A laser shock wave composite material bonding force detection device and method based on sensor unit array

Abstract

The present invention provides a laser shock wave composite material bonding force detection device and method based on a sensor unit array, including a bonding force detection system and a signal acquisition system connected by a wire, using an excitation source (laser) and multiple receiving sources (sensor array), the sensor uses the laser source as the center of the circle to form a circular array, and the array distribution direction corresponds to the composite material ply direction, so as to realize a laser excitation at one time, and the array sensor simultaneously receives multiple shock wave response signals, extracts the "stripping" characteristic information in the array sensor unit receiving signal, obtains the circumferential distribution of the "stripping" characteristic in the laser shock area, and realizes the redefinition of the composite material bonding force index by defining the damage index and the square error. The present invention effectively solves the problem of laser shock wave composite material bonding force detection, and realizes a more comprehensive and accurate evaluation of the bonding force index through one-time excitation, circumferential multi-point reception, and multi-directional data fusion method.

Description

Technical Field

[0001] The present invention belongs to the field of laser technology and material performance testing, and in particular relates to a laser shock wave composite material bonding force detection device and method based on a sensor unit array, which is suitable for measuring the adhesion of thin films or adhesive structures, various composite materials, coatings and other types of interface bonding force. Background Art

[0002] Composite materials have been widely used in aerospace and other fields. Due to their special manufacturing process and relatively harsh service environment, they are prone to delamination, inclusions, and voids. For the above defect types, existing traditional methods such as ultrasound, industrial CT, microwave, and thermal infrared can achieve mature and reliable detection. However, for "kiss" bonding and weak bonding defects, the above traditional detection methods cannot effectively identify them. The above damage will expand during service, affecting the service life and even causing structural damage, resulting in disasters. In order to identify "kiss" bonding and weak bonding defects, it is necessary to effectively detect and evaluate the bonding strength of the composite material bonding layer.

[0003] Theoretically, the bonding strength of composite material adhesive layers can be evaluated through tensile method, bending method and fracture mechanics method, but the above methods are all destructive and difficult to apply to the testing of in-service products. Summary of the invention

[0004] In view of the defects and shortcomings in the prior art, the purpose of the present invention is to provide a laser shock wave composite material bonding force detection device and method based on a sensor unit array, which adopts an excitation source (laser) and multiple receiving sources (sensor array). The sensors are arranged in a circular array with the laser source as the center, so as to accurately detect the bonding force of the composite material.

[0005] The technical solution of the present invention is as follows:

[0006] A laser shock wave composite material bonding force detection device based on a sensor unit array, characterized in that it includes a bonding force detection system and a signal acquisition system connected by a wire,

[0007] The bonding force detection system includes a laser, a flange, a flexible light guide device, a sensor

[0008] A unit, an optical path protection fixture and a sensor excitation receiving device, wherein a plurality of the sensor units are arranged in an array on one side of the composite material to be tested through the flange; the laser shock wave generated by the laser is guided to the detection area of ​​the composite material to be tested through the flexible light guide device, the optical path protection fixture is arranged on the periphery of the port of the flexible light guide device, the flexible light guide device is fixed on the flange through the optical path protection fixture, and the sensor excitation receiving device is connected to the sensor unit through a wire;

[0009] The signal acquisition system comprises a high-speed acquisition system and a computer connected by wires, and the high-speed acquisition system is also connected to the sensor excitation receiving device by wires, and the computer is connected to the laser by wires.

[0010] Preferably, it also includes an energy absorbing layer and an energy confinement layer attached to the energy absorbing layer, wherein the energy absorbing layer is attached to the composite material to be tested, and the attachment position is located at the irradiation spot of the laser;

[0011] Wherein, the energy absorption layer is black tape or aluminum foil, and the energy confinement layer is transparent glass or water.

[0012] Preferably, the sensor unit array and the laser are located on the same side of the composite material to be tested, and the sensor unit array is evenly distributed in a ring shape with the end of the flexible light guide device as the center, and the radius of the ring is adjustable.

[0013] Preferably, the optical path protection fixing device is arranged on the periphery of the port of the flexible light guide device.

[0014] Preferably, the sensor unit includes an electromagnetic ultrasonic sensor unit, a piezoelectric ultrasonic sensor unit or an air-coupled sensor unit.

[0015] Preferably, the distance between the sensor unit and the end of the laser is ≧10 mm, the annular uniform distribution direction of the sensor unit array includes all the ply directions of the composite material, and in each ply direction, two sensor units are symmetrically distributed on both sides of the end of the flexible light guide device, that is, the angle between two adjacent sensor units is

[0016] The n is the number of sensor units, which is a multiple of the number of ply directions, and n is a positive integer; N is the number of composite material ply directions.

[0017] A method for detecting the bonding force of composite materials by laser shock wave based on a sensor unit array is implemented according to a device for detecting the bonding force of composite materials by laser shock wave based on a sensor unit array.

[0018] The specific steps are as follows:

[0019] S1: Adjust the laser parameters so that the tensile stress δ generated by the laser shock wave is not greater than the bonding strength index σ of the composite material bonding layer N Half, that is

[0020] S2: Control the laser to stimulate shock waves in the composite material for the first time, and all units in the sensor unit array simultaneously record the shock wave signals radiated from the laser shock area to the surrounding areas through a high-speed acquisition system and transmit them to the computer;

[0021] S3: Use a computer to extract the relevant signal features of the received signals of each unit in the sensor unit array to define the damage index DI in the corresponding direction of sensor unit i i , draw the circumferential distribution curve DI of the damage index during the first laser impact 1 , where i = 1, 2, ... n, i is the sensor unit number;

[0022] S4: For the composite material to be tested, a large number of qualified standard parts are tested to obtain the damage index distribution curve envelope under normal conditions as a benchmark, and the damage index circumferential distribution curve DI obtained during the first laser impact 1 , observe DI 1 Whether it is within the normal envelope of the damage index can be used to determine whether the bonding strength index of the composite material to be tested meets the requirements;

[0023] S5: If the damage index distribution curve envelope of the qualified standard parts under normal conditions cannot be obtained, the laser parameters need to be readjusted so that the tensile stress δ generated by the laser shock wave is equal to the bonding strength index σ of the composite material bonding layer, that is, δ = σ n According to step S2, the circumferential distribution curve DI of the damage index is obtained during the second laser shock 2 ;

[0024] S6: The damage index DI of the composite material to be tested 1 Distribution Curve and DI 2 The distribution curves are compared to determine whether the bonding strength index of the bonding layer of the tested material meets the requirements.

[0025] Preferably, in step S3, the damage indicators DI in different detection directions are i Definition: Take the amplitude of the defect reflection echo after the spalling in the received signal, the amplitude of the bottom surface reflection echo, the wave packet arrival time or the amplitude of the characteristic frequency point in the spectrum signal as the definition of the damage characteristic value A i ; When the eigenvalue A i When it is positively correlated with the severity of injury, it is calculated according to formula 1; when the eigenvalue A i When the injury severity is negatively correlated, the injury index DI i Calculate according to formula II; this ensures that the degree of damage increases, and the damage index DI i All increased;

[0026]

[0027]

[0028] Preferably, in step S6, DI 1 With DI 2 The distribution curve comparison results are characterized by the square error W. If the square error W is less than the set threshold T, the bonding index meets the requirements. If the square error W is greater than and equal to the set threshold T, the bonding index does not meet the requirements. The threshold T is obtained by testing standard qualified composite material samples.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) The present invention adopts an excitation source, i.e., a laser, and multiple receiving sources, i.e., a sensor array. Through one-time excitation and circumferential multi-point reception, the binding force index of the detection area can be accurately measured, thereby overcoming the disadvantage that the existing detection device configured with a single excitation source and a single receiving source cannot comprehensively and accurately detect the various anisotropic characteristics of the composite material.

[0031] (2) The present invention adopts a new method of using a damage index (curve) to determine whether the bonding strength meets the technical index requirements, thereby redefining the bonding strength index of the composite material and making the detection more comprehensive and accurate.

[0032] (3) The present invention arranges the array sensor in a direction consistent with the composite material laying direction, and the number of array sensor units is a multiple of the laying direction, so that the laser can be excited once, and the array sensor receives shock wave response signals from different directions at the same time, thereby overcoming the problem of single bonding force detection data and poor measurement adaptability.

[0033] (4) The present invention performs a large number of tests on qualified standard parts to obtain the damage index distribution curve envelope under normal conditions as a benchmark. Only one test is performed on the composite to be tested. Whether its damage index distribution curve is within the normal envelope can be used to determine whether the bonding strength index of the composite material to be tested meets the requirements. When there is benchmark data for standard parts, the number of tests can be reduced, the test efficiency can be improved, and costs can be saved.

[0034] (5) This patent can also obtain the damage index distribution through two different energy impacts without the damage index envelope benchmark, and judge the damage condition of the tested area by comparing the square error W with the threshold T. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a laser shock wave composite material bonding force detection device based on a sensor unit array of the present invention;

[0036] Figure 2 It is a structural schematic diagram of a flange in a laser shock wave composite material bonding force detection device based on a sensor unit array of the present invention;

[0037] Figure 3 It is a flow chart of the detection steps of the laser shock wave composite material bonding force detection method based on the sensor unit array of the present invention;

[0038] Figure 4 It is a curve diagram of the signal received by the sensor unit array during two laser shocks in the laser shock wave composite material bonding force detection method based on the sensor unit array of the present invention;

[0039] Figure 5 The damage index DI of the first laser shock in the laser shock wave composite material bonding force detection method based on the sensor unit array of the present invention is 1 Distribution curve;

[0040] Figure 6 The damage index DI of the first laser shock in the laser shock wave composite material bonding force detection method based on the sensor unit array of the present invention is 2 Distribution curve;

[0041] The reference numerals of the present invention are listed as follows:

[0042] 1-computer, 2-composite material to be tested, 3-high-speed acquisition system, 4-sensor excitation receiving device, 5-flexible light guiding device, 6-optical path protection fixing device, 7-laser, 8-fixing nut, 9-flange, 10-sensor unit, 11-energy confinement layer, 12-energy absorption layer. DETAILED DESCRIPTION

[0043] The specific implementation of the present invention is described below in conjunction with the accompanying drawings and embodiments:

[0044] 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.

[0045] 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.

[0046] The present invention includes providing a laser shock wave composite material bonding force detection device and method based on a sensor unit array, which adopts an excitation source (laser) and multiple receiving sources (sensor array). The sensors are arranged in a circular array with the laser source as the center of the circle, and the damage index (curve) is used to accurately detect the bonding force of the composite material.

[0047] The present invention is further described below in conjunction with the accompanying drawings.

[0048] Example 1

[0049] like Figure 1-2 As shown, a laser shock wave composite material bonding force detection device based on a sensor unit array includes a bonding force detection system and a signal acquisition system connected by a wire.

[0050] The bonding force detection system includes a laser 7, a flange 9, a flexible light guide 5, a sensor unit 10, an optical path protection fixture 6 and a sensor excitation receiving device 4. A plurality of sensor units 10 are arranged in an array on one side of the composite material 2 to be tested through the flange 9. Figure 2The flange 9 is provided with a plurality of through holes in an annular distribution, and the sensor unit 10 is fixedly arranged on the flange 9 by a nut 8 to form an array of the sensor unit 10. The laser shock wave generated by the laser 7 is guided to the detection area of ​​the composite material 2 to be tested through the flexible light guide device 5. The optical path protection fixture 6 is arranged on the periphery of the port of the flexible light guide device 5, and the flexible light guide device 5 is fixed on the flange 9 by the optical path protection fixture 6. The sensor excitation receiving device 4 is connected to the sensor unit 10 through a wire.

[0051] The flexible light guide device 7 includes a reflector in order to conduct the laser shock wave excited by the laser 7 to a desired position.

[0052] The signal acquisition system includes a high-speed acquisition system 3 and a computer 1 connected by wires, and the high-speed acquisition system 3 is also connected to the sensor excitation receiving device 4 by wires, and the computer 1 is connected to the laser 7 by wires.

[0053] The high-speed acquisition system 3 is a 16-channel data acquisition NIPXI-6251, with 16 analog input channels, 1.25MS / s (single channel), 1MS / s (multi-channel); 16-bit resolution, ±10V.

[0054] It also includes an energy absorbing layer 12 and an energy confinement layer 11 attached to the energy absorbing layer 12, wherein the energy absorbing layer 12 is attached to the composite material 2 to be tested, and the attachment position is located at the irradiation spot of the laser 7;

[0055] The energy absorption layer 12 is a black tape or aluminum foil, and the energy confinement layer 11 is a transparent glass or water. In this embodiment, water is selected;

[0056] Specifically, the sensor unit 10 array and the laser 7 are located on the same side of the composite material 2 to be tested. The composite material 2 to be tested is of model T300, with a thickness of 2.24 mm, 16 layers, and a ply order of [0 / 45 / 90 / -45] 2s , that is, the number of ply directions is 4; the sensor unit 10 array is evenly distributed in an annular shape with the end of the flexible light guide device 5 as the center, and the radius of the annular shape is adjustable, and the annular radius is set to 30 mm, the distance between the sensor unit 10 and the end of the laser 7 is ≧10 mm, and the sensor unit 10 array is evenly distributed in an annular shape, and its direction includes all ply directions of the composite material, and in each ply direction, there are two sensor units 10 symmetrically distributed on both sides of the end of the laser 7, and the angle between two adjacent sensor units 10 is And n is the number of sensor units, which is a multiple of the number of ply directions, and n is a positive integer; N is the number of composite material ply directions, and the number of sensor units 10 is selected to be 8, which is twice the number of ply directions;

[0057] The flexible light guide device 5 of the detection device of this embodiment is provided with a reflector inside. In order to enable the laser shock wave to be accurately transmitted to the predetermined position, it also includes an optical path protection fixing device 6 arranged outside the flexible light guide device 5. The optical path protection fixing device 6 can ensure that the laser shock wave is not dissipated.

[0058] Specifically, the sensor unit 10 includes an electromagnetic ultrasonic sensor unit, a piezoelectric ultrasonic sensor unit, a laser interferometer and an air coupling sensor unit. The detection device of this embodiment selects an air coupling sensor unit.

[0059] like Figure 3-6 As shown, a method for detecting the bonding force of composite materials by laser shock wave based on a sensor unit array is implemented by using a device for detecting the bonding force of composite materials by laser shock wave based on a sensor unit array. The specific steps are as follows:

[0060] S1: Adjust the parameters of laser 7 so that the tensile stress δ generated by the laser shock wave is not greater than the bonding strength index σ of the adhesive layer of the composite material 2 to be tested N Half, that is In this embodiment, the parameters of the laser 7 are set to an energy density of 4 J, a pulse width of 30 ns, and a spot diameter of 4 mm.

[0061] S2: Control the laser 7 to stimulate shock waves in the composite material for the first time, and all units of the sensor unit 10 array simultaneously record the shock wave signals radiated from the laser shock area to the surrounding areas through the high-speed acquisition system 3, and transmit them to the computer 1;

[0062] S3: Using computer 1 to extract relevant signal features from the received signals of each unit in the sensor unit 10 array, define the damage index DI in the corresponding direction of sensor unit 10i i , draw the circumferential distribution curve DI of the damage index during the first laser impact 1 , where i=1,2,...n, i is the number of the sensor unit 10;

[0063] S4: Figure 5 As shown, for the composite material 2 to be tested, a large number of qualified standard parts are tested to obtain the damage index distribution curve envelope under normal conditions as a benchmark, and the damage index circumferential distribution curve DI obtained during the first laser impact 1 , observe DI 1 Whether it is within the normal envelope of the damage index can be used to determine whether the bonding strength index of the composite material 2 to be tested meets the requirements;

[0064] S5: Figure 6 As shown in Figure 1, if the damage index distribution curve envelope of the qualified standard parts under normal conditions cannot be obtained, the laser 7 parameters need to be readjusted so that the tensile stress δ generated by the laser shock wave is equal to the bonding strength index σ of the composite material bonding layer, that is, δ = σ n According to step S2, the circumferential distribution curve DI of the damage index is obtained during the second laser shock 2 ;

[0065] S6: The damage index DI of the composite material to be tested 1 Distribution Curve and DI 2 The distribution curves are compared to determine whether the bonding strength index of the bonding layer of the tested material meets the requirements.

[0066] Specifically, Figure 4 As shown, in step S3, the damage indicators DI in different detection directions are i Definition: Take the amplitude of the defect reflection echo after the spalling in the received signal, the amplitude of the bottom surface reflection echo, the wave packet arrival time or the amplitude of the characteristic frequency point in the spectrum signal as the definition of the damage characteristic value A i ; When the eigenvalue A i When it is positively correlated with the severity of injury, it is calculated according to formula 1; when the eigenvalue A i When the injury severity is negatively correlated, the injury index DI i Calculate according to formula II; this ensures that the degree of damage increases, and the damage index DI i All increased;

[0067]

[0068]

[0069] Specifically, in step S6, DI 1 With DI 2 The distribution curve comparison results are characterized by the square error W. If the square error W is less than the set threshold T, the bonding index meets the requirements. If the square error W is greater than and equal to the set threshold T, the bonding index does not meet the requirements. The threshold T is obtained by testing standard qualified composite material samples. Different composite materials to be tested have different thresholds T due to different performance.

[0070] Specifically, in step S6, DI 1 With DI 2 The distribution curve comparison results are characterized by the square error W. If the square error W is less than the set threshold T, the bonding index meets the requirements. If the square error W is greater than and equal to the set threshold T, the bonding index does not meet the requirements. The threshold T is obtained by testing standard qualified composite material samples.

[0071] In this embodiment, the threshold value T is 0.05, the actual measured W value of the composite material to be tested is 0.61, W>>T, so the bonding strength index of the composite material to be tested does not meet the requirement.

[0072] The present invention adopts the above method to accurately detect whether the bonding strength index of the adhesive layer of the composite material to be tested meets the requirements.

[0073] 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.

[0074] 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 laser shock wave composite material bonding force detection device based on a sensor unit array, characterized in that: It includes a bonding force detection system and a signal acquisition system connected by wires. The bonding force detection system comprises a laser, a flange, a flexible light guide, a sensor unit, an optical path protection fixture and a sensor excitation receiving device. A plurality of the sensor units are arranged in an array on one side of the composite material to be tested through the flange; the laser shock wave generated by the laser is guided to the detection area of ​​the composite material to be tested through the flexible light guide, the optical path protection fixture is arranged on the periphery of the port of the flexible light guide, the flexible light guide is fixed to the flange through the optical path protection fixture, and the sensor excitation receiving device is connected to the sensor unit through a wire; The signal acquisition system includes a high-speed acquisition system and a computer connected by wires, and the high-speed acquisition system is also connected to the sensor excitation receiving device by wires, and the computer is connected to the laser by wires; The sensor unit array and the laser are located on the same side of the composite material to be tested, and the sensor unit array is evenly distributed in a ring shape with the end of the flexible light guide device as the center, and the radius of the ring is adjustable; The distance between the sensor unit and the end of the laser is ≧10mm, the annular uniform distribution direction of the sensor unit array includes all the ply directions of the composite material, and in each ply direction, two sensor units are symmetrically distributed on both sides of the end of the flexible light guide device, that is, the angle between two adjacent sensor units is The n is the number of sensor units, which is a multiple of the number of ply directions, and n is a positive integer; N is the number of composite material ply directions.

2. According to claim 1, a laser shock wave composite material bonding force detection device based on a sensor unit array is characterized in that: It also includes an energy absorbing layer and an energy confinement layer attached to the energy absorbing layer, wherein the energy absorbing layer is attached to the composite material to be tested, and the attachment position is located at the irradiation spot of the laser; Wherein, the energy absorption layer is black tape or aluminum foil, and the energy confinement layer is transparent glass or water.

3. The laser shock wave composite material bonding force detection device based on a sensor unit array according to claim 1, characterized in that: The sensor unit includes an electromagnetic ultrasonic sensor unit, a piezoelectric ultrasonic sensor unit or an air-coupled sensor unit.

4. A method for detecting the bonding force of composite materials by laser shock wave based on a sensor unit array, characterized in that: The method is implemented by using the laser shock wave composite material bonding force detection device based on the sensor unit array as described in any one of claims 1 to 3, and the specific steps are as follows: S1: Adjust the laser parameters so that the tensile stress δ generated by the laser shock wave is not greater than the bonding strength index σ of the composite material bonding layer N Half, that is S2: Control the laser to stimulate shock waves in the composite material for the first time, and all units in the sensor unit array simultaneously record the shock wave signals radiated from the laser shock area to the surrounding areas through a high-speed acquisition system and transmit them to the computer; S3: Use a computer to extract the relevant signal features of the received signals of each unit in the sensor unit array to define the damage index DI in the corresponding direction of sensor unit i i , draw the circumferential distribution curve DI of the damage index during the first laser impact 1 , where i = 1, 2, ... n, i is the sensor unit number; S4: For the composite material to be tested, a large number of qualified standard parts are tested to obtain the damage index distribution curve envelope under normal conditions as a benchmark, and the damage index circumferential distribution curve DI obtained during the first laser impact 1 , observe DI 1 Whether it is within the normal envelope of the damage index can be used to determine whether the bonding strength index of the composite material to be tested meets the requirements; S5: If the damage index distribution curve envelope of the qualified standard parts under normal conditions cannot be obtained, the laser parameters need to be readjusted so that the tensile stress δ generated by the laser shock wave is equal to the bonding strength index σ of the composite material bonding layer, that is, δ = σ n According to step S2, the circumferential distribution curve DI of the damage index is obtained during the second laser shock 2 ; S6: The damage index DI of the composite material to be tested 1 Distribution Curve and DI 2 The distribution curves are compared to determine whether the bonding strength index of the bonding layer of the tested material meets the requirements.

5. The method for detecting the bonding force of composite materials by laser shock wave based on sensor unit array according to claim 4, characterized in that: In step S3, the damage indicators DI in different detection directions are i Definition: The amplitude of the reflected echo from the defect after the spalling in the received signal, the amplitude of the reflected echo from the bottom surface, the arrival time of the wave packet, or the amplitude of the characteristic frequency point in the spectrum signal is used as the definition of the damage characteristic value A. i ; When the eigenvalue A i When it is positively correlated with the severity of injury, it is calculated according to formula 1; when the eigenvalue A i When the injury severity is negatively correlated, the injury index DI i Calculate according to formula II; this ensures that the degree of damage increases, and the damage index DI i All increased.

6. The method for detecting the bonding force of composite materials by laser shock wave based on sensor unit array according to claim 4, characterized in that: In step S6, DI 1 With DI 2 The distribution curve comparison results are characterized by the square error W. If the square error W is less than the set threshold T, the bonding index meets the requirements. If the square error W is greater than and equal to the set threshold T, the bonding index does not meet the requirements. The threshold T is obtained by testing standard qualified composite material samples.

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