CN117740808A - Method and system for detecting fatigue crack tip by infrared thermal imaging - Google Patents
Method and system for detecting fatigue crack tip by infrared thermal imaging Download PDFInfo
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Abstract
The invention discloses a method and a system for detecting fatigue crack tips by infrared thermal imaging, and relates to the field of crack detection; the detection method comprises the following steps: in the fatigue crack propagation process, acquiring crack images in a detection area to obtain a plurality of crack images; the crack image is an infrared thermal imaging image; converting the plurality of crack images to obtain a plurality of frequency-coordinate images; calculating the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images; the position of the crack tip is detected from the plurality of frequency difference-coordinate images. According to the invention, the position of the crack tip is determined by acquiring the infrared thermal imaging image and processing the infrared thermal imaging image, so that the problem that the crack inside the material cannot be subjected to nondestructive detection in the traditional crack detection method is solved, and the purpose of nondestructive detection of the crack inside the aviation material is achieved.
Description
Technical Field
The invention relates to the field of crack detection, in particular to a method and a system for detecting fatigue crack tips by infrared thermal imaging.
Background
The metal fatigue refers to that micro cracks are formed in a local high-stress area of a mechanical part after a period of time under the action of alternating stress, and the micro cracks are expanded to fracture. More than about 80% of aircraft structural failures have been counted as fatigue failures for over 150 years. The fatigue damage is not easy to be found in time due to the characteristics of time burst, locality in position, sensitivity to environment and defects and the like, and accidents are easy to be caused.
Therefore, in the design work of aircrafts such as airplanes, fatigue tests need to be carried out on a test machine or a fuselage part, crack propagation conditions of weak positions of the fuselage are observed, the positions of crack tips are monitored in real time, dynamic information of crack propagation is mastered, and subsequent analysis and processing and optimization design are facilitated.
The existing crack detection method is mainly used for analyzing and processing a single crack picture, then identifying crack contours, and can not carry out nondestructive detection on cracks in the material, and if internal defects need to be detected, the material needs to be damaged, so that the internal cracks are positioned on the surface.
Disclosure of Invention
The invention aims to provide a method and a system for detecting fatigue crack tips by infrared thermal imaging, which can realize nondestructive detection of cracks in aviation materials.
In order to achieve the above object, the present invention provides the following solutions:
a method of detecting a fatigue crack tip by infrared thermal imaging, the method of detecting a fatigue crack tip by infrared thermal imaging comprising:
in the fatigue crack propagation process, acquiring crack images in a detection area to obtain a plurality of crack images; the crack image is an infrared thermal imaging image;
converting the crack images to obtain a plurality of frequency-coordinate images;
calculating the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images;
the position of the crack tip is detected from a plurality of the frequency difference-coordinate images.
Optionally, the converting process is performed on the plurality of crack images to obtain a plurality of frequency-coordinate images, and then the method further includes:
and denoising a plurality of the frequency-coordinate images by adopting Gaussian filtering.
Optionally, calculating the frequency difference between two adjacent frequency-coordinate images to obtain a plurality of frequency-difference-coordinate images, and further including:
judging whether position offset exists between two adjacent frequency-coordinate images, and obtaining a first judging result;
if the first judgment result is yes, calibrating and correcting the two frequency-coordinate images with the position offset by using a calibration algorithm;
and if the first judgment result is negative, representing that no position deviation exists between two adjacent frequency-coordinate images.
Optionally, detecting the position of the crack tip according to the plurality of frequency difference-coordinate images specifically includes:
judging whether the frequency difference of each pixel point in the frequency difference-coordinate image is larger than a preset threshold value or not to obtain a second judging result;
if the second judgment result is negative, characterizing a growth area which does not correspond to the crack tip in the detection area, returning to the process of fatigue crack propagation, and collecting crack images in the detection area to obtain a plurality of crack images;
if the second judgment result is yes, representing a growth area of the corresponding crack tip of the pixel point corresponding to the frequency difference larger than a preset threshold value;
detecting a plurality of pixel points corresponding to the frequency difference larger than a preset threshold value to obtain the position of the crack tip.
Optionally, detecting positions of the crack tip at a plurality of pixel points corresponding to a frequency difference greater than a preset threshold specifically includes:
performing difference between every two pixel points of the pixel points to obtain a difference value set;
judging whether each difference value in the difference value set is larger than a preset threshold value or not, and obtaining a third judgment result;
if the third judgment result is yes, detecting a pixel point corresponding to each difference value in the difference value set by adopting a canny algorithm to obtain the position of the crack tip;
if the third judgment result is negative, deleting the difference value smaller than the preset threshold value in the difference value set to obtain a deleted difference value set, and detecting the pixel point corresponding to each difference value in the difference value set deleted by a canny algorithm to obtain the position of the crack tip.
Optionally, in the fatigue crack propagation process, acquiring a crack image in the detection area to obtain a plurality of crack images, which specifically includes:
and in the fatigue crack propagation process, acquiring crack images in the detection area by adopting an infrared camera to obtain a plurality of crack images.
A system for detecting a fatigue crack tip by infrared thermal imaging, the system comprising:
the acquisition module is used for acquiring crack images in the detection area in the fatigue crack expansion process to obtain a plurality of crack images;
the conversion module is used for carrying out conversion processing on a plurality of crack images to obtain a plurality of frequency-coordinate images;
the computing module is used for computing the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images;
and the detection module is used for detecting the position of the crack tip according to the plurality of frequency difference-coordinate images.
Optionally, the conversion module specifically includes:
the conversion unit is used for carrying out conversion processing on the plurality of crack images to obtain a plurality of frequency-coordinate images to be denoised;
and the denoising unit is used for denoising a plurality of frequency-coordinate images to be denoised by adopting Gaussian filtering to obtain a plurality of frequency-coordinate images.
An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the method of detecting fatigue crack tips for infrared thermal imaging as described above when executing the computer program.
A computer readable storage medium having stored thereon a computer program which when executed implements the method of detecting fatigue crack tips for infrared thermal imaging as described above.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention discloses a method and a system for detecting fatigue crack tips by infrared thermal imaging, wherein the detection method comprises the following steps: in the fatigue crack propagation process, acquiring crack images in a detection area to obtain a plurality of crack images; the crack image is an infrared thermal imaging image; converting the crack images to obtain a plurality of frequency-coordinate images; calculating the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images; the position of the crack tip is detected from a plurality of the frequency difference-coordinate images. According to the invention, the position of the crack tip is determined by acquiring the infrared thermal imaging image and processing the infrared thermal imaging image, so that the problem that the crack inside the material cannot be subjected to nondestructive detection in the traditional crack detection method is solved, and the purpose of nondestructive detection of the crack inside the aviation material is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for detecting fatigue crack tips by infrared thermal imaging in an embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a method and a system for detecting fatigue crack tips by infrared thermal imaging, which can realize nondestructive detection of cracks in aviation materials.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
As shown in fig. 1, the present invention provides a method for detecting a fatigue crack tip by infrared thermal imaging, which includes:
step 101: and in the fatigue crack propagation process, acquiring a crack image in the detection area to obtain a plurality of crack images. The crack image is an infrared thermal imaging image.
And (5) constructing an image acquisition platform and starting a fatigue test. And acquiring crack images by using an infrared camera aiming at the fatigue crack propagation process.
Step 102: and converting the crack images to obtain a plurality of frequency-coordinate images.
And inputting the acquired picture into a written program, processing the crack image, and converting the infrared thermal imaging picture into a frequency-coordinate picture.
Step 103: and calculating the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images.
Step 104: the position of the crack tip is detected from a plurality of the frequency difference-coordinate images.
As a specific embodiment, the converting process is performed on the plurality of crack images to obtain a plurality of frequency-coordinate images, and then the method further includes:
and denoising a plurality of the frequency-coordinate images by adopting Gaussian filtering. And denoising the image by adopting Gaussian filtering, so that the interference of background noise is reduced or eliminated.
As a specific embodiment, calculating the frequency difference between two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images, further includes:
and judging whether the position offset exists between two adjacent frequency-coordinate images, and obtaining a first judging result.
And if the first judgment result is yes, calibrating and correcting the two frequency-coordinate images with the position offset by using a calibration algorithm.
And if the first judgment result is negative, representing that no position deviation exists between two adjacent frequency-coordinate images.
If the acquired crack images are in the front and rear images and have position deviation due to vibration, calibrating and correcting the cracks by using a calibration algorithm, so that the areas of the front and rear images for performing difference analysis are ensured to be the same. If there is no shift in position of the crack image, this step is skipped.
As a specific embodiment, detecting the position of the crack tip according to a plurality of the frequency difference-coordinate images specifically includes:
and judging whether the frequency difference of each pixel point in the frequency difference-coordinate image is larger than a preset threshold value or not to obtain a second judging result.
And if the second judgment result is negative, characterizing a growth area which does not correspond to the crack tip in the detection area, returning to the fatigue crack propagation process, and collecting crack images in the detection area to obtain a plurality of crack images.
And if the second judgment result is yes, representing the growth area of the corresponding crack tip of the pixel point corresponding to the frequency difference larger than the preset threshold value.
Detecting a plurality of pixel points corresponding to the frequency difference larger than a preset threshold value to obtain the position of the crack tip.
As a specific embodiment, detecting positions of the crack tip at the pixel points corresponding to the frequency differences greater than the preset threshold specifically includes:
and carrying out difference between every two pixel points of the pixel points to obtain a difference value set.
And judging whether each difference value in the difference value set is larger than a preset threshold value or not, and obtaining a third judging result.
And if the third judgment result is yes, detecting the pixel point corresponding to each difference value in the difference value set by adopting a canny algorithm to obtain the position of the crack tip.
If the third judgment result is negative, deleting the difference value smaller than the preset threshold value in the difference value set to obtain a deleted difference value set, and detecting the pixel point corresponding to each difference value in the difference value set deleted by a canny algorithm to obtain the position of the crack tip.
Aiming at the crack expansion process, the frequency of the infrared images acquired in the appointed area before and after the crack expansion is compared, a threshold value N is set, and when the difference value of the frequency before and after the pixel point in the area to be detected is larger than N, the pixel point is indicated to correspond to the growth area of the crack tip, and heat is released during the fracture, so that the frequency of the infrared images acquired at the position is greatly changed. And carrying out binarization processing on the pixel points. And identifying the crack image by using a canny algorithm, and reading the position information of the crack tip.
As a specific embodiment, during the fatigue crack propagation process, acquiring a crack image in the detection area to obtain a plurality of crack images, specifically including:
and in the fatigue crack propagation process, acquiring crack images in the detection area by adopting an infrared camera to obtain a plurality of crack images.
Example 2
A system for detecting a fatigue crack tip by infrared thermal imaging, the system comprising:
and the acquisition module is used for acquiring crack images in the detection area in the fatigue crack expansion process to obtain a plurality of crack images.
And the conversion module is used for carrying out conversion processing on the plurality of crack images to obtain a plurality of frequency-coordinate images.
And the calculating module is used for calculating the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images.
And the detection module is used for detecting the position of the crack tip according to the plurality of frequency difference-coordinate images.
As a specific embodiment, the conversion module specifically includes:
and the conversion unit is used for carrying out conversion processing on the plurality of crack images to obtain a plurality of frequency-coordinate images to be denoised.
And the denoising unit is used for denoising a plurality of frequency-coordinate images to be denoised by adopting Gaussian filtering to obtain a plurality of frequency-coordinate images.
An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the method of detecting fatigue crack tips for infrared thermal imaging as described in embodiment 1 when the computer program is executed.
A computer-readable storage medium having stored thereon a computer program which, when executed, implements the method of detecting fatigue crack tips for infrared thermal imaging as described in embodiment 1.
The method has strong adaptability, can adapt to the surface states of various materials, and is a dynamic crack detection method. The method can detect fine cracks in a poor material surface state, which is difficult to realize by the traditional static crack identification method. The invention only needs to set the main direction and the auxiliary direction, and can automatically detect and judge the coordinate information of the fracture tip. The infrared-based crack detection method can be used for nondestructively detecting the internal defects of the aviation material, and the technology is applied to the field of aviation material detection for the first time.
According to the invention, the position of the crack tip is determined by acquiring the infrared thermal imaging image and processing the infrared thermal imaging image, so that the problem that the crack inside the material cannot be subjected to nondestructive detection in the traditional crack detection method is solved, and the purpose of nondestructive detection of the crack inside the aviation material is achieved.
The method and the system for detecting the fatigue crack tip by infrared thermal imaging have the following beneficial effects that:
(1) Compared with the traditional crack detection method (such as a direct reading method, a flexibility method, a potential method, a flaw detection method and the like), the method provided by the invention has high automation degree, can detect and record crack growth in real time by a method of presetting a main direction and a secondary direction, and has high efficiency and less personnel workload. In addition, the operation level requirement on operators is low, and the safety of the operators can be better ensured in the measuring process.
(2) Compared with a crack detection method based on a neural network, the crack detection method based on the neural network does not need a large number of data sets to meet training requirements, has good adaptability, and has lower requirements on material types and surface states thereof.
(3) Compared with the traditional crack identification method based on image processing, the dynamic crack detection identification method is provided. The traditional crack identification method based on image processing is a static crack identification method, which processes the information of infrared thermal imaging of a single image and then analyzes and detects crack contours, so that crack detection effects on materials with different surface states are different, and when the surface states of the materials are relatively poor, crack tip positions are difficult to accurately detect. The method provided by the invention is a dynamic crack detection method, is based on the processing of gray information of more than or equal to 2 images, can adapt to the surface states of various materials, can accurately detect the expanding part of the crack tip even if the surface states are poor, and has strong adaptability and accurate crack tip detection effect.
(4) The infrared camera is applied, so that the temperature difference generated by crack growth in the material can be identified under the condition that the material is not damaged, and the position of the crack can be accurately identified.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (10)
1. The method for detecting the fatigue crack tip by infrared thermal imaging is characterized by comprising the following steps of:
in the fatigue crack propagation process, acquiring crack images in a detection area to obtain a plurality of crack images; the crack image is an infrared thermal imaging image;
converting the crack images to obtain a plurality of frequency-coordinate images;
calculating the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images;
the position of the crack tip is detected from a plurality of the frequency difference-coordinate images.
2. The method for detecting the fatigue crack tip by infrared thermal imaging according to claim 1, wherein the converting process is performed on a plurality of crack images to obtain a plurality of frequency-coordinate images, and then the method further comprises:
and denoising a plurality of the frequency-coordinate images by adopting Gaussian filtering.
3. The method for detecting a fatigue crack tip by infrared thermal imaging according to claim 1, wherein calculating the frequency difference between two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images, further comprises:
judging whether position offset exists between two adjacent frequency-coordinate images, and obtaining a first judging result;
if the first judgment result is yes, calibrating and correcting the two frequency-coordinate images with the position offset by using a calibration algorithm;
and if the first judgment result is negative, representing that no position deviation exists between two adjacent frequency-coordinate images.
4. The method for detecting a fatigue crack tip by infrared thermal imaging according to claim 1, wherein detecting the position of the crack tip based on a plurality of the frequency difference-coordinate images, specifically comprises:
judging whether the frequency difference of each pixel point in the frequency difference-coordinate image is larger than a preset threshold value or not to obtain a second judging result;
if the second judgment result is negative, characterizing a growth area which does not correspond to the crack tip in the detection area, returning to the process of fatigue crack propagation, and collecting crack images in the detection area to obtain a plurality of crack images;
if the second judgment result is yes, representing a growth area of the corresponding crack tip of the pixel point corresponding to the frequency difference larger than a preset threshold value;
detecting a plurality of pixel points corresponding to the frequency difference larger than a preset threshold value to obtain the position of the crack tip.
5. The method for detecting the fatigue crack tip by infrared thermal imaging according to claim 4, wherein detecting the positions of the crack tip obtained by a plurality of pixels corresponding to the frequency difference larger than a preset threshold value specifically comprises:
performing difference between every two pixel points of the pixel points to obtain a difference value set;
judging whether each difference value in the difference value set is larger than a preset threshold value or not, and obtaining a third judgment result;
if the third judgment result is yes, detecting a pixel point corresponding to each difference value in the difference value set by adopting a canny algorithm to obtain the position of the crack tip;
if the third judgment result is negative, deleting the difference value smaller than the preset threshold value in the difference value set to obtain a deleted difference value set, and detecting the pixel point corresponding to each difference value in the difference value set deleted by a canny algorithm to obtain the position of the crack tip.
6. The method for detecting the tip of a fatigue crack by infrared thermal imaging according to claim 1, wherein the step of acquiring the crack image in the detection area during the propagation of the fatigue crack to obtain a plurality of crack images comprises the steps of:
and in the fatigue crack propagation process, acquiring crack images in the detection area by adopting an infrared camera to obtain a plurality of crack images.
7. An infrared thermal imaging fatigue crack tip detection system, characterized in that the infrared thermal imaging fatigue crack tip detection system comprises:
the acquisition module is used for acquiring crack images in the detection area in the fatigue crack expansion process to obtain a plurality of crack images;
the conversion module is used for carrying out conversion processing on a plurality of crack images to obtain a plurality of frequency-coordinate images;
the computing module is used for computing the frequency difference of two adjacent frequency-coordinate images to obtain a plurality of frequency difference-coordinate images;
and the detection module is used for detecting the position of the crack tip according to the plurality of frequency difference-coordinate images.
8. The infrared thermal imaging fatigue crack tip detection system according to claim 7, wherein the conversion module specifically comprises:
the conversion unit is used for carrying out conversion processing on the plurality of crack images to obtain a plurality of frequency-coordinate images to be denoised;
and the denoising unit is used for denoising a plurality of frequency-coordinate images to be denoised by adopting Gaussian filtering to obtain a plurality of frequency-coordinate images.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the method of any one of claims 1 to 6 when the computer program is executed.
10. A computer readable storage medium, characterized in that the storage medium has stored thereon a computer program which, when executed, implements the method according to any of claims 1 to 6.
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