CN113916937A - Crack detection method, crack detection device, electronic equipment and storage medium - Google Patents

Crack detection method, crack detection device, electronic equipment and storage medium Download PDF

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Publication number
CN113916937A
CN113916937A CN202110975634.9A CN202110975634A CN113916937A CN 113916937 A CN113916937 A CN 113916937A CN 202110975634 A CN202110975634 A CN 202110975634A CN 113916937 A CN113916937 A CN 113916937A
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China
Prior art keywords
detected
crack detection
crack
scanning
determining
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Inventor
董丽虹
王海斗
杨洁
底月兰
郭伟
李荣浩
林恩
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Academy of Armored Forces of PLA
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Academy of Armored Forces of PLA
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Priority to CN202110975634.9A priority Critical patent/CN113916937A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/72—Investigating presence of flaws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity

Abstract

The invention provides a crack detection method, a crack detection device, electronic equipment and a storage medium, wherein the method comprises the following steps: determining a to-be-detected area of a to-be-detected test piece and a detection path on the surface of the to-be-detected area; according to the detection path, performing joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map; determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and determining the positions of the cracks if the cracks exist on the surface of the area to be detected. The invention can realize the detection of the surface cracks of the large-area material by jointly scanning the surface of the area to be detected by using the joint scanner consisting of the laser and the thermal imager, and judges whether the surface of the area to be detected has cracks or not based on the crack detection sampling points in the scanning thermal image, thereby effectively realizing the blind detection of the surface cracks of the area to be detected.

Description

Crack detection method, crack detection device, electronic equipment and storage medium
Technical Field
The present invention relates to the field of crack detection technologies, and in particular, to a crack detection method and apparatus, an electronic device, and a storage medium.
Background
Laser thermal imaging is an emerging infrared thermal imaging nondestructive testing technology. The laser excitation can generate a temperature gradient in the horizontal direction, has great potential in the aspect of surface crack detection, and has the advantages of non-contact, simplicity in operation and the like.
According to the difference of laser excitation process, various laser thermal imaging methods have been formed, such as laser thermal imaging techniques of laser flying spot, laser pulse, long pulse and laser lock phase, etc., and the micro fatigue crack with the surface of several micrometers to tens of micrometers can be found. However, the above methods all require that the fatigue crack position of the structure to be detected can be estimated, and imaging and quantitative evaluation research can be carried out on the premise. Moreover, it is not uncommon for blind detection of surface cracks in large structures, such as aircraft skins, primary structures of spacecraft, etc., to provide a viable detection method.
Disclosure of Invention
The invention provides a crack detection method, a crack detection device, electronic equipment and a storage medium, aiming at the problems in the prior art.
In a first aspect, the present invention provides a crack detection method, comprising:
determining a region to be detected of a test piece to be detected and a detection path on the surface of the region to be detected;
according to the detection path, performing joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map;
determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and if the cracks exist on the surface of the area to be detected, determining the positions of the cracks.
Optionally, according to a crack detection method provided by the present invention, the determining crack detection sampling points in the scanning thermal map includes:
selecting a front edge of a scanning direction of the hot spot in the scanning heat map as a crack detection sampling point, wherein the front edge of the scanning direction of the hot spot is a pixel at a first preset distance from the center of the hot spot along the scanning direction of the hot spot, or a pixel at a second preset distance from a line width central line of the line hot spot along the scanning direction of the line hot spot;
the first preset distance is not more than the radius of the hot spot, and the second preset distance is not more than half of the line width of the line hot spot.
Optionally, according to a crack detection method provided by the present invention, the determining whether a crack exists on the surface of the region to be detected based on the crack detection sampling point, and if the crack exists on the surface of the region to be detected, determining the position of the crack includes:
and taking the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point as the characteristic quantity of crack detection, judging whether cracks exist on the surface of the area to be detected or not according to the characteristic quantity of crack detection, and if so, determining the position of the cracks.
Optionally, according to a crack detection method provided by the present invention, the determining whether there is a crack on the surface of the region to be detected according to the characteristic quantity of crack detection by using the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point as the characteristic quantity of crack detection, and if there is a crack on the surface of the region to be detected, determining the position of the crack includes:
determining a first temperature time series of the crack detection sampling points;
filtering a low-frequency trend term and a high-frequency noise term of the first temperature time sequence by using a wavelet analysis method, and taking the filtered first temperature time sequence as a second temperature time sequence;
and performing self-similarity analysis based on DB wavelet on the second temperature time series to obtain a distribution diagram of self-similarity coefficients, wherein in the distribution diagram, the maximum value of the self-similarity coefficients represents a crack, and the position corresponding to the maximum value of the self-similarity coefficients represents the position of the crack.
Optionally, according to the present invention, there is provided a crack detection method, further comprising:
and setting the laser power of the laser according to the surface absorptivity and the damage threshold of the test piece to be detected so as to enable the central temperature of the hot spot in the scanning heat map to at least reach a preset temperature value.
Optionally, according to the present invention, there is provided a crack detection method, further comprising:
setting the range of the self-similarity coefficient s according to a formula v ═ C, wherein v is a joint scanning speed, and C is a constant;
and the constant C is determined by performing multi-speed detection on the test piece to be detected, and is related to the laser diameter of the laser and the thermal diffusion coefficient of the test piece to be detected.
In a second aspect, the present invention also provides a crack detection device, comprising:
the device comprises a determining module, a judging module and a judging module, wherein the determining module is used for determining a to-be-detected area of a to-be-detected test piece and a detection path on the surface of the to-be-detected area;
the scanning module is used for carrying out joint scanning on the surface of the area to be detected by using a joint scanner consisting of a laser and a thermal imager according to the detection path to obtain a scanning thermal map;
and the detection module is used for determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and determining the positions of the cracks if the cracks exist on the surface of the area to be detected.
In a third aspect, the present invention further provides an electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the steps of the crack detection method according to the first aspect.
In a fourth aspect, the invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the crack detection method according to the first aspect.
In a fifth aspect, the invention also provides a computer program product comprising a computer program which, when executed by a processor, performs the steps of the crack detection method according to the first aspect.
According to the crack detection method, the crack detection device, the electronic equipment and the storage medium, the joint scanner formed by the laser and the thermal imager is used for carrying out joint scanning on the surface of the area to be detected to obtain the scanning thermal image, the detection on the cracks on the surface of the large-area material can be realized, moreover, whether cracks exist on the surface of the area to be detected or not is judged based on the crack detection sampling points in the scanning thermal image, the positions of the cracks are determined under the condition that the cracks exist, and the blind detection on the cracks on the surface of the area to be detected is effectively realized.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a crack detection method provided by the present invention;
FIG. 2 is a schematic diagram illustrating the detection principle of the crack detection method provided by the present invention;
FIG. 3 is a schematic diagram of a crack detection sampling point of the crack detection method provided by the present invention;
FIG. 4 is a second schematic diagram of a crack detection sampling point of the crack detection method provided by the present invention;
FIG. 5 is a schematic diagram of the amplitude and waveform of the temperature change at the crack detection sampling point of the crack detection method provided by the present invention;
FIG. 6 is a second temperature time series diagram of the crack detection method provided by the present invention;
FIG. 7 is a schematic diagram of the distribution of self-similarity coefficients for a crack detection method provided by the present invention;
FIG. 8 is a schematic structural diagram of a crack detection device provided by the present invention;
fig. 9 illustrates a physical structure diagram of an electronic device.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The following describes a crack detection method and apparatus provided by the present invention with reference to fig. 1 to 8.
Fig. 1 is a schematic flow chart of a crack detection method provided by the present invention, and as shown in fig. 1, the method includes the following steps:
step 100, determining a to-be-detected area of a to-be-detected test piece and a detection path on the surface of the to-be-detected area;
step 110, performing joint scanning on the surface of the area to be detected by using a joint scanner composed of a laser and a thermal imager according to the detection path to acquire a scanning thermal map;
and 120, determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and if so, determining the positions of the cracks.
Optionally, the material of the test piece to be tested may include a metal with low surface absorptivity, such as an aluminum alloy, and may also include a common metal, such as steel, iron, and the like.
Alternatively, the detection path may be kept parallel to the surface of the test piece to be inspected.
Optionally, according to the detection path, a joint scanner composed of a laser and a thermal imager may be used to perform joint scanning on the surface of the region to be detected, so as to obtain a scanning thermal map.
Alternatively, the laser focused hot spot emitted by the laser may be a spot hot spot, a line hot spot or an array hot spot, which is not particularly limited in the present invention.
Alternatively, in the case where the laser focused hot spot is a line hot spot, the line hot spot may be kept perpendicular to the scanning direction of the line hot spot during scanning.
Alternatively, the power of the laser may be adjustable on the order of 0-100W.
Alternatively, a semiconductor laser can be used for exciting heat on the surface of the region to be detected, and excitation power is selected according to the surface absorptivity and damage threshold of the region to be detected.
Alternatively, the thermographic Noise Equivalent Temperature Difference (NETD) may be no greater than 50 mK.
Optionally, crack detection sampling points in a scanning thermal map recorded by the thermal imager may be determined, whether cracks exist on the surface of the region to be detected may be determined based on the crack detection sampling points, and if cracks exist on the surface of the region to be detected, the positions of the cracks are determined.
It should be noted that the crack detection method provided by the invention focuses on detecting whether a crack exists on the surface of a test piece to be detected and determining the position of the crack, and the existing laser thermal imaging technology is mainly applied to the visual detection of the crack and is not suitable for large-area and large-scale crack detection scenes.
Fig. 2 is a schematic diagram of a detection principle of the crack detection method provided by the present invention, as shown in fig. 2, the present invention is composed of a power supply, a semiconductor laser, a thermal imager and a terminal control computer, a laser collimator and the thermal imager are fixed on a scanning motion component (e.g., an electric control translation stage, etc.) to form a joint scanning module, and a scanning path is substantially parallel to the surface of a test piece to be detected; the thermal imager, the laser and the moving part are synchronously controlled, and when the combined scanning module starts to move, the thermal imager synchronously triggers to start recording the thermal image.
Optionally, before the joint scanning, the distance from the joint scanning module to the surface of the to-be-tested object and a focusing lens on the surface of the thermal imager can be set, so that the thermal imager can image clear hot spots.
Optionally, the area to be detected and the scanning route may be determined according to the detection task requirement.
Alternatively, the joint scanning can be completed under the control of a computer, the thermal imager synchronously records the scanning thermal image, and the computer synchronously transmits and stores the thermal image recorded by the thermal imager.
Alternatively, the scanning speed may be set arbitrarily according to specific requirements, and the present invention is not particularly limited thereto.
Optionally, the area to be detected of the test piece to be detected and the detection route on the surface of the area to be detected can be determined according to the detection task requirement; then, a joint scanner formed by a laser and a thermal imager can be used for carrying out joint scanning on the surface of the area to be detected based on a detection path, and the relative positions of the laser and the thermal imager can be kept unchanged in the scanning process, so that the position of a hot spot in a thermal map is kept static, and the scanning of the surface of a large-area material can be realized; and finally, determining a crack detection sampling point in the scanning heat map, judging whether a crack exists in the region to be detected or not based on the crack detection sampling point, and determining the position of the crack under the condition that the crack exists, thereby effectively realizing the blind detection of the surface crack of the region to be detected.
According to the crack detection method provided by the invention, the joint scanner consisting of the laser and the thermal imager is used for carrying out joint scanning on the surface of the area to be detected to obtain the scanning thermal image, so that the detection on the surface cracks of the large-area material can be realized, moreover, whether cracks exist on the surface of the area to be detected is judged based on the crack detection sampling points in the scanning thermal image, the positions of the cracks are determined under the condition that the cracks exist, and the blind detection on the surface cracks of the area to be detected is effectively realized.
Optionally, the determining crack detection sampling points in the scanned heat map comprises:
selecting a front edge of a scanning direction of the hot spot in the scanning heat map as a crack detection sampling point, wherein the front edge of the scanning direction of the hot spot is a pixel at a first preset distance from the center of the hot spot along the scanning direction of the hot spot, or a pixel at a second preset distance from a line width central line of the line hot spot along the scanning direction of the line hot spot;
the first preset distance is not more than the radius of the hot spot, and the second preset distance is not more than half of the line width of the line hot spot.
Alternatively, the leading edge of the scan direction of the hot spot in the scan heat map may be selected as a crack detection sampling point.
Alternatively, the leading edge of the scanning direction of the hot spot may be a pixel at a first preset distance from the center of the hot spot along the scanning direction of the hot spot.
Alternatively, the leading edge of the scanning direction of the hot spot may be a pixel element at a second preset distance from the line-width center line of the hot spot along the scanning direction of the hot spot.
Alternatively, the first predetermined distance may be 1/2 hot spot diameters.
Alternatively, the second predetermined distance may be 1/2 line widths of the line hot spots.
Experiments prove that the temperature signal of the crack at the sampling point with the diameter of about 1/2 hot spots in front of the laser excitation point along the scanning direction has a larger signal-to-noise ratio, so that the pixel at the position 1/2 away from the center of the hot spot with the diameter is most suitable for crack detection and is the optimal sampling point, and similarly, the pixel at the position 1/2 away from the line width center line of the hot spot with the distance line is most suitable for crack detection and is the optimal sampling point.
FIG. 3 is a schematic diagram of a crack detection sampling point of the crack detection method provided by the present invention, FIG. 4 is a schematic diagram of a crack detection sampling point of the crack detection method provided by the present invention, and as shown in FIG. 3, when the hot spot is a spot hot spot or an array hot spot, a pixel at a position which is about 1/2 hot spot diameters away from the center of the hot spot along the scanning direction of the hot spot is selected as the crack detection sampling point; as shown in fig. 4, in the case where the hot spot is a linear hot spot, an image element at a line width from a line width center line 1/2 of the linear hot spot in the scanning direction of the hot spot is selected as a crack detection sample point.
According to the method, the hot spots in the heat map are sampled, and the front edges of the hot spots in the scanning direction are selected as the crack detection sampling points, so that the crack signals obtained by the selected crack detection sampling points in scanning have a higher signal-to-noise ratio, and the detection precision of the fatigue cracks on the surface of the low-absorption-rate material is improved.
Optionally, the determining, based on the crack detection sampling point, whether a crack exists on the surface of the region to be detected, and if the crack exists on the surface of the region to be detected, determining a position of the crack includes:
and taking the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point as the characteristic quantity of crack detection, judging whether cracks exist on the surface of the area to be detected or not according to the characteristic quantity of crack detection, and if so, determining the position of the cracks.
Alternatively, the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point may be used as the characteristic amount of crack detection.
Optionally, whether a crack exists on the surface of the region to be detected or not may be determined according to the characteristic quantity of crack detection, and if a crack exists on the surface of the region to be detected, the position of the crack may be determined.
Fig. 5 is a schematic diagram of the amplitude and waveform of the temperature change at the crack detection sampling point of the crack detection method provided by the invention, and as shown in fig. 5, at the laser combined scanning thermal imaging sampling point, the temperature characteristic of the crack has a large temperature change amplitude a and a specific three-pole waveform of "peak-to-valley-to-peak", where δ represents the time difference from the peak to the valley. Under a fixed thermal imager frame frequency (sampling rate), the smaller the delta, the lower the accuracy rate of capturing the amplitude A by the thermal imager is; at a certain frame frequency, a larger amplitude is beneficial for crack characterization.
Optionally, the determining, by using the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point as characteristic quantities of crack detection, whether a crack exists on the surface of the region to be detected according to the characteristic quantities of crack detection, and if a crack exists on the surface of the region to be detected, determining a position of the crack includes:
determining a first temperature time series of the crack detection sampling points;
filtering a low-frequency trend term and a high-frequency noise term of the first temperature time sequence by using a wavelet analysis method, and taking the filtered first temperature time sequence as a second temperature time sequence;
and performing self-similarity analysis based on DB wavelet on the second temperature time series to obtain a distribution diagram of self-similarity coefficients, wherein in the distribution diagram, the maximum value of the self-similarity coefficients represents a crack, and the position corresponding to the maximum value of the self-similarity coefficients represents the position of the crack.
Alternatively, a first temperature time series of crack detection sampling points may be determined from the sampling points in the thermal map.
Optionally, denoising and enhancing may be performed on the first temperature time sequence by using a wavelet analysis method, that is, a low-frequency trend term and a high-frequency noise term of the first temperature time sequence may be filtered, and the rest may be used as the second temperature time sequence.
Optionally, a self-similarity analysis based on the DB wavelet may be performed on the second temperature time series, and a distribution map of self-similarity coefficients may be obtained, in which a maximum value of the self-similarity coefficient may characterize the crack, and a position corresponding to the maximum value of the self-similarity coefficient may characterize a position of the crack.
Optionally, the second temperature time series may be subjected to a self-similarity analysis based on DB4 or DB3 or DB2 wavelets, wherein DB3 and DB2 are applicable for low signal-to-noise cases.
Fig. 6 is a schematic diagram of a second temperature time series of the crack detection method provided by the present invention, fig. 7 is a schematic diagram of a distribution of self-similarity coefficients of the crack detection method provided by the present invention, and as shown in fig. 6 and fig. 7, a self-similarity coefficient position-scale distribution diagram as shown in fig. 7 can be obtained by performing a self-similarity analysis of a DB wavelet on the second temperature time series in fig. 6, wherein a small circle in fig. 7 represents a maximum value of the wavelet similarity coefficient, an abscissa represents a position of a crack, and an ordinate represents a scale of the wavelet, which includes scanning speed information.
As can be seen in connection with fig. 6 and 7, the cracks are characterized by a distribution centered from the larger values (including the extrema) of the similarity coefficient on distinct "ridges" perpendicular to the position coordinates, here exactly the positions of the "valleys" of the thermal signal.
According to the enhanced denoising method based on wavelet decomposition, the low-frequency trend term and the high-frequency noise term of the first temperature time sequence are filtered, the rest is used as the second temperature time sequence, the signal-to-noise ratio is effectively improved, the typical three-pole waveform at the crack can be effectively recovered, further, based on the similarity between the second temperature time sequence and DB wavelet, the amplitude characteristic and the waveform characteristic of the temperature change of the crack in combined scanning are converted into the extreme value of the similarity coefficient, the detection automation of the surface crack is effectively realized, and the enhanced denoising method has sensitive detection capability for the fatigue microcrack of 10 micrometers.
Optionally, the method further comprises:
and setting the laser power of the laser according to the surface absorptivity and the damage threshold of the test piece to be detected so as to enable the central temperature of the hot spot in the scanning heat map to at least reach a preset temperature value.
Optionally, the laser power of the laser may be set according to the surface absorption rate and the damage threshold of the test piece to be detected, so that the central temperature of the hot spot in the scanning thermal map may at least reach a preset temperature value.
Alternatively, the preset temperature value may be set to 1K, 1.5K, 2K, or the like, which is not particularly limited in the present invention.
Optionally, the method further comprises:
setting the range of the self-similarity coefficient s according to a formula v ═ C, wherein v is a joint scanning speed, and C is a constant;
and the constant C is determined by performing multi-speed detection on the test piece to be detected, and is related to the laser diameter of the laser and the thermal diffusion coefficient of the test piece to be detected.
Alternatively, the range of the self-similarity coefficient s may be set according to the formula v × s — C to perform crack detection more accurately, wherein the constant C may be determined by performing multi-speed detection on the test piece to be detected.
The invention is helpful to improve the crack detection precision by presetting the range of the self-similarity coefficient.
The crack detection device provided by the invention is described below, and the crack detection device described below and the crack detection method described above can be referred to correspondingly.
Fig. 8 is a schematic structural diagram of a crack detection apparatus provided in the present invention, and as shown in fig. 8, the apparatus includes: a determination module 810, a scanning module 820, and a detection module 830; wherein:
the determining module 810 is used for determining a to-be-detected area of a to-be-detected test piece and a detection path on the surface of the to-be-detected area;
the scanning module 820 is configured to perform joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager according to the detection path to obtain a scanning thermal map;
the detection module 830 is configured to determine a crack detection sampling point in the scanning thermal map, determine whether a crack exists on the surface of the region to be detected based on the crack detection sampling point, and determine the position of the crack if the crack exists on the surface of the region to be detected.
Optionally, the crack detection apparatus may determine, by the determining module 810, a region to be detected of the test piece to be detected and a detection path on the surface of the region to be detected, and then, according to the detection path, perform joint scanning on the surface of the region to be detected by the scanning module 820 by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map; and determining a crack detection sampling point in the scanning heat map through a detection module 830, determining whether a crack exists on the surface of the region to be detected based on the crack detection sampling point, and if so, determining the position of the crack.
According to the crack detection device provided by the invention, the joint scanner consisting of the laser and the thermal imager is used for carrying out joint scanning on the surface of the area to be detected to obtain the scanning thermal image, so that the detection on the surface cracks of the large-area material can be realized, moreover, whether cracks exist on the surface of the area to be detected is judged based on the crack detection sampling points in the scanning thermal image, the positions of the cracks are determined under the condition that the cracks exist, and the blind detection on the surface cracks of the area to be detected is effectively realized.
Fig. 9 illustrates a physical structure diagram of an electronic device, and as shown in fig. 9, the electronic device may include: a processor (processor)910, a communication Interface (Communications Interface)920, a memory (memory)930, and a communication bus 940, wherein the processor 910, the communication Interface 920, and the memory 930 communicate with each other via the communication bus 940. Processor 910 may invoke logic instructions in memory 930 to perform the crack detection methods provided by the above-described methods, including:
determining a region to be detected of a test piece to be detected and a detection path on the surface of the region to be detected;
according to the detection path, performing joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map;
determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and if the cracks exist on the surface of the area to be detected, determining the positions of the cracks.
Furthermore, the logic instructions in the memory 930 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, the present invention also provides a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, enable the computer to perform the crack detection method provided by the above methods, the method comprising:
determining a region to be detected of a test piece to be detected and a detection path on the surface of the region to be detected;
according to the detection path, performing joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map;
determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and if the cracks exist on the surface of the area to be detected, determining the positions of the cracks.
In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium having stored thereon a computer program which, when executed by a processor, is implemented to perform the crack detection method provided above, the method comprising:
determining a region to be detected of a test piece to be detected and a detection path on the surface of the region to be detected;
according to the detection path, performing joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map;
determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and if the cracks exist on the surface of the area to be detected, determining the positions of the cracks.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A crack detection method, comprising:
determining a region to be detected of a test piece to be detected and a detection path on the surface of the region to be detected;
according to the detection path, performing joint scanning on the surface of the area to be detected by using a joint scanner formed by a laser and a thermal imager to obtain a scanning thermal map;
determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and if the cracks exist on the surface of the area to be detected, determining the positions of the cracks.
2. The crack detection method of claim 1, wherein the determining crack detection sampling points in the scanned thermal map comprises:
selecting a front edge of a scanning direction of the hot spot in the scanning heat map as a crack detection sampling point, wherein the front edge of the scanning direction of the hot spot is a pixel at a first preset distance from the center of the hot spot along the scanning direction of the hot spot, or a pixel at a second preset distance from a line width central line of the line hot spot along the scanning direction of the line hot spot;
the first preset distance is not more than the radius of the hot spot, and the second preset distance is not more than half of the line width of the line hot spot.
3. The crack detection method according to claim 1, wherein the determining whether a crack exists on the surface of the region to be detected based on the crack detection sampling point, and if the crack exists on the surface of the region to be detected, determining the position of the crack comprises:
and taking the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point as the characteristic quantity of crack detection, judging whether cracks exist on the surface of the area to be detected or not according to the characteristic quantity of crack detection, and if so, determining the position of the cracks.
4. The crack detection method according to claim 3, wherein the step of taking the amplitude characteristic and the waveform characteristic of the temperature change at the crack detection sampling point as characteristic quantities of crack detection, judging whether a crack exists on the surface of the region to be detected according to the characteristic quantities of crack detection, and if the crack exists on the surface of the region to be detected, determining the position of the crack comprises the steps of:
determining a first temperature time series of the crack detection sampling points;
filtering a low-frequency trend term and a high-frequency noise term of the first temperature time sequence by using a wavelet analysis method, and taking the filtered first temperature time sequence as a second temperature time sequence;
and performing self-similarity analysis based on DB wavelet on the second temperature time series to obtain a distribution diagram of self-similarity coefficients, wherein in the distribution diagram, the maximum value of the self-similarity coefficients represents a crack, and the position corresponding to the maximum value of the self-similarity coefficients represents the position of the crack.
5. The crack detection method of claim 1, further comprising:
and setting the laser power of the laser according to the surface absorptivity and the damage threshold of the test piece to be detected so as to enable the central temperature of the hot spot in the scanning heat map to at least reach a preset temperature value.
6. The crack detection method of claim 4, further comprising:
setting the range of the self-similarity coefficient s according to a formula v ═ C, wherein v is a joint scanning speed, and C is a constant;
and the constant C is determined by performing multi-speed detection on the test piece to be detected, and is related to the laser diameter of the laser and the thermal diffusion coefficient of the test piece to be detected.
7. A crack detection device, comprising:
the device comprises a determining module, a judging module and a judging module, wherein the determining module is used for determining a to-be-detected area of a to-be-detected test piece and a detection path on the surface of the to-be-detected area;
the scanning module is used for carrying out joint scanning on the surface of the area to be detected by using a joint scanner consisting of a laser and a thermal imager according to the detection path to obtain a scanning thermal map;
and the detection module is used for determining crack detection sampling points in the scanning heat map, judging whether cracks exist on the surface of the area to be detected or not based on the crack detection sampling points, and determining the positions of the cracks if the cracks exist on the surface of the area to be detected.
8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the crack detection method according to any of claims 1 to 6 when executing the program.
9. A non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the crack detection method according to any one of claims 1 to 6.
10. A computer program product comprising a computer program, characterized in that the computer program realizes the steps of the crack detection method according to any of claims 1 to 6 when being executed by a processor.
CN202110975634.9A 2021-08-24 2021-08-24 Crack detection method, crack detection device, electronic equipment and storage medium Pending CN113916937A (en)

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