Calibration method for ultrasonic inspection of composite part

Abstract

A method uses a calibration panel to calibrate a scanning system that detects defects in a woven composite part. The method includes the steps of providing a calibration panel having a woven composite panel and at least one insert positioned within a thickness of the woven composite panel. The method further includes the steps of scanning the calibration panel and comparing results of the scanning of the calibration panel with baseline data for the calibration panel. The method also includes the step of adjusting scan parameters if differences between results of the scanning of the calibration panel and baseline data for the calibration panel are greater than acceptable limits.

Description

CALIBRATION METHOD FOR ULTRASONIC INSPECTION OF COMPOSITEPARTBACKGROUND

[0001] Composite parts are widely used in aerospace, automotive, maritime, and a variety of commercial and consumer applications that require lightweight parts having high strength and durability characteristics. Such parts typically include a binding polymer reinforced with carbon fibers, fiberglass, or other suitable materials. The binding polymer may be a thermoset resin, e.g., epoxy, or any suitable thermoset or thermoplastic polymer. The resulting parts generally have higher strength-to-weight ratios as compared to corresponding metal parts.

[0002] During the manufacturing process, composite parts can develop voids, delaminations, and / or other internal defects that would compromise the structural integrity of the part. Such defects may not be detected by visual inspection. Accordingly, nondestructive (NDT) testing is often utilized to detect internal defects, thereby ensuring that the parts are suitable for their intended use.

[0003] Ultrasonic inspection is a non-destructive testing method often used to inspect composite parts. Non-limiting examples of ultrasonic inspection systems and methods are disclosed in U.S. Patent No. 10,041,828 (“the ‘828 Patent’’), entitled “Method for Inspection by the Transmission of Ultrasounds,” the disclosure of which is incorporated herein by reference in its entirety. The ‘828 Patent issued on August 7, 2018, and is assigned to Safran Aircraft Engines.

[0004] FIGURE 1 shows an ultrasonic transmission inspection system 20 (“inspection system 20”) described in the ’828 Patent. The system 20 includes an emission probe 22 that emits an ultrasound beam in the direction of an object 10 to be inspected. A receiver 24 is positioned on the other side of the object 10 and receives the portion of the ultrasonic beam that passes through the object 10. The emission probe 22 and the receiver 24 are moved by a positioning system 26. As the emission probe 22 and receiver 24 are moved relative to the object, the receiver transmits signals corresponding to the amplitude of the ultrasound beam received by the receiver to a processing unit 28.

[0005] The processing unit 28 associates at each point of the scanned object 10 the amplitude of the ultrasound beam received by the receiver 24 from the probe 22 throughthe object 10. The amplitude received by the receiver 24 at each location is visually represented on a display 30 so that the represented amplitudes form a mapping 40. such as a C-scan visualization, of the inspected object 10. Any amplitude anomalies that may indicate defects in the object are visibly apparent in the mapping 40.

[0006] FIGURES 2A and 2B show representative mappings 40 and 50 of generated by ultrasonic inspection of different objects. FIGURE 2 A shows a representative mapping 40 of the object 10 scanned by the system 20 of FIGURE 1. The mapping 40 includes a number of anomalies 42a, 42b, and 42c indicated by dashed box 42. Each anomaly is the result of a change in the amplitude of the ultrasound passing through a portion of the object having porosities. Thus, the dashed box 42 indicates a cluster of porosities that may represent an unacceptable defect in the object 10.

[0007] FIGURE 2B shows a representative mapping 50 of another object scanned by the system 20 of FIGURE 1. In the illustrated embodiment, the object is a wound composite part, and dashed box 52 indicates a foreign object introduced during winding of the object. The presence of foreign objects in a composite part, when unintentional, can negatively impact the strength and durability of the objects, making the detection of such objects a critical part of the inspection process.

[0008] During NDT, indications appearing on a mapping 40 may result from signal attenuation caused by the presence of a defect, such as delamination, resin porosity, or foreign objects. In some cases, the such indications may indicate structural features of the part, e.g., the interface between two components, a change in part thickness, or the presence of a different material, such as a fiberglass or metallic insert. As a result, some indications are expected due to the form and composition of the object 10; however, unexpected indications may be considered potential defects that require further inspection.

[0009] As the use of composites has become more common, 3D woven composites have replaced simpler laminated composites in many applications to enable the production of more complex structures. For example, FIGURE 3 shows a cross-sectional view of an exemplary turbofan engine 60. The engine 60 receives an airflow 62 along a central axis 64 and includes a fan 66, a low-pressure compressor 70, a high-pressure compressor 72, a combustion chamber 74, a high-pressure turbine 76, and a low-pressure turbine 78 arranged in seriatim along the axis 64. A fan case 68 surrounds the fan 66 and protects the aircraft and passengers in the event of a blade-out event.

[0010] Because of the size and structural requirements of the fan case 68, a composite configuration provides desirable weight savings and improved durability. Further, because of the overall shape of the fan case 68, the use of 3D composite weaving to produce the fan case 68 provides manufacturing and structural advantages as compared to more traditional composite laminates. However, ultrasonic inspection of composite woven parts presents additional challenges.

[0011] Due to the internal structure of 3D woven parts, ultrasonic waves passing through the part are subject to increased dispersion by the woven material and increased absorbance due to the shape of the resin with which the woven material is impregnated. As a result, ultrasonic waves passing through 3D experience significant attenuation of the ultrasonic waves through the material, particularly as compared to laminate composite structures. This attenuation can make it difficult to distinguish anomalies that indicate structural defects from anomalies that result from designed features of a 3D woven part.SUMMARY

[0012] Embodiments of methods for calibrating ultrasonic inspection systems are set forth below according to technologies and methodologies of the present disclosure. The inspection systems utilize non-destructive testing to detect defects in woven composite parts. A calibration panel is made of a woven composite material and is scanned to establish the calibration state of the system.

[0013] A first representative embodiment of a disclosed method uses a calibration panel to calibrate a scanning system that detects defects in a woven composite part. The method includes the steps of providing a calibration panel having a woven composite panel and at least one insert positioned within a thickness of the woven composite panel. The method further includes the steps of scanning the calibration panel and comparing results of the scanning of the calibration panel with baseline data for the calibration panel. The method also includes the step of adjusting scan parameters if differences between results of the scanning of the calibration panel and baseline data for the calibration panel are greater than acceptable linuts.

[0014] In any embodiment, the method further comprises the steps of re-scanning the calibration panel; comparing results of the re-scanning of the calibration panel with baseline data for the calibration panel; and adjusting scan parameters if differences between results of the scanning of the calibration panel and baseline data for the calibration panel are greater than acceptable limits.

[0015] In any embodiment, the method further comprises the steps of scanning at least one inspected part; and determining existence of defects according to anomalies present in scan results.

[0016] In any embodiment, the method further comprises the steps of re-scanning the calibration panel; comparing results of the re-scanning of the calibration panel with baseline data for the calibration panel; and confirming that the scanning system is still calibrated according to differences between results of the re-scanning of the calibration panel and baseline data for the calibration panel.

[0017] In any embodiment, the calibration panel comprises woven carbon fiber.

[0018] In any embodiment, the woven carbon fiber has a warp of 4*24k.

[0019] In any embodiment, the woven carbon fiber has a weft of 4* 24k.

[0020] In any embodiment, the calibration panel comprises a plurality of different thickness, each thickness having at least one insert disposed therein.

[0021] In any embodiment, each thickness has a first insert having a first shape and a second insert having a second shape.

[0022] In any embodiment, the first insert and the second insert are a predetermined distance from a face of the calibration panel.

[0023] In any embodiment, the first shape is a rectangle, and the second shape is a circle.

[0024] In any embodiment, the calibration panel comprises a plurality’ of machined steps, each of the steps defining one of the plurality of different thicknesses.

[0025] In any embodiment, at least one of the at least one inserts comprises PTFE.

[0026] In any embodiment, the scanning system is an ultrasonic scanning system.

[0027] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.DESCRIPTION OF THE DRAWINGS

[0028] The foregoing aspects and many of the attendant advantages of this disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0029] FIGURE 1 shows a schematic view of a known ultrasonic transmission inspection system;

[0030] FIGURES 2A and 2B show C-scan visualizations generated by the inspection of composite parts using the apparatus of FIGURE 1 ;

[0031] FIGURE 3 shows a cross-sectional view of a known turbo-fan engine with a woven composite fan case;

[0032] FIGURE 4A shows a plan view of a representative embodiment of a calibration panel according to aspects of the present disclosure;

[0033] FIGURE 4B shows a cross-sectional view of the calibration panel shown in FIGURE 4A;

[0034] FIGURE 5 A shows a plan view of the calibration panel of FIGURE 4A with inserts;

[0035] FIGURE 5B shows a cross-sectional view of the calibration panel shown in FIGURE 5A;

[0036] FIGURE 6 shows a C-scan visualization of the calibration panel of FIGURE 5A;

[0037] FIGURE 7 is a chart of data from the C-scan visualization of FIGURE 6; and

[0038] FIGURE 8 shows a method for calibrating the ultrasonic transmission inspection system of FIGURE 1.DETAILED DESCRIPTION

[0039] FIGURES 4A-5B show a representative embodiment of a calibration panel 100 suitable for use with the inspection system 20 shown in FIGURE 1. As will be described in further detail, the calibration panel 100 enables calibration of the inspection system 20 to ensure that the effects of a woven composite structure are accounted for during ultrasonic transmission inspection.

[0040] Referring to FIGURES 4A and 4B, the illustrated calibration panel 100 is a rectangular panel formed of a woven composite material. In any embodiment, the woven composite material has weaving configuration in which the warp is 4*24K and the weft is 4*24K. In any embodiment, the w eave configuration is the same as that of the part to be inspected. In any embodiment, the weave configuration is different than the part to be inspected. In any embodiment, the calibration panel 100 has a single weave configuration. In any embodiment, one or more portions of the panel have different weave configurations.

[0041] The panel is manufactured with a nominal thickness, and then a number of steps 102, each having a particular thickness t, are machined into the panel. In the illustrated embodiment, five parallel steps 102a through 102e are machined into the panel, wherein the steps have thicknesses ta through te, respectively, ranging from 9.06mm to 21. 14mm. It will be appreciated that the number and configuration of the steps is exemplary only and should not be considered limiting. In this regard, contemplated embodiments of calibration panels may have any suitable shape, numbers of step, step configurations, step thicknesses, etc. or combinations thereof, and such embodiments should be considered within the scope of the present disclosure.

[0042] Referring now to FIGURES 5 A and 5B, the calibration panel 100 is formed with one or more inserts 104, 106 positioned therein. In the illustrated embodiment, the inserts comprise a Polytetrafluoroethylene (PTFE) material, such as TEFLON. Each step 102 of the calibration panel includes a corresponding pair of inserts 104 and 106 positioned within the panel at a known depth. Inserts 104 have a square / rectangular shape, while inserts 106 have a circular shape. It will be appreciated that the number, shape, size, position, and material of one or more of the inserts can vary, and such variations should be considered within the scope of the present disclosure.

[0043] FIGURES 6 and 7 show a C-scan 200 and corresponding data obtained for the calibration panel 100 using the system 20 of FIGURE 1. For each step 102. indications 204 and 206 of the corresponding inserts 104 and 106 are visually represented. For example, in step 102c, visual indications 204c and 206c, representing inserts 104c and 106c, respectively are visible. As shown in FIGURE 7, the position, size, and attenuation of each indication 204 and 206 are determined by the scan.

[0044] Because the calibration panel 100 characteristics, as well as the size and position of each insert 104 and 106, are known, the resulting C-scan 200 generated by a properly calibrated system 20 is also known, and this C-scan can serve as a baseline for checking the calibration. That is. by ensuring that a given C-span 200 is sufficiently similar to the baseline C-scan, the system 20 can be monitored for proper calibration. Because the calibration panel 100 is made from a woven composite material, any dispersion or absorption of the ultrasonic waves by the structure of a part to be tested is accounted for in the baseline C-scan.

[0045] Scheduled calibration of the system 20 ensures that signal amplification and analysis thresholds for a given inspected part conform to the NDT standards, ensuring the detection of any anomalies present and characterizing them as accurately as possible.

[0046] Referring now to FIGURE 8, a method 300 of calibrating the system 20 using the disclosed calibration panel 100 will be described. The method 300 begins at block 302 and proceeds to block 304. In block 304, a calibration panel 100 is provided. The method 300 proceeds to block 306, wherein the calibration panel 100 is scanned by the system 20. The method 300 then proceeds to block 308.

[0047] In block 308, the scan results from block 306 are compared to a known baseline for the calibration panel 100. If the scan results are not within acceptable limits, the method 300 proceeds to block 310, and the calibration of the system 20 is adjusted. The process 300 then returns to block 306, and the recalibrated system 20 again scans the calibration panel 100. This recalibration loop continues until the scan results in block 308 are determined to be within acceptable limits. When the scan results are within acceptable limits in block 308, the process 300 moves to block 312.

[0048] In block 312, an inspected part is scanned by the system 20. In any embodiment, block 312 may include inspecting a single part or a predetermined number of parts. In any embodiment, block 312 may include inspecting any number of parts during a predetermined amount of time. The method 300 then proceeds to block 314.

[0049] In block 314, the method begins checking to ensure that the system 20 is still properly calibrated by scanning the calibration panel 100. The method then proceeds to block 316.

[0050] In block 316. the scan results from block 314 are compared to the known baseline for the calibration panel 100. If the scan results are not within acceptable limits, the system has gone out of compliance during the scanning of inspected parts, and the method 300 returns to block 306. If the scan results are within acceptable limits in block 316, the process 300 moves to block 318 and ends.

[0051] While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

[0052] Certain embodiments disclosed herein utilize circuitry (e.g., one or more circuits) in order to implement standards, protocols, methodologies or technologies disclosed herein, operably couple two or more components, generate information, processinformation, analyze information, filter signals, generate signals, encode / decode signals, convert signals, transmit and / or receive signals, control other devices, etc. Circuitry of any type can be used. It will be appreciated that the term ‘’information” can be use synonymously with the term “signals” in this paragraph.

[0053] In an embodiment, circuitry includes, among other things, one or more computing devices such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system on a chip (SoC), or the like, or any combinations thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In an embodiment, circuitry includes hardware circuit implementations (e.g., implementations in analog circuitry, implementations in digital circuitry, and the like, and combinations thereof).

[0054] In an embodiment, circuitry includes combinations of circuits and computer program products having software or firmware instructions stored on one or more computer readable memories that work together to cause a device to perform one or more protocols, methodologies or technologies described herein. In an embodiment, circuitry includes circuits, such as, for example, microprocessors or portions of microprocessor that require software, firmware, and the like for operation. In an embodiment, circuitry includes one or more processors or portions thereof and accompanying software, firmware, hardware, and the like.

[0055] For example, the functionality' described herein can be implemented by special purpose hardware-based computer systems or circuits, etc., or combinations of special purpose hardware and computer instructions. Each of these special purpose hardware-based computer systems or circuits, etc., or combinations of special purpose hardware circuits and computer instructions form specifically configured circuits, machines, apparatus, devices, etc., capable of implementing the functionality' described herein.

[0056] In an embodiment, one or more of the components of the system 20 referenced above include circuity programmed to carry' out one or more steps of any of the methods disclosed herein. In an embodiment, one or more computer-readable media associated with or accessible by such circuitry contains computer readable instructions embodied thereon that, when executed by such circuitry, cause the component or circuity to perform one or more steps of any of the methods disclosed herein.

[0057] In an embodiment, the computer readable instructions includes applications, programs, program modules, scripts, source code, program code, object code, byte code, compiled code, interpreted code, machine code, executable instructions, and / or the like (also referred to herein as executable instructions, instructions for execution, program code, computer program instructions, and / or similar terms used herein interchangeably).

[0058] In an embodiment, computer-readable media is any medium that stores computer readable instructions, or other information non-transitorily and is directly or indirectly accessible to a computing device, such as processor circuitry, etc., or other circuity disclosed herein etc. In other words, a computer-readable medium is a non- transitory memory at which one or more computing devices can access instructions, codes, data, or other information. As a non-limiting example, a computer-readable medium may include a volatile random access memory (RAM), a persistent data store such as a hard disk drive or a solid-state drive, or a combination thereof. In an embodiment, memory can be integrated with a processor, separate from a processor, or external to a computing system.

[0059] Accordingly, blocks of the block diagrams and / or flowchart illustrations support various combinations for performing the specified funchons, combinations of operations for performing the specified functions and program instructions for performing the specified functions. These computer program instructions may be loaded onto one or more computer or computing devices, such as special purpose computer(s) or computing device(s) or other programmable data processing apparatus(es) to produce a specifically- configured machine, such that the instructions which execute on one or more computer or computing devices or other programmable data processing apparatus implement the functions specified in the flowchart block or blocks and / or cany' out the methods described herein. Again, it should also be understood that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, or portions thereof, could be implemented by special purpose hardware-based computer systems or circuits, etc., that perform the specified functions or operations, or combinations of special purpose hardware and computer instructions.

[0060] In the foregoing description, specific details are set forth to provide a thorough understanding of representative embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-knownprocess steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein.

[0061] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also, in this regard, the present application may use the term ‘'plurality’’ to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The term “about,” “approximately,” etc., means plus or minus 5% of the stated value.

[0062] It should be noted that for purposes of this disclosure, terminology such as “upper,” “lower,” “vertical,” “horizontal,” “fore,” “aft,” “inner,” “outer,” “front,” “rear,” etc., should be construed as descriptive and not limiting the scope of the claimed subject matter. Further, the use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings.

[0063] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0064] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure, which are intended to be protected, are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure as claimed.

Claims

CLAIMSThe embodiments of the invention in which an exclusive property- or privilege is claimed are defined as follows:

1. A method for calibrating a scanning system configured to detect defects in a woven composite part, the method comprising the steps of: providing a calibration panel comprising a woven composite panel and at least one insert disposed within a thickness of the woven composite panel; scanning the calibration panel; comparing results of the scanning of the calibration panel with baseline data for the calibration panel; and adjusting scan parameters if differences between results of the scanning of the calibration panel and baseline data for the calibration panel are greater than acceptable limits.

2. The method of Claim 1, further comprising the steps of: re-scanning the calibration panel; comparing results of the re-scanning of the calibration panel with baseline data for the calibration panel; and adjusting scan parameters if differences between results of the scanning of the calibration panel and baseline data for the calibration panel are greater than acceptable limits scanning at least one inspected part.

3. The method of Claim 2, further comprising the steps of: scanning at least one inspected part; and determining existence of defects according to anomalies present in scan results.

4. The method of Claim 1, further comprising the steps of: scanning at least one inspected part; and determining existence of defects according to anomalies present in scan results.

5. The method of Claim 4, further comprising the steps of: re-scanning the calibration panel; comparing results of the re-scanning of the calibration panel with baseline data for the calibration panel; andconfirming that the scanning system is still calibrated according to differences between results of the re-scanning of the calibration panel and baseline data for the calibration panel.

6. The method of Claim 1, wherein the calibration panel comprises woven carbon fiber.

7. The method of Claim 6. wherein the woven carbon fiber has a warp of 4*24k.

8. The method of Claim 7, wherein the woven carbon fiber has a weft of 4*24k.

9. The method of Claim 6, wherein the calibration panel compnses a plurality of different thickness, each thickness having at least one insert disposed therein.

10. The method of Claim 9. wherein each thickness has a first insert having a first shape and a second insert having a second shape.

11. The method of Claim 10, wherein the first insert and the second insert are a predetermined distance from a face of the calibration panel.

12. The method of Claim 10, wherein the first shape is a rectangle, and the second shape is a circle.

13. The method of Claim 9, wherein the calibration panel comprises a plurality of machined steps, each of the steps defining one of the plurality of different thicknesses.

14. The method of Claim 1, wherein at least one of the at least one inserts comprises PTFE.

15. The method of Claim 1, wherein the scanning system is an ultrasonic scanning system.

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