Method and apparatus for ultrasonic inspection of composite parts and computer program

Abstract

The invention relates to a method and apparatus for ultrasonic inspection of composite parts and a computer program, the method comprising: providing a composite part (10) to be inspected, the composite part (10) comprising a plurality of layers (11); determining a travel time and / or an attenuation of an ultrasonic signal (15) propagating through the composite part to be inspected; providing a travel time and / or an attenuation of the ultrasonic signal (15) propagating through a reference composite part; subtracting the travel time and / or the attenuation of the ultrasonic signal (15) in the reference composite part from the travel time and / or the attenuation of the ultrasonic signal (15) in the composite part to be inspected, or vice versa; and determining one or more missing and / or additional layers in the composite part (10) to be inspected from the result of the subtraction process. Differences in the travel time and / or the attenuation of the ultrasonic signal (15) in the composite part (10) to be inspected relative to the reference composite part and / or differences in thickness between the composite part (10) and the reference part are visualized.

Description

Technical Field

[0001] This invention relates to a method and apparatus for ultrasonic testing of composite parts, particularly those made of carbon fiber reinforced plastics. Furthermore, this invention relates to a computer program for ultrasonic testing of composite parts, particularly those made of carbon fiber reinforced plastics. Background Technology

[0002] Composite parts comprise, for example, multiple monolayers made of carbon fiber reinforced plastic (i.e., carbon fibers in a resin matrix). These layers are automatically laminated or machine-laminated until they reach a predetermined target thickness. A layer can have a thickness of, for example, 0.25 mm. Typically, layer thicknesses are between 0.125 mm and 0.25 mm. When the layers are fabric or mesh, they can also be thicker, for example, 0.35 mm. These layers can have different orientations. It is important that the part or component achieves its target geometry and thickness, and that its internal quality is guaranteed.

[0003] Figure 4 As an example, an aircraft wing element 40 is shown, which is formed by a large number of layers or plies stacked on top of each other. In this example, a sequence including a first ply 111, a second ply 112, and a third ply 113 is shown. As indicated by the arrows within ply 113, each ply is laid with multiple channels.

[0004] The laminate thickness has tolerances that depend on the thickness of the part. Typically, the laminate thickness is within or below these tolerances. This means that a layer may be missing, for example, due to an interruption in the lamination process or other abnormal events, but because it is absent from the tolerances of the part or assembly, this may go undetected. However, missing layers are crucial for the statics of the part and cannot be omitted.

[0005] Known tests on components or parts use ultrasonic equipment that operates based on known ultrasonic principles. Components are inspected using ultrasonic signals, and the measured signals can be evaluated based on faults.

[0006] However, known tests cannot determine whether all required layers are provided in the inspected component or part. There may be sections where layers are missing, or sections where there are more layers than planned according to the design specifications. Summary of the Invention

[0007] The object of this invention is to provide a method and apparatus for ultrasonic testing of composite parts, which allows for the determination of whether layers are missing or present in composite parts (particularly those made of carbon fiber reinforced plastics) that should not be present. Furthermore, the method and apparatus should allow for the detection of other characteristics of the composite parts under inspection that may degrade their quality, such as delamination, porosity, or foreign debris.

[0008] This objective is achieved through the subject matter of this invention.

[0009] This invention provides a method for ultrasonic testing of composite parts, comprising the following steps: providing a composite part to be tested, the composite part comprising multiple layers; determining the runtime and / or attenuation of an ultrasonic signal propagating through the composite part to be tested; providing the runtime and / or attenuation of an ultrasonic signal propagating through a reference composite part; subtracting the runtime and / or attenuation of the ultrasonic signal in the reference composite part from the runtime and / or attenuation of the ultrasonic signal in the composite part to be tested, or vice versa; and determining one or more missing layers and / or additional layers in the composite part to be tested based on the result of the subtraction process.

[0010] This method is particularly suitable for composite parts that should be inspected through non-destructive testing (NDT). Specifically, the present invention provides a non-destructive testing or inspection method that allows the detection of missing layers in composite parts, such as fiber-reinforced plastic layers (especially carbon fiber reinforced plastic (CFRP) layers) and / or, particularly, metallic layers used for lightning protection, such as, for example, expanded copper foil (ECF) layers. In particular, the composite part is a CFRP part, i.e., it is made of CFRP.

[0011] This method can detect other deviations in the internal quality of a part, such as porosity, delamination, and / or foreign debris.

[0012] Preferably, the raw NDT data is used to detect missing layers in composite parts. However, this method is also applicable to subtracting images (such as JPG files).

[0013] In particular, the ultrasonic data of the composite part being tested and the ultrasonic data of the reference part are subtracted from each other. In other words, the ultrasonic data of one part or cover (such as, for example, the reference part or cover) is subtracted from the ultrasonic data of another part or cover (such as, for example, the part or cover being tested). Of course, the subtraction can also be performed in reverse, that is, the ultrasonic data of the part being tested can be subtracted from the ultrasonic data of the reference part.

[0014] Preferably, the method includes the steps of: visualizing the difference in the runtime and / or attenuation of the ultrasonic signal in the inspected composite part relative to a reference composite part in an image of the inspected composite part, and / or visualizing the difference in thickness between the inspected composite part and the reference part.

[0015] In particular, the differences in the subtracted data are used as indicators of missing and / or additional layers, and this can be visualized in an image or picture. Preferably, the method is executed automatically by artificial intelligence.

[0016] For example, the signal attenuation and / or deviation of the signal run time in the inspected composite part relative to the reference part is visible in the image of the inspected composite part.

[0017] Preferably, an image of the composite part being inspected is generated, the image indicating color values ​​at different coordinates, the color values ​​representing the attenuation of the ultrasonic signal in the composite part being inspected and / or the deviation of the running time compared with a reference composite part.

[0018] The image is, for example, a top view of the composite part being inspected. The color value is, for example, a pixel value.

[0019] Preferably, the pixel value of the coordinate in the image of the reference part is compared with the pixel value of the same coordinate in the image of the part being inspected, and / or the pixel value of the coordinate in the image of the reference part is subtracted from the pixel value of the same coordinate in the image of the part being inspected, wherein the pixel value represents the attenuation and / or running time of the ultrasonic signal in the respective part.

[0020] Preferably, the operating time and / or attenuation determined for the inspected composite part are provided as reference data for the inspection of one or more other composite parts.

[0021] Preferably, the composite part to be inspected is scanned with an ultrasonic signal, and the determined signal runtime and / or attenuation are stored as a two-dimensional matrix for use in the subtraction step. Therefore, the thickness of the composite part at various locations or the entire composite part can be determined.

[0022] Preferably, the thickness difference between the inspected composite part and the reference part is determined by the ultrasonic data of the inspected composite part.

[0023] Preferably, the thickness difference between the inspected part and the reference part is compared with the thickness of the layers of the inspected composite part to detect missing or additional layers.

[0024] Preferably, a two-dimensional pattern is determined based on the deviation of the ultrasonic signal's running time and / or attenuation in the inspected composite part compared to the ultrasonic signal's running time and / or attenuation in a reference composite part, in order to identify areas of missing or added layers and / or areas of reduced quality.

[0025] According to one aspect of the invention, an apparatus for ultrasonic testing of composite parts is provided, comprising: an ultrasonic system designed to determine the runtime and / or attenuation of an ultrasonic signal propagating through the composite part to be tested; and a computer unit designed to subtract, or conversely subtract, the runtime and / or attenuation of an ultrasonic signal propagating through a reference composite part from the runtime and / or attenuation of the ultrasonic signal determined for the composite part to be tested, and to determine, based on the result of the subtraction process, one or more missing layers and / or additional layers in the composite part to be tested.

[0026] Preferably, the device further includes a display device to indicate the areas of the inspected composite part where the missing and / or additional layers of the inspected composite part are determined by subtraction and / or the deviations in the internal quality of the inspected composite part are determined.

[0027] Preferably, the device is designed to perform the method according to the invention.

[0028] According to another aspect, the present invention provides a computer program for ultrasonic testing of composite parts, comprising the following program steps: subtracting the runtime and / or attenuation of an ultrasonic signal propagating through a reference composite part from the runtime and / or attenuation of the ultrasonic signal in the composite part to be tested, or vice versa; and determining one or more missing layers and / or additional layers in the composite part to be tested based on the result of the subtraction process.

[0029] Preferably, the computer program is designed to perform the method according to the invention.

[0030] In particular, the principle of the present invention is to use ultrasonic inspection data and analyze the ultrasonic inspection data by subtraction. This means comparing one or more components or parts with the component or part to be inspected, and preferably making it visible, so as to allow for a quick determination of whether the number of layers meets the specifications of the part and an indication of whether there are any parts of the inspected part with reduced internal quality. Attached Figure Description

[0031] Embodiments of the invention are described in more detail with reference to the illustrative accompanying drawings.

[0032] Figure 1An apparatus for ultrasonic nondestructive testing according to a preferred embodiment of the invention is described during the inspection of composite test parts;

[0033] Figure 2 Images of the composite test part generated during inspection are described, showing the difference in runtime between the composite test part and the composite reference part;

[0034] Figure 3 Images of the composite test part generated during the inspection are described, showing the amplitude difference between the reference part and the test part to be evaluated; and

[0035] Figure 4 The document describes known wing elements of an aircraft, which are formed by a large number of single layers or sheets stacked on top of each other. Detailed Implementation

[0036] Preferred examples of the method according to the invention are described below with reference to the following. Figures 1 to 3 To explain.

[0037] refer to Figure 1 A composite part 10 to be inspected is provided. The composite part 10 (also referred to as the part to be inspected or the test part) comprises multiple layers 11. The composite part or test part 10 is a CFRP part, i.e., it is made of carbon fiber reinforced plastic. In this example, the test part 10 is a skin element of an aircraft wing and has a thickness D of 2.5 mm and a layer thickness of 0.25 mm. (Step 1).

[0038] The ultrasonic testing system 14 is designed to determine the run time and / or attenuation of the ultrasonic signal 15 propagating through the test part 10. The ultrasonic testing system 14 is arranged on one side of the test part 10, in this example on the upper surface 12 of the test part 10.

[0039] The ultrasonic system 14 sends an ultrasonic signal 15 from the upper surface 12 to the test part 10, so that the ultrasonic signal 15 propagates through the test part 10.

[0040] The ultrasonic signal 15 is reflected at the bottom side 13 of the test component 10, and after propagating back and forth through the test component 10, the signal 15 returns to the ultrasonic system 14 and is detected by the ultrasonic system 14. The travel time of the signal 15 along its path through the composite component 10, as well as the amplitude and / or attenuation of the signal 15, are measured.

[0041] In this way, the upper surface 12 of the composite part 10 is scanned by the ultrasonic system 14, thereby collecting ultrasonic data of ultrasonic signal 15 for each pair of coordinates of the surface 12 (step 2).

[0042] Generally, it is also possible to measure the runtime and attenuation of an ultrasonic signal that passes through the test part in only one direction (i.e., without being reflected).

[0043] In addition, the runtime and / or attenuation of the ultrasonic signal propagating through the reference composite part are provided, which are not visible in the figure. The reference composite part (also referred to as the reference part) is constructed to be equivalent to the test part 10 to be inspected. The ultrasonic signal used on the reference part has the same properties or characteristics as that on the test part 10 and is applied in the same manner. (Step 3).

[0044] Now, the runtime and / or attenuation of the ultrasonic signal 15 measured in the reference part are subtracted from the runtime and / or attenuation of the ultrasonic signal 15 measured in the test part 10 by the computer unit 20, or vice versa. This means that the runtime and / or attenuation of the ultrasonic signal 15 in the test part 10 can also be subtracted from the runtime and / or attenuation of the ultrasonic signal in the reference part.

[0045] Based on the results of the subtraction process, one or more missing layers and / or additional layers in the composite test part 10 being inspected are identified, and other deviations in internal quality, such as delamination, porosity, or foreign debris, can also be identified (step 4).

[0046] In step 2 above, the signal propagation time is measured at different locations on the test component 10. The thickness at these different locations is determined by testing the speed of sound within the component 10. The propagation time can be measured for sound waves traveling in one direction through the tested component 10 or for sound waves traveling back and forth within the tested component.

[0047] Ultrasonic scanning across the two-dimensional surface 12 of the test part 10 provides a one-dimensional thickness measurement at a defined point or location. Data representing the thickness of the test part 10 are represented by a first matrix M. i,j (1) is stored in form for further processing in computer unit 20. A second matrix M, serving as a nominal reference, is provided by similar measurements of another part (which is a reference part). i,j (2). By means of M i,j = M i,j (2)-M i,j (1) Subtract the measurement results to determine the thickness difference at different points or locations within the test part 10.

[0048] Ideally, the elements of the value matrix are very small. If the difference in thickness has the same magnitude as the thickness of a single layer 11 of the test part 10, then depending on whether the difference is positive or negative, the difference indicates a missing or additional layer at the corresponding location. Further anomalies in thickness (such as, for example, delamination) also become visible.

[0049] Preferably, the dispersion of the data is taken into account. If it is less than the layer thickness, the method provides higher accuracy.

[0050] For data evaluation, statistical analysis is preferably used to determine the two-dimensional pattern on the test part 10, for example, through pattern recognition. For example, by using the design data of the test part 10 to identify a single missing layer or an additional layer.

[0051] In summary, subtracting the runtime image of the ultrasonic signal was used to detect missing or added CFRP layers. Further details of the preferred embodiment are as follows:

[0052] A reference C-image is compared with the C-image of the test part, i.e., with the C-image of the part 10 to be inspected. The "C-image" is, for example, a top view of the test object or test part 10, in which deviations in sound attenuation or thickness are visualized, for example, through different colors, color differences, or gray levels. The pixel values ​​at each coordinate of the reference part's C-image are compared, and the pixel values ​​at each coordinate of the reference part's C-image are subtracted from the pixel values ​​at the same coordinates of the test part 10's C-image. Rejected test objects or test parts are not permitted as references to the C-scan-subtract-method described herein. The C-image is displayed on monitor 30 for visualization of the results.

[0053] The reference part or component is, for example, a reference housing obtained by averaging various measurements. It can also be a theoretical reference (e.g., CAD data), a previously tested component, or a first sample. The reference part must be formed identically to the test part 10 and must be scanned using the same ultrasonic system and signal properties as the part or component 10 to be evaluated.

[0054] The subtraction process is performed using the mathematical formula described above. For this step, data representing the C-image is loaded into computer unit 20. The mathematical formula is used to define the subtraction of the C-image of the reference part from the C-image of the test part 10. A predefined palette provided in data storage 21 can be selected for visualizing the deviation as described above.

[0055] The assessment is described as follows:

[0056] Figure 2A simplified C-image 16, as a top view, shows the component 10 under test, indicating the differences between the reference part and the test part or component 10. The runtime differences between the reference part and the component 10 to be evaluated are displayed in color on the display 30.

[0057] The thickness difference of component 10 was examined. The missing CFRP layer in region 17 of image 16 is displayed on display 30 in a first color (e.g., "red"). The additional CFRP layer is displayed in a second color (e.g., "green"). Region 18 shows a small thickness difference relative to the reference part (i.e., a difference below a predetermined threshold), and this region 18 is displayed in a third color (e.g., "white"). Of course, other colors and different color differences can also be used.

[0058] Preferably, values ​​measured outside the color chart are displayed in a different color (e.g., "black") in the subtracted image. These areas also need to be evaluated. Because the lamination thickness deviation in such areas is very large, delamination can be observed, which is objected to when evaluating "intrinsic quality".

[0059] Layer separation near the back wall may appear as a missing layer in the subtracted C-image. A missing CFRP layer is an error characteristic. The missing layer can be rendered if it follows the geometric contour.

[0060] Next, the plausibility of the lamination thickness difference is checked. The plausibility check compares the deviation of the color image relative to the subtracted image with the composite thickness value provided by the ultrasonic facility or system 14. This ensures that, even if the order of components in computer unit 20 has been reversed, the correct component is corrected. The plausibility of the thickness difference in the subtracted image is also checked.

[0061] The mathematical formula shown above determines the subtraction of the reference part from the part 10 to be evaluated.

[0062] Therefore, a negative value for the lamination thickness in the generated C-image indicates that part 10 is thinner than the reference part at the corresponding inspection coordinate. A positive value for the lamination thickness in the generated C-image indicates that the part 10 to be evaluated is thicker than the reference part at the corresponding inspection coordinate.

[0063] In addition to the above, the subtraction processing of amplitude images or data is used to detect missing or additional lightning protection layers (such as, for example, bulging copper foil).

[0064] Therefore, a reference C-scan or image is compared with a C-scan or image of the part 10 to be evaluated. The pixel value of each coordinate in the C-image of the reference part is subtracted from the pixel value of the same coordinate in the C-image of the part 10 to be evaluated. Parts rejected by the C-scan subtraction method must not be used as a reference for this procedure.

[0065] The file containing the ultrasonic data of part 10 to be inspected is processed using a file containing ultrasonic data of a reference part. The reference part is preferably a part that appears sequentially after another part. The reference part should be identical to part 10; that is, it should be manufactured based on the same design data as part 10 and scanned by the same ultrasonic system 14 as part 10.

[0066] The subtraction process is performed using the mathematical formula described above. This formula defines the subtraction of the C-scan of the reference part from the C-scan of the part 10 to be evaluated. Here, amplitude data is processed, rather than runtime or thickness data. Further details regarding the subtraction process and visualization can be similar or identical.

[0067] Now for reference Figure 3 Describe the assessment. Figure 3 A simplified generated C-image 26 of the tested component 10 is shown schematically as a top view, in which the amplitude difference between the reference part and the test part 10 to be evaluated is shown in different colors on the display 30.

[0068] Here, the missing or additional surge protection layer of component 10 is examined. Missing surge protection layers are displayed on display 30 in a first color (e.g., "red"), while additional surge protection layers are displayed in a second color (e.g., "green"). In this figure, area 27 of component 10 represents one or more missing surge protection layers.

[0069] Region 28 displays only a small difference relative to the reference part, i.e., a difference below a predetermined threshold. This region 28 is displayed on the display 30 in a third color (e.g., "white"). Of course, other colors can also be used.

[0070] If the corresponding area follows the geometric contour, a missing lightning protection layer can be presented. This satisfies the fault characteristic "missing layer". An unclear indication that does not follow the geometric contour and therefore satisfies the fault characteristic "unidentifiable indication" is also objectionable.

[0071] The reasonableness of the amplitude difference is checked. The reasonableness check involves comparing the deviations, displayed in color around the subtracted image, with the amplitudes provided by the ultrasonic system 14. This ensures that, even if the order of parts in the calculator is reversed, the correct part is incorrect.

[0072] The reasonableness of the amplitude difference in the C-image after subtraction must be checked.

[0073] The mathematical formula specifies that a reference part is subtracted from the part 10 to be evaluated. Therefore, a positive amplitude, as indicated in the region 27 of the generated C-scan, indicates that the part 10 to be evaluated has a missing lightning protection location at the corresponding inspection coordinate.

[0074] Reference symbol list:

[0075] 10 Composite parts / test parts to be inspected

[0076] 11th floor

[0077] 12 Upper surface

[0078] 13 bottom side

[0079] 14 Ultrasonic Systems

[0080] 15ultrasonic signals

[0081] 16 images / C images

[0082] 17. Regions with missing layers

[0083] 18. Regions with small thickness differences

[0084] 20 computer units

[0085] 21 Data Storage

[0086] 26 images / C images

[0087] 27. Regions with missing layers

[0088] 28 regions with small amplitude differences

[0089] 30 monitors

[0090] 40 wing components

[0091] 111 First layer

[0092] 112 Second Layer

[0093] 113 Third Layer

[0094] D Thickness

Claims

1. A method for ultrasonic testing of composite parts, comprising the following steps: A composite part (10) to be inspected is provided, the composite part (10) comprising multiple layers (11). The composite part (10) to be inspected is scanned with an ultrasonic signal (15). Determine the run time and / or attenuation of the ultrasonic signal (15) propagating through the composite part (10) to be inspected; and The running time and / or attenuation of the reference signal are subtracted from the running time and / or attenuation of the ultrasonic signal (15) in the composite part (10) to be inspected, or vice versa; Therefore, one or more missing layers and / or additional layers in the inspected composite part (10) are determined from the results of the subtraction process. Its features are, - The reference signal used for subtraction is an ultrasonic signal propagating through a reference composite part, which is constructed identically to the composite part (10) to be inspected. - Store the determined runtime and / or attenuation of the ultrasonic signal (15) as a two-dimensional matrix for use in subtracting steps. - Compare the C-scan image of the reference composite part with the C-scan images (16, 26) of the composite part (10) to be inspected. - Wherein the pixel value of the coordinate in the C-scan image of the reference composite part is subtracted from the pixel value of the same coordinate in the C-scan image (16, 26) of the composite part (10) being examined, the pixel value representing the running time and / or decay.

2. The method according to claim 1, further comprising the steps of: visualizing in an image the difference in the running time and / or attenuation of the ultrasonic signal (15) in the inspected composite part (10) relative to the reference composite part, and / or visualizing in an image the difference in thickness between the inspected composite part (10) and the reference composite part.

3. The method according to any one of claims 1-2, wherein an image of the tested composite part (10) is generated, the image indicating color values ​​at different coordinates, the color values ​​representing the attenuation and / or deviation of the ultrasonic signal (15) in the tested composite part (10) compared with the reference composite part.

4. The method according to any one of claims 1-2, wherein the operating time and / or attenuation determined for the tested composite part (10) are provided as reference data for testing one or more additional composite parts.

5. The method according to any one of claims 1-2, wherein the thickness difference between the inspected composite part (10) and the reference composite part is determined.

6. The method according to claim 5, wherein the difference in thickness between the inspected composite part (10) and the reference composite part is compared with the thickness of the layer (11) of the inspected composite part (10) to detect missing or additional layers.

7. The method according to any one of claims 1-2, wherein a two-dimensional pattern is determined based on the deviation of the running time and / or attenuation of the ultrasonic signal (15) of the tested composite part (10) compared with that of the reference composite part to identify areas (17, 27) of missing or added layers and / or areas of reduced quality.

8. An apparatus for ultrasonic testing of composite parts, the apparatus comprising: An ultrasonic system (14) is designed to determine the run time and / or attenuation of an ultrasonic signal (15) propagating through the composite part (10) to be inspected. and A computer unit (20) is designed to: subtract the runtime and / or attenuation of a reference signal from the runtime and / or attenuation of an ultrasonic signal (15) determined for the composite part (10) to be inspected, or vice versa, thereby determining one or more missing layers and / or additional layers in the composite part (10) to be inspected based on the comparison results. Its features are, The computer unit (20) is configured to: - The ultrasonic signal propagating through a reference composite part, which is constructed identically to the composite part (10) to be inspected, is used as the reference signal for subtraction. - Store the determined runtime and / or attenuation of the ultrasonic signal (15) as a two-dimensional matrix for use in subtracting steps. - Compare the C-scan image of the reference composite part with the C-scan images (16, 26) of the composite part (10) to be inspected, and - Subtract the pixel value of the coordinate in the C-scan image of the reference composite part from the pixel value of the same coordinate in the C-scan image (16, 26) of the inspected composite part (10), the pixel value representing the running time and / or decay.

9. The device according to claim 8 further includes a display device (30) for indicating regions (17, 27) of the inspected composite part (10) in which the missing layers and / or additional layers of the inspected composite part (10) are determined by the subtraction step and / or regions in which deviations in the internal quality of the inspected composite part (10) are determined.

10. The device according to claim 8 or 9, characterized in that, The device is designed to perform the method according to any one of claims 1 to 7.

11. A computer storage medium comprising a computer program for ultrasonic testing of composite parts, including program steps designed to perform the following operations: The runtime and / or attenuation of the reference signal are subtracted from the runtime and / or attenuation of the ultrasonic signal (15) determined by the ultrasonic system (14) in the composite part (10) to be inspected, or vice versa. Based on the comparison results, one or more missing layers and / or additional layers (20, 27) in the composite part (10) being examined are identified. Its features are, The procedure steps are also designed for the following operations: The ultrasonic signal propagating through a reference composite part, which is constructed identically to the composite part (10) to be tested, is used as the reference signal for subtraction. The runtime and / or attenuation of the ultrasonic signal (15) are stored as a two-dimensional matrix for use in subtracting steps, and The C-scan image of the reference composite part is compared with the C-scan images (16, 26) of the composite part (10) to be inspected. Wherein, the pixel value of the coordinate in the C-scan image of the reference composite part is subtracted from the pixel value of the same coordinate in the C-scan image (16, 26) of the inspected composite part (10), wherein the pixel value represents the running time and / or decay.

12. The computer storage medium according to claim 11, characterized in that, The computer program is designed to perform the method according to any one of claims 1 to 7.

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