Water immersion type ultrasonic residual stress evaluation method and related equipment

Abstract

The invention provides a water immersion type ultrasonic residual stress evaluation method and related equipment. The method comprises the following steps: controlling an ultrasonic probe to vertically enter water in a water tank; the ultrasonic probe is controlled to emit ultrasonic waves at the fixed horizontal height and conduct plane scanning, first ultrasonic echo signals of all the first scanning positions are obtained, and second ultrasonic echo signals of all the second scanning positions are obtained; calculating the sound velocity of each first scanning position based on the first ultrasonic echo signal and the second ultrasonic echo signal; drawing a specified two-dimensional image by using the sound velocity of each first scanning position; and based on the specified two-dimensional image, determining an evaluation index for representing the residual stress of the to-be-tested sample. The to-be-detected sample does not need to be taken out and scanned again, and the evaluation index can be determined only by scanning once, so that errors caused by position change of the reflecting plate are avoided, and the residual stress measurement precision and the detection efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing, and in particular to a method for evaluating residual stress using water immersion ultrasound and related equipment. Background Art

[0002] There is an urgent need for non-destructive measurement of internal residual stress in plates and forgings made of large aluminum alloys, high-temperature alloys and steels.

[0003] The current method for characterizing internal residual stress in large parts involves using a sound velocity diagram in a water-immersion reflector test mode. However, even with a rigidly supported reflector, the reflector's position often shifts due to the rebound of the rigid support after the part is removed. This can cause significant measurement errors and significantly reduce the accuracy of residual stress measurements for large parts. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides a method and related equipment for evaluating residual stress using water immersion ultrasound to solve the problem that the current method of characterizing internal residual stress significantly reduces the accuracy of residual stress measurement for large parts.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A first aspect of an embodiment of the present invention discloses a method for evaluating residual stress using immersion ultrasound, the method comprising:

[0007] Controlling the ultrasonic probe to vertically enter the water in the water tank, a reflector is placed at the bottom of the water tank, and a submerged sample to be tested is placed on the reflector via a pad;

[0008] Controlling the ultrasonic probe to transmit ultrasonic waves at a fixed horizontal height and perform a plane scan to obtain a first ultrasonic echo signal at each first scanning position and a second ultrasonic echo signal at each second scanning position, wherein the first scanning position is within the upper projection range of the sample to be tested, and the second scanning position is outside the upper projection range of the sample to be tested and within the upper projection range of the reflector;

[0009] calculating a sound velocity at each of the first scanning positions based on the first ultrasonic echo signal and the second ultrasonic echo signal;

[0010] Drawing a designated two-dimensional image using the sound velocity at each of the first scanning positions, wherein the designated two-dimensional image is a two-dimensional grayscale image of acoustic time difference distribution or a two-dimensional rainbow image of acoustic time difference distribution;

[0011] Based on the designated two-dimensional image, an evaluation index for characterizing the residual stress of the sample to be tested is determined.

[0012] Preferably, calculating the sound velocity at each of the first scanning positions based on the first ultrasonic echo signal and the second ultrasonic echo signal includes:

[0013] Based on the first ultrasonic echo signal, the following data corresponding to each of the first scanning positions is determined: the first reflector echo time, the time difference between the time when the first bottom wave is received and the time when the first interface wave is received;

[0014] determining, based on the second ultrasonic echo signal, a second reflector echo time corresponding to each second scanning position;

[0015] Using the second reflector echo time, the third reflector echo time corresponding to each of the first scanning positions is obtained by completing the echo time of the third reflector;

[0016] The sound velocity at each of the first scanning positions is calculated using the first reflector echo time, the time difference, and the third reflector echo time.

[0017] Preferably, drawing a designated two-dimensional image using the sound velocity at each of the first scanning positions includes:

[0018] forming a two-dimensional position matrix from the coordinates of each of the first scanning positions;

[0019] determining a designated value corresponding to the speed of sound at each of the first scanning positions, the designated value being a grayscale value or a color value;

[0020] The designated value corresponding to the speed of sound at each of the first scanning positions is filled into the two-dimensional position matrix to draw a designated two-dimensional image.

[0021] Preferably, determining an evaluation index for characterizing the residual stress of the sample to be tested based on the specified two-dimensional image includes:

[0022] Cropping the specified two-dimensional image;

[0023] Calculate an evaluation index of the sound velocity at each of the first scanning positions on the cropped designated two-dimensional image, where the evaluation index is used to characterize the residual stress of the sample to be tested, and the evaluation index is a range, variance, standard deviation, or coefficient of variation.

[0024] Preferably, using the second reflector echo time to complete and obtain the third reflector echo time corresponding to each of the first scanning positions includes:

[0025] Fitting all the second reflector echo times into a plane;

[0026] The fitted plane is completed to obtain the echo time of the third reflector corresponding to each of the first scanning positions.

[0027] A second aspect of an embodiment of the present invention discloses a system for evaluating residual stress using immersion ultrasound, the system comprising:

[0028] a first control unit, configured to control the ultrasonic probe to vertically enter the water in a water tank, wherein a reflector is placed at the bottom of the water tank, and a submerged sample to be tested is placed on the reflector via a spacer;

[0029] a second control unit, configured to control the ultrasonic probe to transmit ultrasonic waves at a fixed horizontal height and perform a plane scan, to obtain a first ultrasonic echo signal at each first scanning position, and to obtain a second ultrasonic echo signal at each second scanning position, wherein the first scanning position is within a projection range above the sample to be tested, and the second scanning position is outside the projection range above the sample to be tested and within a projection range above the reflector;

[0030] a calculation unit, configured to calculate a sound velocity at each of the first scanning positions based on the first ultrasonic echo signal and the second ultrasonic echo signal;

[0031] a drawing unit, configured to draw a specified two-dimensional image using the sound velocity at each of the first scanning positions, wherein the specified two-dimensional image is a two-dimensional grayscale image of acoustic time difference distribution or a two-dimensional rainbow image of acoustic time difference distribution;

[0032] A determination unit is used to determine an evaluation index for characterizing the residual stress of the sample to be tested based on the specified two-dimensional image.

[0033] Preferably, the calculation unit includes:

[0034] A first determining module is configured to determine, based on the first ultrasonic echo signal, the following data corresponding to each of the first scanning positions: a first reflector echo time, and a time difference between a time when a first bottom wave is received and a time when a first interface wave is received;

[0035] a second determining module, configured to determine, based on the second ultrasonic echo signal, a second reflector echo time corresponding to each second scanning position;

[0036] a completion module, configured to use the second reflector echo time to complete and obtain the third reflector echo time corresponding to each of the first scanning positions;

[0037] The calculation module is configured to calculate the sound velocity at each of the first scanning positions by using the first reflector echo time, the time difference, and the third reflector echo time.

[0038] Preferably, the drawing unit includes:

[0039] a forming module, configured to form the coordinates of each of the first scanning positions into a two-dimensional position matrix;

[0040] a determination module, configured to determine a designated value corresponding to the sound velocity at each of the first scanning positions, wherein the designated value is a grayscale value or a color value;

[0041] A filling module is used to fill the specified value corresponding to the sound speed of each first scanning position into the two-dimensional position matrix to draw a specified two-dimensional image.

[0042] A third aspect of an embodiment of the present invention discloses an electronic device, comprising: a processor and a memory, wherein the processor and the memory are connected via a communication bus; wherein the processor is used to call and execute a program stored in the memory; and the memory is used to store a program, wherein the program is used to implement the method for evaluating residual stress by immersion ultrasound disclosed in the first aspect of the embodiment of the present invention.

[0043] A fourth aspect of an embodiment of the present invention discloses a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the method for evaluating residual stress using immersion ultrasound disclosed in the first aspect of the embodiment of the present invention is implemented.

[0044] Based on the above-mentioned embodiment of the present invention, a method and related equipment for evaluating residual stress using water immersion ultrasound are provided. The method comprises the following steps: controlling an ultrasonic probe to vertically enter the water in a water tank; controlling the ultrasonic probe to emit ultrasonic waves at a fixed horizontal height and perform a plane scan to obtain a first ultrasonic echo signal at each first scanning position, and a second ultrasonic echo signal at each second scanning position; calculating the sound velocity at each first scanning position based on the first ultrasonic echo signal and the second ultrasonic echo signal; drawing a specified two-dimensional image using the sound velocity at each first scanning position; and determining an evaluation index for characterizing the residual stress of the sample to be tested based on the specified two-dimensional image. This solution calculates the sound velocity at the first scanning position using the ultrasonic echo signal obtained from a single scan, and then uses the sound velocity at the first scanning position to determine the evaluation index for characterizing the residual stress of the sample to be tested. This method does not require removing the sample to be tested and performing another scan, thereby avoiding errors caused by changes in the position of the reflector and improving the accuracy and efficiency of residual stress measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0046] Figure 1 A flow chart of a method for evaluating residual stress using water immersion ultrasound provided in an embodiment of the present invention;

[0047] Figure 2 A flowchart for calculating the sound velocity at each first scanning position provided by an embodiment of the present invention;

[0048] Figure 3 This is a structural block diagram of a system for evaluating residual stress using immersion ultrasound, provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] In this application, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0051] There's a pressing need for nondestructive measurement of internal residual stresses in large plates and forgings made of aluminum alloys, high-temperature alloys, and steels, but a method suitable for on-site factory production has been lacking. Current methods for characterizing internal residual stresses in large parts use sound velocity mapping in a water-immersion reflector test mode. However, in actual use, this method has been found to exhibit significant accuracy degradation for large parts, sometimes even yielding erroneous results.

[0052] Research has found that because existing methods require scanning the reflector's echoes while the part is placed on the reflector and while the part is removed, and because the reflector's position cannot change with the part present or absent, even with a rigidly supported reflector, the reflector's position frequently shifts when the part is removed, leading to significant measurement errors. The greater the part's mass, the greater the reflector's position shifts, significantly reducing the accuracy of residual stress measurements for large parts.

[0053] To solve the above problems, this solution proposes a method and related equipment for evaluating residual stress using water immersion ultrasound. The sound velocity at the first scanning position is calculated by using the ultrasonic echo signal obtained through a single scan. The sound velocity at the first scanning position is then used to determine the evaluation index for characterizing the residual stress of the sample to be tested. This eliminates the need to remove the sample to be tested and scan it again, thus avoiding errors caused by changes in the position of the reflector and improving the residual stress measurement accuracy and detection efficiency.

[0054] In practical applications, this solution can be applied to the rapid, nondestructive evaluation of internal residual stress in materials such as high-temperature alloys, aluminum alloys, and steel. Compared to most existing residual stress evaluation methods, this solution can achieve rapid, quantitative evaluation of the overall residual stress in large metal plates, disks, forgings, and other materials, as well as qualitative characterization of the residual stress distribution, without any damage. This improves detection efficiency by 30%, making it particularly suitable for engineering applications.

[0055] This solution also overcomes the shortcomings of previous ultrasonic residual stress assessments, which required multiple scans or the use of U-shaped reflectors. It eliminates errors caused by changes in the reflector's position and enables residual stress assessment with a single scan. This approach is particularly suitable for nondestructive assessment of residual stress in large parts. This solution is explained in detail below through various examples.

[0056] Before explaining this solution, the devices used for ultrasonic scanning and their connection relationships are explained. The devices used in this solution include at least a pulse signal generator, a multi-channel digital oscilloscope, and an ultrasonic probe.

[0057] The output interface and synchronization interface of the pulse signal generator are respectively connected to the input interface and synchronization interface of the multi-channel digital oscilloscope (specifically connected through a coaxial cable). The longitudinal wave straight probe with a frequency of 1-25MHz (that is, the ultrasonic probe used in this solution) is connected to the transmit / receive interface of the pulse signal generator through the coaxial cable. The ultrasonic probe is installed on a scanning frame capable of three-axis coordinated movement.

[0058] During ultrasonic scanning, the pulse signal generator generates electrical pulses, and the ultrasonic probe vibrates under the electrical pulses to generate ultrasonic waves. The ultrasonic probe also receives ultrasonic echo signals, converts the ultrasonic echo signals into electrical signals and transmits them to the pulse signal generator, which then transmits the signals to the multi-channel digital oscilloscope.

[0059] See also Figure 1 , which shows a flow chart of a method for evaluating residual stress using water immersion ultrasound according to an embodiment of the present invention, the method comprising:

[0060] Step S101: Control the ultrasonic probe to vertically enter the water in the tank.

[0061] It should be noted that the requirements and placement of the sample to be tested (such as a large part to be inspected) are first explained here: a reflector is placed at the bottom of the water tank, and the sample to be tested submerged in water is placed on the reflector through a pad.

[0062] Specifically, a reflective plate is placed at the bottom of a water tank. When a sample to be tested with a thickness of t is placed on the reflective plate, the sample to be tested is padded with a pad with a thickness of less than 0.2t so that the sample to be tested maintains a certain distance from the reflective plate, and the water in the water tank submerges the sample to be tested by more than 0.25t.

[0063] The projected size of the reflector is larger than the projected size of the sample to be tested. After the sample to be tested is placed on the reflector, the reflector should still protrude from the sample to be tested by more than 20 mm (for example only).

[0064] In the specific implementation of step S101, the position of the ultrasonic probe is controlled so that the ultrasonic probe enters the water in the water tank vertically (the ultrasonic probe is perpendicular to the horizontal plane), and a distance of 0.3-2t is maintained between the ultrasonic probe and "the higher of the two relatively parallel planes on the sample to be tested" (the ultrasonic detection is always in the water).

[0065] It should be noted that the sample to be tested is generally square or flattened cylindrical. For a square sample, the "two relatively parallel planes" mentioned above refer to the planes of the sample to be tested. For a flattened cylindrical sample, the "two relatively parallel planes" mentioned above refer to the upper and lower end surfaces of the sample to be tested. The "two relatively parallel planes" for samples of other shapes are similar, and examples are not provided here.

[0066] Step S102: Control the ultrasonic probe to transmit ultrasonic waves at a fixed horizontal height and perform a plane scan to obtain a first ultrasonic echo signal at each first scanning position and a second ultrasonic echo signal at each second scanning position.

[0067] In the specific implementation of step S102, the scanning frame is used to control the ultrasonic probe to perform a plane scan at a fixed horizontal height (ultrasound waves are emitted during the scanning process), and a first ultrasonic echo signal is obtained at each first scanning position, and a second ultrasonic echo signal is obtained at each second scanning position.

[0068] It should be noted that when performing plane scanning, the scanning range should exceed the projection range of the sample to be measured but not exceed the projection range of the reflector.

[0069] The first scanning position is within the upper projection range of the sample to be measured, that is, the first scanning position is all positions on "two relatively parallel planes" of the sample to be measured.

[0070] The second scanning position is outside the upper projection range of the sample to be measured and within the upper projection range of the reflector, that is, the second scanning position is outside the upper projection range of the sample to be measured and within the upper projection range of the reflector.

[0071] Step S103: Calculating the speed of sound at each first scanning position based on the first ultrasonic echo signal and the second ultrasonic echo signal.

[0072] In the specific implementation of step S103, the sound velocity v at each first scanning position is calculated based on the first ultrasonic echo signal and the second ultrasonic echo signal. i , where i represents the first scanning position i.

[0073] Step S104: drawing a designated two-dimensional image using the sound velocity at each first scanning position.

[0074] In the specific implementation of step S104, the sound velocity v of each first scanning position is used. i , draw a specified two-dimensional image, which is a two-dimensional grayscale image of acoustic time difference distribution or a two-dimensional rainbow image of acoustic time difference distribution.

[0075] In some embodiments, the specific implementation method of drawing the specified two-dimensional image is: forming the coordinates of each first scanning position into a two-dimensional position matrix; determining the specified value corresponding to the sound speed of each first scanning position, which is a grayscale value or a color value; filling the specified value corresponding to the sound speed of each first scanning position into the two-dimensional position matrix to draw the specified two-dimensional image.

[0076] If the specified value is a grayscale value, then the grayscale value corresponding to the sound velocity at each first scanning position is filled into the two-dimensional position matrix, and a specified two-dimensional image of "acoustic time difference distribution two-dimensional grayscale map" can be drawn.

[0077] If the specified value is a color value, then the color value corresponding to the sound velocity at each first scanning position is filled into the two-dimensional position matrix, and a specified two-dimensional image, a "two-dimensional rainbow map of acoustic time difference distribution", can be drawn.

[0078] Specifically, the maximum value of the sound speed is defined as corresponding to "255", the minimum value is defined as corresponding to "0", and the middle is divided into 256 levels, each level corresponds to a grayscale value or color value. In this way, the specified value corresponding to the sound speed of the first scanning position can be determined.

[0079] For example, assuming that a sound speed of 6000 corresponds to a grayscale value of "0," and a sound speed of 6300 corresponds to a grayscale value of "255," the grayscale values ​​are divided into 256 levels. If the sound speed at a first scanning position is 6150, the grayscale value corresponding to the first scanning position is 128.

[0080] The color value can be determined in the same way based on the "8-bit grayscale value to color value conversion table".

[0081] Step S105: Based on the specified two-dimensional image, an evaluation index for characterizing the residual stress of the sample to be tested is determined.

[0082] In the specific implementation of step S105 , an evaluation index of the sound velocity at each first scanning position on the specified two-dimensional image is calculated. The evaluation index is used to characterize the residual stress of the sample to be tested. The evaluation index is the range, variance, standard deviation or coefficient of variation.

[0083] In some embodiments, a specific method for determining the evaluation index characterizing the residual stress of the sample to be tested is: cropping a specified two-dimensional image; and calculating the evaluation index of the sound velocity at each first scanning position on the cropped specified two-dimensional image.

[0084] It should be noted that when calculating the evaluation indicators, any one or more of the range, variance, standard deviation and coefficient of variation can be calculated according to actual needs.

[0085] Cropping a specific 2D image involves finding the edge of the sample on the image and cropping the image at a distance of two ultrasound probe diameters inward from the edge. In other words, the image is cropped from the edge of the sample to a distance of two ultrasound probe diameters inward, leaving the remaining portion as the cropped 2D image.

[0086] In an embodiment of the present invention, the sound velocity at the first scanning position is calculated using the ultrasonic echo signal obtained through a single scan, and the sound velocity at the first scanning position is then used to determine an evaluation index for characterizing the residual stress of the sample to be tested. This eliminates the need to remove the sample to be tested and scan it again, thereby avoiding errors caused by changes in the position of the reflector and improving the residual stress measurement accuracy and detection efficiency.

[0087] In practical applications, the specific parameters of the reflector, water tank, and multi-channel digital oscilloscope mentioned above can be selected by referring to the following (for reference only):

[0088] 1. The reflector should be thick enough to ensure that no obvious bending deformation occurs after the sample to be tested is placed. Ribs can be designed behind the reflector to increase its rigidity.

[0089] 2. The reflector can be made of metals such as stainless steel and titanium alloy. Marble is recommended. If the reflector is made of square marble, the thickness of the reflector should be no less than 10mm for samples under 100kg and no less than 20mm for samples between 100kg and 200kg. For every additional 100kg of sample weight, the thickness of the reflector should be increased by 10mm. If the reflector is made of square stainless steel, its thickness should be at least 50% of the thickness of the marble under the corresponding load. If the reflector is made of titanium alloy, it should be at least 70% of the thickness of the marble.

[0090] 3. If the bottom of the sink is thick enough, you can use the sink bottom to replace the reflector.

[0091] 4. A multi-channel digital oscilloscope with a high sampling frequency can be used. When the thickness of the sample to be tested is more than 100mm, the sampling frequency of the multi-channel digital oscilloscope shall not be less than 100MHz; when the thickness of the sample to be tested is between 75-100mm, the sampling frequency of the multi-channel digital oscilloscope shall not be less than 200MHz; when the thickness of the sample to be tested is between 50-75mm, the sampling frequency of the multi-channel digital oscilloscope shall not be less than 500MHz; when the thickness of the sample to be tested is between 20-50mm, the sampling frequency of the multi-channel digital oscilloscope shall not be less than 1GHz; when the thickness of the sample to be tested is between 10-20mm, the sampling frequency of the multi-channel digital oscilloscope shall not be less than 1.5GHz; when the thickness of the sample to be tested is between 5-10mm, the sampling frequency of the multi-channel digital oscilloscope shall not be less than 2GHz.

[0092] For the above embodiments of the present invention Figure 1 The calculation of the sound velocity at each first scanning position involved in step S103 is as follows: Figure 2 , which shows a flow chart for calculating the sound velocity at each first scanning position provided by an embodiment of the present invention, Figure 2 The steps include:

[0093] Step S201: Based on the first ultrasonic echo signal, the following data corresponding to each first scanning position is determined: the first reflector echo time, and the time difference between the time when the first bottom wave is received and the time when the first interface wave is received.

[0094] In the specific implementation of step S201, based on the first ultrasonic echo signal, a multi-channel digital oscilloscope is used to determine the "first reflector echo time t" corresponding to each first scanning position. 2i ", "The time difference t between the time when the first bottom wave is received and the time when the first interface wave is received 1i ”.

[0095] That is, when the ultrasonic probe is scanning a plane at a fixed horizontal height, a multi-channel digital oscilloscope is used to record the time difference between the time when the first bottom wave is received and the time when the first interface wave is received at all the first scanning positions. This time difference is recorded as t 1i , and record the first reflector echo time corresponding to each first scanning position, the first reflector echo time is recorded as t 2i .

[0096] Among them, the first reflector echo time t corresponding to each first scanning position is 2i Specifically, it refers to the echo time of the reflector when the ultrasonic probe is above the sample to be measured.

[0097] Step S202: Based on the second ultrasonic echo signal, determine the second reflector echo time corresponding to each second scanning position.

[0098] In the specific implementation of step S202, based on the second ultrasonic echo signal, a multi-channel digital oscilloscope is used to determine the second reflector echo time corresponding to each second scanning position. The second reflector echo time is recorded as t 3j , j represents the second scanning position j.

[0099] It should be noted that the ultrasonic probe is located above the sample to be measured but its height remains unchanged, and the ultrasonic probe moves along a plane. Since the size of the reflector is larger than the size of the sample to be measured, there will be a state where the ultrasonic probe is above the sample to be measured, and there will also be a state where the ultrasonic probe moves out of the range above the sample to be measured but not out of the range above the reflector.

[0100] In the state where the ultrasonic probe moves out of the range above the sample to be tested but does not move out of the range above the reflector, the reflector is directly below the ultrasonic probe, so the echo time t of the second reflector corresponding to each second scanning position is 3j Specifically, it refers to the echo time of the reflector when the ultrasonic probe is outside the sample to be measured.

[0101] Step S203: using the second reflector echo time, the third reflector echo time corresponding to each first scanning position is completed.

[0102] In the specific implementation of step S203, the echo time t of all second reflectors is 3j Fit into a plane; complete the fitted plane to obtain the third reflector echo time corresponding to each first scanning position, and the third reflector echo time is recorded as t 3i .

[0103] That is, the echo time of all second reflectors t 3j Fit it into a plane, and use the fitted plane to complete the third reflector echo time t corresponding to each first scanning position 3i .

[0104] Step S204: Calculate the sound velocity at each first scanning position using the first reflector echo time, the time difference, and the third reflector echo time.

[0105] In the specific implementation of step S204, the echo time t 2i , time difference t 1i and the third reflector echo time t 3i , the sound velocity v at each first scanning position is calculated by formula (1) i .

[0106] v i =((t 3i -t 2i )÷t 1i )+1)×1200~1500(1).

[0107] above Figure 2 This section provides instructions for calculating the speed of sound at each first scanning position.

[0108] exist Figure 1 and Figure 2 On this basis, from a holistic perspective, the overall process of evaluating residual stress in this scheme includes A1-A5.

[0109] A1. Control the ultrasonic probe to vertically enter the water in the tank.

[0110] A2. Control the ultrasonic probe to scan the plane at a fixed horizontal height to determine the first reflector echo time t corresponding to each first scanning position. 2i , the time difference t between the time when the first bottom wave is received and the time when the first interface wave is received 1i , and determine the second reflector echo time t corresponding to each second scanning position 3j .

[0111] A3, all the second reflector echo time t 3j Fit it into a plane, and use the fitted plane to complete the third reflector echo time t corresponding to each first scanning position 3i .

[0112] A4. Calculate the sound velocity v at each first scanning position using the above formula (1): i , the coordinates of each first scanning position are formed into a two-dimensional position matrix, and the specified value corresponding to the sound velocity of each first scanning position is filled into the two-dimensional position matrix to draw a specified two-dimensional image.

[0113] A5. Crop the specified two-dimensional image, calculate the range, variance, standard deviation, or coefficient of variation of the sound velocity at each first scanning position on the cropped specified two-dimensional image, and use the calculated range, variance, standard deviation, or coefficient of variation to represent the overall residual stress of the sample to be tested.

[0114] In general, the implementation principle of this solution can be summarized as follows:

[0115] The propagation velocity of ultrasound in a material is affected by the stress within the material, a phenomenon known as the "acoustoelastic effect" of ultrasound. Furthermore, residual stresses throughout a component are always self-balanced. Where there is tensile stress, there must be compressive stress. As residual stress gradually dissipates, both tensile and compressive stresses decrease simultaneously. If a sample has high residual stress, both its tensile and compressive stresses are high; conversely, if its residual stress is low, both its tensile and compressive stresses are low. This approach leverages the acoustoelastic effect of ultrasound to measure the propagation velocity of ultrasound in locations with varying residual stresses, plotting the velocity distribution (specifying a two-dimensional image). Based on the self-balancing nature of residual stress, the dispersion of these velocities is calculated, thereby characterizing the overall residual stress of the component. As can be seen, measuring the velocity of sound is the most critical factor in this process. Because the acoustoelastic effect is a weak effect, the change in velocity due to stress is minimal, requiring high accuracy in velocity measurement. By measuring the propagation time of the echo from the reflector at multiple locations outside the sample's edge, performing a plane fit, and using the fitted plane formula to calculate the propagation time of the echo from the reflector below the sample, measurement errors caused by changes in the reflector's position are avoided.

[0116] The following uses several specific application examples to illustrate the actual application process of this solution.

[0117] Example 1:

[0118] The sample to be tested is an aluminum alloy plate with a size of 2m×5m×100mm, and the residual stress of the aluminum alloy plate needs to be tested.

[0119] 1) Place a stainless steel reflector with a size of 3m×6m×150mm at the bottom of the water tank. When placing the aluminum alloy plate on the reflector, use a 15mm thick pad to support the aluminum alloy plate. The water in the water tank should cover the aluminum alloy plate by 80mm.

[0120] 2) Control the ultrasonic probe with a frequency of 5 MHz to vertically enter the water in the water tank, and maintain a distance of 50 mm between the ultrasonic probe and the "higher of the two relatively parallel planes on the aluminum alloy plate."

[0121] 3) Control the ultrasonic probe to emit ultrasonic waves at a fixed horizontal height and perform plane scanning to determine the first reflector echo time t corresponding to each first scanning position 2i , the time difference t between the time when the first bottom wave is received and the time when the first interface wave is received 1i , and determine the second reflector echo time t corresponding to each second scanning position 3j .

[0122] 4) Set the echo time of all second reflectors t 3j Fit it into a plane and use the fitted plane to complete the third reflector echo time t 3i .

[0123] 5) Based on the above formula (1), by “v i =((t 3i -t 2i )÷t 1i )+1)×1450” to calculate the sound velocity v at each first scanning position i .

[0124] The coordinates of each first scanning position are formed into a two-dimensional position matrix, and the specified value corresponding to the sound velocity of each first scanning position is filled into the two-dimensional position matrix to draw a specified two-dimensional image.

[0125] 6) Crop the specified two-dimensional image, calculate the range of the sound velocity at each first scanning position on the cropped specified two-dimensional image, and use the range to represent the overall residual stress of the aluminum alloy plate.

[0126] Example 2:

[0127] The sample to be tested is a high-temperature alloy disk of Φ600mm×50mm, and the residual stress of the high-temperature alloy disk needs to be tested.

[0128] 1) Place a Φ800mm×50mm stainless steel reflector at the bottom of the water tank. When placing the high-temperature alloy disc on the reflector, use a 10mm thick pad to prop up the high-temperature alloy disc. The water in the water tank should submerge the high-temperature alloy disc by 100mm.

[0129] 2) Control the ultrasonic probe with a frequency of 10 MHz to vertically enter the water in the water tank, and maintain a distance of 40 mm between the ultrasonic probe and the "higher of the two relatively parallel planes on the high-temperature alloy disk."

[0130] 3) Control the ultrasonic probe to emit ultrasonic waves at a fixed horizontal height and perform plane scanning to determine the first reflector echo time t corresponding to each first scanning position 2i , the time difference t between the time when the first bottom wave is received and the time when the first interface wave is received 1i , and determine the second reflector echo time t corresponding to each second scanning position 3j .

[0131] 4) Set the echo time of all second reflectors t 3j Fit it into a plane and use the fitted plane to complete the third reflector echo time t 3i .

[0132] 5) Based on the above formula (1), by “v i =((t 3i -t 2i )÷t 1i )+1)×1480” to calculate the sound velocity v at each first scanning position i .

[0133] The coordinates of each first scanning position are formed into a two-dimensional position matrix, and the specified value corresponding to the sound velocity of each first scanning position is filled into the two-dimensional position matrix to draw a specified two-dimensional image.

[0134] 6) Crop the specified two-dimensional image, calculate the coefficient of variation of the sound velocity at each first scanning position on the cropped specified two-dimensional image, and use the coefficient of variation to represent the overall residual stress of the high-temperature alloy disk.

[0135] It can be seen from the contents of the above embodiments and examples that this solution has the following beneficial effects:

[0136] By scanning the echoes from the reflectors surrounding the sample under test, a plane fitting algorithm is employed to fill in the gaps obscured by the sample under test using the echoes from the surrounding reflectors. This eliminates the need to scan the reflectors again after removing the sample under test. This reduces errors caused by changes in the reflector position and significantly improves detection efficiency by reducing the number of scans required to one instead of two. Compared to other ultrasonic residual stress evaluation methods, this solution does not require calibration, simplifying the implementation process and improving detection efficiency. Compared to destructive residual stress measurement methods, this solution enables non-destructive residual stress evaluation, with measurement speeds over 10 times faster than destructive methods and measurement costs less than one-fifteenth of those of other methods.

[0137] Corresponding to the method for evaluating residual stress by water immersion ultrasound provided in the above embodiment of the present invention, see Figure 3 An embodiment of the present invention also provides a structural block diagram of a system for evaluating residual stress using immersion ultrasound. The system includes: a first control unit 100, a second control unit 200, a calculation unit 300, a drawing unit 400, and a determination unit 500.

[0138] The first control unit 100 is used to control the ultrasonic probe to vertically enter the water in the water tank. A reflector is placed at the bottom of the water tank, and a sample to be tested submerged in water is placed on the reflector via a pad.

[0139] The second control unit 200 is used to control the ultrasonic probe to emit ultrasonic waves at a fixed horizontal height and perform a plane scan to obtain a first ultrasonic echo signal at each first scanning position and a second ultrasonic echo signal at each second scanning position. The first scanning position is within the upper projection range of the sample to be tested, and the second scanning position is outside the upper projection range of the sample to be tested and within the upper projection range of the reflector.

[0140] The calculation unit 300 is configured to calculate the sound velocity at each first scanning position based on the first ultrasonic echo signal and the second ultrasonic echo signal.

[0141] The drawing unit 400 is configured to draw a designated two-dimensional image using the sound velocity at each first scanning position, wherein the designated two-dimensional image is a two-dimensional grayscale image of acoustic time difference distribution or a two-dimensional rainbow image of acoustic time difference distribution.

[0142] The determination unit 500 is configured to determine an evaluation index for characterizing the residual stress of the sample to be tested based on a specified two-dimensional image.

[0143] In a specific implementation, the determination unit 500 is specifically used to: crop a specified two-dimensional image; calculate an evaluation index of the sound velocity at each first scanning position on the cropped specified two-dimensional image, where the evaluation index is used to characterize the residual stress of the sample to be tested, and the evaluation index is the range, variance, standard deviation or coefficient of variation.

[0144] In an embodiment of the present invention, the sound velocity at the first scanning position is calculated using the ultrasonic echo signal obtained through a single scan, and the sound velocity at the first scanning position is then used to determine an evaluation index for characterizing the residual stress of the sample to be tested. This eliminates the need to remove the sample to be tested and scan it again, thereby avoiding errors caused by changes in the position of the reflector and improving the residual stress measurement accuracy and detection efficiency.

[0145] Preferably, combined Figure 3 As shown in the figure, the calculation unit 300 includes a first determination module, a second determination module, a completion module, and a calculation module. The execution principle of each module is as follows:

[0146] The first determination module is configured to determine, based on the first ultrasonic echo signal, the following data corresponding to each first scanning position: the first reflector echo time, and the time difference between the time when the first bottom wave is received and the time when the first interface wave is received.

[0147] The second determining module is configured to determine, based on the second ultrasonic echo signal, the second reflector echo time corresponding to each second scanning position.

[0148] The completion module is used to use the second reflector echo time to complete and obtain the third reflector echo time corresponding to each first scanning position.

[0149] In a specific implementation, the completion module is specifically used to: fit all the second reflector echo times into a plane; and complete the fitted plane to obtain the third reflector echo time corresponding to each first scanning position.

[0150] The calculation module is used to calculate the sound speed at each first scanning position by using the first reflector echo time, the time difference and the third reflector echo time.

[0151] Preferably, combined Figure 3 As shown in the figure, the drawing unit 400 includes a forming module, a determining module, and a filling module. The execution principle of each module is as follows:

[0152] The forming module is used to form the coordinates of each first scanning position into a two-dimensional position matrix.

[0153] The determination module is used to determine a designated value corresponding to the sound velocity at each first scanning position, where the designated value is a grayscale value or a color value.

[0154] The filling module is used to fill the specified value corresponding to the sound speed at each first scanning position into the two-dimensional position matrix to draw a specified two-dimensional image.

[0155] Preferably, an embodiment of the present invention further provides an electronic device, comprising: a processor and a memory, the processor and the memory being connected via a communication bus; wherein the processor is used to call and execute a program stored in the memory; the memory is used to store a program, and the program is used to implement the method for evaluating residual stress by water immersion ultrasound provided in the above method embodiment.

[0156] Preferably, an embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the method for evaluating residual stress using water immersion ultrasound provided in the above method embodiment is implemented.

[0157] In summary, the embodiments of the present invention provide a method and related equipment for evaluating residual stress by water immersion ultrasound. The sound velocity at the first scanning position is calculated by using the ultrasonic echo signal obtained through a single scan, and the sound velocity at the first scanning position is then used to determine an evaluation index for characterizing the residual stress of the sample to be tested. There is no need to remove the sample to be tested and scan it again, which avoids errors caused by changes in the position of the reflector, thereby improving the residual stress measurement accuracy and detection efficiency.

[0158] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0159] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0160] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating residual stress using immersion ultrasound, characterized in that: The method comprises: Controlling the ultrasonic probe to vertically enter the water in the water tank, a reflector is placed at the bottom of the water tank, and a submerged sample to be tested is placed on the reflector via a pad; Controlling the ultrasonic probe to transmit ultrasonic waves at a fixed horizontal height and perform a plane scan to obtain a first ultrasonic echo signal at each first scanning position and a second ultrasonic echo signal at each second scanning position, wherein the first scanning position is within the upper projection range of the sample to be tested, and the second scanning position is outside the upper projection range of the sample to be tested and within the upper projection range of the reflector; calculating a sound velocity at each of the first scanning positions based on the first ultrasonic echo signal and the second ultrasonic echo signal; Drawing a designated two-dimensional image using the sound velocity at each of the first scanning positions, wherein the designated two-dimensional image is a two-dimensional grayscale image of acoustic time difference distribution or a two-dimensional rainbow image of acoustic time difference distribution; Based on the designated two-dimensional image, an evaluation index for characterizing the residual stress of the sample to be tested is determined.

2. The method according to claim 1, characterized in that Calculating the sound velocity at each of the first scanning positions based on the first ultrasonic echo signal and the second ultrasonic echo signal includes: Based on the first ultrasonic echo signal, the following data corresponding to each of the first scanning positions is determined: the first reflector echo time, the time difference between the time when the first bottom wave is received and the time when the first interface wave is received; determining, based on the second ultrasonic echo signal, a second reflector echo time corresponding to each second scanning position; Using the second reflector echo time, the third reflector echo time corresponding to each of the first scanning positions is obtained by completing the echo time of the third reflector; The sound velocity at each of the first scanning positions is calculated using the first reflector echo time, the time difference, and the third reflector echo time.

3. The method according to claim 1, characterized in that Drawing a designated two-dimensional image using the sound velocity at each of the first scanning positions includes: forming a two-dimensional position matrix from the coordinates of each of the first scanning positions; determining a designated value corresponding to the speed of sound at each of the first scanning positions, the designated value being a grayscale value or a color value; The designated value corresponding to the speed of sound at each of the first scanning positions is filled into the two-dimensional position matrix to draw a designated two-dimensional image.

4. The method according to any one of claims 1 to 3, characterized in that Determining an evaluation index for characterizing the residual stress of the sample to be tested based on the specified two-dimensional image includes: Cropping the specified two-dimensional image; Calculate an evaluation index of the sound velocity at each of the first scanning positions on the cropped designated two-dimensional image, where the evaluation index is used to characterize the residual stress of the sample to be tested, and the evaluation index is a range, variance, standard deviation, or coefficient of variation.

5. The method according to claim 2, characterized in that Using the second reflector echo time to complete and obtain the third reflector echo time corresponding to each of the first scanning positions, comprising: Fitting all the second reflector echo times into a plane; The fitted plane is completed to obtain the echo time of the third reflector corresponding to each of the first scanning positions.

6. A system for evaluating residual stress using immersion ultrasound, characterized in that: The system comprises: a first control unit, configured to control the ultrasonic probe to vertically enter the water in a water tank, wherein a reflector is placed at the bottom of the water tank, and a submerged sample to be tested is placed on the reflector via a spacer; a second control unit, configured to control the ultrasonic probe to transmit ultrasonic waves at a fixed horizontal height and perform a plane scan, to obtain a first ultrasonic echo signal at each first scanning position, and to obtain a second ultrasonic echo signal at each second scanning position, wherein the first scanning position is within a projection range above the sample to be tested, and the second scanning position is outside the projection range above the sample to be tested and within a projection range above the reflector; a calculation unit, configured to calculate a sound velocity at each of the first scanning positions based on the first ultrasonic echo signal and the second ultrasonic echo signal; a drawing unit, configured to draw a specified two-dimensional image using the sound velocity at each of the first scanning positions, wherein the specified two-dimensional image is a two-dimensional grayscale image of acoustic time difference distribution or a two-dimensional rainbow image of acoustic time difference distribution; A determination unit is used to determine an evaluation index for characterizing the residual stress of the sample to be tested based on the specified two-dimensional image.

7. The system according to claim 6, characterized in that The calculation unit includes: A first determining module is configured to determine, based on the first ultrasonic echo signal, the following data corresponding to each of the first scanning positions: a first reflector echo time, and a time difference between a time when a first bottom wave is received and a time when a first interface wave is received; a second determining module, configured to determine, based on the second ultrasonic echo signal, a second reflector echo time corresponding to each second scanning position; a completion module, configured to use the second reflector echo time to complete and obtain the third reflector echo time corresponding to each of the first scanning positions; The calculation module is configured to calculate the sound velocity at each of the first scanning positions by using the first reflector echo time, the time difference, and the third reflector echo time.

8. The system according to claim 6, wherein: The drawing unit includes: a forming module, configured to form the coordinates of each of the first scanning positions into a two-dimensional position matrix; a determination module, configured to determine a designated value corresponding to the sound velocity at each of the first scanning positions, wherein the designated value is a grayscale value or a color value; A filling module is used to fill the specified value corresponding to the sound speed of each first scanning position into the two-dimensional position matrix to draw a specified two-dimensional image.

9. An electronic device, characterized in that: include: A processor and a memory, wherein the processor and the memory are connected via a communication bus; wherein the processor is configured to call and execute a program stored in the memory; The memory is used to store a program, and the program is used to implement the method for evaluating residual stress using immersion ultrasound as described in any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for evaluating residual stress using immersion ultrasound as claimed in any one of claims 1 to 5 is implemented.

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