A dynamic prediction method for fatigue crack rate of titanium alloy materials

Abstract

The present invention relates to the technical field of ultrasonic testing materials, and specifically to a method for dynamically predicting fatigue crack rate of titanium alloy materials, comprising: obtaining a waveform diagram corresponding to each position in each cycle, obtaining a plurality of crack regions in each cycle according to the degree to which each position meets the crack region characteristics in each cycle, calculating the degree of change of each wave peak on all waveform diagrams, and then obtaining the extension degree of each crack region in each cycle, calculating the possibility of each crack region in each cycle merging with the adjacent subsequent crack region, and obtaining a plurality of crack groups in each cycle, thereby obtaining the predicted extension rate of each crack group in each cycle, and finally screening out a plurality of crack groups with excessively fast extension rates from all crack groups. The present invention analyzes the extension state of the current crack by the difference in the extension conditions of multiple positions, and predicts the extension rate of the current crack according to different states, thereby improving the accuracy of crack extension prediction.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic testing materials, and in particular to a method for dynamically predicting fatigue crack rate of titanium alloy materials. Background Art

[0002] Titanium alloys have the characteristics of corrosion resistance and easy processing, but in actual use, titanium alloy materials also have fatigue problems, and crack defects caused by fatigue loads often appear. If fatigue cracks cannot be discovered in time and their development trends cannot be accurately judged, the cracks may gradually worsen and eventually break, leading to the collapse of the metal structure. In order to predict the growth rate of fatigue cracks in titanium alloys, ultrasonic testing is often used for non-destructive testing of titanium alloys, that is, titanium alloy materials with good performance are relatively uniform, and there is a difference in acoustic impedance between defective areas and normal areas. Ultrasonic waves are reflected at the interface between the two media, and the reflected waveforms will differ due to the difference in defects (defect location, depth, etc.). Therefore, the nature of the defective area is determined by analyzing the waveform differences. However, in actual use, due to the influence of factors such as load level, stress concentration, and ambient temperature, crack extension causes secondary cracks, or two cracks merge. At this time, the above method cannot distinguish them.

[0003] The existing technology detects and determines the depth, position and length of a single fatigue crack in a titanium alloy material through the propagation and reflection of ultrasonic waves in the structure, and predicts the growth rate of a single crack by comparing the differences in the above characteristics at different times through real-time monitoring. However, during the use of titanium alloy materials, due to the differences in vibration amplitude and stress at the crack tips at different positions, fatigue cracks in titanium alloy materials may merge into one crack when the cracks extend. At this time, the use of existing technology may not be able to accurately distinguish the above situations, resulting in inaccurate prediction results. Summary of the invention

[0004] The invention provides a method for dynamically predicting fatigue crack rate of titanium alloy material to solve the existing problems.

[0005] A method for dynamically predicting fatigue crack rate of titanium alloy material of the present invention adopts the following technical scheme:

[0006] An embodiment of the present invention provides a method for dynamically predicting fatigue crack rate of titanium alloy material, the method comprising the following steps:

[0007] Select several positions on the titanium rod for ultrasonic testing, and obtain the waveform corresponding to each position in each cycle;

[0008] According to the waveform graph corresponding to each position in each cycle, the degree to which each position meets the crack region characteristics in each cycle is obtained; among all positions in each cycle whose degree to which they meet the crack region characteristics is greater than a preset first threshold, the positions are recorded as crack regions;

[0009] According to the waveform graph corresponding to each position in each cycle, the degree of change of each wave peak on the waveform graph corresponding to each position in each cycle is obtained; according to the degree to which all positions in all cycles conform to the crack area characteristics and the degree of change of all wave peaks on the waveform graph corresponding to each position in each cycle, the extension degree of each crack area in each cycle is obtained;

[0010] According to the degree of change of all the peaks on the waveform diagram corresponding to each cycle at all positions, the direction vector of each crack area in each cycle is obtained; according to the extension degree and direction vector of all the crack areas in each cycle, several crack groups in each cycle are obtained;

[0011] According to the extension degree of all crack areas in each cycle, the preset duration of each cycle and all crack groups in all cycles, several crack groups with excessively fast extension rates are screened out from all crack groups in each cycle.

[0012] Furthermore, according to the waveform diagram corresponding to each position in each cycle, the specific calculation formula for obtaining the degree of compliance with the crack region characteristics at each position in each cycle is:

[0013]

[0014] In the formula, Indicates Position in The degree to which the cycle conforms to the characteristics of the crack area; Indicates Position in The number of peaks of the waveform corresponding to each cycle; Indicates Position in The amplitude range of the waveform corresponding to each cycle; No. Position in The average value of the maximum amplitude of all peaks of the waveform graph corresponding to the period; Indicates Position in The sum of the widths of all the peaks of the waveform graph corresponding to the period; Indicates Position in The first cycle of the waveform diagram The maximum amplitude of the peaks; is a linear normalization function; is the absolute value function.

[0015] Furthermore, the step of obtaining the degree of change of each peak on the waveform graph corresponding to each position in each period according to the waveform graph corresponding to each position in each period includes the following specific steps:

[0016] In the The number of positions except In the horizontal coordinate of the maximum amplitude of each peak of the waveform graph corresponding to each cycle outside the cycle, the The first cycle of the waveform diagram The smallest of the absolute values ​​of the differences in the horizontal coordinates of the maximum amplitudes of the peaks is The peak of the waveform corresponding to each cycle outside the cycle is recorded as Position in The first cycle of the waveform diagram The corresponding peaks of the peaks in each cycle;

[0017] According to the waveform graph corresponding to each position in each period and the corresponding peak of each peak of the waveform graph corresponding to each position in each period in each period, the variation degree of each peak on the waveform graph corresponding to each position in each period is obtained.

[0018] Further, according to the waveform graph corresponding to each position in each period and the corresponding peak of each peak of the waveform graph corresponding to each position in each period in each period, the specific calculation formula for obtaining the degree of change of each peak on the waveform graph corresponding to each position in each period is:

[0019]

[0020] In the formula, Indicates Position in The first cycle of the waveform diagram The degree of change of each peak; Indicates The positions are except The number of cycles outside the cycle; Indicates Position in The first cycle of the waveform diagram The peak is The horizontal coordinate of the maximum amplitude of the corresponding peak of the cycle; Indicates Position in The first cycle of the waveform diagram The peak is The horizontal coordinate of the maximum amplitude of the corresponding peak of the cycle; Indicates Position in The first cycle of the waveform diagram The width of the first peak is related to the The absolute value of the difference in the width of the corresponding peaks of the period; Indicates Position in The first cycle of the waveform diagram The peak is The cycle and The absolute value of the difference in the maximum amplitude of the corresponding peaks of the periods.

[0021] Furthermore, the extension degree of each crack region in each cycle is obtained according to the degree to which all positions meet the crack region characteristics in all cycles and the degree of change of all wave peaks on the waveform graph corresponding to each position in each cycle, and the specific steps include the following:

[0022] The extension degree of each crack region in each cycle is recorded as the product of the average value of the degree to which the position corresponding to each crack region in all cycles conforms to the crack region characteristics and the sum of the change degrees of all wave peaks of the waveform graph corresponding to each crack region in each cycle.

[0023] Furthermore, the step of obtaining the direction vector of each crack region in each cycle according to the degree of change of all wave peaks in the waveform graph corresponding to each cycle at all positions includes the following specific steps:

[0024] Get the distance between any two positions on the titanium rod, and the In the waveform corresponding to the cycle, the position of the waveform corresponding to the peak of the maximum change degree is recorded as the target position. The distance and direction of each crack area from the target position in the cycle constitutes the The direction vector of each crack region in cycles.

[0025] Furthermore, the method of obtaining several crack groups in each cycle according to the extension degrees and direction vectors of all crack regions in each cycle includes the following specific steps:

[0026] According to the extension degree and direction vector of each crack region in each cycle, the possibility of merging any two crack regions in each cycle is obtained;

[0027] The inverse of the possibility of merging any two crack regions in each cycle is taken as the clustering distance, and all crack regions in each cycle are clustered to obtain several crack groups in each cycle.

[0028] Furthermore, the specific calculation formula for obtaining the possibility of merging any two crack regions in each cycle according to the extension degree and direction vector of each crack region in each cycle is:

[0029]

[0030] In the formula, Indicates The first cycle The crack area and The possibility of merging of crack regions; Indicates The first cycle The crack area and The distance between the crack areas; Indicates The first cycle The crack area and The mean extension of the crack area, Indicates The first cycle The extension of the crack area, Indicates The first cycle The extension of the crack area, Indicates The first cycle The direction vector of the first crack region is The angle between the direction vectors of the crack regions; is a linear normalization function; is the absolute value function.

[0031] Furthermore, the method of screening out a number of crack groups with excessively fast extension rates from all crack groups in each cycle according to the extension degrees of all crack regions in each cycle, the preset duration of each cycle, and all crack groups in all cycles includes the following specific steps:

[0032] Statistics The first cycle The crack group and The intersection of each crack group in the cycle is The first cycle The crack group and In the intersection of all crack groups in a period, the intersection with the largest number of data points corresponding to the The crack group in the cycle is recorded as The first cycle The corresponding crack group of each crack group;

[0033] According to the extension degree of all crack regions in each cycle, the preset duration of each cycle and the corresponding crack group of each crack group in each cycle, the predicted extension rate of each crack group in each cycle is obtained;

[0034] Among all crack groups in each cycle, all crack groups with predicted extension rates greater than a preset second threshold are recorded as crack groups with excessively fast extension rates.

[0035] Furthermore, the specific calculation formula for obtaining the predicted extension rate of each crack group in each cycle according to the extension degree of all crack areas in each cycle, the preset duration of each cycle and the corresponding crack group of each crack group in each cycle is:

[0036]

[0037] In the formula, Indicates The first cycle The predicted extension rate of each crack group; Indicates The first cycle The mean extension of all crack regions in a crack group; Indicates The first cycle The mean extension of all crack areas in the corresponding crack group of each crack group; Indicates The first cycle The crack group The extension of the crack area; Indicates The first cycle The number of crack regions in a crack group; Indicates The mean of the probability of merging of any two crack regions in cycles; Indicates the duration of each preset cycle; Indicates The first cycle The number of crack regions in each crack group; is a linear normalization function; is the absolute value function.

[0038] The beneficial effects of the technical solution of the present invention are:

[0039] In the embodiment of the present invention, the waveform corresponding to each position in each cycle is obtained, and a more accurate crack region is obtained according to the degree to which each position meets the crack region characteristics in each cycle, and several crack regions in each cycle are obtained; the degree of change of each peak on all waveforms is calculated, and the extension trend of a single crack is accurately judged accordingly, and the extension degree of each crack region in each cycle is obtained, and the possibility of merging each crack region in each cycle with the adjacent subsequent crack region is calculated, and whether there is a crack merging situation is analyzed, and several crack groups in each cycle are obtained, thereby obtaining the predicted extension rate of each crack group in each cycle, and finally, several crack groups with too fast extension rates are screened out from all crack groups in each cycle, which improves the situation in which the existing technology only obtains a single crack extension rate and the prediction accuracy is not high. So far, the present invention obtains the extension direction and extension degree of a single crack according to the difference in waveforms in different time periods, and obtains the extension state of the crack by analyzing the difference in extension direction and extension degree between cracks adjacent to the current crack, thereby determining the crack position and crack extension rate at the next moment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 The present invention is a flowchart of the steps of a method for dynamically predicting fatigue crack rate of titanium alloy materials. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a method for dynamically predicting fatigue crack rates of titanium alloy materials proposed according to the present invention, its specific implementation, structure, features and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0043] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0044] The specific scheme of the method for dynamically predicting fatigue crack rate of titanium alloy material provided by the present invention is described in detail below with reference to the accompanying drawings.

[0045] See also Figure 1 , which shows a flowchart of a method for dynamically predicting fatigue crack rate of a titanium alloy material provided by an embodiment of the present invention, the method comprising the following steps:

[0046] Step S001: Select several positions on the titanium rod for ultrasonic testing, and obtain the waveform corresponding to each position in each cycle.

[0047] Under the repeated action of stress, the mechanical properties of the local structure of titanium alloy material deteriorate, causing fatigue cracks to gradually form. As the use time increases, the stress changes repeatedly, causing the cracks to continue to extend and expand until they completely break. The cracks formed have tiny fine lines that are difficult to identify with the naked eye, and the changes in the extension state are difficult to accurately obtain.

[0048] Several positions are evenly distributed on the upper surface of the titanium rod, and the preset duration of each cycle is taken as one cycle. In each cycle, an ultrasonic probe is set at each position to monitor the amplitude data on the surface of the titanium rod, and a waveform graph corresponding to each position in each cycle is obtained, wherein the horizontal axis of the waveform graph is the sound path and the vertical axis is the amplitude; the distance between any two positions is obtained.

[0049] It should be noted that the duration of each cycle preset in this embodiment is 15 minutes, and an ultrasonic probe is used to record the waveform obtained at different positions within 15 minutes. The waveform has the direction of increasing sound path as the positive direction of the horizontal axis (unit: mm), and the direction of increasing amplitude as the positive direction of the vertical axis (unit: dB). The data obtained from each monitoring is recorded and the corresponding waveform is obtained.

[0050] Step S002: According to the waveform diagram corresponding to each position in each cycle, the degree to which each position meets the crack area characteristics in each cycle is obtained; among all positions in each cycle whose degree of meeting the crack area characteristics is greater than a preset first threshold, the positions are recorded as crack areas.

[0051] Ultrasonic waves have almost no reflection at the interface of the same material, and the obtained waveform is smooth and linear along the horizontal axis. The material distribution in the normal titanium rod area is uniform, while the crack area destroys the uniformity of the normal area, making the acoustic impedance of the normal area and the crack area inconsistent, resulting in a large degree of ultrasonic reflection at the junction of the two areas; when there is a crack defect in the material, the inside of the crack area is uneven, and the reflection amplitude of ultrasonic waves at different positions is also different. Therefore, the ultrasonic amplitude obtained in the crack area fluctuates, that is, the smaller the amplitude of the reflected wave at the deeper crack position, the larger the amplitude reflected at the shallower crack and the crack edge. Therefore, the amplitude at the junction of the normal area and the crack area is large, and the amplitude inside the crack is small, that is, the more peaks the waveform obtained at a certain position has, the smaller the amplitude, the more uneven the distribution, the wider the peak, and the more serious the crack in the area.

[0052] According to the waveform diagram corresponding to each position in each cycle, the degree to which each position meets the crack area characteristics in each cycle is obtained, and the corresponding calculation formula is:

[0053]

[0054] In the formula, Indicates Position in The degree to which the cycle conforms to the characteristics of the crack area; Indicates Position in The number of peaks of the waveform corresponding to each cycle; Indicates Position in The amplitude range of the waveform corresponding to each cycle; No. Position in The average value of the maximum amplitude of all peaks of the waveform graph corresponding to the period; Indicates Position in The sum of the widths of all the peaks of the waveform graph corresponding to the period; Indicates Position in The first cycle of the waveform diagram The maximum amplitude of the peaks; is a linear normalization function that normalizes the data value to within the interval; is the absolute value function.

[0055] It should be noted that Position in The number of peaks of the waveform corresponding to each cycle The more, the Position in The more inconsistent the acoustic impedance of each cycle is; Indicates Position in The average value of the maximum amplitude of all the peaks of the waveform corresponding to the cycle accounts for the amplitude range. The larger the value, the Position in The greater the severity of the crack in each cycle; Indicates Position in The uniformity of all the peaks of the waveform graph corresponding to a period; in this embodiment, a peak detection algorithm is used to divide the waveform graph corresponding to each position in each period into several peaks, which is a well-known technology; the amplitude range of the waveform graph refers to the maximum range of the waveform in the vertical direction (amplitude).

[0056] The first threshold value preset in this embodiment is 0.7, which is used as an example for description. Other implementations may set it to other values, which are not limited in this embodiment;

[0057] All positions in each cycle that meet the crack region characteristics and have a degree greater than a preset first threshold are recorded as crack regions; thus, a number of crack regions in each cycle are obtained.

[0058] Step S003: According to the waveform graph corresponding to each position in each cycle, obtain the degree of change of each peak on the waveform graph corresponding to each position in each cycle; according to the degree to which all positions meet the crack area characteristics in all cycles and the degree of change of all peaks on the waveform graph corresponding to each position in each cycle, obtain the extension degree of each crack area in each cycle.

[0059] In the actual working process, as the titanium rod is used for a longer time, stress acts repeatedly on the fatigue crack, causing fatigue damage, which makes the fatigue crack gradually extend. Due to the different stress concentration levels in different areas, the stress magnitudes are also different, so there are differences in the extension of different fatigue cracks, that is, there are situations where the fatigue crack deepens and the fatigue crack becomes longer along its own extension direction. Therefore, the extension trend of a single diagonal line is analyzed through multiple scanning results. Taking a certain crack area as an example, if the length change and deepening degree of the crack along the extension direction are small in the multiple scanning results, it means that the stress concentration level in the current crack area is small, the fatigue damage level is low, and the extension degree of the crack is small.

[0060] The above characteristics are manifested in the waveform diagram as follows: in the multiple scanning amplitude curves of a single crack area, if there is a peak value whose degree of change over time is greater, the direction of the peak position is the extension direction of the current crack area, and the greater the difference in the degree to which the crack area conforms to the crack characteristics, the greater the extension degree of the current crack area during the test time.

[0061] In the The number of positions except In the horizontal coordinate of the maximum amplitude of each peak of the waveform graph corresponding to each cycle outside the cycle, the The first cycle of the waveform diagram The smallest of the absolute values ​​of the differences in the horizontal coordinates of the maximum amplitudes of the peaks is The peak of the waveform corresponding to each cycle outside the cycle is recorded as Position in The first cycle of the waveform diagram The corresponding peaks in each cycle.

[0062] According to the above method, the corresponding peak of each peak of the waveform graph corresponding to each position in each period is obtained;

[0063] According to the waveform graph corresponding to each position in each period and the corresponding peak of each peak of the waveform graph corresponding to each position in each period in each period, the degree of change of each peak on the waveform graph corresponding to each position in each period is obtained, and the corresponding calculation formula is as follows:

[0064]

[0065] In the formula, Indicates Position in The first cycle of the waveform diagram The degree of change of each peak; Indicates The positions are except The number of cycles outside the cycle; Indicates Position in The first cycle of the waveform diagram The peak is The horizontal coordinate of the maximum amplitude of the corresponding peak of the cycle; Indicates Position in The first cycle of the waveform diagram The peak is The horizontal coordinate of the maximum amplitude of the corresponding peak of the cycle; Indicates Position in The first cycle of the waveform diagram The width of the first peak is related to the The absolute value of the difference in the width of the corresponding peaks of the period; Indicates Position in The first cycle of the waveform diagram The peak is The cycle and The absolute value of the difference in the maximum amplitude of the corresponding peaks of the periods.

[0066] According to the degree to which all positions conform to the crack area characteristics in all cycles and the degree of change of all wave peaks on the waveform graph corresponding to each position in each cycle, the extension degree of each crack area in each cycle is obtained. The corresponding calculation formula is as follows:

[0067]

[0068] In the formula, Indicates The first cycle The extension of the crack area; Indicates The first cycle The average value of the degree to which the position corresponding to each crack region conforms to the characteristics of the crack region in all cycles, Indicates The first cycle The waveform corresponding to the crack area The degree of change of each peak; Indicates The first cycle The number of peaks in the waveform corresponding to each crack area.

[0069] Step S004: According to the degree of change of all wave peaks at all positions on the waveform diagram corresponding to each cycle, the direction vector of each crack area in each cycle is obtained; according to the extension degree and direction vector of all crack areas in each cycle, several crack groups in each cycle are obtained.

[0070] Due to the influence of stress, a single crack has different degrees of extension along its extension direction. However, during the crack extension process, there are multiple microcracks that are close in distance and dispersed, and they continue to extend with stress until they intersect and merge into a deeper crack. At this time, the extension of the microcracks "stops" and the extension of the new crack obtained by merging deepens. In order to distinguish between the merging of microcracks and the extension of a single crack, the possibility of multiple cracks in adjacent positions merging into one crack is analyzed. Therefore, taking a certain crack area as an example for analysis, the larger the angle between the crack and the extension direction of the adjacent crack, the greater the possibility of intersection, the greater the extension, the faster the merging speed, and the greater the possibility of merging.

[0071] In all positions In the waveform corresponding to the cycle, the position of the waveform corresponding to the peak of the maximum change degree is recorded as the target position. The distance and direction of each crack area from the target position in the cycle constitutes the The direction vector of each crack area in each cycle; if there are multiple maximum changes, any one is selected as an example for analysis.

[0072] According to the extension degree and direction vector of each crack area in each cycle, the possibility of merging any two crack areas in each cycle is obtained. The corresponding calculation formula is:

[0073]

[0074] In the formula, Indicates The first cycle The crack area and The possibility of merging of crack regions; Indicates The first cycle The crack area and The distance between the crack areas; Indicates The first cycle The direction vector of the crack region; Indicates The first cycle The direction vector of the crack region; Indicates The first cycle The crack area and The mean extension of the crack area, Indicates The first cycle The extension of the crack area, Indicates The first cycle The extension of the crack area, Indicates The first cycle The direction vector of the first crack region is The angle between the direction vectors of the crack regions; is a linear normalization function that normalizes the data value to within the interval; is the absolute value function.

[0075] It should be noted that The first cycle The direction vector of the first crack region is The angle between the direction vectors of the crack regions The larger it is, the more likely it is to intersect and merge; Indicates The first cycle Crack area The smaller the difference in the extension degree of the crack areas, the greater the average extension degree and the greater the tendency to merge.

[0076] The reciprocal of the possibility of merging all two arbitrary crack regions in each cycle is taken as the clustering distance, and the K-means clustering algorithm is used to cluster all crack regions in each cycle to obtain several crack groups in each cycle, wherein the K-means clustering algorithm is a well-known technology;

[0077] It should be noted that each cluster obtained by clustering all crack regions in each cycle is used as a crack group in each cycle, and the cluster data in the K-means clustering algorithm is obtained according to the elbow method, which is a well-known technology.

[0078] Step S005: According to the extension degree of all crack areas in each cycle, the preset duration of each cycle and all crack groups in all cycles, several crack groups with excessively fast extension rates are screened out from all crack groups in each cycle.

[0079] Fatigue crack extension has a tendency to extend in the horizontal and vertical directions (the horizontal direction refers to the degree of crack extension along the surface of the titanium rod, and the vertical direction refers to the degree of crack deepening). The extension rate is mainly determined by the degree of horizontal extension. In a certain period of time, the greater the degree of horizontal extension, the greater the corresponding extension rate. That is, if the number of probes contained in the crack group corresponding to a certain probe position obtained in the above steps in a certain cycle is greater than the number of probes in the previous cycle and the greater the degree, the greater the crack extension rate in the cycle. Therefore, by analyzing the difference in the extension degree of the crack group corresponding to a certain probe position in the current cycle and the previous cycle, the predicted value of the crack extension rate in the next cycle is obtained.

[0080] Statistics The first cycle The crack group and The intersection of each crack group in the cycle is The first cycle The crack group and In the intersection of all crack groups in a period, the intersection with the largest number of data points is selected. The crack group in the cycle is recorded as The first cycle The corresponding crack group of each crack group;

[0081] It should be noted that when The first cycle The crack group and When there are multiple intersections with the largest number of data in the intersection of all crack groups in a period, select one of them as the first The first cycle The corresponding crack group of each crack group.

[0082] According to the extension degree of all crack areas in each cycle, the preset duration of each cycle and the corresponding crack group of each crack group in each cycle, the predicted extension rate of each crack group in each cycle is obtained, and the corresponding calculation formula is as follows:

[0083]

[0084] In the formula, Indicates The first cycle The predicted extension rate of each crack group; Indicates The first cycle The mean extension of all crack regions in a crack group; Indicates The first cycle The mean extension of all crack areas in the corresponding crack group of each crack group; Indicates The first cycle The crack group The extension of the crack area; Indicates The first cycle The number of crack regions in a crack group; Indicates The mean of the probability of merging of any two crack regions in cycles; Indicates the duration of each preset cycle; Indicates The first cycle The number of crack regions in each crack group; is a linear normalization function that normalizes the data value to within the interval; is the absolute value function.

[0085] It should be noted that The predicted extension rate of the crack group is not calculated; Indicates The first cycle The difference between the mean extension of a crack group and all crack regions in its corresponding crack group, Indicates The first cycle The difference in extension of all crack regions within a crack group, Indicates The first cycle The difference between the number of crack groups and the number of crack areas in their corresponding crack groups.

[0086] The second threshold value preset in this embodiment is 0.5, which is described as an example. In other implementations, it can be set to other values, which are not limited in this embodiment;

[0087] Among all crack groups in each cycle, all crack groups with predicted extension rates greater than a preset second threshold are recorded as crack groups with excessively fast extension rates.

[0088] It should be noted that the crack extension information is output to the staff through the display device based on the fatigue crack growth data obtained above. If the crack extension rate at a certain position is too fast and the extension degree is large, an alarm message is set and the corresponding predicted rate is displayed to facilitate the staff to adjust the equipment and avoid excessive stress concentration at the crack position, which leads to continued deepening of the crack extension degree.

[0089] So far, the present invention is completed.

[0090] In summary, in an embodiment of the present invention, the waveform graph corresponding to each position in each cycle is obtained, and several crack regions in each cycle are obtained according to the degree to which each position meets the crack region characteristics in each cycle, and the degree of change of each peak on all waveform graphs is calculated, thereby obtaining the extension degree of each crack region in each cycle, and calculating the possibility of each crack region in each cycle merging with the adjacent subsequent crack region, and obtaining several crack groups in each cycle, thereby obtaining the predicted extension rate of each crack group in each cycle, and finally screening out several crack groups with too fast extension rates from all crack groups in each cycle. The present invention analyzes the extension state of the current crack through the difference in the extension conditions of multiple positions, and predicts the expansion rate of the current crack according to different states, thereby improving the accuracy of crack extension prediction.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for dynamically predicting fatigue crack rate of titanium alloy material, characterized in that: The method comprises the following steps: Select several positions on the titanium rod for ultrasonic testing, and obtain the waveform corresponding to each position in each cycle; According to the waveform graph corresponding to each position in each cycle, the degree to which each position meets the crack region characteristics in each cycle is obtained; among all positions in each cycle whose degree to which they meet the crack region characteristics is greater than a preset first threshold, the positions are recorded as crack regions; According to the waveform graph corresponding to each position in each cycle, the degree of change of each wave peak on the waveform graph corresponding to each position in each cycle is obtained; according to the degree to which all positions in all cycles conform to the crack area characteristics and the degree of change of all wave peaks on the waveform graph corresponding to each position in each cycle, the extension degree of each crack area in each cycle is obtained; According to the degree of change of all the peaks on the waveform diagram corresponding to each cycle at all positions, the direction vector of each crack area in each cycle is obtained; according to the extension degree and direction vector of all the crack areas in each cycle, several crack groups in each cycle are obtained; According to the extension degree of all crack areas in each cycle, the preset duration of each cycle and all crack groups in all cycles, several crack groups with excessively fast extension rates are screened out from all crack groups in each cycle; The method of obtaining several crack groups in each cycle according to the extension degree and direction vector of all crack regions in each cycle includes the following specific steps: According to the extension degree and direction vector of each crack region in each cycle, the specific calculation formula for the possibility of merging any two crack regions in each cycle is obtained as follows: In the formula, Indicates The first cycle The crack area and The possibility of merging of crack regions; Indicates The first cycle The crack area and The distance between the crack areas; Indicates The first cycle The crack area and The mean extension of the crack area, Indicates The first cycle The extension of the crack area, Indicates The first cycle The extension of the crack area, Indicates The first cycle The direction vector of the first crack region is The angle between the direction vectors of the crack regions; is a linear normalization function; is the absolute value function; Taking the inverse of the possibility of merging any two crack regions in each cycle as the clustering distance, all crack regions in each cycle are clustered to obtain several crack groups in each cycle. The method of selecting a plurality of crack groups with excessively fast extension rates from all crack groups in each cycle according to the extension degrees of all crack regions in each cycle, the preset duration of each cycle, and all crack groups in all cycles includes the following specific steps: Statistics The first cycle The crack group and The intersection of each crack group in the cycle is The first cycle The crack group and In the intersection of all crack groups in a period, the intersection with the largest number of data points corresponding to the first The crack group in the cycle is recorded as The first cycle The corresponding crack group of each crack group; According to the extension degree of all crack regions in each cycle, the preset duration of each cycle and the corresponding crack group of each crack group in each cycle, the predicted extension rate of each crack group in each cycle is obtained; Among all crack groups in each cycle, all crack groups with predicted extension rates greater than a preset second threshold are recorded as crack groups with excessively fast extension rates.

2. A method for dynamically predicting fatigue crack rate of titanium alloy material according to claim 1, characterized in that: The specific calculation formula for obtaining the degree of compliance with the crack region characteristics at each position in each cycle according to the waveform diagram corresponding to each position in each cycle is: In the formula, Indicates Position in The degree to which the cycle conforms to the characteristics of the crack area; Indicates Position in The number of peaks of the waveform corresponding to each cycle; Indicates Position in The amplitude range of the waveform corresponding to each cycle; No. Position in The average value of the maximum amplitude of all peaks of the waveform graph corresponding to the period; Indicates Position in The sum of the widths of all the peaks of the waveform graph corresponding to the period; Indicates Position in The first cycle of the waveform diagram The maximum amplitude of the peaks; is a linear normalization function; is the absolute value function.

3. The method for dynamic prediction of fatigue crack rate of titanium alloy material according to claim 1, characterized in that: The step of obtaining the degree of change of each peak on the waveform graph corresponding to each position in each period according to the waveform graph corresponding to each position in each period includes the following specific steps: In the The number of positions except In the horizontal coordinate of the maximum amplitude of each peak of the waveform graph corresponding to each cycle outside the cycle, the The first cycle of the waveform diagram The smallest of the absolute values ​​of the differences in the horizontal coordinates of the maximum amplitudes of the peaks is The peak of the waveform corresponding to each cycle outside the cycle is recorded as Position in The first cycle of the waveform diagram The corresponding peaks of the peaks in each cycle; According to the waveform graph corresponding to each position in each period and the corresponding peak of each peak of the waveform graph corresponding to each position in each period in each period, the variation degree of each peak on the waveform graph corresponding to each position in each period is obtained.

4. A method for dynamically predicting fatigue crack rate of titanium alloy material according to claim 3, characterized in that: The specific calculation formula for obtaining the degree of change of each peak on the waveform graph corresponding to each position in each cycle according to the waveform graph corresponding to each position in each cycle and the corresponding peak of each peak in the waveform graph corresponding to each position in each cycle is: In the formula, Indicates Position in The first cycle of the waveform diagram The degree of change of each peak; Indicates The positions are except The number of cycles outside of cycles; Indicates Position in The first cycle of the waveform diagram The peak is The horizontal coordinate of the maximum amplitude of the corresponding peak of the cycle; Indicates Position in The first cycle of the waveform diagram The peak is The horizontal coordinate of the maximum amplitude of the corresponding peak of the cycle; Indicates Position in The first cycle of the waveform diagram The width of the first peak is related to the The absolute value of the difference in the width of the corresponding peaks of the period; Indicates Position in The first cycle of the waveform diagram The peak is The cycle and The absolute value of the difference in the maximum amplitude of the corresponding peaks of the periods.

5. The method for dynamic prediction of fatigue crack rate of titanium alloy material according to claim 1, characterized in that: The method of obtaining the extension degree of each crack region in each cycle according to the degree to which all positions meet the crack region characteristics in all cycles and the degree of change of all wave peaks on the waveform graph corresponding to each position in each cycle includes the following specific steps: The extension degree of each crack region in each cycle is recorded as the product of the average value of the degree to which the position corresponding to each crack region in all cycles conforms to the crack region characteristics and the sum of the change degrees of all wave peaks of the waveform graph corresponding to each crack region in each cycle.

6. The method for dynamic prediction of fatigue crack rate of titanium alloy material according to claim 1, characterized in that: The specific steps of obtaining the direction vector of each crack region in each cycle according to the degree of change of all wave peaks in the waveform graph corresponding to each cycle at all positions are as follows: Get the distance between any two positions on the titanium rod, and the In the waveform corresponding to the cycle, the position of the waveform corresponding to the peak of the maximum change degree is recorded as the target position. The distance and direction of each crack area from the target position in the cycle constitutes the The direction vector of each crack region in cycles.

7. The method for dynamically predicting fatigue crack rate of titanium alloy material according to claim 1, characterized in that: The specific calculation formula for obtaining the predicted extension rate of each crack group in each cycle according to the extension degree of all crack areas in each cycle, the preset duration of each cycle and the corresponding crack group of each crack group in each cycle is: In the formula, Indicates The first cycle The predicted extension rate of each crack group; Indicates The first cycle The mean extension of all crack regions in a crack group; Indicates The first cycle The mean extension of all crack areas in the corresponding crack group of each crack group; Indicates The first cycle The crack group The extension of the crack area; Indicates The first cycle The number of crack regions in a crack group; Indicates The mean of the probability of merging of any two crack regions in cycles; Indicates the duration of each preset cycle; Indicates The first cycle The number of crack regions in each crack group; is a linear normalization function; is the absolute value function.

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