Carrier rocket storage tank acoustic emission detection damage area positioning method and system

Abstract

The invention provides a carrier rocket storage tank acoustic emission detection damage area positioning method and a carrier rocket storage tank acoustic emission detection damage area positioning system. The carrier rocket storage tank acoustic emission detection damage area positioning method comprises the following steps: a preliminary judgment step: taking a polygonal area enclosed by a plurality of acoustic emission sensors which acoustic emission signals reach first as a preliminary area in which damage exists; and an accurate positioning step: further positioning the damage position in the initial region by using a table look-up comparison method. According to the positioning method provided by the invention, the problem that the precision is limited due to the influence of factors such as a complex structure and a welding seam when a traditional acoustic emission detection time difference positioning method based on constant wave velocity, the shortest propagation path and equation set solution is applied to a carrier rocket storage tank is solved.

Description

Technical Field

[0001] This invention relates to the field of industrial inspection, specifically to a method and system for locating damage areas in the acoustic emission detection of rocket propellant tanks, and more particularly to a method and system for locating damage in the acoustic emission detection of rocket propellant tanks based on voxel discretization and lookup table optimization. Background Technology

[0002] Acoustic emission testing is a method for defect detection that captures transient elastic stress waves released when the microstructure of a material undergoes localized, immutable deformation or damage. It boasts advantages such as wide coverage and high detection efficiency, making it suitable for comprehensive health inspection of large structures like storage tanks, bridges, and wind turbine blades. It also shows great promise for application in the inspection of launch vehicle propellant tanks. However, for reusable launch vehicle propellant tanks that remain in their original, in-situ configuration after reentry, traditional testing methods face numerous difficulties in implementation and result interpretation due to the thick external insulation layer and the complex internal structure and components.

[0003] At present, damage localization based on acoustic emission detection is mostly based on the traditional time difference localization method.

[0004] Patent document CN119470655 provides a multi-objective optimization-enhanced acoustic emission localization method for damage to orthotropic steel bridge decks. It extracts the arrival time of the first arrival mode of the acoustic emission signal through the Akaike information criterion and evaluates the damage location by solving the multi-objective optimization model through the hierarchical sequence method.

[0005] The search results revealed that existing patents on damage location techniques related to acoustic emission detection are mostly based on time-of-flight (TOF) positioning. This approach assumes that the acoustic emission signal propagates along the shortest path and improves positioning accuracy by enhancing the accuracy of time difference and wave velocity assessments. However, the main structure of a launch vehicle's propellant tank has numerous welds and a complex structure. Furthermore, it has an external insulation layer and is internally equipped with various other components. The propagation path of the acoustic emission signal varies significantly and is difficult to predict, making traditional TOF positioning methods inadequate for accurately assessing damage location. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for locating damage areas in the acoustic emission detection of launch vehicle propellant tanks.

[0007] A method for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank according to the present invention includes: Preliminary determination steps: The polygonal area enclosed by several acoustic emission sensors where the acoustic emission signals first arrive is taken as the initial area where damage exists. Precise location steps: The location of the damage is further located within the initial area using a lookup table comparison method.

[0008] Preferably, the preliminary judgment step includes: The reused structure was divided into voxels, and the time information of the acoustic emission signal at the center point of each voxel to the acoustic emission sensor was obtained by combining theoretical calculations and actual experiments, and recorded in tabular form.

[0009] Preferably, the propagation time information of the acoustic emission signal corresponding to the voxel is acquired offline before the rocket's maiden flight, and this operation is performed only once.

[0010] Preferably, the precise positioning step includes: When performing table lookup comparison, the error between the measured time information and the time information corresponding to each voxel center point is calculated and sorted from smallest to largest; if the error corresponding to a certain voxel center point is less than the preset range, then the voxel center point is taken as the damage location; if the errors corresponding to multiple voxel center points are all less than the preset range, then the damage location is determined by coordinate interpolation.

[0011] Preferably, when performing coordinate interpolation, the difference between the acoustic emission signal propagation time information recorded in the table and the measured results is minimized by solving an optimization problem, thereby achieving accurate damage localization.

[0012] A system for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank, according to the present invention, comprises: Preliminary assessment module: The polygonal area enclosed by several acoustic emission sensors where the acoustic emission signal first arrives is taken as the preliminary area where damage exists; Precise positioning module: Uses a lookup table comparison method to further locate the damage location within the initial area.

[0013] Preferably, the preliminary judgment module includes: The reused structure was divided into voxels, and the time information of the acoustic emission signal at the center point of each voxel to the acoustic emission sensor was obtained by combining theoretical calculations and actual experiments, and recorded in tabular form.

[0014] Preferably, the propagation time information of the acoustic emission signal corresponding to the voxel is acquired offline before the rocket's maiden flight, and this operation is performed only once.

[0015] Preferably, the precise positioning module includes: When performing table lookup comparison, the error between the measured time information and the time information corresponding to each voxel center point is calculated and sorted from smallest to largest; if the error corresponding to a certain voxel center point is less than the preset range, then the voxel center point is taken as the damage location; if the errors corresponding to multiple voxel center points are all less than the preset range, then the damage location is determined by coordinate interpolation.

[0016] Preferably, when performing coordinate interpolation, the difference between the acoustic emission signal propagation time information recorded in the table and the measured results is minimized by solving an optimization problem, thereby achieving accurate damage localization.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention first determines the damage location roughly based on the time sequence of arrival of acoustic emission signals at each acoustic emission sensor, and then uses a method based on voxel discretization and table lookup comparison to further locate the damage, overcoming the problem that the traditional time difference localization method has a heavy calculation task and relatively low efficiency when the geometric size of the tested structure is large.

[0018] 2. This invention discretizes the test reusable structure into voxels and then uses a combination of theoretical calculations and actual experiments to obtain the time information required for the acoustic emission signal from the center of each voxel to propagate to each acoustic emission sensor. This overcomes the problem that the traditional time difference positioning method has relatively large errors when estimating the damage area when the test structure has non-uniform and anisotropic material structure and other interference factors, such as various components installed inside the tank and the external thermal insulation protection material.

[0019] 3. In this invention, since the geometry of the reusable structure and the arrangement of the acoustic emission detection sensors remain unchanged after each return of the rocket, the acquisition of voxel discretization and acoustic emission signal propagation time information only needs to be performed once, and can be done offline before the rocket's first flight. Therefore, this operation will not significantly affect the detection efficiency, especially for the re-flight efficiency of reusable launch vehicles. Attached Figure Description

[0020] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart of the method of the present invention.

[0021] Figure 2 This is a flowchart illustrating a method for rapid detection and localization of damage to a reusable rocket body structure according to an embodiment of the present invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0023] Reference Figure 1 and Figure 2As shown, a method for detecting and locating damage in rocket propellant tanks based on voxel discretization and lookup table optimization includes: Preliminary determination steps: The polygonal area enclosed by several acoustic emission sensors where the acoustic emission signals first arrive is taken as the initial area where damage exists. Precise location steps: The location of the damage is further located within the initial area using a lookup table comparison method.

[0024] This involves first making a preliminary assessment of the damaged area, and then further locating the damage within that area.

[0025] Specifically, acoustic emission testing is used to rapidly assess the overall structural health of the launch vehicle's propellant tanks. For the same launch vehicle propellant tank, the arrangement of the acoustic emission testing probe array remains unchanged. When locating damage areas using acoustic emission testing, the approximate area of ​​the acoustic emission source is first determined based on the order in which the acoustic emission signals arrive at each probe in the acoustic emission sensor array. Then, the arrival times of the acoustic emission signals at each point within that area are looked up in a table and compared with the test results to further determine the location of the damage.

[0026] To achieve the lookup and comparison function in the process of further focusing on the damage location, the rocket reuse structure is discretized into voxels. The time or time difference of the acoustic emission signal at the center point of each voxel reaching each probe in the acoustic emission sensor array is obtained through theoretical calculation or actual experiment, and recorded in tabular form.

[0027] When the reusable rocket structure is discretized into voxel form, the size of the voxel is determined based on the regional positioning accuracy requirements and the capabilities of the acoustic emission detection equipment.

[0028] When obtaining the time information of the acoustic emission signal at the center point of the voxel arriving at each probe in the acoustic emission sensor array, key locations such as welds and stress concentration points are obtained through actual experiments; general locations with lower risk are obtained through theoretical calculations.

[0029] Since the geometry of the rocket's reusable structure and the arrangement of the acoustic emission detection sensors remain unchanged after each rocket return, the acquisition of the aforementioned voxel discretization and acoustic emission signal propagation time information only needs to be performed once, and subsequent acoustic emission detections can be based on this data. The relevant data acquisition process can be completed before the rocket's first flight.

[0030] During the table lookup and comparison process, if the acoustic emission signal propagation time information of a single voxel center point is close to the measured value, then that point is taken as the damage location.

[0031] If the acoustic emission signal propagation time information of multiple voxel center points is close to the measured value, then interpolation is performed based on the error between the signal propagation time corresponding to each voxel center point and the actual measurement time. By solving the optimization problem, the difference between the acoustic emission signal propagation time information recorded in the table and the measured result is minimized to accurately estimate the damage location.

[0032] Example 1 This embodiment uses a launch vehicle propellant tank as the detection object and employs the acoustic emission detection damage area localization method provided by this invention to assess its health status. According to the implementation principle of this invention, firstly, acoustic emission signal propagation time information is obtained from the rocket propellant tank before its first flight, specifically including: (1) Determine the sensor array arrangement scheme for acoustic emission detection based on the structural characteristics of the storage tank.

[0033] (2) Install acoustic emission detection sensors on the tank and connect them to the detection system according to the sensor array layout scheme.

[0034] (3) Based on the regional positioning accuracy requirements and the capabilities of the acoustic emission detection equipment, the tank structure is discretized into voxels of appropriate size. Generally, the voxel size should not exceed the regional positioning accuracy requirements.

[0035] (4) For welds and other local areas with large loads and prone to damage, lead fracture tests were performed at the center point of each voxel, and the time difference between the acoustic emission signal at the center of the voxel and the arrival time at different acoustic emission sensors was recorded. For other voxels with a low probability of damage, relevant time difference information was obtained by theoretical calculation.

[0036] (5) Assume coexistence N The first acoustic emission sensor, then the second... i The time difference information corresponding to the individual element center is denoted as Δ. t i,jk ,in jk 1≤ j < k ≤ N All binary combinations. For distance from the first... i For sensors whose individual pixel centers are far away and cannot receive effective acoustic emission signals, then all Δ... t i,jk Record it as null.

[0037] (6) Record all the above time information in one OK, M In the column matrix, where M The number of voxels in the structure being tested.

[0038] After obtaining the propagation time information of the aforementioned acoustic emission signals, an overall health status assessment of the returned multiplexing structure is performed using acoustic emission detection, specifically including: (1) Arrange the acoustic emission detection sensor array according to the established acoustic emission sensor arrangement strategy and connect it to the detection system.

[0039] (2) The working pressure is the highest pressure. The airtightness test of the tank is carried out by adopting the step pressurization-pressure holding strategy, and the acoustic emission signal data is recorded during the process.

[0040] (3) After preprocessing the acoustic emission signals such as filtering and noise reduction, the time sequence of the signals of the same acoustic emission event arriving at different sensors in the array is determined by an appropriate algorithm, and the corresponding time difference is accurately calculated and denoted by a similar rule. .

[0041] (4) The acoustic emission signal arrives first at n The polygonal area enclosed by the sensors serves as the approximate area where the acoustic emission specimen appears. Under the condition that the acoustic emission sensor array is relatively uniformly arranged, n 3 or 4 are acceptable.

[0042] (5) Compare the actual measured time difference information with the time difference information corresponding to all voxel center points in the preliminarily determined damage area one by one, calculate the error between the two and sort them. The following formula provides an example of an error definition:

[0043] In the formula For the first i The error corresponding to the individual pixel center. When calculating the error using the above definition, if... or If it is null, then... jk Combinations are not included in the summation. The maximum number of combinations involved in the summation is . .

[0044] (6) Compare the errors corresponding to different voxel centers. If the error corresponding to a certain voxel center is less than 20% of the errors corresponding to other voxels, then the location of that voxel center is taken as the damage location; if there is... N t If the errors corresponding to voxels are small and close to each other, then these voxels are arranged in ascending order of their corresponding error values, and their center position is denoted as . r i The error value is denoted as ,in The location of the damage is estimated using the following formula. r d :

[0045] The launch vehicle propellant tank is primarily a thin-walled structure, and acoustic emission signals mainly propagate within the walls. Therefore, the defect location problem can be considered a two-dimensional location problem. After measuring the attenuation characteristics of the acoustic emission signals within the propellant tank wall structure, a reasonable arrangement scheme and probe spacing can be selected based on the results, providing a foundation for the implementation of the defect location method proposed in this invention. Furthermore, the nature of the two-dimensional location problem means that the propagation time of the voxel center acoustic emission signal to each acoustic emission probe required in the defect location method proposed in this invention can be obtained through actual experiments, improving location accuracy. In addition, due to the large size of the launch vehicle propellant tank, the acoustic emission signal will attenuate with distance during propagation, and the impact of reflected waves on location is relatively small.

[0046] Furthermore, the defect localization method proposed in this invention is independent of probe arrangement, spacing, and the material and structure of the test specimen, and can be extended to one-dimensional or three-dimensional problems. For three-dimensional problems, the propagation time of acoustic emission signals on the outer surface can be obtained experimentally, while that on the interior needs to be obtained through simulation, but the overall localization process remains unchanged. In addition, the defect localization method proposed in this invention is performed independently for each individual acoustic emission event; if multiple acoustic emission specimens occur during the pressure holding process, defect localization needs to be performed for each acoustic emission event. If defining a single acoustic emission specimen and determining that the impacts it contains are not the focus of this invention, this step can be implemented using existing technologies.

[0047] By performing the inspection of the launch vehicle's propellant tank structure according to the steps described in this embodiment, the damaged area can be located with high accuracy and efficiency. This provides necessary information for subsequent detailed inspection and quantitative description of defects, damage repair, and reuse decisions, supporting the short-cycle reuse of the launch vehicle.

[0048] The present invention also provides a system for locating the acoustic emission damage area of ​​a launch vehicle propellant tank. The system can be implemented by executing the process steps of the method for locating the acoustic emission damage area of ​​a launch vehicle propellant tank. That is, those skilled in the art can understand the method for locating the acoustic emission damage area of ​​a launch vehicle propellant tank as a preferred embodiment of the system for locating the acoustic emission damage area of ​​a launch vehicle propellant tank.

[0049] Specifically, a system for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank includes: Preliminary assessment module: The polygonal area enclosed by several acoustic emission sensors where the acoustic emission signal first arrives is taken as the preliminary area where damage exists; Precise positioning module: Uses a lookup table comparison method to further locate the damage location within the initial area.

[0050] The preliminary judgment module includes: The reused structure was divided into voxels, and the time information of the acoustic emission signal at the center point of each voxel to the acoustic emission sensor was obtained by combining theoretical calculations and actual experiments, and recorded in tabular form.

[0051] The propagation time information of the acoustic emission signal corresponding to the voxel was acquired offline before the rocket's maiden flight, and this operation was performed only once.

[0052] The precise positioning module includes: When performing table lookup comparison, the error between the measured time information and the time information corresponding to each voxel center point is calculated and sorted from smallest to largest; if the error corresponding to a certain voxel center point is less than the preset range, then the voxel center point is taken as the damage location; if the errors corresponding to multiple voxel center points are all less than the preset range, then the damage location is determined by coordinate interpolation.

[0053] When performing coordinate interpolation, the difference between the acoustic emission signal propagation time information recorded in the table and the measured results is minimized by solving an optimization problem, thereby achieving accurate damage location.

[0054] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0055] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for locating damaged areas in the acoustic emission detection of a launch vehicle propellant tank, characterized in that, include: Preliminary determination steps: The polygonal area enclosed by several acoustic emission sensors where the acoustic emission signals first arrive is taken as the initial area where damage exists. Precise location steps: The location of the damage is further located within the initial area using a lookup table comparison method.

2. The method for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank according to claim 1, characterized in that, The preliminary judgment steps include: The reused structure was divided into voxels, and the time information of the acoustic emission signal at the center point of each voxel to the acoustic emission sensor was obtained by combining theoretical calculations and actual experiments, and recorded in tabular form.

3. The method for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank according to claim 2, characterized in that, The propagation time information of the acoustic emission signal corresponding to the voxel was acquired offline before the rocket's maiden flight, and this operation was performed only once.

4. The method for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank according to claim 1, characterized in that, The precise positioning steps include: When performing table lookup comparison, the error between the measured time information and the time information corresponding to each voxel center point is calculated and sorted from smallest to largest; if the error corresponding to a certain voxel center point is less than the preset range, then the voxel center point is taken as the damage location; if the errors corresponding to multiple voxel center points are all less than the preset range, then the damage location is determined by coordinate interpolation.

5. The method for locating damage areas in the acoustic emission detection of a launch vehicle propellant tank according to claim 4, characterized in that, When performing coordinate interpolation, the difference between the acoustic emission signal propagation time information recorded in the table and the measured results is minimized by solving an optimization problem, thereby achieving accurate damage location.

6. A system for locating damaged areas in the acoustic emission detection of a launch vehicle propellant tank, characterized in that, include: Preliminary assessment module: The polygonal area enclosed by several acoustic emission sensors where the acoustic emission signal first arrives is taken as the preliminary area where damage exists; Precise positioning module: Uses a lookup table comparison method to further locate the damage location within the initial area.

7. The acoustic emission detection damage area positioning system for launch vehicle propellant tanks according to claim 6, characterized in that, The preliminary judgment module includes: The reused structure was divided into voxels, and the time information of the acoustic emission signal at the center point of each voxel to the acoustic emission sensor was obtained by combining theoretical calculations and actual experiments, and recorded in tabular form.

8. The acoustic emission detection damage area positioning system for launch vehicle propellant tanks according to claim 7, characterized in that, The propagation time information of the acoustic emission signal corresponding to the voxel was acquired offline before the rocket's maiden flight, and this operation was performed only once.

9. The acoustic emission detection damage area positioning system for launch vehicle propellant tanks according to claim 6, characterized in that, The precise positioning module includes: When performing table lookup comparison, the error between the measured time information and the time information corresponding to each voxel center point is calculated and sorted from smallest to largest; if the error corresponding to a certain voxel center point is less than the preset range, then the voxel center point is taken as the damage location; if the errors corresponding to multiple voxel center points are all less than the preset range, then the damage location is determined by coordinate interpolation.

10. The acoustic emission detection damage area positioning system for launch vehicle propellant tanks according to claim 9, characterized in that, When performing coordinate interpolation, the difference between the acoustic emission signal propagation time information recorded in the table and the measured results is minimized by solving an optimization problem, thereby achieving accurate damage location.

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