CN-121994932-A - Aircraft composite material structure health monitoring system and method

CN121994932ACN 121994932 ACN121994932 ACN 121994932ACN-121994932-A

Abstract

The application discloses a health monitoring system and method for an aircraft composite material structure, and relates to the field of aircraft material health monitoring, wherein the system comprises a DAS integrated optical module, a single-mode optical fiber sensor network and a data processing module, wherein the DAS integrated optical module is used for generating and transmitting heterodyne phase-modulated optical pulse pairs to the single-mode optical fiber sensor network and converting back Rayleigh scattered light into electric signals; the single-mode fiber sensing network is arranged on the surface of the aircraft composite material structure and is used for converting an acoustic emission signal containing physical changes of the aircraft composite material structure into an optical phase change signal by utilizing a coherent Rayleigh scattering effect, the digital signal processing module is used for processing the electrical signal by utilizing a heterodyne phase modulation method based on instantaneous frequency tracking so as to identify and position the damage of the aircraft composite material structure, and the alarm output module is used for outputting the damage position, the damage degree grade and the alarm signal of the aircraft composite material structure in real time when the structural damage is detected, so that full-distribution and wide-range online accurate monitoring is realized.

Inventors

YANG SUFAN
DONG YULIANG
WANG LEI
LI SIYUAN
HUANG ZULIANG
CHEN HAIHANG
HUA ZONGZHI
LI PEIZE
ZHONG GUOYU

Assignees

成都航空职业技术大学

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (10)

1. An aircraft composite structural health monitoring system, the aircraft composite structural health monitoring system comprising: The DAS integrated optical module is used for generating and transmitting the heterodyne phase modulated optical pulse pair to a single-mode optical fiber sensing network, receiving the back Rayleigh scattered light carrying the optical phase change signal from the single-mode optical fiber sensing network, and converting the back Rayleigh scattered light into an electric signal; The single-mode fiber sensing network is arranged on the surface of the aircraft composite material structure and is used for converting an acoustic emission signal containing the physical change of the aircraft composite material structure into an optical phase change signal by utilizing the coherent Rayleigh scattering effect; the digital signal processing module is electrically connected with the DAS integrated optical module and is used for processing the electric signals by using a heterodyne phase modulation method based on instantaneous frequency tracking so as to identify and position the damage of the aircraft composite material structure; and the alarm output module is in communication connection with the digital signal processing module and is used for outputting the damage position, the damage degree grade and the alarm signal of the aircraft composite material structure in real time when the structural damage is detected.
2. The aircraft composite structural health monitoring system according to claim 1, wherein said DAS integrated optical module comprises a narrow linewidth laser, a semiconductor optical amplifier, an unbalanced Mach-Zehnder interferometer and a photodetector; the narrow linewidth laser is used for providing a detection light source and emitting continuous light; A semiconductor optical amplifier for converting continuous light into pulse light; The unbalanced Mach-Zehnder interferometer is used for performing frequency shift processing and continuous phase modulation processing on pulse light respectively, synthesizing an optical signal after the frequency shift processing and an optical signal after the phase modulation processing into an optical pulse pair, and interfering back Rayleigh scattered light carrying an optical phase change signal to obtain an interference optical signal; and the photoelectric detector is used for converting the interference optical signal into an electric signal.
3. The aircraft composite structural health monitoring system according to claim 2, wherein one arm of said unbalanced Mach-Zehnder interferometer comprises an acousto-optic modulator, the other arm comprises a first optical circulator, an integrated optical phase modulator, a faraday rotating mirror and an optical fiber delay ring, one end of the acousto-optic modulator and one end of the first optical circulator are connected with a semiconductor optical amplifier through a first single-mode fiber coupler, the other end of the acousto-optic modulator and the other end of the first optical circulator are connected with a second optical circulator through a second single-mode fiber coupler, and the second optical circulator is used for connecting a DAS integrated optical module, a single-mode fiber sensing network and a digital signal processing module; The integrated optical phase modulator is used for introducing high-frequency phase modulation and continuously applying phase modulation treatment to the pulse light.
4. An aircraft composite structural health monitoring system according to claim 3, wherein the electrical signal is represented as: ; Wherein, the Is that An electrical signal at a moment; The amplitude of the alternating current signal detected by the detector is given; Is a sine function; heterodyne frequencies generated for the acousto-optic modulator; phase change for acoustic emission signals; A modulation signal generated for the integrated optical phase modulator; Is the initial phase.
5. The aircraft composite structural health monitoring system according to claim 1, wherein, in terms of signal processing of the electrical signal using a heterodyne phase modulation method based on instantaneous frequency tracking, the digital signal processing module is configured to: Performing low-pass filtering on the electric signal to obtain a filtered signal; performing IQ demodulation on the filtered signal to obtain an acoustic wave phase signal; calculating the instantaneous frequency of the acoustic wave signal; determining a rotation direction of demodulation output and a correction factor frequency band where an average instantaneous carrier frequency is based on the instantaneous frequency; Determining and applying a correction factor according to the rotation direction and the correction factor frequency band, and correcting the sound wave phase signal obtained by IQ demodulation to eliminate phase winding; judging whether the aircraft composite material structure has structural damage or not based on the corrected phase information; and calculating the damage position of the aircraft composite material structure based on the distribution position information of the distributed optical fiber sensing network and the transmission time difference of the optical pulse and combining the space distribution characteristic of the Rayleigh scattered light.
6. The aircraft composite structural health monitoring system according to claim 5, wherein said digital signal processing module is configured to, based on the corrected phase information, determine whether structural damage exists to the aircraft composite structure: performing spectrum analysis and feature extraction on the corrected phase information, and calculating the power spectrum density and the signal-to-noise ratio of the signal; And when the signal amplitude exceeds the dynamic threshold value and the signal to noise ratio is superior to the set signal to noise ratio value, judging that the aircraft composite material structure has structural damage.
7. The aircraft composite structural health monitoring system according to claim 1, wherein said single-mode fiber sensor network is fixed to the surface of the aircraft composite structure in a combination of spiral winding and straight line bonding, the arrangement pitch in the stress concentration area is no more than 5cm, and the arrangement pitch in the non-stress concentration area is no more than 15cm.
8. An aircraft composite structural health monitoring method based on the aircraft composite structural health monitoring system of claim 1, wherein the aircraft composite structural health monitoring method comprises: the method comprises the steps of generating and transmitting heterodyne phase modulated optical pulse pairs to a single-mode optical fiber sensing network through a DAS integrated optical module, converting acoustic emission signals containing physical changes of an aircraft composite material structure into optical phase change signals by utilizing a coherent Rayleigh scattering effect, and converting back Rayleigh scattering light carrying the optical phase change signals into electric signals; performing signal processing on the electric signal by using a heterodyne phase modulation method based on instantaneous frequency tracking so as to identify and locate damage to the aircraft composite structure; And outputting the damage position, the damage degree grade and the alarm signal of the aircraft composite material structure in real time when the structural damage is detected.
9. The method of claim 8, wherein the electrical signal is signal processed using heterodyne phase modulation based on instantaneous frequency tracking to identify and locate damage to the aircraft composite structure, comprising: Performing low-pass filtering on the electric signal to obtain a filtered signal; performing IQ demodulation on the filtered signal to obtain an acoustic wave phase signal; calculating the instantaneous frequency of the acoustic wave signal; determining a rotation direction of demodulation output and a correction factor frequency band where an average instantaneous carrier frequency is based on the instantaneous frequency; Determining and applying a correction factor according to the rotation direction and the correction factor frequency band, and correcting the sound wave phase signal obtained by IQ demodulation to eliminate phase winding; judging whether the aircraft composite material structure has structural damage or not based on the corrected phase information; and calculating the damage position of the aircraft composite material structure based on the distribution position information of the distributed optical fiber sensing network and the transmission time difference of the optical pulse and combining the space distribution characteristic of the Rayleigh scattered light.
10. The method for aircraft composite structural health monitoring according to claim 9, wherein determining whether structural damage exists in an aircraft composite structure based on the corrected phase information comprises: performing spectrum analysis and feature extraction on the corrected phase information, and calculating the power spectrum density and the signal-to-noise ratio of the signal; And when the signal amplitude exceeds the dynamic threshold value and the signal to noise ratio is superior to the set signal to noise ratio value, judging that the aircraft composite material structure has structural damage.

Description

Aircraft composite material structure health monitoring system and method Technical Field The application relates to the field of aircraft material health monitoring, in particular to a system and a method for monitoring the health of an aircraft composite material structure. Background With the rapid development of the aviation industry, the composite material is widely applied to key structures such as an airplane body and an airplane wing due to the advantages of high strength, light weight, corrosion resistance and the like, and the proportion of the composite material to the weight of the airplane structure is more than 50 percent. However, in the long-term service process of the aircraft, the aircraft is influenced by factors such as flight load, airflow impact, temperature circulation, external collision and the like, the composite material structure is easy to generate micro cracks, interlayer peeling and other damages, and if the damages cannot be found in time, the damages can be gradually expanded along with the increase of the flight times, so that the flight safety is seriously threatened. The conventional aircraft composite material structure health monitoring technology has the defects that 1) a large number of sensor nodes are required to be distributed on the structure surface by the conventional point type sensing technology (such as strain gauges, piezoelectric sensors and the like), a monitoring blind area exists, the structural integrity of the composite material is damaged to a certain extent due to sensor installation, and meanwhile, the large-range and full-distribution monitoring requirements are difficult to adapt to, 2) the conventional optical fiber sensing technology (such as a sensing scheme based on an optical Fiber Bragg Grating (FBG)) has certain distributed monitoring capability, but a demodulation system is complex and high in cost, the dynamic range is limited, and is difficult to capture sound emission signals of tiny damages, the heterodyne frequency is limited by heterodyne frequency and system bandwidth by the conventional interference type optical fiber sensing scheme, the heterodyne frequency is increased, the system bandwidth requirement is increased, and the airborne system bandwidth resource is limited, so that the dynamic range and the monitoring sensitivity are difficult to consider. 3) The ultrasonic detection and infrared thermal imaging technology needs to perform manual detection when the aircraft is stopped, cannot realize online real-time monitoring, has insufficient identification capability on early tiny damage, has low detection efficiency, and is difficult to meet the requirements of full life cycle health management of the aircraft. Therefore, there is a need for an aircraft composite structural health monitoring technology that has full distribution, wide-range on-line monitoring capability, and is adapted to the on-board environment. Disclosure of Invention The application aims to provide a health monitoring system and method for an aircraft composite material structure, which can realize full-distribution and wide-range online accurate monitoring. In order to achieve the above object, the present application provides the following solutions: in a first aspect, the present application provides an aircraft composite structural health monitoring system comprising: The DAS integrated optical module is used for generating and transmitting the heterodyne phase modulated optical pulse pair to a single-mode optical fiber sensing network, receiving the back Rayleigh scattered light carrying the optical phase change signal from the single-mode optical fiber sensing network, and converting the back Rayleigh scattered light into an electric signal; The single-mode fiber sensing network is arranged on the surface of the aircraft composite material structure and is used for converting an acoustic emission signal containing the physical change of the aircraft composite material structure into an optical phase change signal by utilizing the coherent Rayleigh scattering effect; the digital signal processing module is electrically connected with the DAS integrated optical module and is used for processing the electric signals by using a heterodyne phase modulation method based on instantaneous frequency tracking so as to identify and position the damage of the aircraft composite material structure; and the alarm output module is in communication connection with the digital signal processing module and is used for outputting the damage position, the damage degree grade and the alarm signal of the aircraft composite material structure in real time when the structural damage is detected. In a second aspect, the present application provides an aircraft composite structural health monitoring method based on the aircraft composite structural health monitoring system of the first aspect, comprising: the method comprises the steps of generating and transmitting heterodyne