Method and system for steel plate plane stress ultrasonic testing using porosity

Abstract

The application provides a method and system for steel plate plane stress ultrasonic detection by using a plurality of holes, belongs to the technical field of ultrasonic detection, and is used for solving the technical problems of how to accurately measure the wave speed of ultrasonic waves in a steel plate and how to obtain the stress and strain parameters of the steel plate by using the wave speed. The method comprises the following steps: establishing a rectangular coordinate system I located on the plane of the measured steel plate, wherein the origin is O, the horizontal axis is X1, and the vertical axis is Y1; establishing a rectangular coordinate system II located on the plane of the measured steel plate, wherein the rectangular coordinate system II is obtained by rotating the rectangular coordinate system I around the origin O by an angle of θ, the origin is O, the horizontal axis is X2, and the vertical axis is Y2; obtaining the propagation speed of ultrasonic waves in each axial direction; obtaining normal strain in each axial direction based on a first equation and the propagation speed; obtaining normal stress in each axial direction based on a second equation and the normal strain; and obtaining shear stress of each coordinate system based on a third equation and the normal stress. The application has the technical effect of improving the accuracy of wave speed detection and then improving the accuracy of stress and strain detection.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic testing technology, and more specifically to a method and system for ultrasonic testing of planar stress in steel plates using porous structures. Background Technology

[0002] Ultrasonic testing, as an important technology in the field of non-destructive testing, is widely used in steel plate inspection. Leveraging the propagation characteristics of ultrasonic waves within steel plates, it can deeply examine the internal condition of the steel plate, which is of great significance for assessing the stress-strain state of the steel plate. This helps to promptly identify potential problems and ensure the safety and stability of steel structures during construction and operation.

[0003] Currently, ultrasonic testing in steel plate inspection is mostly used for damage detection, focusing on qualitative assessment of the steel to determine the presence of defects, but it is difficult to achieve more accurate quantitative assessment of stress and strain. This is mainly because there are technical challenges in accurately measuring the wave velocity of ultrasonic waves in the steel plate and using the wave velocity to obtain stress and strain parameters.

[0004] Existing technologies cannot effectively overcome the above-mentioned problems, resulting in insufficient and inaccurate assessment of stress and strain in steel plates, which fails to meet the refined requirements of engineering practice for structural safety assessment. Therefore, new technical solutions are urgently needed to address these issues. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a method and system for ultrasonic testing of planar stress in steel plates using porous structures. This method solves the technical problems of how to accurately measure the wave velocity of ultrasonic waves in steel plates and how to use this wave velocity to obtain the stress and strain parameters of the steel plates.

[0006] The technical solution adopted in this invention is a method and system for ultrasonic testing of planar stress in steel plates using porous structures.

[0007] Among them, the method for ultrasonic testing of plane stress in steel plates using porous structures includes:

[0008] Establish a rectangular coordinate system on the plane of the steel plate being measured, with the origin at O, the horizontal axis X1, and the vertical axis Y1;

[0009] Establish a second rectangular coordinate system located on the plane of the steel plate being measured. The second rectangular coordinate system is obtained by rotating the first rectangular coordinate system by θ around the origin O. The origin is O, the horizontal axis is X2, and the vertical axis is Y2.

[0010] Obtain the propagation speed of ultrasound along each axis in Cartesian coordinate system 1 and Cartesian coordinate system 2;

[0011] The normal strain along each axis is obtained based on the first equation and the propagation velocity;

[0012] The normal stress in each axis is obtained based on the second equation and the normal strain.

[0013] The shear stress in each coordinate system is obtained based on the third-party process and the normal stress.

[0014] Optionally, the step of obtaining the propagation speed of ultrasound in each axis includes: establishing a first measurement point and a second measurement point along the axes of a Cartesian coordinate system with horizontal axis X1 and vertical axis Y1, and a Cartesian coordinate system with horizontal axis X2 and vertical axis Y2, respectively; emitting ultrasound along the axes; the ultrasound reaching the first and second measurement points being reflected and received by the ultrasound head; obtaining the distance between the first and second measurement points and the corresponding ultrasound propagation time; and obtaining the propagation speed based on the fourth equation.

[0015] Optionally, the first and second measuring points are countersunk holes on the surface of the steel plate being measured. The first measuring point is located between the ultrasonic head and the second measuring point. Along the ultrasonic wave propagation direction determined by the ultrasonic head, the first measuring point, and the second measuring point, the projected cross section of the countersunk hole at the first measuring point cannot completely block the cross section of the countersunk hole at the second measuring point.

[0016] Optionally, the fourth equation is:

[0017] ;

[0018] in, The speed of the ultrasonic wave is represented by the horizontal axis X1, and L represents the distance between the first and second measurement points. This represents the time difference between the opening of the ultrasonic head and the detection of the reflected wave from the second measurement point in the horizontal axis X1 direction. This represents the time difference from when the ultrasonic head opens to when the reflected wave from the first measurement point is detected in the horizontal axis X1 direction; by measuring the other axes, the ultrasonic velocity in the vertical axis Y1 direction can be obtained. Ultrasonic speed in the x2 direction (horizontal axis) ultrasonic velocity in the vertical axis Y2 direction .

[0019] Optionally, the first equation in the x-axis X1 direction is:

[0020] ;

[0021] The first equation in the vertical direction Y1 is:

[0022] ;

[0023] The first equation in the x2 direction is:

[0024] ;

[0025] The first equation in the Y2 direction is:

[0026] ;

[0027] Where ρ represents the density of the steel plate material, λ and μ represent Lamé constants, and m and l represent the third-order elastic constants of the Monahan elasticity. This represents the normal strain on the horizontal axis X1. This represents the normal strain along the vertical axis Y1. This represents the normal strain on the horizontal axis X2. This represents the normal strain along the vertical axis Y2.

[0028] Alternatively, the second equation of Cartesian coordinate system one is:

[0029] ;

[0030] The second equation of the Cartesian coordinate system II is:

[0031] ;

[0032] Where E represents the elastic modulus of the steel plate material, and ν represents Poisson's ratio. This represents the normal stress along the horizontal axis X1. This represents the normal stress along the vertical axis Y1. This represents the normal stress along the horizontal axis X2. This represents the normal stress along the vertical axis Y2.

[0033] Optionally, the third-party program is:

[0034] ;

[0035] Where θ represents the angle between coordinate system 1 and coordinate system 2. This represents the shear stress in coordinate system 1. This represents the shear stress in coordinate system 2.

[0036] Optionally, the borehole walls of the first and second measurement points facing the ultrasonic head are both arc-shaped or both are planar; or, the borehole wall of the first measurement point facing the ultrasonic head is an arc-shaped surface, and the borehole wall of the second measurement point facing the ultrasonic head is a planar surface.

[0037] The system for ultrasonic testing of plane stress in steel plates using porous structures is used to implement the method for ultrasonic testing of plane stress in steel plates using porous structures as described above, including:

[0038] An ultrasonic head is used to transmit and receive ultrasonic waves, and to obtain the time difference between transmitting and receiving ultrasonic waves.

[0039] The steel plate to be tested has at least four sets of measuring points, which are respectively set on four axes.

[0040] Optionally, the four sets of measurement points include a total of eight independent measurement points; the eight independent measurement points are equidistant from the origin O, and / or the eight independent measurement points are equidistantly distributed around the circumference of the origin O.

[0041] As can be seen from the above technical solution, the beneficial technical effects of the present invention are as follows:

[0042] This invention proposes a method for ultrasonic testing of planar stress in steel plates using a porous structure. By establishing two Cartesian coordinate systems with an included angle, the propagation velocity of ultrasonic waves in each axis is accurately obtained, and normal strain, normal stress, and shear stress are sequentially obtained based on a series of equations. This method effectively overcomes the key technical challenges of accurately measuring the ultrasonic wave velocity in steel plates and using this velocity to obtain the stress and strain parameters of the steel plates. It not only significantly improves the accuracy of wave velocity detection, thereby greatly enhancing the precision of stress and strain testing, but also transforms the qualitative assessment of damage in existing technologies into a quantitative assessment of stress and strain, achieving a qualitative leap in assessment methods. Simultaneously, it broadens the application scenarios, extending from damage detection after overload to load assessment before damage, providing a more comprehensive, accurate, and widely applicable technical solution for stress and strain testing of steel plates. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0044] Figure 1 This is a top view of the measurement system.

[0045] Figure 2 This is a schematic diagram showing the distribution of measurement points.

[0046] Figure 3 This is a schematic diagram of the cross-section of the measurement system.

[0047] Figure 4 This is a schematic diagram of a local section of the first measurement point.

[0048] Figure 5 This is a schematic diagram of the distribution of normal stress and shear stress.

[0049] Figure labels: 1. Steel plate under test, 2. Ultrasonic head, 3. First measurement point, 4. Second measurement point. Detailed Implementation

[0050] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0051] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0052] For the method of ultrasonic testing of plane stress in steel plates using porous structures, please refer to the appendix. Figures 1-4 One possible implementation method is as follows:

[0053] Establish a first rectangular coordinate system on the plane of the steel plate 1 being measured, with the origin at O, the horizontal axis X1, and the vertical axis Y1. Establish a second rectangular coordinate system on the plane of the steel plate 1, obtained by rotating the first rectangular coordinate system by θ around the origin O, with the origin at O, the horizontal axis X2, and the vertical axis Y2. In practice, the origin O is preferably the center of the area to be measured on the steel plate. The horizontal axis X1 is aligned with the main force direction on the plane of the steel plate 1, and the vertical axis Y1 is perpendicular to the horizontal axis X1. The included angle θ is set according to the secondary force direction; if there are no special requirements, it can be set to 45 degrees. In mechanics of materials, normal stress refers to stress perpendicular to the cross-section of an object. When an object is subjected to external forces, internal forces perpendicular to that cross-section are generated on its internal cross-section; the internal force per unit area is the normal stress. Normal stress causes tensile or compressive deformation in an object. For example, a taut rope subjected to tension has tensile normal stress along the rope's axis. Shear stress, on the other hand, is stress parallel to the cross-section of an object. When an external force causes relative displacement between adjacent parts of an object, an internal force parallel to the cross-section is generated within the cross-section. This internal force per unit area is called shear stress. For example, when cutting paper with scissors, the paper experiences shear stress at the point where the scissors are applied, causing the paper to cut. In this scheme, two rectangular coordinate systems with an included angle θ are established: one (origin O, horizontal axis X1, vertical axis Y1) and another (origin O, horizontal axis X2, vertical axis Y2). The normal stress on the steel plate plane is along the axial directions (X1, Y1, X2, Y2) of each coordinate system. Shear stress exists within the plane of each coordinate system and is perpendicular to the corresponding axial direction. Specifically, in coordinate system 1, shear stress exists in the X1Y1 plane, perpendicular to the X1 and Y1 axes; in coordinate system 2, shear stress exists in the X2Y2 plane, perpendicular to the X2 and Y2 axes. (See appendix for details.) Figure 5 In coordinate system In the plane stress distribution, and It is normal stress. and This is shear stress.

[0054] The propagation speed of ultrasonic waves in each axis of Cartesian coordinate system I and Cartesian coordinate system II is obtained, that is, the propagation speed along the X1, Y1, X2, Y2 directions in the steel plate being tested, especially the propagation speed in the area being tested.

[0055] The normal strain along each axis is obtained based on the first equation and the propagation velocity;

[0056] The normal stress in each axis is obtained based on the second equation and normal strain.

[0057] The shear stress in each coordinate system is obtained based on the third process and normal stress.

[0058] The above process achieves the goal of obtaining the internal stress and strain of the steel plate by measuring the ultrasonic wave velocity. By changing the angle θ between the two coordinate systems, the normal stress and shear stress in different directions of the steel plate plane can be measured, thus realizing the normal stress and shear stress in any direction within the steel plate plane. For example, multiple coordinate systems and detection structures with certain angles can be preset on the steel plate. During implementation, the coordinate system and detection structure can be selected as needed for measurement, thereby enabling the detection of stress and strain in specific locations and directions of the steel plate.

[0059] The above-mentioned solution offers several significant advantages. First, it breaks through traditional limitations, transforming the qualitative analysis of damage detection using ultrasound into a quantitative analysis of stress in all directions within the steel plate. This allows structural damage detection to be moved from post-event result detection to pre-event load detection, enabling early identification of potential risks and providing accurate data for structural safety assessments, greatly benefiting routine structural safety maintenance. Second, stress detection offers high flexibility, allowing for stress detection in any direction on the steel plate plane according to actual needs. Furthermore, the detection range is comprehensive, covering both normal and shear stresses in all directions, providing strong technical support for a comprehensive and in-depth understanding of the stress state of the steel plate.

[0060] In one possible implementation, see Appendix Figure 1 and Figure 2 The steps for obtaining the propagation speed of ultrasound in each axis include: establishing a first measurement point 3 and a second measurement point 4 along the axes of a rectangular coordinate system with horizontal axis X1 and vertical axis Y1, and a rectangular coordinate system with horizontal axis X2 and vertical axis Y2, respectively. In a preferred embodiment, the midpoint of the line connecting the first measurement point 3 and the second measurement point 4 coincides with the origin O. The ultrasound head 2 emits ultrasound along the axis, and the ultrasound reaches the first measurement point 3 and the second measurement point 4, is reflected, and is received by the ultrasound head 2. The distance between the first measurement point 3 and the second measurement point 4 and the corresponding ultrasound propagation time are obtained (read by the ultrasound head 2), and the propagation speed is obtained based on the fourth equation.

[0061] Furthermore, the first measuring point 3 and the second measuring point 4 are countersunk holes located on the surface of the steel plate being measured. The first measuring point 3 is located between the ultrasonic head 2 and the second measuring point 4, along the ultrasonic wave propagation direction determined by the ultrasonic head 2, the first measuring point 3, and the second measuring point 4, such as... Figure 1 As shown, the projected cross-section of the countersunk hole at the first measuring point 3 cannot completely obscure the cross-section of the countersunk hole at the second measuring point 4. In a specific implementation, the cross-section of the hole at the first measuring point 3 along the ultrasonic wave propagation direction can be smaller than that of the hole at the second measuring point 4, allowing the ultrasonic wave to pass through both sides of the hole at the first measuring point 3 and reach the second measuring point 4; alternatively, the holes at the first measuring point 3 and the second measuring point 4 can be misaligned along the ultrasonic wave propagation direction, thus preventing the path from the ultrasonic head to the second measuring point 4 from being completely blocked by the first measuring point 3. When the ultrasonic wave emitted by the ultrasonic head 2 reaches the first measuring point 3, part of the ultrasonic wave is reflected by the hole wall of the first measuring point 3 and returns to the ultrasonic head 2 along the same path. Due to the difference in hole cross-sections, another portion of the ultrasonic wave is unaffected by the first measuring point 3 and passes outside the hole cross-section of the first measuring point 3 to reach the second measuring point 4, where it is then reflected by the hole wall of the second measuring point 4 and returns to the ultrasonic head 2 along the same path. After the ultrasonic head 2 emits an ultrasonic wave at time 0, it will detect the reflected wave twice: the first time from the first measurement point 3, and the second time from the second measurement point 4. The time difference between the two detections corresponds to the greater distance the propagation path of the wave reaching and being reflected from the second measurement point 4 is than the propagation path of the wave reaching only the first measurement point 3, which is twice the distance between the first measurement point 3 and the second measurement point 4. Therefore, the fourth equation can be determined as follows:

[0062] ;

[0063] in, The speed of the ultrasonic wave is represented by the horizontal axis X1, and L represents the distance between the first measurement point 3 and the second measurement point 4. This represents the time difference between the opening of the ultrasonic head 2 and the detection of the reflected wave from the second measurement point 4 in the horizontal axis X1 direction. This represents the time difference between the opening of the ultrasonic head 2 and the detection of the reflected wave at the first measurement point 3 in the horizontal axis X1 direction; by measuring the other axes, the ultrasonic velocity in the vertical axis Y1 direction can be obtained. Ultrasonic speed in the x2 direction (horizontal axis) ultrasonic velocity in the vertical axis Y2 direction .

[0064] In one possible implementation, the hole walls of the first measuring point 3 and the second measuring point 4 facing the ultrasonic head 2 are both arc-shaped surfaces (such as circular holes) or both flat surfaces (such as square holes); or, the hole wall of the first measuring point 3 facing the ultrasonic head 2 is an arc-shaped surface, and the hole wall of the second measuring point 4 facing the ultrasonic head 2 is a flat surface. In the measuring point hole design involved in the above embodiments, if a circular hole structure is used, its advantages are simple processing technology, low manufacturing cost, and the ability to ensure the uniformity of the hole wall; while the square hole structure is relatively complex to process, its flat hole wall has a more significant effect on the reflection of ultrasonic waves, which helps to improve the intensity and clarity of the reflected wave signal, thereby providing more accurate data support for subsequent wave velocity measurement.

[0065] In the above implementation, it is also required that the aperture of the first measuring point 3 is smaller than the wave width (so that the ultrasonic wave is not completely blocked by the first measuring point 3), the aperture of the second measuring point 4 is larger than the aperture of the first measuring point 3 (so that it can receive and reflect the wave), and the depth of the first measuring point 3 and the second measuring point 4 is greater than the wave thickness but less than the thickness of the steel plate. When the ultrasonic wave propagates in the steel plate, it will be reflected back along the original path when it encounters a hole. This is mainly because the acoustic impedance difference between the steel plate and the air inside the hole is extremely large, resulting in high-intensity reflection of the ultrasonic wave at the interface. At the same time, if the hole wall on the side facing the ultrasonic head is a plane (a circular hole is also equivalent to a plane in a local area at the microscopic level), the incident angle of the ultrasonic wave is zero or approximately zero. According to the law of reflection, the reflected wave will strictly return along the original path.

[0066] In the above embodiment, the ultrasonic head 2 is a dual-crystal probe (existing technology), a type of ultrasonic probe widely used in industrial non-destructive testing. It consists of two independent components: a transmitting crystal and a receiving crystal, with a sound insulation layer providing physical isolation between the sound wave transmission and reception functions. Depending on their operating modes, dual-crystal probes can be divided into contact-type dual-crystal straight probes and contact-type dual-crystal angle probes. The former is suitable for detecting defects perpendicular to the detection surface, while the latter is used to detect defects at a certain angle to the surface. In this solution, a dual-crystal angle probe can be used. The probe is angled and enters the steel plate 1 being tested at a certain angle. When the angled sound beam contacts the steel plate surface interface at an incident angle close to the critical angle, the ultrasonic energy forms a creeping wave that propagates a certain distance below the steel plate surface.

[0067] The above-mentioned scheme has several significant advantages. First, it innovatively utilizes the distance difference between the first measurement point 3 and the second measurement point 4, as well as the ultrasonic wave propagation time difference, to determine the wave velocity. This measurement method effectively reduces measurement errors. Since there is no need to measure the distance between the probe installation position and the measurement point, and the positions of the first and second measurement points can be precisely determined and fixed, the wave velocity measurement results are more accurate and reliable. Second, the ultrasonic head 2 is a mature existing technology, and its stability and reliability have been verified through long-term practice. Furthermore, this probe has high accuracy in detecting time differences, providing a solid technical guarantee for the entire detection process and ensuring the quality and reliability of the detection data.

[0068] Climbing waves have a similar sound velocity to surface waves and are less affected by surface roughness during propagation. They are extremely sensitive to changes in stress and strain states on and near the surface of steel plates, accurately capturing minute variations. Therefore, the stress and strain state can be inferred from changes in the ultrasonic wave propagation velocity within the steel plate. In one possible implementation, see Appendix. Figure 2 The first equation (sound velocity-strain relationship) in the horizontal axis X1 direction is:

[0069] ;

[0070] The first equation in the vertical direction Y1 is:

[0071] ;

[0072] The first equation in the x2 direction is:

[0073] ;

[0074] The first equation in the Y2 direction is:

[0075] ;

[0076] Where ρ represents the density of the steel plate material, λ and μ represent the Lamé constants of the steel plate material, and m and l represent the Murnaghan third-order elastic constants of the steel plate material. This represents the normal strain on the horizontal axis X1. This represents the normal strain along the vertical axis Y1. This represents the normal strain on the horizontal axis X2. This represents the normal strain along the vertical axis Y2.

[0077] In the above embodiments, the Lamé constant is an important parameter describing the elastic properties of a material, comprising two constants: λ and μ. λ is related to the volume change of the material under hydrostatic pressure, while μ is the shear modulus, reflecting the material's ability to resist shear deformation. The Lamé constant can be obtained experimentally. A common method is to conduct static tensile or compressive tests, measure the strain of the material under different stresses, and then derive it using Hooke's law. Furthermore, for materials with known crystal structures, the Lamé constant can be obtained through theoretical calculations based on parameters such as interatomic interaction forces. In this embodiment, a material similar to the steel plate being tested can be used beforehand to experimentally determine its Lamé constant. It should be understood that those skilled in the art can measure the Lamé constant of materials without any inventive effort, based on existing technology.

[0078] In the above embodiments, the Mönahan third-order elastic constant is an important parameter describing the nonlinear elastic behavior of materials. It contains three independent components: l, m, and n, and is used to characterize the mechanical response of materials under high pressure or large deformation. Essentially, it is the coefficient of the cubic strain term in the solid strain energy expansion formula, closely related to the crystal lattice microstructure. The methods for obtaining it mainly include: experimentally, measuring the change in ultrasonic velocity in the strain medium and then inversely deducing it using the acoustoelastic formula; theoretically, using empirical force constant models, molecular dynamics fluctuation formulas, or first-principles calculations of uniform deformation methods, among which first-principles calculations have universal significance. The core reason why this scheme only requires l and m is that the combination of the detection method (ultrasonic velocity) and the plane stress state makes the contribution of n to the target parameters (wave velocity, in-plane stress) negligible or absorbed through model simplification. This choice reflects the common strategy in engineering practice of "simplifying the model while meeting accuracy requirements." It should be noted that those skilled in the art can measure the Mönahan third-order elastic constant of materials based on existing technology without creative effort.

[0079] In the above embodiments, the normal strain in coordinate system 1 can be obtained by combining the first equation in the horizontal axis X1 direction and the first equation in the vertical axis Y1 direction. and By combining the first equation in the x2 direction (horizontal axis) and the first equation in the y2 direction (vertical axis), the normal strain in coordinate system 2 can be obtained. and ).

[0080] Furthermore, the second equation (stress-strain relationship) in Cartesian coordinate system one is:

[0081] ;

[0082] The second equation of the Cartesian coordinate system II is:

[0083] ;

[0084] Where E represents the elastic modulus of the steel plate material, and ν represents Poisson's ratio. This represents the normal stress along the horizontal axis X1. This represents the normal stress along the vertical axis Y1.

[0085] In one possible implementation, the third-party process is:

[0086] ;

[0087] Where θ represents the angle between coordinate system 1 and coordinate system 2. This represents the shear stress in coordinate system 1. This represents the shear stress in coordinate system 2.

[0088] This ultrasonic testing solution for planar stress in steel plates offers several significant advantages: First, it represents a breakthrough from qualitative to quantitative analysis, transforming traditional ultrasonic damage detection into precise measurement of stress and strain in all directions of the steel plate. This allows structural testing to move from post-incident (damage) detection to pre-incident load testing, providing a reliable basis for structural safety assessment and facilitating routine maintenance. Second, it offers high flexibility and comprehensive coverage, enabling the testing of stress and strain at any direction / location on the steel plate plane, covering normal strain, normal stress, and shear stress in any direction. Third, it innovates the measurement method by utilizing the difference in measurement point spacing and ultrasonic time difference to determine the wave velocity, reducing errors and improving accuracy. The use of a mature dual-crystal probe ensures high detection precision and data quality. Fourth, by leveraging the sensitivity of creeping waves to stress and strain, it captures changes in wave velocity on and near the surface of the steel plate, inferring the stress and strain state through wave velocity changes, providing efficient, accurate, and comprehensive technical support for steel plate stress testing.

[0089] One possible implementation of the system for ultrasonic testing of plane stress in steel plates using porous structures is as follows, comprising the following methods for implementing the above-mentioned ultrasonic testing of plane stress in steel plates using porous structures:

[0090] The ultrasonic head 2 is used to transmit and receive ultrasonic waves and to obtain the time difference between transmitting and receiving ultrasonic waves; the steel plate under test 1 has at least four sets of measurement points, which are respectively set on four axes. The four sets of measurement points include a total of eight independent measurement points; the eight independent measurement points are equidistant from the origin O, and / or the eight independent measurement points are equidistantly distributed around the circumference of the origin O.

[0091] In actual implementation, multiple sets of detection structures can be pre-set in important areas of the steel plate according to the load conditions of the steel plate. Each set of detection structures includes multiple coordinate systems with a certain angle, and two monitoring points are set on each coordinate system axis.

[0092] This system for ultrasonic testing of planar stress in steel plates using a multi-aperture design employs an ultrasonic head to emit and receive ultrasonic waves and acquire the time difference. Four groups of eight independent measurement points are set on the steel plate along four axes, with each point equidistant from the origin or equidistantly distributed around the origin. The measurement area lies within this surrounding area. This design offers significant advantages: firstly, the rational layout of the independent measurement points comprehensively covers different directions of the steel plate's plane, accurately acquiring ultrasonic propagation information along each axis, providing a rich and accurate data foundation for stress-strain analysis; secondly, the measurement area, located within the area surrounded by the measurement points, enables precise localized measurements of the steel plate, focusing on critical areas and promptly detecting localized stress anomalies, avoiding the situation where localized problems are overlooked due to overall measurement, or where localized issues are absorbed by the overall system and fail to become apparent. Furthermore, this layout makes the measurement more targeted and systematic, helping to improve testing efficiency and reduce costs, providing an efficient, accurate, and reliable solution for steel plate stress testing.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for ultrasonic testing of plane stress in steel plates using a porous structure, characterized in that, include: Establish a rectangular coordinate system on the plane of the steel plate (1) to be measured, with the origin at O, the horizontal axis X1, and the vertical axis Y1; Establish a second rectangular coordinate system located on the plane of the steel plate (1) being measured. The second rectangular coordinate system is obtained by rotating the first rectangular coordinate system by θ around the origin O. The origin is O, the horizontal axis is X2, and the vertical axis is Y2. Obtain the propagation speed of ultrasound along each axis in Cartesian coordinate system 1 and Cartesian coordinate system 2; The normal strain along each axis is obtained based on the first equation and the propagation velocity; The normal stress in each axis is obtained based on the second equation and the normal strain. The shear stress in each coordinate system is obtained based on the third-party process and the normal stress. The step of obtaining the propagation speed of ultrasonic waves along each axis includes: establishing a first measurement point (3) and a second measurement point (4) along the axes of a rectangular coordinate system with horizontal axis X1 and vertical axis Y1, and horizontal axis X2 and vertical axis Y2, respectively; the ultrasonic head (2) emits ultrasonic waves along the axes; the ultrasonic waves reach the first measurement point (3) and the second measurement point (4), are reflected, and are received by the ultrasonic head (2); the distance between the first measurement point (3) and the second measurement point (4) and the corresponding ultrasonic wave propagation time are obtained; and the propagation speed is obtained based on the fourth equation; the fourth equation is: ； in, The speed of the ultrasonic wave is represented by the horizontal axis X1, and L represents the distance between the first measurement point (3) and the second measurement point (4). This indicates the time difference between when the ultrasonic head (2) is turned on in the horizontal axis X1 direction and when the reflected wave from the second measurement point (4) is detected. The time difference between the opening of the ultrasonic head (2) in the horizontal axis X1 direction and the detection of the reflected wave from the first measurement point (3) is represented by the measurement. The same measurement is performed on the other axes to obtain the distance between the first measurement point (3) and the second measurement point (4) and the ultrasonic wave propagation time in each axis. The ultrasonic speed in the vertical axis Y1 direction can then be obtained. Ultrasonic speed in the horizontal X2 direction ultrasonic velocity in the Y2 direction and vertical axis ; The first equation in the horizontal axis X1 direction is: ； The first equation in the vertical direction Y1 is: ； The first equation in the x2 direction is: ； The first equation in the Y2 direction is: ； Where ρ represents the density of the steel plate material, λ and μ represent Lamé constants, and m and l represent the third-order elastic constants of the Monahan elasticity. This represents the normal strain on the horizontal axis X1. This represents the normal strain along the vertical axis Y1. This represents the normal strain on the horizontal axis X2. This represents the normal strain along the vertical axis Y2; The second equation of the first rectangular coordinate system is: ； The second equation of the Cartesian coordinate system II is: ； Where E represents the elastic modulus of the steel plate material, and ν represents Poisson's ratio. This represents the normal stress along the horizontal axis X1. This represents the normal stress along the vertical axis Y1. This represents the normal stress along the horizontal axis X2. This represents the normal stress along the vertical axis Y2; The third-party program is: ； Where θ represents the angle between coordinate system 1 and coordinate system 2. This represents the shear stress in coordinate system 1. This represents the shear stress in coordinate system 2.

2. The method for ultrasonic testing of plane stress in steel plates using porous structures as described in claim 1, characterized in that: The first measurement point (3) and the second measurement point (4) are countersunk holes set on the surface of the steel plate being measured. The first measurement point (3) is located between the ultrasonic head (2) and the second measurement point (4). Along the ultrasonic wave propagation direction determined by the ultrasonic head (2), the first measurement point (3) and the second measurement point (4), the projected cross section of the countersunk hole of the first measurement point (3) cannot completely block the cross section of the countersunk hole of the second measurement point (4).

3. The method for ultrasonic testing of plane stress in steel plates using porous structures as described in claim 1, characterized in that: The holes at the first measuring point (3) and the second measuring point (4) facing the ultrasonic head (2) are either arc-shaped or flat. Alternatively, the hole wall of the first measurement point (3) facing the ultrasonic head (2) is an arc-shaped surface, and the hole wall of the second measurement point (4) facing the ultrasonic head (2) is a plane.

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