A method for rapid evaluation of fatigue cracks and scratches on the surface of a metal part

Abstract

This invention provides a rapid assessment method for fatigue cracks and scratches on the surface of metal components. It is a detection and analysis method for distinguishing between fatigue cracks and micro-scratches on metal surfaces, and for analyzing and predicting defect development. Its key feature is that it differentiates between fatigue cracks and micro-scratches by detecting and identifying the shape of the opening extending along the depth direction of the defect. This invention utilizes a large amount of data analysis to determine the shape of the defect opening edge, achieving clear differentiation and significantly reducing safety hazards caused by missed detections.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nondestructive testing, in particular to a detection device for an irregularly curved metal surface, and more particularly to a rapid evaluation method for surface fatigue cracks and scratches of a metal part. BACKGROUND

[0002] Safety evaluation of in-service major equipment, such as parts of an aircraft, usually cannot be separated from nondestructive testing methods. Due to the complex working environment of in-service equipment, it is necessary to make a prediction of the later development of defects because of the high safety requirement. For larger defect cracks, it is easy to determine and analyze. However, for micro defects, in addition to normal fatigue cracks, there are also unintentional scratches, etc. According to the current detection and maintenance standard, if the surface is a stress fatigue crack, it must be determined as waste, and if it is a scratch, it can be passed. In practice, how to distinguish and judge depends entirely on the experience of the detection engineer. Therefore, misjudgment and missed judgment often occur in engineering applications, resulting in unnecessary losses or safety accidents.

[0003] In view of the above problems, the present application is further improved by using the following technical scheme. SUMMARY

[0004] The purpose of the present application is to provide a rapid evaluation method for surface fatigue cracks and scratches of a metal part. The technical scheme disclosed is as follows:

[0005] A rapid evaluation method for surface fatigue cracks and scratches of a metal part, which is used to distinguish and identify the detection and analysis method of metal surface fatigue cracks and micro scratches, analyze and predict defect development, characterized in that the opening shape extending in the defect depth direction is detected and identified to distinguish and determine fatigue cracks and micro scratches. The specific eddy current detection method steps are as follows:

[0006] a. Defect opening detection data extraction: small diameter eddy current detection sensor device is used for scanning detection of defects, and a multi-frequency eddy current sensor detection instrument is used to scan and detect the surface of the detected object to extract detection data;

[0007] b. Defect edge shape analysis: through the detection data extracted in step a, the crack characteristics of the object under test are refined and the image is reconstructed, and the curve shape in the opening depth direction of the crack is analyzed. When the opening shape of the crack analyzed by the eddy current detection thinning image tends to be V-shaped, it is determined to be a metal fatigue crack. When the opening shape of the crack analyzed by the eddy current detection thinning image tends to be U-shaped, it is determined to be a scratch. Natural fatigue cracks are caused by metal deformation and do not have metal component loss. The opening shape is complementary and symmetrical, the crack surface opening is narrow, and due to the elastic deformation characteristics of the metal, the bottom is V-shaped. Scratches are caused by external invading objects and have metal component loss. The metal component between scratches no longer has the characteristics of elastic deformation, the bottom is arc-shaped, the opening is linearly symmetrical, and occasionally convex or concave. The crack opening is relatively flat on both sides, the width is wider, and it tends to be U-shaped.

[0008] Further, in the defect opening detection data extraction, detailed information is extracted for re-detection after detecting a crack defect. The multi-frequency eddy current sensor detection instrument detects the width of the defect crack at different depths by using different transformed alternating currents at different frequencies to depict the crack opening shape in a point-to-line manner. The eddy current detection signal has a skin effect characteristic. Different frequencies detect different depths. Generally, when a higher frequency electrical signal is detected, the eddy current detection is shallow on the surface of the metal being detected. When a lower frequency alternating power source is used for eddy current detection, the signal detected is deeper.

[0009] Further, in the detection of the width of the defect crack at different depths, three points in the electromagnetic eddy current sensing information near the bottom are extracted. The three points of the detection data of one side edge of the defect are connected in a line to evaluate the range of the straight line of the middle point offset to determine the opening curvature. Further, in the extraction of the three-point connection of the detection data of the edge, three-point signals of the same height on the other side edge of the same height are also extracted. After connection analysis, the symmetry of the two sides is compared to evaluate the curvature of the opening of the defect crack, thereby determining whether the defect is a fatigue crack or a scratch.

[0010] Further, it also includes extracting an unlimited number of three-point detection signals and connecting large data to evaluate and analyze the defect edge shape information.

[0011] Further, the eddy current multi-frequency detection sensor is an arrayed eddy current detection sensor. Multiple eddy current detection sensors extract edge information in the length direction of the defect, analyze the symmetry, and use it as additional data in combination with edge information in the opening depth direction of the defect to analyze and determine whether the defect is a fatigue crack or a scratch.

[0012] Further, the arrayed eddy current detection sensor is set as a small-diameter eddy current sensor. After scanning one side of the defect edge shape, it returns to scan and detect the other side of the defect edge for a second time to comprehensively analyze and determine whether the defect is a fatigue crack or a scratch.

[0013] Further, the extracted three-point detection signal is used to extract three points of the middle, opening end and bottom end of the two edges of the defect respectively, and the included angle of the lines connected after the three points is evaluated to analyze the shape of the defect.

[0014] Further, in the detection of the width of the defect crack with different depths, two points in the electromagnetic eddy current induction information of the opening end and the bottom of the defect are extracted respectively, the included angle of the lines connected after the two points is evaluated, and the shape of the defect is analyzed. When the included angle is less than a certain value, or the two lines are parallel, the fatigue crack is evaluated and determined, and when the included angle is greater than a certain value, the scratch is determined.

[0015] Further, the eddy current detection probe used is an array type small diameter eddy current sensor, and the array type eddy current sensor is arranged as an array of eddy current sensors shielded by a shielded cover on one side, and the detection data is extracted by repeatedly scanning back and forth along the edge of the defect in the scanning detection process.

[0016] According to the above technical scheme, the present application has the following beneficial effects: through a large amount of practical work, the present application analyzes and summarizes the shape and characteristics of dangerous fatigue cracks and scratches, and proposes a corresponding non-destructive testing method, thereby helping the operator to accurately evaluate the safety state of the detected workpiece. Generally speaking, natural fatigue damage cracks are caused by abnormal stress concentration in equipment in use. Once a crack is found or suspected, it is easy to develop into a large crack defect under the same working condition, and eventually may cause a fracture failure. In the present application, the opening shape of the natural crack is complementary and symmetrical, the bottom is V-shaped, the surface opening is narrow, usually only a few microns or tens of microns; while the scratch is different, the bottom is V-shaped, the opening is linearly symmetrical, occasionally convex or concave, the crack opening is relatively flat, symmetrical and wide, etc. The characteristics are analyzed and evaluated, and the characteristics are suitable for extracting a large amount of data to analyze and evaluate the opening shape of the defect, so as to distinguish fatigue cracks and scratches. For example, if the currently popular in-service crack of 0.2mm deep is used as the judgment standard, the two are not distinguished, and the possibility of misjudgment and omission is great. The present application uses a large amount of detection data to analyze the opening edge shape of the defect, realizes the distinction and judgment, and greatly reduces the safety hidden danger caused by omission. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The eddy current detection detection state diagram of the best embodiment of the present application;

[0018] Figure 2 The defect diagram of the metal material workpiece of the best embodiment of the present application;

[0019] Figure 3 The defect diagram of the metal material workpiece of the best embodiment of the present application;

[0020] Figure 4 A defect data extraction schematic diagram for the best embodiment of the present application;

[0021] Figure 5 A defect data extraction schematic diagram for the best embodiment of the present application;

[0022] Figure 6 A defect data extraction schematic diagram for the best embodiment of the present application.

[0023] Figure 7 A defect data extraction schematic diagram for the best embodiment of the present application;

[0024] Figure 8 A defect data extraction schematic diagram for the best embodiment of the present application;

[0025] Figure 9 A defect data extraction schematic diagram for the best embodiment of the present application;

[0026] Figure 10 A defect data extraction schematic diagram for the best embodiment of the present application;

[0027] Figure 11 A defect data extraction schematic diagram for the best embodiment of the present application;

[0028] Figure 12 An array eddy current sensor schematic diagram for the best embodiment of the present application. DETAILED DESCRIPTION

[0029] The present application is further described below in conjunction with the accompanying drawings and specific embodiments.

[0030] As Figures 1 to 12 shown, a rapid evaluation method for metal component surface fatigue cracks and scratches is used to distinguish and identify the detection and analysis method of metal component 1 surface fatigue cracks and micro scratches 11, analyze and predict defect development, characterized in that the fatigue cracks and micro scratches are distinguished and judged by detecting and identifying the opening shape extending in the defect depth direction; the specific eddy current detection method steps are as follows:

[0031] a. Defect opening detection data extraction: a small diameter eddy current detection sensor device is used to scan and detect defects, and a multi-frequency eddy current sensor detection instrument is used to scan and detect the surface of the detected object to extract detection data;

[0032] b. Defect edge shape analysis: through the detection data extracted in step a, the crack characteristics of the detected object are refined and the image is reconstructed, and the curve shape in the crack opening depth direction is analyzed; when the eddy current detection refined image analyzes the crack opening shape to be V-shaped, it is determined to be a metal fatigue crack; when the eddy current detection refined image analyzes the crack opening shape to be U-shaped, it is determined to be a scratch.

[0033] As shown in Figure 3 Natural fatigue cracks are caused by metal deformation itself, and do not have metal component loss. The opening shape is complementary and symmetrical, and the crack surface opening will be narrow. Due to the elastic deformation characteristics of the metal, the bottom is in V shape; while scratches, as shown in Figure 2 The scratches are caused by external invading objects, have metal component loss, and the metal component between the scratches no longer has the characteristics of elastic deformation. The bottom is in arc shape, the opening is linearly symmetrical, and occasionally has protrusions or depressions. The crack opening two edges are relatively flat, the width is wider, and it tends to be U-shaped.

[0034] In the defect opening detection data extraction, detailed information is extracted for the second detection after the crack defect has been detected. The multi-frequency eddy current sensor detection instrument detects the width of the defect crack at different depths by using different transformed alternating currents at different frequencies, and depicts the crack opening shape in the form of point connection. The eddy current detection signal has skin effect characteristics. The detection depth is different at different frequencies. Generally, when a higher frequency electrical signal is detected, the eddy current detection is shallow on the metal surface. When a lower frequency alternating power source is used for eddy current detection, the signal is deeper.

[0035] As shown in Figure 4 and Figure 5 In the detection of the width of the defect crack at different depths, three points a, b, and c in the electromagnetic eddy current sensing information near the bottom are extracted. The three points of the detection data of the edge of the defect are connected to evaluate the range of the straight line of the offset middle point to determine the opening arc. In the extraction of the three-point connection of the edge detection data, the three-point signals of the same height on the other edge are also extracted. After connection analysis, the symmetry of the two edges is compared to evaluate the arc of the defect crack opening, so as to determine whether the defect is a fatigue crack or a scratch. In addition, an unlimited number of three-point detection signals are extracted, and the large data of the connected lines are evaluated and analyzed to obtain the defect edge shape information.

[0036] As shown in Figure 6 and Figure 7 The eddy current multi-frequency detection sensor is an array type eddy current detection sensor. The edge information in the length direction of the defect is extracted by multiple eddy current detection sensors, and the symmetry is analyzed as additional data. The edge information in the depth direction of the defect opening is combined to analyze and determine whether the defect is a fatigue crack or a scratch.

[0037] As shown in Figure 12 The array type eddy current detection sensor is set as a small diameter eddy current sensor. After scanning one side of the defect edge shape, it returns to scan and detect the other side of the defect edge for the second time. The defect property is comprehensively analyzed and determined to be a fatigue crack or a scratch.

[0038] As shown in Figure 6 and Figure 7As shown in the figure, the extracted three-point detection signal is three points extracted from the middle, opening end and bottom end of the two edges of the defect, respectively. After connecting the lines, the included angle of the lines connecting the two edges of the defect is evaluated to analyze the shape of the defect.

[0039] As shown in the figure, Figure 8 and Figure 9 As shown in the figure, in the detection of the width of the defect crack with different depths, two points in the electromagnetic eddy current induction information of the opening end and the bottom of the defect are extracted, respectively, and after connecting the lines, the included angle of the lines connecting the two edges of the defect is evaluated to analyze the shape of the defect. When the included angle is less than a certain value, or the two lines are parallel, the fatigue crack is evaluated and determined, and when the included angle is greater than a certain value, the scratch is determined.

[0040] As shown in the figure, Figure 12 As shown in the figure, the eddy current detection probe 2 used is an array type small diameter eddy current sensor 21, which is arranged as an array of eddy current sensors shielded by a shield 22 on one side. During the scanning detection process, the detection data is extracted by repeatedly scanning back and forth along the edge of the defect in the defect direction.

[0041] The above is one of the embodiments of the present application. In addition, it should be noted that any equivalent or simple changes made according to the structure, features and principles described in the patent concept are included in the protection scope of the patent.

Claims

1. A method for rapid evaluation of surface fatigue cracks and scratches on a metal part, characterized in that The fatigue crack and the micro scratch are distinguished by detecting the opening shape extending in the depth direction of the defect; the specific eddy current detection method steps are as follows: a. Defect opening detection data extraction: small diameter eddy current detection sensor device is used for scanning detection of defects, and a multi-frequency eddy current sensor detection instrument is used for scanning detection of the surface of the detected object to extract detection data; b. Defect edge shape analysis: through the detection data extracted in step a, the crack characteristics of the detected object are refined and the image is reconstructed, and the curve shape in the depth direction of the crack opening is analyzed; when the eddy current detection refined image analyzes the crack opening shape to be V-shaped, it is determined to be a metal fatigue crack; when the eddy current detection refined image analyzes the crack opening shape to be U-shaped, it is determined to be a scratch; In the defect opening detection data extraction, detailed information is extracted for re-detection after detecting the crack defect; the multi-frequency eddy current sensor detection instrument detects the width of the defect crack at different depths by using different alternating currents with different frequencies, and depicts the crack opening shape in the detection of the width of the defect crack at different depths; three points in the electromagnetic eddy current sensing information close to the bottom are extracted, the three points of the detection data of one side edge of the defect are connected in a line, the range of the straight line with the offset of the middle point is evaluated, and the opening curvature is determined; in the three-point connection of the edge detection data, the three-point signals of the other side edge detection data at the same height are also extracted, and after connection analysis, the symmetry of the two sides is compared to evaluate the curvature of the defect crack opening, so as to determine whether the defect is a fatigue crack or a scratch. An unlimited number of three-point detection signals are also extracted, and the large data of the connected lines are evaluated and analyzed to obtain the defect edge shape information.

2. A method for rapid evaluation of surface fatigue cracks and scratches of a metal component according to claim 1, characterized in that The eddy current multi-frequency detection sensor is an array type eddy current detection sensor, a plurality of eddy current detection sensors extract the edge information in the length direction of the defect, analyze the symmetry, and use the edge information in the depth direction of the defect opening as additional data to analyze and determine whether the defect is a fatigue crack or a scratch.

3. The method of claim 1, wherein The array type eddy current detection sensor is set as a small diameter eddy current sensor, which scans one side of the defect edge shape and returns to scan the other side of the defect edge for the second time to comprehensively analyze and determine whether the defect is a fatigue crack or a scratch.

4. A method of rapid assessment of surface fatigue cracks and scratches on a metal component according to claim 3, characterized in that The extracted three-point detection signals are three points of the middle, opening end and bottom of the two edges of the defect, which are connected in a line to evaluate the included angle of the two edge lines of the defect and analyze the defect shape.

5. The method of claim 1, wherein In the detection of the width of the defect crack at different depths, two points in the electromagnetic eddy current sensing information of the opening end and the bottom of the defect are extracted, respectively, and the included angle of the two edge lines of the defect is evaluated after connection to analyze the defect shape.

6. The method of claim 1, wherein The eddy current detection probe used is an array type small diameter eddy current sensor, which is set as an array of eddy current sensors shielded by a shielded cover on one side, and the detection data is extracted by repeatedly scanning the edge of the defect in the defect direction during the scanning detection process.

7. A method of rapid evaluation of surface fatigue cracks and scratches of a metal part according to claim 4, characterized in that ​

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