the quantity of more than 60% in |, is more than the frequency deviation threshold value delta F, the fuse wire 13 is fused, the heat-proof layer 14 is burnt, and the step (11) is carried out; otherwise, the fuse wire 13 is normally communicated, the heat-proof layer 14 is healthy, and the step (12) is carried out;
step (11): evaluating the burning loss of the heat-proof layer 14 according to the position and the depth of the embedded fuse wire 13 to obtain the serious condition and the position information of the burning loss of the heat-proof layer 14, and turning to the step (12);
step (12): transmitting the health/burn-out status of the heat-protective layer to a warning output unit;
and (3) repeating the steps (1) to (12).
In the light of the above example 10,
a preparation method of a metal wall embedded single-port passive burning loss sensing device, as shown in fig. 5, specifically comprises the following steps:
step A: the fuse wire 13 is made of a conductive material with a high melting point, the fuse wire 13 is embedded in a raw material for preparing the heat-proof layer 14 in a snake-shaped bent configuration and covers an area needing to be monitored, meanwhile, two ends of the fuse wire 13 are led out, and the fuse wire 13 is made of a nickel wire with the diameter of 0.05 mm.
And B: through the preparation processes of foaming, high-temperature sintering or three-dimensional weaving and the like, the raw material of the heat-proof layer 14 embedded with the fuse wire 13 is integrally processed, the functional composite heat-proof layer 14 is directly formed, and meanwhile, the leads at two ends of the fuse wire 13 are exposed.
And C: the axes of the transducer 12 inside the cabin and the transducer 16 outside the cabin are correspondingly clung to the two sides of the metal cabin wall 11 by adhesive;
drilling a plurality of small holes slightly larger than the diameter of the fuse wire 13 on the mechanical isolation cover 15 so as to facilitate the lead to pass through; the mechanical isolation hood 15 is a circular table which is made of 1060 pure aluminum and has the wall back 1mm, the height 4mm, the bottom surface diameter 40mm and the top surface diameter 25mm, the bottom surface is hollow, and two small holes with the diameter of 1mm are drilled on the top surface of the mechanical isolation hood to enable the fuse wire 13 to pass through;
a part which has the same shape with the mechanical isolation cover 15 and is slightly larger than the mechanical isolation cover is cut off from the strain isolation pad 26, so that the assembly of the mechanical isolation cover 15 and the strain isolation pad 26 is convenient; simultaneously, drilling a plurality of small holes slightly larger than the diameter of the fuse wire 13 on the strain isolation pad 26, wherein the hole diameter is 1mm, and the small holes are used for leading wires to pass through;
the mechanical isolation cover 15 and the strain isolation pad 26 facilitate connection of the fuse wire 13 embedded in the heat-proof layer 14 and a cross-cabin transduction structure, so that the performance of the transducer is ensured, and the monitoring precision is improved.
Step D: assembling the heat-proof layer 14, the strain isolation pad 26, the mechanical isolation cover 15 and the metal bulkhead 11 to which the transducer is attached by using an adhesive to finally form a composite structure; wherein the mechanical shield 15 is required to cover above it without mechanical contact with the transducer; leading-out ends of the fuse wires 13 sequentially pass through the strain isolation pads 26 and the small holes in the mechanical isolation cover 15 and are welded with two electrodes of the extravehicular transducer 16; adhering the strain isolation pad 26 and the heat protection layer 14 together with silica gel; the cut space of the strain isolation pad 26 corresponds to the position of the mechanical isolation cover 15 by using silica gel to be adhered together; the mechanical isolation cover 15 covers the extravehicular transducer 16, and the bottom edge of the mechanical isolation cover is adhered to the metal bulkhead 11 by silica gel.
Step E: and manufacturing a circuit monitoring system 2 with corresponding functions according to the circuit system shown in the figure 1, and connecting a monitoring end of the circuit monitoring system 2 with the cabin transducer 12 to obtain the circuit monitoring system.
In some embodiments, the method of making the thermal barrier 14 employs any one of three methods;
the method comprises the following steps: the fuse wire 13 and the rigid heat insulation tile raw material (such as quartz fiber) are directly molded into a functional composite rigid heat insulation layer of integrated heat insulation tile-fuse wire through high-temperature sintering and die pressing.
The method 2 comprises the following steps: the fuse wire 13 and materials such as high silica glass fiber and the like are subjected to three-dimensional weaving and Resin Transfer Molding (RTM) to prepare the functional composite thin-wall heat-insulating layer.
The method 3 comprises the following steps: the fuse wire 13 and a foaming material (such as polyurethane foam) are foamed and molded to prepare the functional composite heat-proof layer.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A cross-metal-wall-embedded single-port-based passive burning loss sensing device is characterized by comprising a passive sensing system (1) and a circuit monitoring system (2);
the passive sensing system (1) comprises a bulkhead composite structure, wherein the bulkhead composite structure consists of an intra-cabin transducer (12), a metal bulkhead (11), an extra-cabin transducer (16) and a fusible wire (13) embedded in a heat-proof layer (14); a group of in-cabin transducers (12) and out-cabin transducers (16) are respectively arranged on the inner side and the outer side of the metal cabin wall (11) and used for transmitting energy to the outside of the cabin across the metal cabin wall (11) through sound waves and reflecting sound wave signals carrying on-off states of the melting wire lines (13) back to the cabin;
the circuit monitoring system (2) is used for transmitting alternating current signals for exciting the transducer (12) in the cabin, monitoring electrical complex impedance seen from two electrodes of the transducer (12) in the cabin into the cabin wall composite structure, obtaining a resonant frequency value of the cabin wall composite structure through impedance measurement, and judging the on-off condition of the fusible link (13) according to the deviation condition of the resonant frequency value.
2. The passive burnout sensing device based on the single-port embedded type crossing metal wall as claimed in claim 1, wherein the cabin interior transducer (12) and the cabin exterior transducer (16) are coaxial and can generate axial longitudinal waves, and the cabin interior transducer (12) and the cabin exterior transducer (16) have the same resonance frequency; two electrodes of the outdoor transducer (16) are connected to two ends of the fusible link (13), the heat-proof layer (14) is arranged on the outer wall of the metal bulkhead (11), and the outdoor transducer (16) is provided with a free mechanical boundary;
two electrodes of the transducer (12) in the cabin are connected with a measuring port of the impedance measuring unit (21), an output end of the sweep frequency signal source (23) is connected with an input end of the impedance measuring unit (21), and an output end of the impedance measuring unit (21) is connected with an input end of the damage judging unit (22).
3. The cross-metal-wall-embedded-type single-port-based passive burning loss sensing device is characterized in that the circuit monitoring system (2) comprises a frequency sweep signal source (23), an impedance measuring unit (21) and a damage judging unit (22);
the output end of the sweep frequency signal source (23) is connected with two electrodes of the transducer (12) in the cabin, and the sweep frequency signal source (23) is used for generating an alternating current signal for exciting the transducer (12) in the cabin and providing a local reference signal with adjustable frequency for the impedance measuring unit (21); the frequency scanning range of the frequency scanning signal source (23) covers the resonance frequency band of the bulkhead composite structure;
the impedance measuring unit (21) is used for measuring the electrical complex impedance of the cabin wall composite structure seen from the two electrodes of the cabin transducer (12);
and the damage judgment unit (22) is used for analyzing the result of the impedance measurement unit (21) and judging the damage condition of the heat-proof layer (14).
4. The device for sensing the burning loss based on the single-port embedded type crossing metal wall as claimed in claim 3, wherein the impedance measuring unit (21) comprises an impedance calculating module (27), a power divider (28) and a directional coupler (29); alternating current signals generated by the sweep frequency signal source (23) are separated into incident and outgoing components through the power divider (28) and are used as reference signals to be transmitted to the impedance calculation module (27), the rest alternating current signals are applied to the cabin transducer (12) through the directional coupler (29), reflection signals of the cabin transducer (12) are transmitted to the impedance calculation module (27) through the directional coupler (29), the impedance calculation module (27) calculates the reflection coefficient S11 of a port of the cabin transducer (12) at the frequency point according to the two received signals, and then the electrical complex impedance of the port of the cabin transducer (12) at the frequency point is calculated.
5. The device for sensing the burning loss based on the single-port embedded crossing metal wall as claimed in claim 3, wherein the impedance measuring unit (21) comprises an impedance calculating module (27), a port voltage sampling module (30) and an inlet voltage sampling module (31); the output end of the sweep frequency signal source (23) is connected with two electrodes of the transducer (12) in the cabin, a known constant value resistor is connected in series between the sweep frequency signal source (23) and the transducer (12) in the cabin, an inlet voltage sampling module (31) is connected at the inlet of the sweep frequency signal source (23), port voltage sampling modules (30) are connected at the ports of the two electrodes of the transducer (12) in the cabin, and the electrical complex impedance of the port of the transducer (12) in the cabin at the frequency point is calculated according to the voltage division ratio and the phase delay relationship of the constant value resistor and the port resistor of the transducer (12) in the cabin.
6. The device for sensing the burning loss based on the single-port embedded crossing metal wall as claimed in claim 3, wherein the impedance measuring unit (21) comprises an impedance calculating module (27), a port voltage sampling module (30) and a port current sampling module (32); the output end of the sweep frequency signal source (23) is connected with two electrodes of the transducer (12) in the cabin, alternating current signals of the sweep frequency signal source (23) are directly applied to a port of the transducer (12) in the cabin, port voltage sampling modules (30) are connected to ports of the two electrodes of the transducer (12) in the cabin, a port current sampling module (32) is connected to a circuit between the sweep frequency signal source (23) and the transducer (12) in the cabin, voltage and current waveforms of the port of the transducer (12) in the cabin are sampled simultaneously, and electrical complex impedance of the port of the transducer (12) in the cabin at the frequency point is calculated according to amplitude and phase of the voltage and the current waveforms.
7. The passive burning loss sensing device based on the metal wall-spanning embedded single-port is characterized in that a strain isolation pad (26) is arranged between the metal bulkhead (11) and the heat-proof layer (14), a mechanical isolation cover (15) is embedded in the strain isolation pad (26), the mechanical isolation cover (15) covers the outside of the extravehicular transducer (16), a gap is kept between the mechanical isolation cover (15) and the extravehicular transducer (16) without mechanical contact, the outer side of the extravehicular transducer (16) is provided with a free mechanical boundary, the top surface of the mechanical isolation cover (15) is provided with an opening, and a fusible wire (13) penetrates through the opening to be connected with two electrodes of the extravehicular transducer (16).
8. The passive burning loss sensing device based on the cross-metal-wall embedded single-port type is characterized in that the circuit monitoring system (2) further comprises a warning output unit (24), an input end of the warning output unit (24) is connected with an output end of the damage judging unit (22), and the warning output unit (24) is in signal connection with the flight control computer (25) and is used for converting a judgment result into a signal form which can be recognized and received by the flight control computer (25).
9. The monitoring method based on the cross-metal-wall embedded type single-port passive burning loss sensing device as claimed in any one of claims 1 to 8 is characterized by comprising the following steps:
step 1: frequency sweeping is carried out in the bandwidth of +/-10-20% of the main resonance frequency point of the acoustic composite structure through the circuit monitoring system (2), and the frequency sweeping is recorded asf 1…f nAt a frequency interval off w，f wTaking 1/50-1/100 frequency sweep bandwidth; setting a frequency offset threshold value to be delta F, and taking 1/10-1/40 of the sweep frequency bandwidth;
step 2: in the process of frequency sweeping, the electrical complex impedance of the port of the transducer (12) in the measuring cabin at each frequency point is measuredZ 1…Zn；
And step 3: finding a plurality of frequency points corresponding to the local minimum value of the absolute value of the argument of the complex impedance in the step 2, measuring for many times, and storing;
and 4, step 4: finding the peak frequency point of the complex impedance module value and the peak frequency point of the absolute value of the real part of the complex impedance, measuring for many times, and storing;
and 5: and (3) comparing the frequency point obtained in the step (3) or the peak frequency point obtained in the step (4) of the current measurement with the corresponding frequency points stored in the previous measurements to obtain a difference absolute value, then comparing the difference absolute value with a frequency deviation threshold delta F, obtaining the current electrical state of the fusible link wire (13) according to the comparison result, and further judging the health or burning loss state of the heat-proof layer (14) at the embedding part of the fusible link wire (13).
10. The preparation method of the cross-metal-wall-embedded single-port passive burning loss sensing device according to any one of claims 1 to 8, which is specifically carried out according to the following steps:
step A: selecting a conductive material to manufacture a fuse wire (13), embedding the fuse wire (13) in a raw material for preparing a heat-proof layer (14) in a snake-shaped bent configuration, covering the raw material in a region to be monitored, and simultaneously leading out two ends of the fuse wire (13);
and B: integrally processing the raw material of the heat-proof layer (14) embedded with the fuse wire (13), forming the composite heat-proof layer (14), and exposing the leads at two ends of the fuse wire (13);
and C: an in-cabin transducer (12) and an out-cabin transducer (16) are respectively arranged on the inner side and the outer side of the metal bulkhead (11);
step D: assembling a metal bulkhead (11) provided with an in-cabin transducer (12) and an out-cabin transducer (16) and a heat-proof layer (14) to form a bulkhead composite structure, wherein lead wires at two ends of a fusible wire (13) are connected with a positive electrode and a negative electrode of the out-cabin transducer (16);
step E: and manufacturing a circuit monitoring system (2) with corresponding functions, and connecting the monitoring end of the circuit monitoring system (2) with the transducer (12) in the cabin to obtain the circuit monitoring system.
CN202110976412.9A 2021-08-24 2021-08-24 Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method Active CN113835047B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110976412.9A CN113835047B (en) 2021-08-24 2021-08-24 Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110976412.9A CN113835047B (en) 2021-08-24 2021-08-24 Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method

Publications (2)

Publication Number Publication Date
CN113835047A true CN113835047A (en) 2021-12-24
CN113835047B CN113835047B (en) 2022-12-20

Family

ID=78961112

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110976412.9A Active CN113835047B (en) 2021-08-24 2021-08-24 Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method

Country Status (1)

Country Link
CN (1) CN113835047B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115307689A (en) * 2022-10-09 2022-11-08 中国石油大学(华东) Wireless passive temperature and humidity monitoring device and method

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050043906A1 (en) * 2001-08-01 2005-02-24 Theodor Funck Method and device for determining the acoustic parameters of fluids in a resonator device
WO2006110089A1 (en) * 2005-04-14 2006-10-19 University Of Warwick Method and apparatus for assessing quality of rivets using ultrasound
US20080319692A1 (en) * 2007-06-21 2008-12-25 Davis Christopher L Transducer health diagnostics for structural health monitoring (shm) systems
CN103245454A (en) * 2013-05-14 2013-08-14 西南石油大学 Non-intrusive pipeline real-time monitoring, prewarning and fault locating system
WO2015000705A1 (en) * 2013-07-02 2015-01-08 Koninklijke Philips N.V. Problem monitoring in cable system with fuses
CN105406611A (en) * 2015-10-28 2016-03-16 中国人民解放军国防科学技术大学 Device and method of determining through-metal wall ultrasonic sound wireless energy transmission channel optimization frequency
US20160313286A1 (en) * 2014-11-25 2016-10-27 Rohr, Inc. Detecting damage in a composite panel without removing overlying insulation
US20170201131A1 (en) * 2014-06-25 2017-07-13 Dalhousie University Power Links and Methods for Improved Efficiency
US20170350868A1 (en) * 2016-06-03 2017-12-07 Infineon Technologies Ag Acoustic wave detector
WO2018015722A1 (en) * 2016-07-18 2018-01-25 Theta Technologies Limited Non-destructive testing apparatus
CN107702698A (en) * 2017-10-11 2018-02-16 青岛深海云海洋科技有限公司 A kind of deep-sea is against formula echo sounding system and measuring method
CN107991388A (en) * 2017-11-21 2018-05-04 中国人民解放军陆军工程大学 Reinforcing steel corrosion monitoring sensor based on surface acoustic wave
CN109932052A (en) * 2019-02-27 2019-06-25 天津大学 The fast track device and method of ultrasonic transducer mechanical resonant frequency
CN110118612A (en) * 2018-02-05 2019-08-13 艾尔默斯半导体股份公司 Detect the method and device of the temperature of the vibrating elements of ultrasonic transducer
CN209858640U (en) * 2019-04-16 2019-12-27 河南科技学院 Ultrasonic transducer multi-resonance-point characteristic parameter measuring device

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050043906A1 (en) * 2001-08-01 2005-02-24 Theodor Funck Method and device for determining the acoustic parameters of fluids in a resonator device
WO2006110089A1 (en) * 2005-04-14 2006-10-19 University Of Warwick Method and apparatus for assessing quality of rivets using ultrasound
US20080319692A1 (en) * 2007-06-21 2008-12-25 Davis Christopher L Transducer health diagnostics for structural health monitoring (shm) systems
CN103245454A (en) * 2013-05-14 2013-08-14 西南石油大学 Non-intrusive pipeline real-time monitoring, prewarning and fault locating system
WO2015000705A1 (en) * 2013-07-02 2015-01-08 Koninklijke Philips N.V. Problem monitoring in cable system with fuses
US20170201131A1 (en) * 2014-06-25 2017-07-13 Dalhousie University Power Links and Methods for Improved Efficiency
US20160313286A1 (en) * 2014-11-25 2016-10-27 Rohr, Inc. Detecting damage in a composite panel without removing overlying insulation
CN105406611A (en) * 2015-10-28 2016-03-16 中国人民解放军国防科学技术大学 Device and method of determining through-metal wall ultrasonic sound wireless energy transmission channel optimization frequency
US20170350868A1 (en) * 2016-06-03 2017-12-07 Infineon Technologies Ag Acoustic wave detector
WO2018015722A1 (en) * 2016-07-18 2018-01-25 Theta Technologies Limited Non-destructive testing apparatus
CN107702698A (en) * 2017-10-11 2018-02-16 青岛深海云海洋科技有限公司 A kind of deep-sea is against formula echo sounding system and measuring method
CN107991388A (en) * 2017-11-21 2018-05-04 中国人民解放军陆军工程大学 Reinforcing steel corrosion monitoring sensor based on surface acoustic wave
CN110118612A (en) * 2018-02-05 2019-08-13 艾尔默斯半导体股份公司 Detect the method and device of the temperature of the vibrating elements of ultrasonic transducer
CN109932052A (en) * 2019-02-27 2019-06-25 天津大学 The fast track device and method of ultrasonic transducer mechanical resonant frequency
CN209858640U (en) * 2019-04-16 2019-12-27 河南科技学院 Ultrasonic transducer multi-resonance-point characteristic parameter measuring device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
郭云冲;谢楷等: "跨飞行器金属舱壁无线无源烧损传感技术", 《遥测遥控》, vol. 42, no. 3, 15 May 2021 (2021-05-15), pages 79 - 83 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115307689A (en) * 2022-10-09 2022-11-08 中国石油大学(华东) Wireless passive temperature and humidity monitoring device and method
CN115307689B (en) * 2022-10-09 2023-01-24 中国石油大学(华东) Wireless passive temperature and humidity monitoring device and method

Also Published As

Publication number Publication date
CN113835047B (en) 2022-12-20

Similar Documents

Publication Publication Date Title
US7322244B2 (en) Interrogation system for active monitoring of structural conditions
US7246521B2 (en) Diagnostic system for monitoring structural health conditions
US20090157358A1 (en) System for diagnosing and monitoring structural health conditions
US7536912B2 (en) Flexible diagnostic patches for structural health monitoring
US20070266788A1 (en) Diagnostic systems of optical fiber coil sensors for structural health monitoring
US7729035B2 (en) Acousto-optic modulators for modulating light signals
CN113835047B (en) Cross-metal-wall embedded single-port passive burning loss sensing device, monitoring method and manufacturing method
CN104142191B (en) Vacuum isolation circuit breakers In-Line Temperature Measure System
CN109406032A (en) A kind of cable accessory interfacial pressure online testing device
CN112414601B (en) Wide frequency ultrasonic transducer
CN109188219A (en) Built-in GIS shelf depreciation ultrasonic wave and light pulse combined detection system and method
US20070108050A1 (en) Sensors
CN109975674A (en) A kind of intermediate joint of electric cable state of insulation on-line measuring device
CN107727266A (en) A kind of MEMS temperature sensor and its switch cubicle temp measuring system
CN110161116B (en) Displacement and acoustic emission integrated sensing device
CN104913839A (en) Fluctuation sensor based on optical fiber M-Z interferometer
CN116087326B (en) Tunnel lining defect intelligent monitoring device based on space-solid coupling seismic wave detection
KR100754718B1 (en) Sensors and systems for structural health monitoring
US11913842B2 (en) Temperature sensor and temperature measurement apparatus
CN212845185U (en) Ultrasonic detection and lightning protection fixing device
JP2003004713A (en) High temperature sensor
CN204807189U (en) Undulant sensor based on optic fibre M -Z interferometer
JP2986581B2 (en) Ultrasonic probe
KR100772292B1 (en) Sensors and systems for structural health monitoring
KR100754719B1 (en) Sensors and systems for structural health monitoring

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant