CN117825524A

CN117825524A - Damage assessment method for aluminum-based composite material

Info

Publication number: CN117825524A
Application number: CN202311847537.7A
Authority: CN
Inventors: 王帅; 程爽爽; 顾晓春; 李婷; 王昭; 祥福
Original assignee: Beijing Xinghang Electromechanical Equipment Co Ltd
Current assignee: Beijing Xinghang Electromechanical Equipment Co Ltd
Priority date: 2023-12-29
Filing date: 2023-12-29
Publication date: 2024-04-05

Abstract

The invention relates to the technical field of ultrasonic nondestructive testing, in particular to a damage assessment method of an aluminum-based composite material, which comprises the following steps: acquiring an ultrasonic detection signal and an electromagnetic ultrasonic detection signal of the composite material to be detected based on an integrated detector; preprocessing the ultrasonic detection signals and the electromagnetic ultrasonic detection signals to obtain corresponding digital signals; mixing the ultrasonic detection signals and the digital signals of the electromagnetic ultrasonic detection signals to obtain composite detection signals; and evaluating the internal damage of the aluminum-based composite material based on the synthesized detection signal. According to the invention, the ultrasonic and electromagnetic ultrasonic detection signals are subjected to analog-to-digital conversion and frequency mixing treatment to obtain the composite detection signal, so that the display information of the display simultaneously contains characteristic information brought by the ultrasonic and electromagnetic ultrasonic detection signals, the problem of poor detection precision of the traditional ultrasonic detection on a structure with a small size and a cavity structure is solved, and the sensitivity and resolution are improved.

Description

Damage assessment method for aluminum-based composite material

Technical Field

The invention relates to the technical field of ultrasonic nondestructive testing, in particular to a damage assessment method of an aluminum matrix composite.

Background

The aluminum-based composite material is formed by compounding two or more materials with different properties through various technological means, has the advantages of light weight, high rigidity, corrosion resistance and the like compared with the traditional material, and has wide application prospect in the fields of aviation, aerospace, automobiles and the like. However, during the preparation of the aluminum-based composite material and the service process thereof, defects such as debonding, inclusion, holes, looseness, cracks and the like can be generated. In order to ensure the safety of the materials in the preparation and use processes, various nondestructive tests are used for detecting aluminum-based composite materials.

In the prior art, ultrasonic nondestructive detection is a common detection method, on one hand, excitation pulse signals commonly used in ultrasonic detection, such as single pulse, spike pulse or sine wave and cosine wave pulse, have poor penetrating capability, cannot penetrate an aluminum-based composite material with high acoustic attenuation, and cause serious consequences of defect omission; on the other hand, the ultrasonic detection can accurately detect internal defects by using a pulse signal with stronger penetrating power, but the inherent characteristics of the ultrasonic waves determine that the ultrasonic detection is difficult to detect on rough, irregular, small, thin materials and cavity structures; ultrasonic waves are prone to acoustic diffraction for object detection in the vicinity of its wavelength, and air in the cavity structure can interfere with ultrasonic wave propagation and detection. In summary, there is a need in the art for a method for achieving accurate detection and damage assessment of aluminum-based composites of small size and having a cavity structure.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a damage assessment method for an aluminum-based composite material, which is used for solving at least one of the problems of difficulty in detecting small-sized aluminum-based composite materials with cavity structures and poor accuracy in ultrasonic nondestructive detection in the prior art.

The aim of the invention is mainly realized by the following technical scheme:

the invention provides a damage assessment method of an aluminum-based composite material, which comprises the following steps:

acquiring an ultrasonic detection signal and an electromagnetic ultrasonic detection signal of the composite material to be detected;

preprocessing the ultrasonic detection signals and the electromagnetic ultrasonic detection signals to obtain corresponding digital signals;

mixing the ultrasonic detection signals and the digital signals of the electromagnetic ultrasonic detection signals to obtain composite detection signals;

and evaluating the internal damage of the aluminum-based composite material based on the synthesized detection signal.

Preferably, the evaluating the internal damage of the aluminum-based composite material comprises:

obtaining a measurement distance h between a reflecting surface and an incident surface in the composite material based on the synthesized detection signal _Measuring ；

Based on measuring distance h _Measuring And screening out the defective area.

S401: obtaining actual distance h between reflecting surface and incident surface in composite material based on composite material size _{Real world} ；

S402: obtaining a measurement distance h between a reflecting surface and an incident surface in the composite material based on the synthesized detection signal _Measuring ；

S403: comparison h _{Real world} 、h _Measuring Screening out the defect area and determining the distance h between the incident surface and the defect area _{Lack of supply} ；

S404: moving the integrated detector on the surface of the incidence plane to obtain the length a and the width b of the complete defect area;

s405: based on the length a, the width b and the measured distance h between the reflecting surface and the incident surface _Measuring And (5) performing internal damage assessment of the aluminum-based composite material.

Preferably, the obtaining of the actual distance between the reflecting surface and the incident surface in the composite material in S401 includes: the actual distance between the reflecting surface and the incident surface is determined by recording the difference between the transmitted and received reflection times and the propagation speed of sound in the material, and the measured distance between the reflecting surface and the incident surface is determined in the same manner in S402.

Preferably, the distance h between the incident surface and the defective area is determined in S403 _{Lack of supply} Comprising the following steps:

h _measuring ≥h _{Real world} Indicating that no reflection type defect exists at the current position;

h _measuring ＜h _{Real world} Indicating that reflection type defects exist at the corresponding depth of the sound path of the current position, and h _Measuring I.e. the distance h between the incident surface and the defect area _{Lack of supply} 。

Preferably, acquiring the length a and the width b of the defect area in S404 includes: and detecting adjacent areas of the defect areas screened in the step S403, obtaining complete defect areas according to the method of the step S401-S403, and determining the length a and the width b of the complete defect areas.

Preferably, the digital signal mixing process includes: and mixing digital signals corresponding to the ultrasonic detection signals and the electromagnetic ultrasonic detection signals through multiplication.

Preferably, the signal Z (f) output after the digital signal mixing process satisfies:

wherein A is ₁ 、A ₂ The amplitudes of the ultrasonic detection signal and the electromagnetic ultrasonic detection signal are respectively; f (f) ₁ 、f ₂ The frequency of the ultrasonic detection signal and the frequency of the electromagnetic ultrasonic detection signal are respectively, t is time, and u is a multiplication variable.

Preferably, the aluminum-based composite material internal damage assessment comprises: the synthesized detection signals after the multi-frequency mixing processing are comprehensively displayed on a display.

Preferably, the aluminum-based composite material internal damage assessment comprises: judging whether debonding, inclusion, holes, looseness and crack defects exist in each region according to waveform characteristics of a synthesized detection signal of the composite material to be detected.

Compared with the prior art, the invention has at least one of the following beneficial effects:

(1) According to the invention, the ultrasonic and electromagnetic ultrasonic detection signals are subjected to analog-to-digital conversion and frequency mixing treatment to obtain the synthesized detection signals, so that the display information of the display simultaneously contains characteristic information brought by the ultrasonic and electromagnetic ultrasonic detection signals, and the problem of poor detection precision of the traditional ultrasonic detection on a structure with a small size and a cavity structure can be solved; meanwhile, compared with the pure electromagnetic ultrasonic detection, the method greatly improves the defect of lower sensitivity and resolution of the region to be detected caused by low transduction efficiency.

(2) The mixing formula of the invention has the following advantages over the conventional mixing formula: in one aspect, the mixing formula includes A ₁ Sin(2πf ₁ t) (ultrasonic detection Signal) and A ₂ sin(2πf ₂ The functional expression of (t-u) (electromagnetic ultrasonic detection signal) can reflect the variation rule of the intensity of ultrasonic detection signal and electromagnetic ultrasonic detection signal along with time t; on the other hand, by mixing the formulas of the ultrasonic detection signal and the electromagnetic ultrasonic detection signal with respect to integration, instead of simple addition, important detection information display caused by large amplitude and frequency differences of the two signals can be effectively reduced, omission is caused, and meanwhile, the resolution, the signal-to-noise ratio and the detection accuracy of important detection features are improved.

(3) The invention combines the ultrasonic detection signal and the electromagnetic ultrasonic detection signal by adopting multi-frequency mixing to obtain a composite signal containing two detection information, and compared with the pure ultrasonic detection signal in the prior art, the composite signal can contain the characteristic information of a cavity structure and a small-size structure (such as less than 2 mm), is convenient for further analyzing and processing the state of the cavity structure and the small-size structure, and greatly improves the defect that the cavity structure and the small-size structure are difficult to detect and analyze in the prior art.

(4) After the frequency mixing treatment is adopted, the characteristics of two detection signals including ultrasonic and electromagnetic ultrasonic are comprehensively displayed on a display: on one hand, the surface and the inside of the small part and the cavity structural part can be comprehensively detected based on the respective advantages of the two detection signals, so that the omission ratio is reduced, and the sensitivity is improved; on the other hand, the areas where the two detection signals can be detected can be mutually verified, errors caused by interference are discharged, and accuracy is improved.

(5) According to the invention, different digital filters are respectively selected for the digital signals of the ultrasonic detection signals and the digital signals of the electromagnetic ultrasonic detection signals, on one hand, specific frequency components can be extracted or removed from complex signals, a highly controllable filtering effect is provided, separation of different signal sources is facilitated, and mutual interference of the two detection signals is reduced; on the other hand, the interference of the small-size structure and the cavity structure on ultrasonic detection signals can be improved, the interference of electromagnetic ultrasonic detection is reduced, and the detection accuracy and sensitivity are improved; in addition, digital filters generally have better stability from environmental conditions and component drift, which makes them more reliable in long term use and under changing operating environments.

(6) The invention carries out phase modulation on the signal through phase rotation, and can extract specific frequency or characteristic in the signal, thereby being beneficial to better identifying targets or structures and improving the resolution and the identification sensitivity of ultrasonic detection and electromagnetic ultrasonic detection. In addition, the phase rotation of the invention can be realized through adaptive control, and real-time adjustment is carried out according to environmental change and signal characteristic change, so that the system can maintain optimal performance under different conditions, and the detection capability and interference resistance to complex structures are improved.

In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the embodiments of the invention particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.

FIG. 1 is a flow chart of a composite ultrasonic nondestructive testing method of an aluminum-based composite material;

FIG. 2 is a cross-sectional view of the aluminum-based composite of example 2;

FIG. 3 is a schematic defect diagram of the aluminum-based composite material of example 3;

FIG. 4 is an ultrasonic spectrum of the test result of example 2;

FIG. 5 is an ultrasonic spectrum of the test result of comparative example 1;

FIG. 6 is a schematic diagram of an ultrasonic nondestructive testing device for aluminum-based composite materials in an embodiment of the invention.

Detailed Description

The following detailed description of preferred embodiments of the invention is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the invention, are used to explain the principles of the invention and are not intended to limit the scope of the invention.

The invention introduces electromagnetic ultrasonic detection in common ultrasonic detection to detect the flaw of the thin-wall tubular material and the small-sized material, greatly improves the detection accuracy of ultrasonic detection, and overcomes the defect that the common ultrasonic detection is difficult to be used for the thin-wall tubular material and the small-sized material.

Meanwhile, the invention combines ultrasonic detection and electromagnetic ultrasonic detection, so that the detection results of the detected objects are mutually inspected, and meanwhile, the detection results can be mutually compensated, thereby changing the defect of weaker electromagnetic ultrasonic detection sensitivity.

Specifically, in order to realize nondestructive testing of the aluminum-based composite material, the invention is realized by the following technical scheme:

on the one hand, the invention also discloses a method for evaluating the internal damage of the aluminum-based composite material, which is shown in fig. 1 and comprises the following steps:

s1: acquiring an ultrasonic detection signal and an electromagnetic ultrasonic detection signal of the composite material to be detected based on an integrated detector;

s2: preprocessing an ultrasonic detection signal and an electromagnetic ultrasonic detection signal to obtain a corresponding digital signal;

s3: mixing the ultrasonic detection signals and the digital signals of the electromagnetic ultrasonic detection signals to obtain composite detection signals;

s4: and evaluating the internal damage of the aluminum-based composite material based on the synthesized detection signal.

Specifically, the integrated detector consists of a waveform generator, a detection coil capable of generating a dynamic alternating magnetic field and a signal receiving device.

It should be noted that, the ultrasonic detection signal and the electromagnetic ultrasonic detection signal may be received by two signal receiving apparatuses respectively or the same signal receiving apparatus receives the mixed signal and then pre-processes the mixed signal by two independent signal processing circuits respectively; this is because the ultrasonic frequencies generated by the waveform generator and the detection coil are different, and the ultrasonic detection signals and the electromagnetic ultrasonic detection signals with the characteristic frequencies can be screened out after pretreatment.

When in implementation, the waveform generator sends out a preset continuous wave or pulse signal excitation to emit ultrasonic waves to the detected object;

the detection coil is excited by a preset high pulse signal sent by the signal generator, and generates Lorentz force/magnetostriction force in the detected object to form ultrasonic waves;

the signal receiving device receives the ultrasonic detection signal and the electromagnetic ultrasonic detection signal;

the ultrasonic and electromagnetic ultrasonic detection signals are subjected to analog-to-digital conversion to obtain digital signals, and the digital signals are subjected to frequency mixing treatment to obtain composite detection signals;

the synthesized detection signals are displayed through a display, and a technician can judge whether reflection type defects such as debonding, inclusion, holes, looseness, cracks and the like exist in each area according to waveform characteristics of the synthesized detection signals of the composite material to be detected.

By way of example, fig. 4 shows an ultrasonic spectrum of the detection result of the debonding delamination defect:

the system can determine the ultrasonic travel according to the transmitting and reflecting time, and then determine the distance between the incident surface and the reflecting surface; the display identifies the signal, forms the ultrasonic spectrogram which takes the distance between the reflecting surface and the incident surface as the abscissa and takes the signal intensity as the ordinate;

When the debonding layer defect exists, the debonding layer is used as a new reflection surface to influence the detection result, and defect waves are displayed at a shorter distance from the incidence surface.

Compared with the prior art, the invention obtains the synthesized detection signal after the ultrasonic and electromagnetic ultrasonic detection signals are subjected to analog-to-digital conversion and frequency mixing treatment, so that the display displays the characteristic information brought by the ultrasonic and electromagnetic ultrasonic detection signals in the detection signal waveform, thereby improving the near-surface resolution, and solving the problem that the traditional ultrasonic detection has poor detection precision on materials with small size (such as less than 2 mm) and cavity structure; meanwhile, compared with the pure electromagnetic ultrasonic detection, the method greatly improves the defects of lower sensitivity and resolution.

Specifically, the preprocessing in S2 includes:

s201: respectively amplifying the ultrasonic detection signals and the electromagnetic ultrasonic detection signals independently to obtain analog signals corresponding to the two detection signals;

s202: analog signals corresponding to the two detection signals are subjected to analog-to-digital conversion to obtain digital signals corresponding to the two detection signals.

Preferably, S201 further includes demodulating the analog signal by a phase sensitive detector, and extracting an analog signal with a specific frequency from the analog signal.

In particular, the analog signal of a particular frequency may be characterized by a phase and amplitude that includes a change in acoustic impedance, a change in propagation velocity.

Preferably, the demodulation processing further comprises an analog signal filtering processing for the specific frequency, so as to further remove clutter outside the specific frequency.

Specifically, the analog signal is a two-dimensional information signal having an X/Y component, and digital signal decoding can be performed through analog-to-digital conversion to obtain a digital signal.

Specifically, the digital signal mixing process in S3 includes: and mixing digital signals corresponding to the ultrasonic detection signals and the electromagnetic ultrasonic detection signals through multiplication.

Specifically, the signal Z (f) output after the digital signal mixing process in S3 satisfies:

It will be appreciated that the following advantages over conventional mixing formulas are achieved: in one aspect, the mixing formula includes A ₁ Sin(2πf ₁ t) (ultrasonic detection Signal) and A ₂ sin(2πf ₂ The functional expression of (t-u) (electromagnetic ultrasonic detection signal) can reflect the variation rule of the intensity of ultrasonic detection signal and electromagnetic ultrasonic detection signal along with time t; on the other hand, by mixing the formulas of the ultrasonic detection signal and the electromagnetic ultrasonic detection signal with respect to integration, instead of simple addition, important detection information display caused by large amplitude and frequency differences of the two signals can be effectively reduced, omission is caused, and meanwhile, the resolution, the signal-to-noise ratio and the detection accuracy of important detection features are improved.

Specifically, by this convolution operation, the spectrum of the mixed signal can be obtained, which contains information of two frequency components: one frequency component is used to measure defect information (electromagnetic ultrasonic detection signal) of near-surface or cavity structure material, and the other frequency component is used for detection of deeper structures (ordinary ultrasonic detection signal).

By way of example, for small pieces with a diameter of less than 2mm, fig. 4 shows an ultrasonic spectrum of a composite ultrasonic test result of a debonding delamination defect, and fig. 5 shows an ultrasonic spectrum of a single ultrasonic test result of a debonding delamination defect:

as shown in fig. 5, in a normal state, an incident wave emitted by the integrated detector or formed on the detection surface enters the surface of the part to be detected and propagates to the reflection surface to be reflected to the signal receiving device in the integrated detector, and the system can determine the ultrasonic travel according to the emission and reflection time, so as to determine the distance between the incident surface and the reflection surface; the display identifies the signal, forms the ultrasonic spectrogram which takes the distance between the reflecting surface and the incident surface as the abscissa and takes the signal intensity as the ordinate; because the single ultrasonic detection has poor detection effect on small pieces with the diameter smaller than 2mm, as shown in fig. 5, the debonding delamination defect can not be detected, and the spectrogram only shows the bottom wave detection data; this is because only the normal ultrasonic detection signal features are displayed;

As shown in fig. 4, when the debonding delamination defect exists in the ultrasonic and electromagnetic ultrasonic composite detection, the debonding delamination affects the detection result as a new reflection surface except for the bottom surface wave, and the defect wave is displayed at a shorter distance from the incident surface. This is because the characteristics of both the normal ultrasonic detection signal and the electromagnetic ultrasonic detection signal are displayed.

It will be appreciated that as shown in fig. 4, multi-frequency mixing may be used to integrate information in multiple frequency ranges, thereby obtaining more comprehensive and multi-level signal characteristics; aiming at ultrasonic and electromagnetic ultrasonic composite detection, when debonding layering defects exist, multiple frequency components can be extracted from an original signal through multi-frequency mixing, and the characteristics of the multiple frequency components are contained, so that frequency spectrum information is enhanced, and higher resolution can be obtained on a frequency domain.

Compared with the prior art, the invention adopts multi-frequency mixing to compound the characteristics of the ultrasonic detection signal and the electromagnetic ultrasonic detection signal to obtain a composite signal containing two detection information, and compared with the pure ultrasonic detection signal in the prior art, the composite signal can contain the characteristic information of a cavity structure and a small-size structure (such as less than 2 mm), is convenient for further analyzing and processing the state of the cavity structure and the small-size structure, and greatly improves the defect that the cavity structure and the small-size structure are difficult to detect and analyze in the prior art.

Preferably, the step S3 further comprises a filtering process for the digital signal before the digital signal mixing process.

Specifically, the filtering process includes: and carrying out band-pass filtering on the digital signal of the ultrasonic detection signal, and carrying out self-adaptive filtering on the digital signal of the electromagnetic ultrasonic detection signal.

It should be noted that, the bandpass filtering can highlight the ultrasonic detection signal, so as to reduce the interference of the small-size structure and the cavity structure to the ultrasonic detection signal; the self-adaptive filter can adjust electromagnetic wave signals in real time in a complex environment, so that electromagnetic ultrasonic detection is adapted to the change of signals and the influence of interference when the complex structure is detected, and the detection accuracy and sensitivity are improved.

Compared with the prior art, the invention respectively selects the bandpass filter and the self-adaptive filter for the digital signal of the ultrasonic detection signal and the digital signal of the electromagnetic ultrasonic detection signal, on one hand, the invention can extract or remove specific frequency components in complex signals, provides highly controllable filtering effect, is beneficial to separating different signal sources and reduces the mutual interference of the two detection signals; on the other hand, the interference of the small-size structure and the cavity structure on ultrasonic detection signals can be improved, the interference of electromagnetic ultrasonic detection during complex structure detection is improved, and the detection accuracy and sensitivity are improved; in addition, digital filters generally have better stability from environmental conditions and component drift, which makes them more reliable in long term use and under changing operating environments.

Specifically, the filtering process includes: and setting two filtering channels of band-pass filtering and self-adaptive filtering, and filtering different signals.

When the method is implemented, the two-channel filtering can realize the adaptive filtering according to whether the input ultrasonic detection signal or the electromagnetic ultrasonic detection signal is: the use of bandpass filtering or adaptive filtering is dynamically selected according to the characteristics of the input signal, which enables the system to better adapt to different types of inputs and perform better under different conditions.

Preferably, the filtering process further includes the step of observing output: and observing the filtered output wave frequency information, and checking whether the expected signal processing effect is achieved.

Specifically, checking whether the expected signal processing effect is achieved includes: analyzing the proportion of different frequency signals in the filtered detection signals through a waveform detector; and continuing filtering until the proportion of the target waveform signals is higher than the preset threshold value.

Specifically, the characteristic dynamics of the input signal include frequency and amplitude; based on the difference of frequency and amplitude between the digital signal of the ultrasonic detection signal and the digital signal of the electromagnetic ultrasonic detection signal, matched filtering channels are selected for the two detection signals.

In practice, the digital signal of the ultrasonic detection signal has an amplitude significantly greater than that of the digital signal of the electromagnetic ultrasonic detection signal and a frequency significantly less than that of the latter, and can be easily distinguished based on a waveform judgment device (e.g., an oscilloscope) and manual judgment.

Preferably, the filtering process includes: the digital signal of the ultrasonic detection signal after the filtering processing and the digital signal of the electromagnetic ultrasonic detection signal are modulated in phase, so that the relative time position of the signals is changed.

Specifically, the phase modulation method includes: the rotation angle is selected and the signal is phase rotated.

Specifically, the phase rotation includes rotating the phase in either the forward or reverse direction by an angle such that the proportion of the particular frequency signal in the output signal increases.

It should be noted that the phase rotation helps to extract specific frequencies or features in the signal, thereby helping to better identify the object or structure.

Preferably, the phase rotation can be achieved by adaptive control, with real-time adjustment according to environmental changes and changes in signal characteristics, which enables the system to maintain optimal performance under different conditions.

Specifically, the adaptive control of the phase rotation includes:

s301: adjusting the angle of phase rotation;

S302: detecting the proportion of the signal with a specific frequency after phase modulation of the output signal based on a frequency integrated detector;

s303: and (3) carrying out angle feedback control on the phase rotation based on the detection result of the specific frequency signal proportion until the specific frequency signal proportion detection reaches a certain set threshold value.

Compared with the prior art, the invention carries out phase modulation on the signals through phase rotation, and can extract specific frequency or characteristics in the signals, thereby being beneficial to better identifying targets or structures and improving the resolution and the identification sensitivity of ultrasonic detection and electromagnetic ultrasonic detection. In addition, the phase rotation of the invention can be realized through adaptive control, and real-time adjustment is carried out according to environmental change and signal characteristic change, so that the system can maintain optimal performance under different conditions, and the detection capability and interference resistance to complex structures are improved.

Specifically, the internal damage assessment of the aluminum-based composite material in S4 includes:

the synthesized detection signals after the multi-frequency mixing processing are comprehensively displayed on a display.

In the implementation process, a technician can judge whether the region has structural defects according to whether the waveform characteristics of the determined region of the composite material to be detected have mutation relative to the waveform characteristics of the adjacent region.

It will be appreciated that the combined display of the mixed signals on a display allows the viewer to see the interaction between the two frequency components at the same time, which helps to fully understand the characteristics of the ultrasound signals in different frequency ranges, and the new frequency components they form after mixing, for easier comparison and interaction.

Specifically, as shown in fig. 4, for the ultrasonic and electromagnetic ultrasonic composite detection, when the debonding and layering defects exist, the characteristics of the common ultrasonic detection signal and the electromagnetic ultrasonic detection signal are displayed, and the comprehensive effect result between the two frequency components can be seen at the same time, so that the comprehensive understanding of the characteristics of the ultrasonic signals in two frequency sources and the new frequency components formed after mixing the ultrasonic signals is facilitated, and comparison and interaction are easier.

Compared with the prior art, the invention adopts the mixing treatment and then comprehensively displays the characteristics of two detection signals including ultrasonic and electromagnetic ultrasonic on one display: on one hand, the surface and the inside of the small part and the cavity structural part can be comprehensively detected based on the respective advantages of the two detection signals, so that the omission ratio is reduced, and the sensitivity is improved; on the other hand, the areas where the two detection signals can be detected can be mutually verified, errors caused by interference are discharged, and accuracy is improved.

Specifically, the internal damage evaluation of the aluminum-based composite material in S4 includes:

Based on measuring distance h _Measuring And screening out the defective area.

Specifically, the method comprises the following steps:

Specifically, the step S401 of obtaining the actual distance between the reflecting surface and the incident surface in the composite material includes: the actual distance between the reflecting surface and the incident surface is determined by recording the difference between the transmitted and received reflection times and the propagation speed of sound in the material, and the measured distance between the reflecting surface and the incident surface is determined in the same manner in S402.

Specifically, the distance h between the incident surface and the defective region is determined in S403 _{Lack of supply} Comprising the following steps:

h _measuring ＜h _{Real world} Then is described inThe reflection type defect exists in the corresponding depth of the current position sound path, h _Measuring I.e. the distance h between the incident surface and the defect area _{Lack of supply} 。

It will be appreciated that the upper surface of the defect area becomes a new reflective surface, the distance h between the incident surface and the defect area _{Lack of supply} ＝h _Measuring 。

Specifically, acquiring the length a and the width b of the defect area in S404 includes: and detecting adjacent areas of the defect areas screened in the step S403, obtaining complete defect areas according to the method of the step S401-S403, and determining the length a and the width b of the complete defect areas.

In the prior art, the ultrasonic nondestructive testing needs to use the testing means with different penetrating power and resolution to test the cavity structural member and the small-sized member from different testing surfaces respectively, so that the complete size and position information of the defect area can be obtained; compared with the prior art, the method and the device can obtain the complete size and position information of the defect area only by detecting the corresponding outer surface of the defect area, thereby greatly improving the detection efficiency and the defect identification capability.

On the other hand, the invention also discloses an aluminum-based composite material composite ultrasonic nondestructive testing device, as shown in fig. 6, comprising: the integrated detector, the first signal processing module, the second signal processing module and the mixing processing module;

The integrated detector detects the surface of the material to be detected to obtain an ultrasonic detection signal and an electromagnetic ultrasonic detection signal;

the first signal processing module is used for preprocessing the ultrasonic detection signals to obtain digital signals of the ultrasonic detection signals;

the second signal processing module preprocesses the electromagnetic ultrasonic detection signal to obtain a digital signal of the electromagnetic ultrasonic detection signal;

the frequency mixing processing module is used for carrying out frequency mixing processing on the ultrasonic detection signals and the digital signals of the electromagnetic ultrasonic detection signals to obtain a composite detection signal with two signal characteristics, and the internal damage of the aluminum-based composite material is evaluated based on the composite detection signal.

Specifically, the integrated detector is provided with a waveform generator, a detection coil and a signal receiving device;

the waveform generator is capable of transmitting ultrasonic waves to the object to be detected;

the detection coil can generate a dynamic alternating magnetic field, and the dynamic alternating magnetic field generates Lorentz force/magnetostriction force in the detected object and forms ultrasonic waves;

the signal receiving device is capable of receiving an ultrasonic detection signal and an electromagnetic ultrasonic detection signal.

Preferably, the signal receiving means is provided with one for receiving the ultrasonic detection signal and the electromagnetic ultrasonic detection signal at the same time.

It should be noted that, the waveform generator and the detection coil can be provided with two independent signal processing modules for respective preprocessing after receiving the ultrasonic frequencies generated by the waveform generator and the detection coil by the signal receiving device.

Compared with the prior art, the signal receiving device is shared, so that the integration level is improved, the volume is reduced, and the cost is reduced.

Specifically, the first signal processing module comprises a first amplifier, a first phase sensitive detector, a first filter and a first analog-to-digital converter which are sequentially communicated in a circuit one-way manner; the second signal processing module comprises a second amplifier, a second phase sensitive detector, a second filter and a second analog-to-digital converter which are communicated in sequence in a circuit unidirectional manner;

the first amplifier and the second amplifier are respectively used for amplifying the ultrasonic detection signal and the electromagnetic ultrasonic detection signal; the first phase-sensitive detector and the second phase-sensitive detector are respectively used for demodulating the amplified ultrasonic detection signals and the electromagnetic ultrasonic detection signals and extracting analog signals with specific frequencies from the analog signals; the analog signal of a particular frequency may be a signal that includes phase and amplitude characteristics of acoustic impedance changes, propagation velocity changes.

The first filter and the second filter are respectively used for further removing clutter and reserving analog signals with specific frequencies for the ultrasonic detection signals and the electromagnetic ultrasonic detection signals after demodulation processing.

The first analog-to-digital converter and the second analog-to-digital converter are used for converting the ultrasonic detection signal and the electromagnetic ultrasonic detection signal from analog signals to digital signals.

It should be noted that the amplifier, the phase sensitive detector, the filter and the analog-to-digital converter may be reasonably set according to different frequencies and amplitudes of the detection signals.

Specifically, the mixing processing module comprises a first electronic filter, a second electronic filter, a first phase modulation unit, a second phase modulation unit and a mixer; the first electronic filter, the first phase modulation unit and the mixer are communicated in one direction through a circuit, and the second electronic filter, the second phase modulation unit and the mixer are communicated in one direction through a circuit.

Specifically, the first electronic filter is used for digitally filtering the digital signal of the ultrasonic detection signal, the second electronic filter is used for digitally filtering the digital signal of the electromagnetic ultrasonic detection signal, and the digital signal with specific frequency is extracted from the digital signal to remove clutter.

Preferably, the first electronic filter selects a bandpass filter and the second electronic filter selects an adaptive filter.

Compared with the prior art, the invention selects different digital filters for the digital signal of the ultrasonic detection signal and the digital signal of the electromagnetic ultrasonic detection signal respectively, on one hand, specific frequency components can be extracted or removed from complex signals, a highly controllable filtering effect is provided, the separation of different signal sources is facilitated, and the mutual interference of the two detection signals is reduced; on the other hand, the interference of the small-size structure and the cavity structure on ultrasonic detection signals can be improved, the interference of electromagnetic ultrasonic detection during complex structure detection is improved, and the detection accuracy and sensitivity are improved; in addition, digital filters generally have better stability from environmental conditions and component drift, which makes them more reliable in long term use and under changing operating environments.

Specifically, the first phase modulation unit is used for carrying out phase modulation on the digital signal of the ultrasonic detection signal, and the second phase modulation unit is used for carrying out phase modulation on the digital signal of the ultrasonic detection signal, and the phase modulation unit comprises forward rotation or reverse rotation for a certain angle, so that the proportion of the specific frequency signal in the output signal is increased, and the object or structure can be better identified.

Preferably, the first phase modulation unit and the second phase modulation unit are further connected with an adaptive control unit, and the adaptive control unit can realize real-time adjustment according to environmental changes and changes of signal characteristics through adaptive control, so that the system can maintain optimal performance under different conditions.

Specifically, the adaptive control unit includes: a frequency integrated detector and a feedback control module.

When the method is implemented, the proportion of the signals with specific frequencies after phase modulation is output based on the frequency integrated detector;

inputting the detection result of the specific frequency signal proportion into a feedback control module, setting a certain set threshold value in the feedback control module, and respectively performing feedback control on the angles of the first phase modulation unit and the second phase modulation unit based on the feedback control module until the specific frequency signal proportion detection reaches the certain set threshold value.

Specifically, the mixer is provided with a mixing calculation module, which can perform mixing calculation on two detection signals, and the output synthesized detection signal Z (f) meets the following conditions:

Specifically, by this convolution operation, the spectrum of the mixed signal can be obtained, which contains information of two frequency components: one component is used to measure defect information of near-surface or cavity structure material and the other frequency component is used for detection of deeper structures.

It will be appreciated that multi-frequency mixing may be used to integrate information over multiple frequency ranges, thereby obtaining more comprehensive, multi-level signal characteristics; the multi-frequency mixing can extract a plurality of frequency components from the original signal, and the characteristics of the plurality of frequency components are included, so that the frequency spectrum information is enhanced, and higher resolution can be obtained in the frequency domain.

For a better illustration of the invention, the following examples and comparative examples are set forth:

example 1

The embodiment discloses an aluminium base combined material compound supersound nondestructive test device, includes:

the integrated detector, the first signal processing module, the second signal processing module and the mixing processing module;

the frequency mixing processing module carries out frequency mixing processing on the ultrasonic detection signals and the digital signals of the electromagnetic ultrasonic detection signals to obtain a composite detection signal with two signal characteristics, and the internal damage evaluation of the aluminum-based composite material can be carried out based on the composite detection signal.

The integrated detector is provided with a waveform generator, a detection coil and a signal receiving device;

The signal receiving device receives the ultrasonic detection signal and the electromagnetic ultrasonic detection signal simultaneously.

the first amplifier and the second amplifier are respectively used for amplifying the ultrasonic detection signal and the electromagnetic ultrasonic detection signal; the first phase-sensitive detector and the second phase-sensitive detector are respectively used for demodulating the amplified ultrasonic detection signals and the electromagnetic ultrasonic detection signals and extracting analog signals with specific frequencies from the analog signals; analog signals of a particular frequency are phase and amplitude characteristics that include a change in acoustic impedance and a change in propagation velocity.

The frequency mixing processing module comprises a band-pass filter, a second electronic filter, a first phase modulation unit, a second phase modulation unit and a frequency mixer; the band-pass filter, the first phase modulation unit and the mixer are communicated in one direction through a circuit, and the adaptive filter, the second phase modulation unit and the mixer are communicated in one direction through the circuit.

On the one hand, the filter can extract or remove specific frequency components from complex signals, provides a highly controllable filtering effect, is beneficial to separating different signal sources, and reduces mutual interference of two detection signals; on the other hand, the interference of the small-size structure and the cavity structure on ultrasonic detection signals can be improved, the interference of electromagnetic ultrasonic detection during complex structure detection is improved, and the detection accuracy and sensitivity are improved; in addition, digital filters generally have better stability from environmental conditions and component drift, which makes them more reliable in long term use and under changing operating environments.

The first phase modulation unit is used for carrying out phase modulation on the digital signal of the ultrasonic detection signal, the second phase modulation unit is used for carrying out phase modulation on the digital signal of the ultrasonic detection signal, and the forward or reverse rotation phase is adopted for a certain angle, so that the proportion of the specific frequency signal in the output signal is increased, and the object or structure can be better identified.

The first phase modulation unit and the second phase modulation unit are also connected with an adaptive control unit, and real-time adjustment according to environmental changes and changes of signal characteristics can be realized through the adaptive control, so that the system can maintain optimal performance under different conditions.

The adaptive control unit is provided with a frequency integrated detector and a feedback control module.

Detecting the proportion of the signal with a specific frequency after phase modulation of the output signal based on a frequency integrated detector;

The mixer is provided with a mixing calculation module, can carry out mixing calculation on two detection signals, and the output synthesized detection signal Z (f) meets the following conditions:

Example 2

The embodiment discloses an internal damage evaluation method of an aluminum-based composite material, which uses the device of the embodiment 1 to evaluate small-size aluminum-based alloy The cylinder) composite material detection, the internal prefabrication layering defect, the composite ultrasonic nondestructive detection method comprises the following specific steps:

as shown in fig. 1, includes:

s1: the integrated detector acquires an ultrasonic detection signal and an electromagnetic ultrasonic detection signal of the composite material to be detected;

the integrated detector is provided with a waveform generator, a detection coil capable of generating a dynamic alternating magnetic field and a signal receiving device;

the waveform generator sends out a preset continuous wave or pulse signal excitation to emit ultrasonic waves to the detected object;

the signals picked up by the ultrasonic signal receiving device and the electromagnetic ultrasonic signal receiving device respectively enter the first signal processing module and the second signal processing module for processing.

s202: the two analog signals are subjected to demodulation treatment and filtering treatment by a phase sensitive detector in sequence, and the analog signals with specific frequencies are extracted to filter clutter;

S203: and obtaining two digital signals by analog-to-digital conversion of the two analog signals subjected to the filtering treatment.

S3: filtering, phase modulating and mixing digital signals of the ultrasonic detection signals and the electromagnetic ultrasonic detection signals to obtain a composite detection signal;

carrying out band-pass filtering on the digital signal of the ultrasonic detection signal and carrying out self-adaptive filtering on the digital signal of the electromagnetic ultrasonic detection signal;

selecting a rotation angle, and carrying out phase rotation on the signal;

s301: adjusting the left-right rotation angle of the phase;

s303: and (3) carrying out angle feedback control on the phase rotation based on the detection result of the specific frequency signal proportion until the detection of the specific frequency signal proportion reaches a set threshold (90%).

The mixing calculation module is used for mixing and calculating two detection signals, and the output synthesized detection signal Z (f) meets the following conditions:

wherein the frequency of the ultrasonic detection signal is 5MHz, the frequency of the electromagnetic ultrasonic detection signal is 50MHz, t is time, and u is multiplication variable.

And S4, evaluating the internal damage of the aluminum-based composite material, wherein the method comprises the following steps of:

s401: recording the difference between the transmitted and received reflection times and determining the actual distance h between the reflecting surface and the incident surface by the propagation velocity of sound in the material _{Real world} ；

S402: recording the difference between the transmitted and received reflection times and determining the measured distance h between the reflecting surface and the incident surface of the material at the propagation velocity of the sound _Measuring ；

S403: comparison h _{Real world} 、h _Measuring If h _Measuring ＜h _{Real world} Indicating that reflection type defects exist at the corresponding depth of the sound path of the current position, and h _Measuring I.e. the distance h between the incident surface and the defect area _{Lack of supply} ；

S404: detecting the adjacent areas of the defect areas screened in S403, obtaining complete defect areas according to the S401-S403 method, determining the length a and the width b of the complete defect areas, and measuring the distance h between the reflecting surface and the incident surface based on the length a and the width b _Measuring And (5) evaluating the internal damage of the aluminum-based composite material.

In this example, defect detection is performed on a small-sized aluminum-based composite material from the top, bottom, left and right multiple times of approaching the defect region in the operation view, and the detection results are shown in table 1 and fig. 4:

TABLE 1

The detected defect type is an aluminum-sandwiched layer, the depth is 0.68mm, the thickness is 0.09mm, and the defect type is compared with the actual situation (shown in fig. 2) and accords with the actual defect type and size. The method can accurately identify the defects of the small-size sample, and the repeated measurement results are basically consistent, so that the reliability is high.

Fig. 4 shows an ultrasonic spectrum diagram of the detection result of the debonding delamination defect:

when the debonding layer defect exists, the debonding layer affects the detection result as a new reflection surface, and a defect wave (160.1 mm) is displayed at a shorter distance from the incidence surface.

Example 3

The embodiment discloses an internal damage assessment method for an aluminum-based composite material, which uses the device of the embodiment 1 to detect the aluminum-based composite material with a hollow cavity structure (a hollow cylinder with the inner diameter of 50mm and the outer diameter of 80 mm), and comprises the following specific steps:

as shown in fig. 1, includes:

the waveform generator emits a preset continuous wave or pulse signal excitation and emits ultrasonic waves (2.5 MHz and other frequency electromagnetic waves) to the detected object;

The detection coil is excited by a preset high-pulse signal (electromagnetic wave with the same frequency as 50 MHz) sent by the signal generator, and generates Lorentz force/magnetostriction force in the detected object to form ultrasonic waves;

signals picked up by the ultrasonic signal receiving device and the electromagnetic ultrasonic signal receiving device respectively enter the first signal processing module and the second signal processing module for processing.

Selecting a rotation angle, and carrying out phase rotation on the signal;

s301: adjusting the left-right rotation angle of the phase;

wherein the frequency of the ultrasonic detection signal is 2.5MHz, the frequency of the electromagnetic ultrasonic detection signal is 50MHz, t is time, and u is multiplication variable.

S402: recording the difference between the transmitted and received reflection times and determining the speed of propagation of sound in the material between the reflecting surface and the incident surfaceMeasuring distance h _Measuring ；

In the embodiment, the aluminum-based composite material with the cavity structure is subjected to defect detection, wherein the detected defect type is holes, the depth is 7.5mm, and the size isAs shown in FIG. 3, the defect detection of the aluminum-based composite material with the cavity structure by the method is shown.

Comparative example 1

The present example discloses a damage assessment method for an aluminum-based composite material, which differs from example 2 only in that:

the detection coil and electromagnetic ultrasonic detection function were turned off, and the small-sized aluminum piece of example 2 was detected using a single ultrasonic nondestructive detection function.

Fig. 5 shows an ultrasonic spectrum diagram of a single ultrasonic detection result of the debonding delamination defect:

as shown in fig. 5, in a normal state, an incident wave emitted by the integrated detector or formed on the detection surface enters the surface of the part to be detected and propagates to the reflection surface to be reflected to the signal receiving device in the integrated detector, and the system can determine the ultrasonic travel according to the emission and reflection time, so as to determine the distance between the incident surface and the reflection surface; the display identifies the signal, forms the ultrasonic spectrogram which takes the distance between the reflecting surface and the incident surface as the abscissa and takes the signal intensity as the ordinate; because the single ultrasonic detection has poor detection effect on small pieces with the diameter smaller than 2mm, as shown in fig. 5, the debonding delamination defect can not be detected, and the spectrogram only shows the bottom wave detection data; this is because only the normal ultrasonic detection signal features are displayed.

In this comparative example, there was a problem of blind area in single ultrasonic nondestructive testing of small-sized aluminum pieces, which was unable to detect them.

Comparative example 2

The present example discloses a damage assessment method for an aluminum-based composite material, which is unique from example 3 in that:

the detection coil and electromagnetic ultrasonic detection function are closed, and the cavity structure aluminum-based composite material of the embodiment 3 is detected by adopting a single ultrasonic nondestructive detection function.

In the comparative example, the aluminum-based composite material with the cavity structure cannot be detected by the single ultrasonic nondestructive detection function due to the interference of the cavity structure.

Comparative example 3

the waveform generator and ultrasonic detection function were turned off and the small-sized aluminum piece of example 2 was detected using a single electromagnetic ultrasonic detection function.

In this embodiment, defect detection is performed on the small-size aluminum-based composite material, the detection result is shown in table 1, the detected defect type is an aluminum-sandwiched layer, the depth is 1.2mm, the thickness is 0.15mm, and compared with the actual situation, the difference between the position and the size of the detected defect is larger.

Comparative examples 2 and 3 and comparative examples 1, 2 and 3 show that the detection effect of ultrasonic detection on small-sized composite aluminum parts and aluminum parts with cavity structures can be remarkably improved by adopting the scheme of examples 2-3 according to the invention; compared with single electromagnetic ultrasonic detection, the sensitivity, accuracy and precision of precise measurement can be greatly improved.

The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.

Claims

1. A method for evaluating damage to an aluminum-based composite material, comprising:

2. The method of claim 1, wherein the evaluating the internal damage to the aluminum-based composite material comprises:

Based on measuring distance h _Measuring And screening out the defective area.

3. The method of claim 2, wherein the evaluating the internal damage to the aluminum-based composite material comprises:

4. A method according to claim 3, wherein obtaining the actual distance between the reflecting surface and the incident surface in the composite material in S401 comprises: the actual distance between the reflecting surface and the incident surface is determined by recording the difference between the transmitted and received reflection times and the propagation speed of sound in the material, and the measured distance between the reflecting surface and the incident surface is determined in the same manner in S402.

5. A method according to claim 3, wherein the distance h between the incidence plane and the defect region is determined in S403 _{Lack of supply} Comprising the following steps:

6. The method of claim 3, wherein obtaining the length a and the width b of the defective area in S404 comprises: and detecting adjacent areas of the defect areas screened in the step S403, obtaining complete defect areas according to the method of the step S401-S403, and determining the length a and the width b of the complete defect areas.

7. The method of any of claims 1-6, wherein the digital signal mixing process comprises: and mixing digital signals corresponding to the ultrasonic detection signals and the electromagnetic ultrasonic detection signals through multiplication.

8. The method of claim 7, wherein the signal Z (f) output after the digital signal mixing process satisfies:

wherein A is ₁ 、A ₂ Ultrasonic detection signals and electromagnetic ultrasonic detection signals respectivelyMeasuring the amplitude of the signal; f (f) ₁ 、f ₂ The frequency of the ultrasonic detection signal and the frequency of the electromagnetic ultrasonic detection signal are respectively, t is time, and u is a multiplication variable.

9. The method of claim 8, wherein the aluminum-based composite internal damage assessment comprises: the synthesized detection signals after the multi-frequency mixing processing are comprehensively displayed on a display.

10. The method of claim 9, wherein the aluminum-based composite internal damage assessment comprises: judging whether debonding, inclusion, holes, looseness and crack defects exist in each region according to waveform characteristics of a synthesized detection signal of the composite material to be detected.