Material elastic constant array ultrasonic in-situ detection method

Abstract

The invention discloses a material elastic constant array ultrasonic in-situ detection method, and belongs to the technical field of ultrasonic nondestructive testing and material characterization. The method comprises the following steps: carrying out primary orthogonal coding data acquisition on a detected material, determining a refraction point under a preset elastic anisotropy constant C of the detected material based on the Fermat theorem, and carrying out delayed superposition imaging on a reflector in a target area of the detected material by adopting a synthetic aperture focusing or full-focusing algorithm, and calculating the ratio F (C) of the maximum amplitude value of the synthetic image to the entropy value of the image as an evaluation objective function, and obtaining an optimal elastic constant corresponding to the global maximum value of the F (C) by adopting optimization tools such as a genetic algorithm, namely the elastic constant of the detected material. The array ultrasonic device is used for one-time orthogonal coding data acquisition, the detected material and the ultrasonic probe do not need to be moved or rotated for many times, the detection efficiency is improved, the method is not affected by the parallelism and thickness uniformity of the surface interface of the detected material, and in-situ, lossless and rapid detection of the elastic constant of the complex component in a service environment can be achieved.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic nondestructive testing and material characterization technology, specifically to an ultrasonic in-situ detection method for material elastic constant arrays. Background Technology

[0002] In high-end equipment fields such as aerospace and nuclear engineering, composite materials and additive manufacturing alloys often exhibit significant elastic anisotropy due to their fabrication processes and microstructure characteristics. A complete elastic constant tensor is not only an intrinsic fingerprint characterizing the macroscopic mechanical behavior of materials but also a crucial link connecting theoretical modeling, experimental testing, and engineering applications. Taking ultrasonic imaging in nondestructive testing as an example, elastic anisotropy causes variations in ultrasonic velocity with propagation direction, leading to defocusing, image distortion, and errors in defect localization and quantification in conventional array ultrasonic imaging algorithms (such as SAFT and TFM). Effective solutions to these problems depend on a precise understanding of the anisotropic elastic constants of materials. However, in practical engineering, material elastic parameters are often affected by the dispersion of manufacturing processes and evolve under complex service environments such as high temperature, high pressure, and cyclic loading. Pre-existing off-site measurements alone cannot reflect their true state. Therefore, developing technologies applicable to complex components and capable of in-situ, nondestructive, and rapid detection of material elastic constants under service conditions has significant scientific value and engineering urgency.

[0003] In evaluating the elastic properties of materials, traditional mechanical testing methods often require destructive treatment of the specimen or component, which is not only costly and time-consuming but also difficult to apply to the performance evaluation of in-service structures. To address this challenge, existing research has focused on developing non-destructive measurement techniques for elastic constants based on ultrasound. Previously, the inventors' team successfully measured the elastic constants of plasma-sprayed coatings and composite materials using the ultrasonic single-probe water immersion back reflection method. However, this method requires the specimen to be completely immersed in water and relies on mechanical rotation to adjust the incident angle of the sound waves, making the operation complex and time-consuming.

[0004] To further improve the efficiency of ultrasonic measurements, some studies have introduced ultrasonic linear array probe measurement methods. By acquiring bottom surface reflection signals at different incident angles, the group velocity of the corresponding path is calculated, and then the phase velocity distribution is inferred to ultimately solve for all elastic constants. In addition, other methods utilize ultrasonic phased array equipment to perform full-matrix data acquisition on one side of fiber-reinforced composite materials. A single measurement can extract the transit time and group velocity of each propagation path, and by fitting the experimental group velocity with the theoretical model, the complete elastic constants of the material can be inverted.

[0005] However, all of the aforementioned ultrasonic methods require the test sample to have parallel surfaces and to obtain accurate material thickness as an input parameter beforehand. Measurement errors in material thickness significantly affect the accuracy of elastic constant inversion, which limits the application of these methods in complex components with uneven thickness or irregular geometry, making it difficult to meet the practical needs of high-precision in-situ non-destructive testing. Summary of the Invention

[0006] The purpose of this invention is to provide an array ultrasonic in-situ detection method for the elastic constants of materials. This method directly performs synthetic aperture focusing or full-focus imaging on the material under test, using the weighted value of the image coherence coefficient and maximum amplitude of the reflector in the target region (ROI) as the evaluation target. In-situ detection of the elastic constants of the material is achieved through multi-parameter inversion. This method uses array ultrasonic single-pass orthogonal encoded data acquisition, eliminating the need for multiple movements or rotations of the sample and transducer, thus improving detection efficiency. It also overcomes the limitation of requiring the tested material to be a flat plate with a known thickness. This method can meet the requirements for in-situ, non-destructive, and rapid detection of the elastic constants of complex components in service environments. Furthermore, it can be extended to improve the defect localization and quantitative accuracy of SAFT and TFM testing for elastic anisotropic materials, resulting in significant economic and social benefits.

[0007] The technical solution adopted in this invention is: an array ultrasonic in-situ detection method for the elastic constant of materials. The device used in this method includes the material under test, an ultrasonic probe, an ultrasonic testing instrument, an array scanning stepper encoder, and signal processing software. The detection method includes the following steps:

[0008] S1. Data Acquisition and System Configuration: Perform coded scanning detection on the object under inspection, and acquire N coded A-mode ultrasound signals P. H (x i Then, keeping the center position of the ultrasonic probe unchanged, rotate it 90° and orthogonally acquire another N encoded type A ultrasonic signals P. V (y j ,t), where x i y j These represent the i-th and j-th encoded positions scanned by the probe, respectively, and t represents the sound wave propagation time;

[0009] S2. Determination of phase velocity and group velocity under anisotropic elastic constants of the tested material: For a tested material with elastic anisotropy, the ultrasonic wave is incident at an arbitrary angle θ along the isotropic axis. Its elastic constant is expressed as vector C = [C 11 C 12 C 13 C 33 C 44 The function of ], that is, the theoretical quasi-longitudinal wave phase velocity v in the tested material at different angles θ is calculated.pl (θ) and the theoretical quasi-transverse wave velocity v ps (θ):

[0010] (1)

[0011] (2)

[0012] Where θ is called the phase angle, ρ is the density of the material being tested, and A and B are calculated using the following formulas:

[0013] (3)

[0014] (4)

[0015] Because the material under test exhibits elastic anisotropy, the direction of ultrasonic energy propagation is the group velocity, which is the speed of sound measured in the experiment, and the group velocity angle is... There exists a deflection angle ψ with respect to the phase angle θ:

[0016] , (5)

[0017] (6)

[0018] S3. Determine the refraction point and acoustic delay at the interface between the coupling medium and the tested material based on Fermat's principle: Perform initial synthetic aperture focusing or full-focus imaging with a preset elastic constant C, and analyze the local target region based on the scanned image; the ultrasonic probe passes through the coded position S(x i ,y j ,-h w The image point at the point of incidence within the ROI of the material under inspection is Q(x,y,z), and the unknown refraction point at the interface between the coupling medium and the material under inspection is M(x,y,z). m ,y m According to Snell's Law:

[0019] (7)

[0020] Where α is the incident angle in the coupling medium, v w h represents the speed of sound in the coupling medium. w Let θ be the thickness of the coupling medium and θ be the refractive phase angle within the material being inspected; calculate the minimum total acoustic delay T from the ultrasonic probe's encoding position S to the imaging point Q. min According to Fermat's theorem, the refraction point M is the interface position that minimizes the sound delay T.

[0021] (8)

[0022] S4. Construct a coherence evaluation function for synthetic aperture focusing imaging within the ROI.

[0023] Based on the shortest propagation time T from all probe coding positions S determined in step S3 to all imaging points Q within the local target area. min Perform time-delayed superposition synthetic aperture focusing or total focusing imaging;

[0024] (9)

[0025] The amplitude entropy AE and the maximum amplitude A of the image within the local target region are calculated based on the signal synthesized using formula (9). max :

[0026] , (10)

[0027] (11)

[0028] Based on formulas (10) and (11), construct the objective function F(C) for inverting the elastic constant C:

[0029] (12)

[0030] Combine genetic algorithm optimization to obtain the maximum corresponding value of objective function F(C) , which is the elastic constant of the material being tested.

[0031] Furthermore, in step S1, before performing the scanning detection, the ultrasonic detector, ultrasonic probe, and array scanning stepper encoder are calibrated.

[0032] Furthermore, in step S3, the local target area is a region containing a strong reflector, which includes pores, delamination defects, or the bottom surface of the material being inspected.

[0033] Furthermore, in step S3, Snell's law also applies to the case where the probe is directly coupled to the material being tested, i.e., h w =0.

[0034] Furthermore, in step S4, the imaging display mode is either a B-scan image or a C-scan image.

[0035] The beneficial effects of this invention are as follows: By synthesizing aperture or full-focus imaging from ultrasonic data acquired through a single orthogonal encoding, and innovatively using the image coherence coefficient and maximum amplitude weighted within the ROI as evaluation indicators, in-situ detection of material elastic constants can be completed in one step. This method eliminates the need for repeated movement or rotation of the sample and probe, and overcomes the stringent limitations of traditional methods on the shape and thickness of the tested material. It can meet the requirements for in-situ, non-destructive, and rapid detection of elastic constants of complex components in service environments. Its implementation is simple, fast, and highly accurate, not only meeting the needs of rapid quantitative detection in industrial settings but also providing technical support for improving the accuracy of defect localization and quantification in ultrasonic imaging detection of elastic anisotropic materials. It has significant engineering application value and substantial economic and social benefits. Attached Figure Description

[0036] Figure 1 It is an ultrasonic in-situ detection device for the elastic constants of materials.

[0037] Figure 2 It is a B-type display of electronic scanning for 10L16 linear array ultrasonic testing of 3D printed test materials.

[0038] Figure 3 The phase velocity and group velocity of the tested material under a preset elastic constant C are: (a) longitudinal wave velocity; (b) transverse wave velocity.

[0039] Figure 4 The composite aperture focusing B-type display is performed on the local ROI area centered on the corresponding flat-bottomed hole defect: the left image is optimal. The middle diagram is isotropic; the right diagram is... .

[0040] Figure 5 It is isotropic and optimal and 1.15 A comparison of the results between the quasi-longitudinal wave sound velocity and the true longitudinal wave sound velocity;

[0041] In the diagram: 1. Material under inspection; 2. Linear array ultrasonic probe; 3. Ultrasonic phased array ultrasonic testing instrument; 4. Built-in array stepper encoder of the ultrasonic testing instrument; 5. Signal processing software. Detailed Implementation

[0042] An array ultrasonic in-situ testing method for the elastic constants of materials includes an ultrasonic testing device consisting of the material under test, an ultrasonic probe, an ultrasonic testing instrument, an array scanning stepper encoder, and signal processing software. The testing method includes the following steps:

[0043] (1) Data acquisition and system configuration

[0044] The ultrasonic testing instrument, ultrasonic probe, and array scanning stepper encoder are calibrated. The object under inspection is then scanned and inspected using encoding methods, and N encoded type A ultrasonic signals P are acquired. H (x i Then, keeping the center position of the ultrasonic probe unchanged, rotate it 90° and orthogonally acquire another N encoded type A ultrasonic signals P. V (y j ,t), where x i y j These represent the i-th and j-th encoded positions scanned by the probe, respectively, and t represents the sound wave propagation time;

[0045] (2) Determination of phase velocity and group velocity of the material under anisotropic elastic constant

[0046] For anisotropic materials under test, when ultrasonic waves are incident at an arbitrary angle θ along an isotropic axis, the elastic constant can be expressed as vector C = [C 11 C 12 C 13 C 33 C 44 The theoretical quasi-longitudinal wave phase velocity v at different angles θ in the tested material can be calculated using the function of θ. pl (θ) and the theoretical quasi-transverse wave velocity v ps (θ):

[0047] (1)

[0048] (2)

[0049] Where θ is called the phase angle, ρ is the density of the material being tested, and A and B are calculated using the following formulas:

[0050] (3)

[0051] (4)

[0052] Because the material under test exhibits elastic anisotropy, the direction of ultrasonic energy propagation is the group velocity, which is the speed of sound measured in the experiment. The group velocity angle ϕ and the phase angle θ are deflected by an angle ψ.

[0053] , (5)

[0054] (6)

[0055] (3) Determine the refraction point and acoustic delay at the interface between the coupling medium and the tested material based on Fermat's principle.

[0056] Initial synthetic aperture focusing or full-focus imaging is performed using a preset elastic constant C. Based on the scanned image, a local target region (ROI) containing obvious strong reflectors such as pores, delamination defects, or the bottom surface of the inspected material is selected for analysis. The ultrasonic probe passes through the coded position S(x) i ,y j ,-h w The image point at the point of incidence within the ROI of the material under inspection is Q(x,y,z), and the unknown refraction point at the interface between the coupling medium and the material under inspection is M(x,y,z). m ,y m According to Snell's Law:

[0057] (7)

[0058] Where α is the incident angle in the coupling medium, v w h represents the speed of sound in the coupling medium. w Where θ is the thickness of the coupling medium, and h is the refractive phase angle within the material under test. This also applies to the case where the probe is directly coupled to the material under test. w =0; Calculate the minimum total acoustic delay T from the ultrasonic probe's encoding position S to the imaging point Q. min According to Fermat's theorem, the refraction point M is the interface position that minimizes the sound delay T.

[0059] (8)

[0060] (4) Construct a coherence evaluation function for synthetic aperture focusing imaging within the ROI.

[0061] Based on the shortest propagation time T from all probe coding positions S to all imaging points Q within the ROI determined in step (3). min It performs time-delay superposition synthetic aperture focusing or total focusing imaging, and the imaging display mode can be B-scan image, C-scan image, etc.

[0062] (9)

[0063] The amplitude entropy (AE) and maximum amplitude A of the image within the ROI are calculated based on the signal synthesized using formula (9). max :

[0064] , (10) (11)

[0065] Based on formulas (10) and (11), construct the objective function F(C) for inverting the elastic constant C:

[0066] (12)

[0067] Combine genetic algorithm optimization to obtain the maximum corresponding value of objective function F(C) , which is the elastic constant of the material being tested.

[0068] Example 1

[0069] Figure 1 An array ultrasonic in-situ quantitative detection device for the elastic constants of materials is shown, comprising: 1. a 3D-printed material to be tested containing a flat-bottomed hole; 2. an Olympus 10L16 linear array ultrasonic probe; 3. a Robust-32 / 64 ultrasonic phased array detector; 4. an electronic array encoder built into the ultrasonic detector; and 5. signal processing software. The detection method using this device includes the following steps:

[0070] The density of the 3D printed test material 1, ρ = 7190 kg / m³, was obtained in advance using methods such as Archimedes' displacement method. 3 .

[0071] (1) Data acquisition and system configuration:

[0072] The Robust-32 / 64 ultrasonic phased array detector 2, the Olympus 10L16 linear array ultrasonic probe 3, and the built-in electronic array encoder were calibrated. The ultrasonic probe was positioned 4 mm above the surface of the material under test. The ultrasonic waves from the probe were used to perform electronic scanning detection on the 3D printed material under test 1 along the printing direction, and 16 sets of coded ultrasonic A-mode signals P were acquired. H (xi,t), then keeping the center position of the ultrasonic probe unchanged, rotate 90°, and orthogonally acquire 16 sets of coded type A ultrasonic signals P. V (yj,t), the original electron scan B-type display, such as Figure 2 As shown.

[0073] (2) Determination of phase velocity and group velocity of the tested material under anisotropic elastic constants:

[0074] For the 3D printed material under inspection, the preset elastic constant vector C = [C 11 =278GPa, C 12 =117 GPa, C 13 =117 GPa, C 33 =256 GPa, C 44 The theoretical quasi-longitudinal wave phase velocity v of the tested material at different refraction angles θ can be calculated using a function of [ =85 GPa]. pl(θ) and the theoretical quasi-transverse wave velocity v ps (θ):

[0075] (1)

[0076] (2)

[0077] Where θ is the angle between the ultrasonic wave propagation direction and the isotropic axis in the tested material, ρ is the density of the tested material, and A and B are calculated using the following formula:

[0078] (3)

[0079] (4)

[0080] Because the material under test exhibits elastic anisotropy, the direction of ultrasonic energy propagation is the group velocity, which is the speed of sound measured in the experiment, and the group velocity angle is... There is a deflection angle with phase angle θ :

[0081] , (5)

[0082] (6)

[0083] Figure 3 The phase velocity v is given under the preset elastic constant C. p Group velocity V g .

[0084] (3) Determine the refraction point and acoustic delay at the interface between the coupling medium and the tested material based on Fermat's principle.

[0085] The ultrasonic probe passes through the coded position S(x) i ,y j ,-h w The image point at the point of incidence within the ROI of the material under inspection is Q(x,y,z), and the unknown refraction point at the interface between the coupling medium and the material under inspection is M(x,y,z). m ,y m According to Snell's Law:

[0086] (7)

[0087] Where α is the incident angle in the coupling medium, h w Let θ be the thickness of the coupling medium and θ be the refractive phase angle within the material being inspected; calculate the minimum total acoustic delay T from the ultrasonic probe's encoding position S to the imaging point Q. min According to Fermat's theorem, the refraction point M is the interface position that minimizes T.

[0088] (8)

[0089] (4) Constructing a coherence evaluation function for ROI synthetic aperture focusing imaging

[0090] Based on the shortest propagation time T from all probe coding positions S to all imaging points Q within the ROI determined in step (3). min Perform direct longitudinal wave and transverse wave dual-mode time-delay superposition synthetic aperture focusing or total focusing imaging:

[0091] (9)

[0092] The amplitude quotient (AE) and maximum amplitude A of the image within the ROI are calculated based on the signal synthesized using formula (9). max :

[0093] , (10) (11)

[0094] Based on formulas (10) and (11), construct the objective function F(C) for inverting the elastic constant C:

[0095] (12)

[0096] The genetic algorithm is used to optimize and obtain the maximum value of the objective function F(C). The corresponding optimal A synthetic aperture focusing B-mode display is performed on the local ROI region centered on the corresponding flat-bottomed hole defect, which is defined as [-1.2 mm, 1.2 mm]. Figure 4 The left-hand image shows the results. When the elastic constants C=[C11=194.4GPa, C33=194.4GPa, C13=65.0 GPa, C44=64.7GPa] are input as an isotropic material, the corresponding flat-bottomed hole defect synthetic aperture focused B-type display result is as follows. Figure 4 As shown in the middle image, .when The corresponding flat-bottom hole defect synthesis aperture focusing B-type display result is as follows: Figure 4 As shown in the right-hand figure, .

[0097] Figure 5 The optimal A comparison of the quasi-longitudinal wave velocity determined by [C11=276.5GPa, C12=118.8 GPa, C13=118.8 GPa, C33=253.2 GPa, C44=86.0 GPa] with the actual longitudinal wave velocity reveals a strong consistency between the longitudinal wave velocity determined based on the inversion elastic constants of this invention and the actual longitudinal wave velocity, thus verifying the effectiveness of this invention.

[0098] 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.

Claims

1. A method for in-situ ultrasonic detection of the elastic constants of materials, characterized in that: The apparatus used in this method includes the material under test, an ultrasonic probe, an ultrasonic testing instrument, an array scanning stepper encoder, and signal processing software. The testing method includes the following steps: S1. Data Acquisition and System Configuration: Perform coded scanning detection on the object under inspection, and acquire N coded A-mode ultrasound signals P. H (x i Then, keeping the center position of the ultrasonic probe unchanged, rotate it 90° and orthogonally acquire another N encoded type A ultrasonic signals P. V (y j ,t), where x i y j These represent the i-th and j-th encoded positions scanned by the probe, respectively, and t represents the sound wave propagation time; S2. Determination of phase velocity and group velocity under anisotropic elastic constants of the tested material: For a tested material with elastic anisotropy, the ultrasonic wave is incident at an arbitrary angle θ along the isotropic axis. Its elastic constant is expressed as vector C = [C 11 C 12 C 13 C 33 C 44 The function of ], that is, the theoretical quasi-longitudinal wave phase velocity v in the tested material at different angles θ is calculated. pl (θ) and the theoretical quasi-transverse wave velocity v ps (θ): (1)； (2)； Where θ is called the phase angle, ρ is the density of the material being tested, and A and B are calculated using the following formulas: (3)； (4)； Because the material under test exhibits elastic anisotropy, the direction of ultrasonic energy propagation is the group velocity, which is the speed of sound measured in the experiment, and the group velocity angle is... There is a deflection angle with phase angle θ : ， (5)； (6)； S3. Determine the refraction point and acoustic delay at the interface between the coupling medium and the tested material based on Fermat's principle: Perform initial synthetic aperture focusing or full-focus imaging with a preset elastic constant C, and analyze the local target region based on the scanned image; the ultrasonic probe passes through the coded position S(x i ,y j ,-h w The image point at the point of incidence within the ROI of the material under inspection is Q(x,y,z), and the unknown refraction point at the interface between the coupling medium and the material under inspection is M(x,y,z). m ,y m According to Snell's Law: (7)； Where α is the incident angle in the coupling medium, v w h represents the speed of sound in the coupling medium. w Let θ be the thickness of the coupling medium and θ be the refractive phase angle within the material being inspected; calculate the minimum total acoustic delay T from the ultrasonic probe's encoding position S to the imaging point Q. min According to Fermat's theorem, the refraction point M is the interface position that minimizes the sound delay T. (8)； S4. Construct a coherence evaluation function for synthetic aperture focusing imaging within the ROI: Based on the shortest propagation time T from all probe coding positions S determined in step S3 to all imaging points Q within the local target area. min Perform time-delayed superposition synthetic aperture focusing or total focusing imaging; (9)； The amplitude entropy AE and the maximum amplitude A of the image within the local target region are calculated based on the signal synthesized using formula (9). max : , (10)； (11)； Based on formulas (10) and (11), construct the objective function F(C) for inverting the elastic constant C: (12)； Combine genetic algorithm optimization to obtain the maximum corresponding value of objective function F(C) , which is the elastic constant of the material being tested.

2. The method for in-situ ultrasonic detection of material elastic constants according to claim 1, characterized in that: In step S1, before performing scanning detection, the ultrasonic detector, ultrasonic probe, and array scanning stepper encoder are calibrated.

3. The method for in-situ ultrasonic detection of material elastic constants according to claim 1, characterized in that: In step S3, the local target area is a region containing a strong reflector, which includes pores, delamination defects, or the bottom surface of the material being inspected.

4. The method for in-situ ultrasonic detection of material elastic constants according to claim 1, characterized in that: In step S3, Snell's law also applies to the case where the probe is directly coupled to the material being tested, i.e., h w =0.

5. The method for in-situ ultrasonic detection of material elastic constants according to claim 1, characterized in that: In step S4, the imaging display mode is either a B-scan image or a C-scan image.

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