PE hot melting joint nondestructive testing method and system based on ultrasonic phased array

Abstract

The invention relates to the technical field of nondestructive testing, in particular to an ultrasonic phased array-based PE (Poly Ethylene) hot-melt joint nondestructive testing method and system, which comprises the following steps: acquiring material parameters in real time, establishing an anisotropic finite element model, dynamically compensating a sound wave path, spirally scanning a detection area, fusing and analyzing defect characteristics, optimizing three-dimensional imaging and the like. The system comprises an ultrasonic phased array probe array, a dynamic compensation controller, a six-axis mechanical arm and an imaging optimization engine. The invention solves or at least alleviates the problem of insufficient detection precision caused by non-uniform material anisotropy, dynamic density gradient and elastic modulus distribution in the nondestructive detection of the PE hot-melting joint in the traditional ultrasonic detection method, and provides the nondestructive detection method and system for the PE hot-melting joint based on the ultrasonic phased array.

Description

Technical Field

[0001] The present invention belongs to the technical field of nondestructive testing, and in particular relates to a nondestructive testing method and system for PE heat-melt joints based on an ultrasonic phased array. Background Art

[0002] Currently, PE hot-melt joints form oriented crystals during the cooling process (Reference 1: Macromolecules, 2019). This characteristic results in a radial gradient in the material's mechanical properties, with the elastic modulus between the molten and non-molten zones varying by 30%-50%. Traditional ultrasonic testing methods typically assume isotropic material properties (ASTM F2620 standard), ignoring the effect of crystallization orientation on the sound wave propagation path. This assumption has significant limitations in practical applications, particularly in oblique defect detection, where anisotropy can lead to errors in sound velocity calculations exceeding 12% (Reference 2: Ultrasonics, 2021).

[0003] Existing technologies have certain shortcomings in addressing this issue. For example, the method using the fixed delay rule (CN117494393A) does not fully consider the density gradient of the dynamic changes in the melt interface, making it difficult to adapt to changes brought about by different welding process parameters. For example, the static hardness test proposed in CN101393170B ignores the hardness distribution during dynamic acquisition and does not consider the temperature gradient, indicating that its applicability in dynamic environments is limited. Although infrared thermal imaging technology can provide surface temperature field information (Reference 3: NDT&E Int., 2020), it fails to correlate the internal elastic modulus distribution, nor does it establish a three-dimensional mapping relationship between melt index, hardness and acoustic impedance, resulting in its application in complex scenarios being limited. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art, solve or at least alleviate the problem of insufficient detection accuracy of traditional ultrasonic detection methods in non-destructive testing of PE heat-melt joints due to material anisotropy, dynamic density gradient and uneven distribution of elastic modulus, and provide a non-destructive testing method and system for PE heat-melt joints based on ultrasonic phased array.

[0005] To achieve the above object, the present invention provides the following technical solution: a nondestructive testing method for PE heat-melt joints based on ultrasonic phased array, comprising the following steps: Step S1: real-time acquisition of material parameters to obtain hardness distribution and temperature gradient data; Step S2: establishing an anisotropic finite element model and calculating the elastic modulus attenuation curve; Step S3: dynamically compensate the acoustic wave path and adjust the phased array transmission delay parameter; Step S4, controlling the robotic arm to spirally scan the detection area; Step S5: Fusion analysis of defect features and marking of structural defects; Step S6: Optimize the three-dimensional imaging and determine the secondary scanning conditions.

[0006] In order to further realize the present invention, the following technical solutions may be preferably used: Preferably, in step S1, when the temperature change is detected to be greater than 0.5°C, the real-time update of the anisotropic finite element model is triggered, and the surface hardness distribution data is synchronously obtained through the micro-indenter. The micro-indenter and the ultrasonic probe array are fixed to the end of the six-axis robotic arm through a flexible connector, and the relative position error between the two is less than 0.05mm.

[0007] Preferably, step S3 includes the following sub-steps: Step S31: Generate an acoustic wave conduction probability cloud map to distinguish between priority paths and shielded paths; Step S32: extract the forward scattering characteristic spectrum and determine the source of distortion; Step S33: Implement quantized delay compensation and phase inversion emission strategy.

[0008] Preferably, step S31 includes the following specific operations: Step S311: collecting the triaxial residual stress distribution of the melting zone in real time, with a sampling frequency of not less than 100 Hz; Step S312: When the deviation between the residual stress direction and the molecular chain orientation angle is greater than 15°, triggering the re-ordering of the path priority; Step S313: generate a probability cloud map by fusing the stress field and the orientation angle, and mark the priority paths with probability values ​​greater than or equal to 85%; Step S314: temperature gradient compensation is performed on the shielding path. For every 1°C increase in temperature, the acoustic energy attenuation increases by 0.6 dB.

[0009] Preferably, the quantization delay compensation in step S33 includes the following: a. Switch the time quantum window according to the material attenuation coefficient. When the attenuation coefficient is less than or equal to 2dB / mm, use a 10ns window and inject a high-energy pulse greater than 1μJ in the leading period. When the attenuation coefficient is greater than 2dB / mm, switch to a 5ns window and limit the energy in the decay period to less than or equal to 0.2μJ. b. When adjacent array element signals interfere with each other, the overlap between the interference area and the probability cloud map is calculated. If the overlap is less than 70%, the time slice weighted elimination process is started.

[0010] Preferably, the phase reversal transmission strategy in step S33 includes the following: A. Odd and even array elements transmit positive and negative phase pulses alternately. Odd-numbered array elements transmit positive phase pulses of 10ns, while even-numbered array elements transmit negative phase pulses with a delay of 2.5ns. B. Perform interference cancellation when receiving signals, calculate the correlation coefficient of adjacent signals in 5ns slices, and when the correlation coefficient is less than 0.7, compress the amplitude according to the formula (1-R / 0.7)²; C. Dynamic adjustment strategy: When the signal-to-noise ratio is less than 15dB, the negative phase energy is enhanced by 20%. When the temperature is higher than 80°C, the single-phase mode is switched and the sampling frequency is increased to 20MHz.

[0011] Preferably, the planning accuracy of the spiral path in step S4 is 0.01 mm. When the distance deviation between the probe and the surface is greater than 0.1 mm, position correction is performed through a closed-loop feedback control system.

[0012] Preferably, step S6 includes the following sub-steps: Sub-step S601: Perform a sound velocity consistency check on the overlapping area data, and remove data points with a sound velocity deviation greater than ±5%; Sub-step S602: dynamically selecting a quantum tunneling assisted imaging algorithm or a synthetic aperture focusing algorithm according to the signal-to-noise ratio; Sub-step S603: When the interface fuzzy area is greater than 5 mm², inject the phonon tunneling correction factor β and start the local fine scanning mode.

[0013] A nondestructive testing system for PE heat-melt joints based on ultrasonic phased array, which is applicable to the above method, is characterized by comprising the following components: Ultrasonic phased array probe array, configured with 64 array elements arranged in an arc shape, integrated with residual stress sensor and micro indenter; A dynamic compensation controller, including a quantized time window module and a phase reversal drive circuit; Six-axis robotic arm equipped with a laser ranging sensor and Doppler shift correction module; Imaging optimization engine, integrating sound velocity consistency verification module, quantum tunneling imaging module and neural network sharpening module; The closed-loop feedback control system consists of a laser ranging sensor and a Doppler frequency shift correction module.

[0014] Preferably, the dynamic compensation controller is connected to the ultrasonic phased array probe array via a high-speed optical fiber interface with a transmission rate of 10 Gbps, and a shielded cable is used to connect the output end of the phase reversal drive circuit to the probe array element.

[0015] The beneficial effects of the present invention are: This method dynamically adjusts the acoustic wave propagation path by collecting material parameters in real time and incorporating anisotropic finite element models. This solves the problem of sound velocity deviation caused by traditional ultrasonic testing methods that ignore material anisotropy. By introducing quantized delay compensation and a phase-reversal transmission strategy, the interference effect of adjacent element signals is effectively suppressed, improving detection accuracy.

[0016] Furthermore, the present invention generates a probability cloud map of acoustic wave transmission by real-time monitoring of the triaxial residual stress distribution and molecular chain orientation angles in the melt zone. This identifies the preferred and shielded paths, thus avoiding detection blind spots caused by improper path selection. Furthermore, the stability of acoustic wave propagation is further enhanced through a temperature gradient compensation mechanism.

[0017] Furthermore, the spiral scanning path planning accuracy of the present invention reaches 0.01mm. Combined with a closed-loop feedback control system, this ensures precise alignment of the probe and the inspection surface, reducing errors caused by positional deviations. The quantum tunneling-assisted imaging algorithm significantly improves defect edge resolution by introducing a correction factor β, meeting the detection requirements in complex scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flow chart of the detection method of the present invention.

[0019] Figure 2 This is a sub-flowchart of step S3 of the present invention.

[0020] Figure 3 This is a sub-flowchart of step S6 of the present invention.

[0021] Figure 4 This is a block diagram of the detection system of the present invention.

[0022] Figure 5 This is a connection block diagram of the dynamic compensation controller of the present invention. DETAILED DESCRIPTION

[0023] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0024] 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 those skilled in the art without creative work shall fall within the scope of protection of the present invention. Example 1

[0025] Currently, PE hot-melt joints form molecular chain-oriented crystallization during the cooling process. This characteristic causes the material's mechanical properties to exhibit a radial gradient distribution, with the elastic modulus between the molten zone and the non-molten zone differing by up to 30%-50%. Traditional ultrasonic testing methods typically assume that the material has isotropic properties, ignoring the deflection effect of the crystallization direction on the sound wave propagation path. This assumption has obvious limitations in practical applications, especially in oblique defect detection, where anisotropy can cause sound velocity calculations to deviate by more than 12%. In addition, the lack of real-time modeling technology further limits improvements in detection accuracy, and a three-dimensional mapping relationship between melt index, hardness, and acoustic impedance has not been established, limiting its application in complex scenarios.

[0026] Reference Figure 4 and Figure 5 The present invention provides a nondestructive testing system for PE heat-melt joints based on ultrasonic phased array, comprising the following components: Ultrasonic phased array probe array, configured with 64 array elements arranged in an arc shape, integrated with residual stress sensor and micro indenter; A dynamic compensation controller, including a quantized time window module and a phase reversal drive circuit; Six-axis robotic arm equipped with a laser ranging sensor and Doppler shift correction module; Imaging optimization engine, integrating sound velocity consistency verification module, quantum tunneling imaging module and neural network sharpening module; The closed-loop feedback control system consists of a laser ranging sensor and a Doppler frequency shift correction module.

[0027] The dynamic compensation controller is connected to the ultrasonic phased array probe array through a high-speed optical fiber interface with a transmission rate of 10Gbps. The output end of the phase reversal drive circuit and the probe array element are connected with a shielded cable.

[0028] At the same time, refer to Figure 1 The present invention also provides a nondestructive testing method for PE hot melt joints based on ultrasonic phased array, comprising the following steps: Step S1: real-time acquisition of material parameters to obtain hardness distribution and temperature gradient data; Step S2: establishing an anisotropic finite element model and calculating the elastic modulus attenuation curve; Step S3: dynamically compensate the acoustic wave path and adjust the phased array transmission delay parameter; Step S4, controlling the robotic arm to spirally scan the detection area; Step S5: Fusion analysis of defect features and marking of structural defects; Step S6: Optimize the three-dimensional imaging and determine the secondary scanning conditions.

[0029] In step S1, when the temperature change is detected to be greater than 0.5°C, the real-time update of the anisotropic finite element model is triggered, and the surface hardness distribution data is synchronously obtained through the micro-indenter. The micro-indenter and the ultrasonic probe array are fixed to the end of the six-axis robotic arm through a flexible connector, and the relative position error between the two is less than 0.05mm.

[0030] Reference Figure 2 , step S3 includes the following sub-steps: Step S31: Generate an acoustic wave conduction probability cloud map to distinguish between priority paths and shielded paths; Step S32: extract the forward scattering characteristic spectrum and determine the source of distortion; Step S33: Implement quantized delay compensation and phase inversion emission strategy.

[0031] Step S31 includes the following specific operations: Step S311: collecting the triaxial residual stress distribution of the melting zone in real time, with a sampling frequency of not less than 100 Hz; Step S312: When the deviation between the residual stress direction and the molecular chain orientation angle is greater than 15°, triggering the re-ordering of the path priority; Step S313: generate a probability cloud map by fusing the stress field and the orientation angle, and mark the priority paths with probability values ​​greater than or equal to 85%; Step S314: temperature gradient compensation is performed on the shielding path. For every 1°C increase in temperature, the acoustic energy attenuation increases by 0.6 dB.

[0032] The quantization delay compensation in step S33 includes the following: a. Switch the time quantum window according to the material attenuation coefficient. When the attenuation coefficient is less than or equal to 2dB / mm, use a 10ns window and inject a high-energy pulse greater than 1μJ in the leading period. When the attenuation coefficient is greater than 2dB / mm, switch to a 5ns window and limit the energy in the decay period to less than or equal to 0.2μJ. b. When adjacent array element signals interfere with each other, the overlap between the interference area and the probability cloud map is calculated. If the overlap is less than 70%, the time slice weighted elimination process is started.

[0033] The phase reversal transmission strategy in step S33 includes the following: A. Odd and even array elements transmit positive and negative phase pulses alternately. Odd-numbered array elements transmit positive phase pulses of 10ns, while even-numbered array elements transmit negative phase pulses with a delay of 2.5ns. B. Perform interference cancellation when receiving signals, calculate the correlation coefficient of adjacent signals in 5ns slices, and when the correlation coefficient is less than 0.7, compress the amplitude according to the formula (1-R / 0.7)²; C. Dynamic adjustment strategy: When the signal-to-noise ratio is less than 15dB, the negative phase energy is enhanced by 20%. When the temperature is higher than 80°C, the single-phase mode is switched and the sampling frequency is increased to 20MHz.

[0034] The planning accuracy of the spiral path in step S4 is 0.01 mm. When the distance deviation between the probe and the surface is greater than 0.1 mm, position correction is implemented through a closed-loop feedback control system.

[0035] Reference Figure 3 , step S6 includes the following sub-steps: Sub-step S601: Perform a sound velocity consistency check on the overlapping area data, and remove data points with a sound velocity deviation greater than ±5%; Sub-step S602: dynamically selecting a quantum tunneling assisted imaging algorithm or a synthetic aperture focusing algorithm according to the signal-to-noise ratio; Sub-step S603: When the interface fuzzy area is greater than 5 mm², inject the phonon tunneling correction factor β and start the local fine scanning mode.

[0036] This method dynamically adjusts the acoustic wave propagation path by collecting material parameters in real time and incorporating anisotropic finite element models. This solves the problem of sound velocity deviation caused by traditional ultrasonic testing methods that ignore material anisotropy. By introducing quantized delay compensation and a phase-reversal transmission strategy, the interference effect of adjacent element signals is effectively suppressed, improving detection accuracy.

[0037] This invention generates a probability cloud map of acoustic wave transmission by real-time monitoring of the triaxial residual stress distribution and molecular chain orientation angles in the melt zone. This identifies preferred and shielded paths, avoiding detection blind spots caused by improper path selection. Furthermore, a temperature gradient compensation mechanism further enhances the stability of acoustic wave propagation.

[0038] The spiral scanning path planning accuracy of the present invention reaches 0.01mm, and combined with a closed-loop feedback control system, it ensures the precise fit of the probe and the detection surface, reducing errors caused by position deviation.

[0039] Furthermore, the detection system of this invention utilizes a modular design, with functional modules tightly integrated via high-speed interfaces, ensuring high real-time performance and reliability. The dynamic compensation controller and imaging optimization engine work together to seamlessly integrate dynamic acoustic path adjustment with 3D imaging optimization, providing a comprehensive solution for nondestructive testing of PE heat-melt joints. Example 2

[0040] In order to better enable relevant personnel in this technical field to fully understand and implement the present invention, the specific implementation principle of the present invention is supplemented below with reference to a specific application scenario.

[0041] A nondestructive testing system and method for PE heat-melt joints based on an ultrasonic phased array is described. The system's overall structure comprises an ultrasonic phased array probe array, a dynamic compensation controller, a six-axis robotic arm, an imaging optimization engine, and a closed-loop feedback control system. These modules work together through physical connections and signal transmission, ensuring high accuracy and reliability during the testing process.

[0042] In actual applications, the ultrasonic phased array probe array is designed to have 64 elements arranged in an arc shape, and each element has independent transmitting and receiving functions. The surface of the probe array is integrated with residual stress sensors and micro-indenters for real-time acquisition of material parameters. The probe array is connected to the dynamic compensation controller via a shielded cable. The design of the shielded cable effectively reduces the impact of electromagnetic interference on signal transmission. The dynamic compensation controller integrates a quantized time window module and a phase reversal drive circuit. The quantized time window module can be programmed to switch between 5ns or 10ns time windows, while the phase reversal drive circuit is responsible for controlling the odd and even elements to alternately emit positive and negative phase pulses. The dynamic compensation controller is connected to the ultrasonic phased array probe array via a high-speed optical fiber interface, with a transmission rate of 10Gbps to ensure real-time data.

[0043] The six-axis robotic arm, serving as the actuator for the entire system, is equipped with a laser ranging sensor and a Doppler shift correction module. The end of the robotic arm secures the ultrasonic phased array probe array and micro-indenter via a flexible connector. The design of the flexible connector ensures a relative position error of less than 0.05mm between the two. The robotic arm's movement is controlled by a closed-loop feedback control system consisting of a laser ranging sensor and a Doppler shift correction module. The laser ranging sensor monitors the distance deviation between the probe array and the test surface in real time. If the deviation exceeds 0.1mm, the Doppler shift correction module transmits the output signal to the controller, which then processes the signal and drives the robotic arm for fine-tuning, ensuring precise alignment of the probe array with the test surface.

[0044] The imaging optimization engine is the system's core processing unit, utilizing an FPGA architecture to support parallel computing. It integrates a speed consistency verification module, a quantum tunneling imaging module, and a neural network sharpening module. The speed consistency verification module eliminates data points with speed deviations exceeding ±5%. The quantum tunneling imaging module improves defect edge resolution by introducing a correction factor β. The neural network sharpening module, pre-trained with a variety of typical defect samples, automatically identifies and enhances defect edge features. The imaging optimization engine connects to the dynamic compensation controller and six-axis robotic arm via a high-speed data bus, ensuring efficient and reliable data exchange between modules.

[0045] During the actual inspection process, a six-axis robotic arm first moves the ultrasonic phased array probe array along a preset spiral path to the inspection area. The spiral path is planned with an accuracy of 0.01mm, and the robotic arm ensures precise alignment of the probe array with the inspection surface through a closed-loop feedback control system. A laser ranging sensor monitors the distance deviation between the probe array and the inspection surface in real time. When the deviation exceeds 0.1mm, the Doppler shift correction module outputs a signal to the controller, which then processes the signal and drives the robotic arm to make fine adjustments, ensuring that the relative position error between the probe array and the inspection surface is less than 0.05mm. This process ensures full coverage of the inspection area and provides a high-precision foundation for subsequent data acquisition.

[0046] During the detection process, the ultrasonic phased array probe array collects hardness distribution and temperature gradient data in real time through its integrated residual stress sensor and micro-indenter. When the temperature change is detected to exceed 0.5°C, the finite element model update module in the dynamic compensation controller is triggered to generate a new elastic modulus attenuation curve. The finite element model is based on the three-axis residual stress distribution data collected in real time, with a sampling frequency of not less than 100Hz, ensuring the dynamic update of material parameters. When the deviation between the residual stress direction and the molecular chain orientation angle is greater than 15°, the dynamic compensation controller re-orders the priority path of sound wave propagation and implements temperature gradient compensation for the shielding path. For every 1°C increase, the sound energy attenuation increases by 0.6dB. This mechanism effectively improves the stability of sound wave propagation.

[0047] During the acoustic wave propagation path adjustment phase, the dynamic compensation controller generates an acoustic wave propagation probability cloud map, extracts the forward scattering characteristic spectrum, and implements quantized delay compensation and phase reversal transmission strategies. The quantized time window module switches the time window based on the material attenuation coefficient. When the attenuation coefficient is less than or equal to 2dB / mm, a 10ns window is used, with high-energy pulses greater than 1μJ injected during the preamble period. When the attenuation coefficient is greater than 2dB / mm, the window is switched to a 5ns window, with the energy during the decay period limited to 0.2μJ. Odd and even elements alternately transmit positive and negative phase pulses: odd elements transmit positive phase pulses of 10ns, while even elements transmit negative phase pulses with a 2.5ns delay. When receiving signals, the correlation coefficient of adjacent signals is calculated using 5ns slices. When the correlation coefficient is less than 0.7, the amplitude is compressed according to the formula. Furthermore, when the signal-to-noise ratio is less than 15dB, the negative phase energy is boosted by 20%. When the temperature exceeds 80°C, the system switches to single-phase mode and increases the sampling frequency to 20MHz. These operations effectively suppress the interference effect of adjacent element signals, improving detection accuracy.

[0048] After completing the dynamic adjustment of the acoustic wave path, the imaging optimization engine processes the received data. First, a sound velocity consistency check is performed on the overlapping area data, and data points with sound velocity deviations greater than ±5% are eliminated. Then, based on the signal-to-noise ratio, the quantum tunneling-assisted imaging algorithm or the synthetic aperture focusing algorithm is dynamically selected. The quantum tunneling-assisted imaging algorithm measures the acoustic impedance gradient ΔZ at the defect edge and calculates the tunneling probability based on the improved Kane model. It generates a reverse tunneling signal reconstruction curve and incorporates the correction factor β into the imaging algorithm, improving the edge resolution to 25μm. When the interface blur area is greater than 5mm², the phonon tunneling correction factor β is injected and the local fine scanning mode is activated. This process significantly improves the resolution of defect edges, meeting the detection needs in complex scenarios.

[0049] Ultimately, the system generates a three-dimensional imaging result and determines the secondary scanning conditions. The entire inspection process is collaboratively completed by a six-axis robotic arm, a dynamic compensation controller, an imaging optimization engine, and a closed-loop feedback control system. These modules collaborate closely via high-speed interfaces to ensure high real-time and reliable inspection performance. Through these steps, the present invention achieves comprehensive coverage and high-precision nondestructive testing of PE heat-melt joints, resolving the issue of insufficient inspection accuracy associated with traditional methods due to material anisotropy and dynamic density gradients.

[0050] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A nondestructive testing method for PE hot melt joints based on ultrasonic phased array, characterized in that: The following steps are involved: Step S1: real-time acquisition of material parameters to obtain hardness distribution and temperature gradient data; Step S2: establishing an anisotropic finite element model and calculating the elastic modulus attenuation curve; Step S3: dynamically compensate the acoustic wave path and adjust the phased array transmission delay parameter; Step S4, controlling the robotic arm to spirally scan the detection area; Step S5: Fusion analysis of defect features and marking of structural defects; Step S6: Optimize the three-dimensional imaging and determine the secondary scanning conditions.

2. The nondestructive testing method for PE hot melt joints based on ultrasonic phased array according to claim 1 is characterized in that: In step S1, when the temperature change is detected to be greater than 0.5°C, the real-time update of the anisotropic finite element model is triggered, and the surface hardness distribution data is synchronously obtained through the micro-indenter. The micro-indenter and the ultrasonic probe array are fixed to the end of the six-axis robotic arm through a flexible connector, and the relative position error between the two is less than 0.05mm.

3. The nondestructive testing method for PE hot melt joints based on ultrasonic phased array according to claim 1, characterized in that: Step S3 includes the following sub-steps: Step S31: Generate an acoustic wave conduction probability cloud map to distinguish between priority paths and shielded paths; Step S32: extract the forward scattering characteristic spectrum and determine the source of distortion; Step S33: Implement quantized delay compensation and phase inversion emission strategy.

4. The nondestructive testing method for PE hot melt joints based on ultrasonic phased array according to claim 3 is characterized in that: Step S31 includes the following specific operations: Step S311: collecting the triaxial residual stress distribution of the melting zone in real time, with a sampling frequency of not less than 100 Hz; Step S312: When the deviation between the residual stress direction and the molecular chain orientation angle is greater than 15°, triggering the re-ordering of the path priority; Step S313: generate a probability cloud map by fusing the stress field and the orientation angle, and mark the priority paths with probability values ​​greater than or equal to 85%; Step S314: temperature gradient compensation is performed on the shielding path. For every 1°C increase in temperature, the acoustic energy attenuation increases by 0.6 dB.

5. The nondestructive testing method for PE heat-melt joints based on ultrasonic phased array according to claim 3, characterized in that: The quantization delay compensation in step S33 includes the following: a. Switch the time quantum window according to the material attenuation coefficient. When the attenuation coefficient is less than or equal to 2dB / mm, use a 10ns window and inject a high-energy pulse greater than 1μJ in the leading period. When the attenuation coefficient is greater than 2dB / mm, switch to a 5ns window and limit the energy in the decay period to less than or equal to 0.2μJ. b. When adjacent array element signals interfere with each other, the overlap between the interference area and the probability cloud map is calculated. If the overlap is less than 70%, the time slice weighted elimination process is started.

6. The nondestructive testing method for PE heat-melt joints based on ultrasonic phased array according to claim 3, characterized in that: The phase reversal transmission strategy in step S33 includes the following: A. Odd and even array elements transmit positive and negative phase pulses alternately. Odd-numbered array elements transmit positive phase pulses of 10ns, while even-numbered array elements transmit negative phase pulses with a delay of 2.5ns. B. Perform interference cancellation when receiving signals, calculate the correlation coefficient of adjacent signals in 5ns slices, and when the correlation coefficient is less than 0.7, compress the amplitude according to the formula (1-R / 0.7)²; C. Dynamic adjustment strategy: When the signal-to-noise ratio is less than 15dB, the negative phase energy is enhanced by 20%. When the temperature is higher than 80°C, the single-phase mode is switched and the sampling frequency is increased to 20MHz.

7. The nondestructive testing method for PE heat-melt joints based on ultrasonic phased array according to claim 1, characterized in that: The planning accuracy of the spiral path in step S4 is 0.01 mm. When the distance deviation between the probe and the surface is greater than 0.1 mm, position correction is implemented through a closed-loop feedback control system.

8. The nondestructive testing method for PE heat-melt joints based on ultrasonic phased array according to claim 1, characterized in that: Step S6 includes the following sub-steps: Sub-step S601: Perform a sound velocity consistency check on the overlapping area data, and remove data points with a sound velocity deviation greater than ±5%; Sub-step S602: dynamically selecting a quantum tunneling assisted imaging algorithm or a synthetic aperture focusing algorithm according to the signal-to-noise ratio; Sub-step S603: When the interface fuzzy area is greater than 5 mm², inject the phonon tunneling correction factor β and start the local fine scanning mode.

9. A nondestructive testing system for PE heat-melt joints based on ultrasonic phased array, which is applicable to the method according to any one of claims 1 to 8, characterized in that: Includes the following components: Ultrasonic phased array probe array, configured with 64 array elements arranged in an arc shape, integrated with residual stress sensor and micro indenter; A dynamic compensation controller, including a quantized time window module and a phase reversal drive circuit; Six-axis robotic arm equipped with a laser ranging sensor and Doppler shift correction module; Imaging optimization engine, integrating sound velocity consistency verification module, quantum tunneling imaging module and neural network sharpening module; The closed-loop feedback control system consists of a laser ranging sensor and a Doppler frequency shift correction module.

10. The nondestructive testing system for PE heat-melt joints based on ultrasonic phased array according to claim 9, characterized in that: The dynamic compensation controller is connected to the ultrasonic phased array probe array through a high-speed optical fiber interface with a transmission rate of 10Gbps. The output end of the phase reversal drive circuit and the probe array element are connected with a shielded cable.

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