An online rapid detection device and method for composite material bonding force combining laser shock wave and Lamb wave

Abstract

The present invention provides an online rapid detection device and method for composite material bonding force combining laser shock wave and Lamb wave, comprising an excitation ultrasonic sensor, a receiving ultrasonic sensor, a laser, a light guide device, a sensor excitation receiving device, and a computer, wherein the excitation ultrasonic sensor and the receiving ultrasonic sensor are respectively connected to the sensor excitation receiving device through a wire, the light guide device is connected to the laser, the excitation ultrasonic sensor and the receiving ultrasonic sensor are symmetrically arranged on both sides of the laser, and the three are located on the same side of the composite material plate; in terms of sound wave selection, Lamb waves with higher "spacing" sensitivity are used to scan "spacing"; in terms of signal acquisition, an active excitation method is used to greatly improve the purity of the detection signal and extract more "spacing" feature information. The present invention effectively solves the problems of large signal interference and difficult defect identification in the process of laser shock wave composite material bonding force detection.

Description

Technical Field

[0001] The present invention belongs to the technical fields of laser application and nondestructive testing of composite materials, and in particular to an online rapid detection device and method for composite material bonding force combining laser shock wave and Lamb wave, which is suitable for the adhesion measurement of thin films or adhesive structures, various composite materials, coatings and other types of interface bonding force measurement. Background Art

[0002] The bonding point of composite materials is the key part of the composite material structure and also the weak part of the structural strength. Insufficient bonding force will greatly reduce the strength of the material, which may cause catastrophic consequences in severe cases. Therefore, the bonding strength testing of composite materials is very important.

[0003] Laser shock waves are ultrasonic waves generated by the explosion of laser-induced high-pressure, high-energy plasma on the surface of materials. They are mainly reflected and coupled at the material interface in the form of longitudinal waves, which can form large tensile stress on the bonding surface of composite materials. If the stress value exceeds the bonding strength index of the material, local "lamination" will occur inside the material.

[0004] In order to capture the "layer cracking" phenomenon, Zhou Ming and others from Jiangsu University used a velocity interferometer to monitor the particle velocity on the back of the material in the patent CN1215320C "Quantitative determination method and device for laser shock of interface bonding strength", and used this to determine whether "layer cracking" occurred. This method is difficult to test, has high precision requirements, and takes a long time to detect, and cannot achieve online rapid detection of composite material structures; Nie Xiangfan and others from the Air Force Engineering University used piezoelectric sensors or electromagnetic ultrasonic sensors to receive interface reflection echo signals in patents CN201710874872 "A method for online rapid detection of composite material adhesion based on laser shock waves" and CN201810997996 "A method for detecting laser shock wave bonding based on electromagnetic ultrasonic technology" to determine whether "layer cracking" occurred. This method has very high requirements for laser performance parameters, and the bonding consistency of the conductive sheet or ferromagnetic sheet on the surface of the composite material has a greater impact on the detection results.

[0005] On the one hand, both of the above methods use lasers to generate longitudinal waves in the material to be tested for detection. The propagation direction of the sound wave is the thickness direction, and there is only one vibration mode, which has limited ability to characterize the "spallation" feature; while Lamb waves have a wider propagation range and diverse modes, and are more sensitive to the "spallation" feature. On the other hand, the above methods all passively receive the signal scattered by the material when the laser is impacted, which will largely introduce interference information such as noise generated during the laser impact process, making it more difficult to extract the "spallation" feature information. Summary of the invention

[0006] In view of the defects and shortcomings in the prior art, the purpose of the present invention is to provide an online rapid detection device and method for the bonding strength of composite materials combining laser shock wave and Lamb wave, adopting a detection method combining laser shock wave and Lamb wave; in ultrasonic selection, Lamb wave (guided wave) with higher "lamination" sensitivity is used instead of longitudinal wave (body wave) to scan the "lamination"; in signal acquisition, active excitation and reception are used instead of the passive reception method of previous bonding strength detection methods, which greatly improves the purity of the detection signal and extracts more "lamination" characteristic information, so as to achieve the purpose of accurate detection of the bonding strength of composite materials.

[0007] The technical solution of the present invention is as follows:

[0008] An online rapid detection device for composite material bonding force combining laser shock wave and Lamb wave, comprising an excitation ultrasonic sensor, a receiving ultrasonic sensor, a laser, a light guide device, a sensor excitation receiving device and a computer.

[0009] The excitation ultrasonic sensor and the receiving ultrasonic sensor are respectively connected to the sensor excitation receiving device through wires, the light guide device is connected to the laser, the excitation ultrasonic sensor and the receiving ultrasonic sensor are symmetrically arranged on both sides of the laser, and the three are located on the same side of the composite material plate;

[0010] The computer is connected to the laser and the sensor excitation receiving device.

[0011] Preferably, it also includes an energy absorbing layer and an energy confinement layer bonded to the energy absorbing layer, wherein the energy absorbing layer is bonded to the composite material plate, and the bonding position is located at the irradiation spot of the laser.

[0012] Preferably, the energy absorbing layer is black tape or aluminum foil, and the energy confinement layer is transparent glass or water.

[0013] A method for online rapid detection of composite material bonding force combining laser shock wave and Lamb wave is implemented by using an online rapid detection device for composite material bonding force combining laser shock wave and Lamb wave, and the specific steps are as follows:

[0014] S1: controlling the excitation ultrasonic sensor to excite Lamb waves in the composite material plate for the first time through the sensor excitation receiving device, and receiving the Lamb waves with the receiving ultrasonic sensor;

[0015] S2: adjusting the light guide device so that the end of the laser is located in the middle area of ​​the propagation path of the Lamb wave;

[0016] S3: Setting laser parameters, so that the tensile stress generated by the laser shock wave in the bonding layer of the composite material plate through the laser controller is equal to the bonding strength index of the bonding layer of the composite material plate;

[0017] S4: Keeping the relative positions of the excitation ultrasonic sensor, the receiving ultrasonic sensor and the composite material plate unchanged, and controlling the excitation ultrasonic sensor to excite and receive the Lamb wave again through the sensor excitation receiving device;

[0018] S5: comparing the signal difference of the Lamb waves received twice in step S1 and step S4, and evaluating whether the composite material plate is delaminated or whether the bonding strength meets the requirements;

[0019] S6: Complete signal acquisition, feature extraction and result analysis through computer.

[0020] Preferably, the excitation ultrasonic sensor and the receiving ultrasonic sensor in steps S1 and S4 are non-contact air-coupled sensors, and the distance between the excitation ultrasonic sensor and the receiving ultrasonic sensor is ≧50 mm. When the two are arranged, they form a certain angle with the laser, that is, the incident angle, which conforms to Snell's law.

[0021] Preferably, the excitation signal for exciting the ultrasonic sensor in step S1 and step S4 is a modulated narrow-band signal.

[0022] Preferably, in steps S1 and S4, the ultrasonic sensor is excited to excite low-order Lamb waves in the composite material plate for detection.

[0023] Preferably, in step S5, the signal difference of the Lamb wave includes changes in the time domain, frequency domain and time-frequency comprehensive characteristics of the received signal;

[0024] Among them, the time domain characteristics of the signal include the time, amplitude, phase of the direct wave, as well as the defect reflection wave packet and the wave packet of modal transformation and its characteristics; the frequency domain characteristics of the signal are extracted by Fourier transform, including the distribution of spectrum peak points, amplitude or energy; the short-time Fourier transform, continuous wavelet transform or Wenger-Wiener transform are used to obtain the time-frequency characteristics of the signal, including the distribution of signal energy in time and frequency.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention uses Lamb waves to scan "spatial fissures" in terms of ultrasonic wave selection. Lamb waves have a wider propagation range, diverse modes, and are more sensitive to "spatial fissure" characteristics.

[0027] (2) In terms of signal acquisition, the present invention adopts active excitation and reception instead of the passive reception method of the previous bonding force detection method, which reduces the interference information such as noise generated during the laser impact process, greatly improves the purity of the detection signal, and extracts more "spatial cracking" characteristic information. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a structural schematic diagram of an online rapid detection device for composite material bonding force combining laser shock wave and Lamb wave of the present invention;

[0029] Figure 2 It is a flow chart of the detection steps of the online rapid detection method of the bonding force of composite materials combining laser shock wave and Lamb wave of the present invention;

[0030] Figure 3 It is a curve diagram of the time domain signal received by the air coupling sensor for the first time in the online rapid detection method of the composite material bonding force combining laser shock wave and Lamb wave of the present invention;

[0031] Figure 4 It is a curve diagram of the time domain signal received by the air coupling sensor for the second time in the online rapid detection method of the composite material bonding force combining laser shock wave and Lamb wave of the present invention;

[0032] The reference numerals of the present invention are listed as follows:

[0033] 1-excitation ultrasonic sensor, 2-light guiding device, 3-energy confinement layer, 4-energy absorption layer, 5-computer, 6-receiving ultrasonic sensor, 7-laser, 8-sensor excitation receiving device, 9-adhesive layer, 10-composite material plate. DETAILED DESCRIPTION

[0034] The specific implementation of the present invention is described below in conjunction with the accompanying drawings and embodiments:

[0035] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0036] At the same time, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and are not used to limit the scope of the present invention. The change or adjustment of the relative relationship should also be regarded as the scope of the present invention without substantially changing the technical content. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features shown. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly indicate the number of technical features indicated. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0037] The present invention provides an online rapid detection device and method for composite material bonding force combining laser shock wave and Lamb wave, and adopts a detection method combining laser shock wave and Lamb wave to accurately detect the bonding force of composite materials.

[0038] The present invention is further described below in conjunction with the accompanying drawings.

[0039] Example 1

[0040] like Figure 1 As shown, an online rapid detection device for composite material bonding force combining laser shock wave and Lamb wave comprises an excitation ultrasonic sensor 1, a receiving ultrasonic sensor 6, a laser 7, a light guide device 2, a sensor excitation receiving device 8 and a computer 5.

[0041] Among them, the excitation ultrasonic sensor 1 and the receiving ultrasonic sensor 8 are respectively connected to the sensor excitation receiving device 8 through wires, the light guide device 2 is connected to the laser 7, the excitation ultrasonic sensor 1 and the receiving ultrasonic sensor 6 are symmetrically arranged on both sides of the end of the light guide device 2, and the three are located on the same side of the composite material plate 10; the sensor excitation receiving device 8 controls the excitation ultrasonic sensor 1 and the receiving ultrasonic sensor 6 to excite low-order Lamb waves; the excitation ultrasonic sensor 1 is used to excite Lamb waves in the composite material plate 10 for the first time, and the receiving ultrasonic sensor 6 is used to receive the Lamb waves, and by adjusting the light guide device 2, the laser impact position is located in the middle area of ​​the propagation path of the Lamb waves excited by the excitation ultrasonic sensor 1.

[0042] The computer 5 is connected to the laser 7 and the sensor excitation receiving device 8, and the computer 5 is used to perform data analysis and feed back the detection results.

[0043] In addition, an energy confinement layer 3 is arranged on the energy absorption layer 4 . The energy absorption layer 4 is bonded to the composite material plate 10 , and the bonding position is located where the laser 7 generates an irradiation spot.

[0044] Specifically, the energy absorption layer 4 is a black tape or aluminum foil, and the energy confinement layer 3 is transparent glass or water. In this embodiment, the energy absorption layer 4 is a black tape, and the energy confinement layer 3 is water.

[0045] In this embodiment, a composite material plate 10 with an adhesive layer 9 is selected as a test object, and two excitation ultrasonic sensors 1 and receiving ultrasonic sensors 6 are fixed on the same side of the composite material plate 10, 100 mm apart, wherein the performance parameters of the excitation ultrasonic sensor 1 and the receiving ultrasonic sensor 6 are the same.

[0046] like Figure 2-4 As shown, a method for online rapid detection of composite material bonding force combining laser shock wave and Lamb wave is implemented by using an online rapid detection device for composite material bonding force combining laser shock wave and Lamb wave. The specific steps are as follows: Figure 2 As shown:

[0047] S1: The excitation ultrasonic sensor 1 is controlled by the sensor excitation receiving device 8 to excite Lamb waves in the composite material plate 10 for the first time, and the receiving ultrasonic sensor 6 is used to receive the Lamb waves; the sensor excitation receiving device 8 selects Retic-RPR4000, and the excitation ultrasonic sensor 1 and the receiving ultrasonic sensor 6 use air-coupled sensors with a center frequency of 200kHz. Based on Snell's theorem and dispersion curve, the installation angle is adjusted to 14°, which can excite a relatively single low-order A0 mode Lamb wave. The signal is as follows Figure 3 As shown in the figure, the excitation signal is a 5-cycle sine wave modulated by a Hanning window, namely a tone burst signal.

[0048] Among them, Snell's theorem states that when light waves propagate from one medium to another medium with a different refractive index, refraction will occur, reflecting the relationship between the angle of incidence and the angle of refraction.

[0049] S2: adjusting the light guide device 2 so that the end of the light guide device 2 is located in the middle area of ​​the propagation path of the Lamb wave;

[0050] S3: Set the parameters of laser 7. The model of laser 7 is selected as Nd: Glass. The tensile stress generated by guiding the laser shock wave at the adhesive layer 9 of the composite material plate 10 through the light guiding device is equal to the bonding strength index of the adhesive layer 9 of the composite material plate 10. If the bonding strength of the adhesive layer 9 does not meet the index requirements, "layer cracking" will occur; otherwise, "layer cracking" will not occur and no damage will occur.

[0051] S4: Keep the relative positions of the excitation ultrasonic sensor 1 and the receiving ultrasonic sensor 6 and the composite material plate 10 unchanged, and excite and receive the Lamb wave again through the sensor excitation receiving device 8, and receive the signal as shown in FIG. Figure 4 ;

[0052] S5: comparing the signal difference of the Lamb waves received twice in step S1 and step S4, and evaluating whether the composite material plate 10 is delaminated or whether the bonding strength meets the requirements;

[0053] Specifically, in step S5, the signal difference of the Lamb wave includes changes in the time domain, frequency domain and time-frequency comprehensive characteristics of the received signal;

[0054] The time domain characteristics of the received signal include the time, amplitude, phase of the direct wave, whether there is a defect reflection wave packet and the wave packet of mode conversion and its characteristics;

[0055] Receive the frequency domain characteristics of the signal and use Fourier transform to extract the frequency domain characteristics of the signal, including the distribution of spectrum peak points, amplitude or energy;

[0056] The time-frequency characteristics of the received signal are obtained by using short-time Fourier transform, continuous wavelet transform or Wenger-Wiener transform, including the distribution of signal energy in time and frequency.

[0057] S6: Complete signal acquisition, feature extraction and result analysis through computer 5; take the direct wave time and amplitude in the time domain characteristics of the received signal as an example to analyze whether "stripping" occurs. Use computer 5 to extract the time domain characteristics of the two signals before and after the laser shock. It can be seen that after the laser shock, the amplitude of the direct A0 modal wave packet decreases from 9.23mV to 5.68mV; the arrival time is delayed from 116.5μs to 113.8μs; it means that the composite material plate 5 has "stripping" under the laser shock, and its bonding strength index does not meet the requirements. On the contrary, the direct wave signal amplitude and arrival time should remain unchanged, indicating that the adhesive layer 9 of the composite material plate 10 has not "stripping" and the bonding strength index meets the requirements.

[0058] The present invention adopts the above method to accurately detect whether the bonding strength index of the adhesive layer of the composite material plate 10 meets the requirements.

[0059] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

[0060] Many other changes and modifications may be made without departing from the concept and scope of the present invention.It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for rapid online detection of composite material bonding strength combining laser shock wave and Lamb wave, characterized in that: The method is realized by using an online rapid detection device for the bonding force of composite materials combining laser shock waves and Lamb waves, wherein the online rapid detection device for the bonding force of composite materials combining laser shock waves and Lamb waves comprises an excitation ultrasonic sensor, a receiving ultrasonic sensor, a laser, a light guide device, a sensor excitation receiving device and a computer; The excitation ultrasonic sensor and the receiving ultrasonic sensor are connected to the sensor excitation receiving device through wires, respectively, and the light guide device is connected to the laser; the excitation ultrasonic sensor and the receiving ultrasonic sensor are symmetrically arranged on both sides of the laser, and the three are located on the same side of the composite material plate; the computer is connected to the laser and the sensor excitation receiving device; It also includes an energy absorbing layer and an energy confinement layer disposed on the energy absorbing layer, wherein the energy absorbing layer is bonded to the composite material plate, and the bonding position is located at the irradiation spot of the laser; The energy absorption layer is black tape or aluminum foil, and the energy confinement layer is transparent glass or water; The online rapid detection method of composite material bonding force combining laser shock wave and Lamb wave has the following specific steps: S1: controlling the excitation ultrasonic sensor to excite Lamb waves in the composite material plate for the first time through the sensor excitation receiving device, and receiving the Lamb waves with the receiving ultrasonic sensor; S2: adjusting the light guide device so that the end of the laser is located in the middle area of ​​the propagation path of the Lamb wave emitted by the excitation ultrasonic sensor; S3: setting laser parameters, so that the tensile stress generated in the bonding layer of the composite material plate by the laser shock wave emitted by the laser is equal to the bonding strength index of the bonding layer of the composite material plate; S4: Keeping the relative positions of the excitation ultrasonic sensor, the receiving ultrasonic sensor and the composite material plate unchanged, and controlling the excitation ultrasonic sensor to excite and receive the Lamb wave again through the sensor excitation receiving device; S5: comparing the signal difference of the Lamb waves received twice in step S1 and step S4, and evaluating whether the composite material plate is delaminated or whether the bonding strength meets the requirements; S6: Complete signal acquisition, feature extraction and result analysis through computer.

2. The online rapid detection method of composite material bonding strength combining laser shock wave and Lamb wave according to claim 1 is characterized in that: The excitation ultrasonic sensor and the receiving ultrasonic sensor in steps S1 and S4 are air-coupled sensors, and the distance between the excitation ultrasonic sensor and the receiving ultrasonic sensor is ≧50 mm, and the two are arranged to form a certain angle with the laser, that is, the incident angle, which conforms to Snell's law.

3. The online rapid detection method of composite material bonding strength combining laser shock wave and Lamb wave according to claim 1 is characterized in that: The excitation signal for exciting the ultrasonic sensor in step S1 and step S4 is a modulated narrow frequency band.

4. The online rapid detection method of composite material bonding force combining laser shock wave and Lamb wave according to claim 1 is characterized in that: In the steps S1 and S4, the ultrasonic sensor is excited to excite low-order Lamb waves in the composite material plate for detection.

5. The online rapid detection method of composite material bonding force combining laser shock wave and Lamb wave according to claim 1 is characterized in that: In step S5, the signal difference of the Lamb wave includes the changes in the time domain, frequency domain and time-frequency comprehensive characteristics of the received signal; wherein the signal time domain characteristics include the direct wave time, amplitude, phase and the defect reflection wave packet and the modal conversion wave packet and its characteristics; the signal frequency domain characteristics are extracted by Fourier transform, including the spectrum peak point distribution, amplitude or energy; the signal time-frequency characteristics are obtained by short-time Fourier transform, continuous wavelet transform or Wenger-Wiener transform, including the distribution of signal energy in time and frequency.

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