(19)
(11)EP 2 618 142 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
26.08.2020 Bulletin 2020/35

(21)Application number: 13150766.7

(22)Date of filing:  10.01.2013
(51)Int. Cl.: 
G01N 29/04  (2006.01)
G06T 7/00  (2017.01)
G01N 29/44  (2006.01)
G01N 29/06  (2006.01)

(54)

Ultrasonic modeling for inspection of composite irregularities

Ultraschallmodellierung zur Überprüfung von Verbundwerkstoff-Unregelmäßigkeiten

Modélisation ultrasonore pour l'inspection des irrégularités des composites


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 20.01.2012 US 201213355100

(43)Date of publication of application:
24.07.2013 Bulletin 2013/30

(73)Proprietor: The Boeing Company
Chicago, IL 60606-1596 (US)

(72)Inventors:
  • Lin, John Z
    Tukwila, WA Washington 98108 (US)
  • Tat, Hong
    Seattle, WA Washington 98124 (US)
  • Bossi, Richard H
    Seattle, WA Washington 98124 (US)

(74)Representative: Shipp, Nicholas et al
Kilburn & Strode LLP Lacon London 84 Theobalds Road
London WC1X 8NL
London WC1X 8NL (GB)


(56)References cited: : 
US-A- 6 092 419
US-A1- 2005 102 109
US-A1- 2004 193 938
US-A1- 2007 095 141
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND



    [0001] The present disclosure relates generally to nondestructive evaluation of materials and, more particularly, to methods for use in inspecting a composite structure for irregularities.

    [0002] Known aircraft systems are increasingly being fabricated from composite materials. At least some structures fabricated from composite materials may include irregularities, such as wrinkles, formed during fabrication that may affect and/or alter a mechanical property of the composite material. As such, at least some structures fabricated from composite materials undergo nondestructive evaluation and/or inspection prior to installation and/or use.

    [0003] One known method of inspecting such structures includes pulse-echo ultrasound and/or X-ray radiography. At least some such methods, however, only detect a shadow of the irregularity and, thus, a severity and/or a depth of the irregularity may not be fully characterized. Moreover, at least some such methods may be tedious and/or time consuming.

    [0004] US 2005/102109 A1 describes a system and method for detecting defects in a manufactured object. These defects include flaws, delaminations, voids, fractures, fissures, or cracks, among others. The system utilizes an ultrasound measurement system, a signal analyzer and an expected result. The signal analyzer compares the signal from the measurement system to the expected result. The analysis detects a defect or measures an attribute of the manufactured object. Further, the analysis is displayed or represented. In addition, the expected result is generated from a model such as a wave propagation model. The signal analyzer compares the measured ultrasonic signal to an expected result; this expected result is generated from a wave propagation model. The analysis is then displayed on a monitor.

    [0005] US 2007/095141 A1 describes a porosity reference standard for ultrasonic inspection of composite materials which includes a right prism manufactured from a solid isotropic material and a porosity created within the right prism. The porosity reference standard is a glass block that encloses a plurality of simulated voids created through laser etching. The porosity reference standard is manufactured by using a sub surface laser engraving process. By creating a porosity within the glass block, the level of the porosity can be exactly determined and is spatially constant over a desired area within the glass block. The laser-etched porosity reference standard is used for ultrasonic porosity inspection of composite laminate parts, such as wings, empennage and fuselage skins, sub-skin structures, frames stringer, and shear ties, used in the aircraft airframe industry, both commercial and defense.

    BRIEF SUMMARY



    [0006] In one aspect, a computer-implemented method according to claim 1 is provided for use in inspecting a composite structure.

    [0007] In another aspect, a computer-readable storage device is provided having encoded thereon computer readable instructions that are executable by a processor to perform functions according to claim 4.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0008] 

    FIG. 1 is a plan view of an exemplary aircraft;

    FIG. 2 is a cross-sectional view of an exemplary composite structure that may be used with the aircraft shown in FIG. 1;

    FIG. 3 is a detailed cross-sectional view of the composite structure shown in FIG. 2;

    FIG. 4 is a model of the composite structure shown in FIGS. 2 and 3;

    FIG. 5 is a schematic illustration of an exemplary computer system that may be used to inspect the composite structure shown in FIG. 2;

    FIG. 6 is a screenshot of an exemplary virtual image of the model shown in FIG. 4;

    FIG. 7 is a screenshot of an exemplary user interface that may be used to facilitate inspecting the composite structure shown in FIG. 2; and

    FIG. 8 is a flowchart of an exemplary method that may be implemented to inspect the composite structure shown in FIG. 2 using the computer system shown in FIG. 5.



    [0009] Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.

    DETAILED DESCRIPTION



    [0010] The subject matter described herein relates generally to nondestructive evaluation of materials and, more particularly, to methods for use in inspecting a composite structure for irregularities. In one embodiment, a first simulated inspection is conducted to produce a first waveform data set associated with the at least one irregularity parameter. The first simulated inspection is conducted using a first evaluation setting, and a first image is produced based on the first waveform set. If the quality of the first image satisfies a predetermined threshold, the first evaluation setting is identified as a desired evaluation setting. As such, the first evaluation setting may be used to physically inspect the composite structure for irregularities, such as wrinkles.

    [0011] An exemplary technical effect of the methods described herein includes at least one of: (a) defining at least one irregularity parameter; (b) defining at least one composite structure parameter; (c) defining at least one stimulation parameter; (d) generating at least one model based on the at least one irregularity parameter; (e) conducting a first simulated inspection to provide a first waveform data set associated with at least one irregularity parameter; (f) determining whether a quality of the first image satisfies a predetermined threshold; and (g) identifying the first evaluation setting as a desired evaluation setting for use in inspecting the composite structure.

    [0012] An element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural elements or steps unless such exclusion is explicitly recited. Moreover, references to "one embodiment" of the present invention and/or the "exemplary embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

    [0013] FIG. 1 is a plan view of an exemplary aircraft 100. In the exemplary embodiment, aircraft 100 includes a body 110 that includes a fuselage 120 and a pair of wings 130 extending from fuselage 120. In the exemplary embodiment, at least one engine 140 is coupled to each wing 130 to provide thrust to aircraft 100. Aircraft 100 may include any number of engines 140 that enables aircraft 100 to function as described herein. In the exemplary embodiment, aircraft 100 includes at least one component and/or structure that is fabricated from a composite material.

    [0014] FIGS. 2 and 3 are cross-sectional views of a portion or coupon of an exemplary composite structure 200 that may be used with aircraft 100. In the exemplary embodiment, composite structure 200 includes a plurality of plies 210, a top surface 220, and a bottom surface 230. In the exemplary embodiment, each ply 210 includes a fiber-rich layer 240 and a resin layer 242 (not shown in FIG. 2). In the exemplary embodiment, resin layer 242 is generally disposed between adjacent fiber-rich layers 240.

    [0015] In the exemplary embodiment, fiber-rich layers 240 include at least one first layer 244 and at least one second layer 246. In the exemplary embodiment, first layer 244 has fibers arranged in a first orientation, and second layer 246 has fibers arranged in a second orientation. Alternatively, fibers of each fiber rich layer 240 may be arranged in any orientation that enables the methods and systems to function as described herein.

    [0016] In the exemplary embodiment, composite structure 200 has at least one composite structure parameter including an outer ply thickness (i.e., a thickness of an entire ply 210, including resin layer 242), an inner ply thickness (i.e., a thickness of fiber-rich layer 240), a number of plies, a ply layup, a composite structure thickness, a material used to fabricate at least a portion of the at least one composite structure, a resin thickness, and/or a resin density. For example, in the exemplary embodiment, each ply 210 has a thickness 250, and composite structure 200 has a total thickness 260 extending between top surface 220 and bottom surface 230.

    [0017] A portion of structure 200 includes an irregularity 270 positioned between surfaces 220 and 230. That is, in the exemplary embodiment, plies 210 are not substantially uniform along a coupon length 280 of composite structure 200. In general, an ith ply distortion in an n-ply composite structure 200 may be described by a generic function of its bounding surfaces:

    wherein yi is a non-distorted position of a ply surface, S(x) is an arbitrary shape function of the ply distortion, and h(yi) modulates the through-the-thickness severity of the distortion (h(yi) = 0 in non-distorted region). The x and y-coordinates represent the horizontal and vertical positions of a point in composite structure 200, respectively. More specifically, in the exemplary embodiment, irregularity 270 has at least one irregularity parameter including at least one of an irregularity thickness 290, an irregularity width 300, an irregularity length, an irregularity location, and an irregularity shape.

    [0018] In the exemplary embodiment, irregularity 270 is positioned entirely within composite structure 200, such that a degree of irregularity 270 (e.g., irregularity thickness 290) is generally reduced near top surface 220 and/or a bottom surface 230 of composite structure 200. A two-dimensional cross-sectional area of a wrinkled ith ply may be calculated by:

    wherein "+" is for the lower half of composite structure 200, and "-" is for the upper half of composite structure 200. Moreover, additional irregularity parameters may be expressed using:



    wherein H is the maximum irregularity thickness 290. Furthermore, density, elastic properties, and/or other material properties of composite structure 200 may also be adjusted according to a rule of mixtures where the changes in area are due to resin distribution. Alternatively, irregularity 270 may have any irregularity parameters that enable the methods and systems to function as described herein.

    [0019] FIG. 4 is an exemplary model 400 of composite structure 200 (shown in FIGS. 2 and 3). That is, in the exemplary embodiment, model 400 is a virtual representation of each ply 210 (shown in FIGS. 2 and 3). More specifically, in the exemplary embodiment, model 400 includes a plurality of plies 410 that are associated with plies 210. In the exemplary embodiment, each ply 410 includes a fiber-rich layer 420 and a resin layer 422, as shown in insert 424.

    [0020] In the exemplary embodiment, model 400 includes a top surface 430, a bottom surface 440, and an irregularity 450 positioned therebetween. In the exemplary embodiment, each ply 410 has a thickness 460, and model 400 has a total thickness 470 extending between top surface 430 and bottom surface 440. In the exemplary embodiment, irregularity 450 has at least one irregularity parameter including at least one of an irregularity thickness 480, an irregularity width 490, an irregularity length, an irregularity location, and an irregularity shape.

    [0021] FIG. 5 is a schematic illustration of an exemplary computer system 500 that may be used to inspect composite structure 200 and/or irregularity 270. In the exemplary embodiment, computer system 500 includes a memory device 510 and a processor 520 coupled to memory device 510 for use in executing instructions. More specifically, in the exemplary embodiment, computer system 500 is configurable to perform one or more operations described herein by programming memory device 510 and/or processor 520. For example, processor 520 may be programmed by encoding an operation as one or more executable instructions and by providing the executable instructions in memory device 510.

    [0022] Processor 520 may include one or more processing units (e.g., in a multi-core configuration). As used herein, the term "processor" is not limited to integrated circuits referred to in the art as a computer, but rather broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits.

    [0023] In the exemplary embodiment, memory device 510 includes one or more devices (not shown) that enable information such as executable instructions and/or other data to be selectively stored and retrieved. In the exemplary embodiment, such data may include, but is not limited to, properties of composite materials, properties of ultrasonic waves, modeling data, imaging data, calibration curves, operational data, and/or control algorithms. In the exemplary embodiment, computer system 500 is configured to automatically implement a parametric finite element analysis to determine a desired evaluation setting for use in inspecting composite structure 200 and/or irregularity 270. Alternatively, computer system 500 may use any algorithm and/or method that enable the methods to function as described herein. Memory device 510 may also include one or more computer readable media, such as, without limitation, dynamic random access memory (DRAM), static random access memory (SRAM), a solid state disk, and/or a hard disk.

    [0024] In the exemplary embodiment, computer system 500 includes a presentation interface 530 that is coupled to processor 520 for use in presenting information to a user. For example, presentation interface 530 may include a display adapter (not shown) that may couple to a display device (not shown), such as, without limitation, a cathode ray tube (CRT), a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, an "electronic ink" display, and/or a printer. In some embodiments, presentation interface 530 includes one or more display devices.

    [0025] Computer system 500, in the exemplary embodiment, includes an input interface 540 for receiving input from the user. For example, in the exemplary embodiment, input interface 540 receives information suitable for use with the methods described herein. Input interface 540 is coupled to processor 520 and may include, for example, a joystick, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), and/or a position detector. It should be noted that a single component, for example, a touch screen, may function as both presentation interface 530 and as input interface 540.

    [0026] In the exemplary embodiment, computer system 500 includes a communication interface 550 that is coupled to processor 520. In the exemplary embodiment, communication interface 550 communicates with at least one remote device. For example, communication interface 550 may use, without limitation, a wired network adapter, a wireless network adapter, and/or a mobile telecommunications adapter. A network (not shown) used to couple computer system 500 to the remote device may include, without limitation, the Internet, a local area network (LAN), a wide area network (WAN), a wireless LAN (WLAN), a mesh network, and/or a virtual private network (VPN) or other suitable communication means.

    [0027] In the exemplary embodiment, computer system 500 includes at least a modeling module 560, an imaging module 570, and an evaluating module 580 that enable the methods to function as described herein. In the exemplary embodiment, modeling module 560 conducts a simulated inspection using a predefined evaluation setting to provide a waveform data set associated with at least one irregularity parameter. In the exemplary embodiment, modeling module 560 generates at least one model, as shown in FIG. 4, based on the at least one irregularity parameter. In the exemplary embodiment, at least one simulated ultrasound wave is transmitted towards the at least one model at a plurality of scanning positions, and at least one reflected and/or transmitted ultrasound wave is "detected" (i.e., projected and/or calculated by computer system 500) to facilitate providing the waveform data set. In the exemplary embodiment, the ultrasound waves may be transmitted towards and/or detected from any direction that enables the methods to function as described herein.

    [0028] In the exemplary embodiment, imaging module 570 produces an image based on the waveform set, and determines whether a quality of the image satisfies a predetermined threshold. FIG. 6 is a screenshot of a virtual image 572 of composite structure 200 produced by imaging module 570. If the quality of the image satisfies the predetermined threshold, in the exemplary embodiment, evaluating module 580 identifies the predefined evaluation setting as a desired evaluation setting for use in inspecting composite structure 200. If the quality of the image does not satisfy the predetermined threshold, in the exemplary embodiment, evaluating module 580 iteratively repeats the process using a finite element analysis until at least one desired evaluation setting is identified.

    [0029] FIG. 7 is a screenshot of an exemplary user interface 600 that may be presented to a user on presentation interface 530. More specifically, in the exemplary embodiment, user interface 600 includes a plurality of fields 610 for use in providing data associated with modeling composite structure 200 and/or irregularity 270. For example, in the exemplary embodiment, fields 610 associated with modeling composite structure include at least an outer ply thickness, an inner ply thickness, a number of plies, a total laminate thickness, a ply layup (e.g., orientation of fiber rich layers 240), a material used to fabricate at least a portion of composite structure 200, a type of couplant, a couplant thickness, and/or material damping parameters. Moreover, in the exemplary embodiment, fields 610 associated with modeling irregularity 270 include at least a maximum irregularity thickness and/or a irregularity width. In addition to the aforementioned fields 610, in the exemplary embodiment, at least some fields 610 are associated with spacing for output points and/or a number of element layers per ply to enable each fiber-rich layer 240 and/or resin layer 242 to be precisely modeled. In the exemplary embodiment, the use of material properties may be dynamically obtained (e.g., in-plane velocity measurements) and may be used with an expandable material systems library (not shown).

    [0030] Furthermore, in the exemplary embodiment, user interface 600 includes a plurality of fields 620 for use in providing data associated with an ultrasonic testing (UT) source or stimulating mechanism (not shown) and/or a stimulation of composite structure 200. For example, in the exemplary embodiment, fields 620 associated with the stimulating mechanism include at least a type of stimulation source, a stimulation source beam width, a distance between the at least one stimulating mechanism and the composite structure, a distance between the at least one stimulating mechanism and a sensor, and/or a stimulation source impulse shape and center frequency. In the exemplary embodiment, the stimulating mechanism is at least one of a laser excitation UT source, a surface-mounted piezoelectric excitation UT source, and a water-coupled piezoelectric excitation UT source. Alternatively, the stimulating mechanism may be any UT source that enables the methods to function as described herein. Moreover, in the exemplary embodiment, the UT source may be configured to transmit any wave mode that enables the methods to function as described herein including, without limitation, longitudinal waves, shear waves, Lamb waves, and/or Rayleigh waves.

    [0031] FIG. 8 is a flowchart of an exemplary method 700 that may be implemented by computer system 500 to inspect composite structure 200 and/or irregularity 270. During operation, in the exemplary embodiment, at least one irregularity parameter is defined 710 by computer system 500 and/or a user. In the exemplary embodiment, the irregularity parameters may include an irregularity thickness 290, an irregularity width 300, an irregularity length, an irregularity location, and/or an irregularity shape. In the exemplary embodiment, a model is generated 720 based on the irregularity parameters, and the model is inspected 730 to provide a waveform data set associated with the irregularity parameter and/or the model. More specifically, in the exemplary embodiment, the model is inspected 730 using an evaluation setting associated with an ultrasonic testing (UT) source or stimulating mechanism defined by computer system 500 and/or the user.

    [0032] In the exemplary embodiment, an imaging algorithm is applied to produce 740 a virtual image based on the waveform set, and it is determined 750 whether a quality of the virtual image satisfies a predetermined threshold. If the quality of the virtual image satisfies the predetermined threshold, in the exemplary embodiment, the evaluation setting is identified 760 as a desired evaluation setting for use in inspecting composite structure 200. If the quality of the virtual image does not satisfy the predetermined threshold, in the exemplary embodiment, another evaluation setting associated with the stimulating mechanism is defined 770 by computer system 500 and/or the user, and another model is generated 720 based on the irregularity parameters using the re-defined evaluation setting. For example, in the exemplary embodiment, the evaluation setting is re-defined using a finite element analysis. Alternatively, the evaluation setting may be re-defined using any method and/or process that enable the methods to function as described herein. In the exemplary embodiment, method 700 is iteratively repeated until at least one desired evaluation setting is identified 760.

    [0033] Below are aspects, variants, instances, and examples of illustrations disclosed in the text and the figures above. In one aspect, a method is disclosed for use in inspecting a composite structure 200, the method includes defining at least one irregularity 270, 450 parameter, conducting a first simulated inspection to provide a first waveform data set associated with the at least one irregularity 270, 450 parameter, wherein the first simulated inspection is conducted using a first evaluation setting, producing a first image 572 based on the first waveform set, and determining whether a quality of the first image 572 satisfies a predetermined threshold. In one variant, a method is disclosed further including identifying the first evaluation setting as a desired evaluation setting for use in inspecting the composite structure 200. In another variant, a method is disclosed further including conducting a second simulated inspection to provide a second waveform data set associated with the at least one irregularity 270, 450 parameter, wherein the second simulated inspection is conducted using a second evaluation setting that is different from the first evaluation setting, wherein the quality of the first image 572 does not satisfy the predetermined threshold, producing a second image 572 based on the second waveform set, determining that a quality of the second image 572 satisfies a predetermined threshold, and identifying the second evaluation setting as a desired evaluation setting for use in inspecting the composite structure 200.

    [0034] In one variant, the method further includes generating at least one model 400 based on the at least one irregularity 270, 450 parameter, wherein the model 400 is a graphical representation of the at least one irregularity 270, 450 parameter. In yet another variant, the method includes wherein defining at least one irregularity 270, 450 parameter further comprises defining at least one irregularity 270, 450 parameter including at least one of an irregularity thickness 290, 480, an irregularity width 300, 490, an irregularity length, an irregularity location, and an irregularity shape.

    [0035] In yet another variant, the method further includes defining at least one composite structure parameter including at least one of an outer ply thickness 210, an inner ply thickness 240, a number of plies, a ply layup, a composite structure 200 thickness, a material used to fabricate at least a portion of the at least one composite structure 200, a number of element layers per ply, a resin thickness 242, 422, and a resin density. In still another variant, the method further includes defining at least one stimulation parameter including at least one of a type of stimulating mechanism, a beam width, a wave mode, a relative orientation of at least one stimulating mechanism with respect to the composite structure 200, a distance between the at least one stimulating mechanism and the composite structure 200, a distance between the at least one stimulating mechanism and a sensor, an impulse shape and center frequency, a couplant, and a couplant thickness.

    [0036] In another aspect, a computer-readable storage device is disclosed having encoded thereon computer readable instructions that are executable by a processor 520 to perform functions including: conducting a first simulated inspection to provide a first waveform data set associated with at least one irregularity 270, 540 parameter, wherein the first simulated inspection is conducted using a first evaluation setting, producing a first image 572 based on the first waveform set, and determining whether a quality of the first image 572 satisfies a predetermined threshold. In one variant, a computer-readable storage device is disclosed wherein the functions performed by the processor 520 further comprise identifying the first evaluation setting as a desired evaluation setting for use in inspecting the composite structure 200. In yet another variant, a computer-readable storage device is disclosed wherein the functions performed by the processor 520 further include: conducting a second simulated inspection to provide a second waveform data set associated with the at least one irregularity 270, 450 parameter, wherein the second simulated inspection is conducted using a second evaluation setting that is different from the first evaluation setting, wherein the quality of the first image 572 does not satisfy the predetermined threshold, producing a second image 572 based on the second waveform set, determining that a quality of the second image 572 satisfies a predetermined threshold; and identifying the second evaluation setting as a desired evaluation setting for use in inspecting the composite structure 200.

    [0037] In one instance, a computer-readable storage device includes wherein the functions performed by the processor 520 further include generating at least one model 400 based on the at least one irregularity 270, 450 parameter, wherein the model 400 is a graphical representation of the at least one irregularity 270, 450 parameter. In another instance, a computer-readable storage device includes wherein the functions performed by the processor 520 further comprise defining at least one irregularity 270, 450 parameter including at least one of an irregularity thickness 290, 480, an irregularity width 300, 490, an irregularity length, an irregularity location, and an irregularity shape. In another instance, a computer-readable storage device includes wherein the functions performed by the processor 520 further include defining at least one composite structure parameter including at least one of an outer ply thickness 210, an inner ply thickness 240, a number of plies 210, 410, a ply layup, a composite structure 200 thickness, a material used to fabricate at least a portion of the at least one composite structure 200, a number of element layers per ply 210, a resin thickness 242, 422, and a resin density.

    [0038] In one example, a computer-readable storage device includes wherein the functions performed by the processor 520 further includes defining at least one stimulation parameter including at least one of a type of stimulating mechanism, a beam width, a wave mode, a relative orientation of at least one stimulating mechanism with respect to the composite structure 200, a distance between the at least one stimulating mechanism and the composite structure 200, a distance between the at least one stimulating mechanism and a sensor, an impulse shape and center frequency, a couplant, and a couplant thickness.

    [0039] In a further example, not presently claimed, a system is disclosed including: a modeling module 560 configured to conduct a first simulated inspection to provide a first waveform data set associated with at least one irregularity 270, 450 parameter, wherein the first simulated inspection is conducted using a first evaluation setting; and an imaging module 570 configured to produce a first image 572 based on the first waveform set, and determine whether a quality of the first image 572 satisfies a predetermined threshold. In one variant, the system further includes an evaluating module 580 configured to identify the first evaluation setting as a desired evaluation setting for use in inspecting the composite structure 200. In another variant, the system includes wherein the modeling module 560 is further configured to conduct a second simulated inspection to provide a second waveform data set associated with the at least one irregularity 270, 450 parameter, the imaging module 570 is further configured to produce a second image 572 based on the second waveform set, and determine that a quality of the second image 572 satisfies a predetermined threshold, and the system further comprises an evaluating module 580 configured to identify a second evaluation setting as a desired evaluation setting for use in inspecting the composite structure 200, wherein the second simulated inspection is conducted using the second evaluation setting that is different from the first evaluation setting, wherein the quality of the first image 572 does not satisfy the predetermined threshold.

    [0040] In one instance, the system includes wherein the modeling module 560 is further configured to generate at least one model 400 based on the at least one irregularity 270, 450 parameter, wherein the model 400 is a graphical representation of the at least one irregularity 270, 450 parameter. In another instance, the system includes wherein the modeling module 560 is further configured to define at least one irregularity 270, 450 parameter including at least one of an irregularity thickness 290, 480, an irregularity width 300, 490, an irregularity length, an irregularity location, and an irregularity shape, and define at least one composite structure parameter including at least one of an outer ply thickness 210, an inner ply thickness 240, a number of plies, a ply layup, a composite structure 200 thickness, a material used to fabricate at least a portion of the at least one composite structure 200, a number of element layers per ply, a resin thickness 242, 422, and a resin density. In still another instance, the system includes wherein the modeling module 560 is further configured to define at least one stimulation parameter including at least one of a type of stimulating mechanism, a beam width, a wave mode, a relative orientation of at least one stimulating mechanism with respect to the composite structure 200, a distance between the at least one stimulating mechanism and the composite structure 200, a distance between the at least one stimulating mechanism and a sensor, an impulse shape and center frequency, a couplant, and a couplant thickness.

    [0041] The embodiments described herein relate generally to nondestructive evaluation of materials and, more particularly, to methods for use in inspecting a composite structure for irregularities. The embodiments described herein facilitate analytically and systematically obtaining ultrasonic responses associated with composite laminate layup structures. That is, the embodiments described herein use a finite element-based method to model composite structures at a detailed level to geometrically and/or physically characterize irregularities within the composite structure. As such, the embodiments described herein enable effectively and accurately understanding ultrasonic wave propagation within composite structures.

    [0042] Exemplary embodiments of methods for inspecting composite structures for irregularities are described above in detail. The methods are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the method may be utilized independently and separately from other components and/or steps described herein. Each method step and each component may also be used in combination with other method steps and/or components. Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.


    Claims

    1. A computer-implemented method for use in inspecting a composite structure (200), said method comprising:

    defining at least one irregularity (270, 450) parameter, wherein defining the at least one irregularity (270, 450) parameter further comprises defining the at least one irregularity (270, 450) parameter including at least one of an irregularity thickness (290, 480), an irregularity width (300, 490), an irregularity length, an irregularity location, and an irregularity shape;

    defining at least one composite structure parameter;

    generating at least one model (400) based on the at least one irregularity (270, 450) parameter, wherein the model (400) is a graphical representation of the at least one irregularity (270, 450) parameter;

    conducting a first simulated inspection to provide a first waveform data set associated with the at least one irregularity (270, 450) parameter, wherein the first simulated inspection is conducted using a first evaluation setting for use in inspecting the composite structure (200), wherein the first evaluation setting is associated with a stimulating mechanism for stimulation of the composite structure;

    producing a first image (572) based on the first waveform data set;

    determining whether a quality of the first image (572) satisfies a predetermined threshold; and

    wherein, if the quality of the first image satisfies the predetermined threshold, the method further comprises:

    identifying the first evaluation setting as a desired evaluation setting for use in inspecting the composite structure (200); or

    if the quality of the first image does not satisfy the predetermined threshold, the method further comprises:

    conducting a second simulated inspection to provide a second waveform data set associated with the at least one irregularity (270, 450) parameter, wherein the second simulated inspection is conducted using a second evaluation setting that is different from the first evaluation setting, wherein the quality of the first image (572) does not satisfy the predetermined threshold;

    producing a second image (572) based on the second waveform data set;

    determining that a quality of the second image (572) satisfies a predetermined threshold; and

    identifying the second evaluation setting as a desired evaluation setting for use in inspecting the composite structure (200).


     
    2. A computer-implemented method in accordance with Claim 1 wherein the at least one composite structure parameter includes at least one of an outer ply thickness (210), an inner ply thickness (240), a number of plies, a ply layup, a composite structure (200) thickness, a material used to fabricate at least a portion of the at least one composite structure (200), a number of element layers per ply, a resin thickness (242, 422), and a resin density.
     
    3. A computer-implemented method in accordance with any of Claims 1-2 further comprising defining at least one stimulation parameter associated with the stimulation mechanism for stimulation of the composite structure (200), wherein the at least one stimulation parameter includes at least one of a type of stimulating mechanism, a beam width, a wave mode, a relative orientation of at least one stimulating mechanism with respect to the composite structure (200), a distance between the at least one stimulating mechanism and the composite structure (200), a distance between the at least one stimulating mechanism and a sensor, an impulse shape and center frequency, a couplant, and a couplant thickness.
     
    4. A computer-readable storage device having encoded thereon computer readable instructions that are executable by a processor (520) to perform functions comprising:

    defining at least one irregularity (270, 450) parameter, wherein defining at least one irregularity (270, 450) parameter includes defining at least one of an irregularity thickness (290, 480), an irregularity width (300, 490), an irregularity length, an irregularity location, and an irregularity shape;

    defining at least one composite structure parameter;

    generating at least one model (400) based on the at least one irregularity (270, 450) parameter, wherein the model (400) is a graphical representation of the at least one irregularity (270, 450) parameter;

    conducting a first simulated inspection of a composite structure (200) to provide a first waveform data set associated with at least one irregularity (270, 540) parameter, wherein the first simulated inspection is conducted using a first evaluation setting for use in inspecting the composite structure (200), wherein the first evaluation setting is associated with a stimulating mechanism for stimulation of the composite structure;

    producing a first image (572) based on the first waveform data set; and

    determining whether a quality of the first image (572) satisfies a predetermined threshold

    wherein, if the quality of the first image satisfies the predetermined threshold, the functions performed by the processor (520) further comprise identifying the first evaluation setting as a desired evaluation setting for use in inspecting the composite structure (200); and

    wherein, if the quality of the first image does not satisfy the predetermined threshold, the functions performed by the processor (520) further comprise:

    conducting a second simulated inspection to provide a second waveform data set associated with the at least one irregularity (270, 450) parameter, wherein the second simulated inspection is conducted using a second evaluation setting that is different from the first evaluation setting, wherein the quality of the first image (572) does not satisfy the predetermined threshold;

    producing a second image (572) based on the second waveform data set;

    determining that a quality of the second image (572) satisfies a predetermined threshold; and

    identifying the second evaluation setting as a desired evaluation setting for use in inspecting the composite structure (200).


     
    5. A computer-readable storage device in accordance with Claims 4, wherein the at least one composite structure parameter includes at least one of an outer ply thickness (210), an inner ply thickness (240), a number of plies, a ply layup, a composite structure (200) thickness, a material used to fabricate at least a portion of the at least one composite structure (200), a number of element layers per ply, a resin thickness (242, 422), and a resin density.
     
    6. A computer-readable storage device in accordance with any of Claims 4-5, wherein the functions performed by the processor (520) further comprise defining at least one stimulation parameter associated with the stimulation mechanism for stimulation of the composite structure (200), wherein the at least one stimulation parameter includes at least one of a type of stimulating mechanism, a beam width, a wave mode, a relative orientation of at least one stimulating mechanism with respect to the composite structure (200), a distance between the at least one stimulating mechanism and the composite structure (200), a distance between the at least one stimulating mechanism and a sensor, an impulse shape and center frequency, a couplant, and a couplant thickness.
     


    Ansprüche

    1. Computerimplementiertes Verfahren zur Verwendung bei der Überprüfung einer Verbundstruktur (200), wobei das Verfahren aufweist:

    Definieren wenigstens eines Unregelmäßigkeits- (270, 450) - Parameters, wobei das Definieren des wenigstens einen Unregelmäßigkeits-(270, 450) -Parameters des Weiteren das Definieren des wenigstens einen Unregelmäßigkeits- (270, 450) -Parameters aufweist, der wenigstens eines aufweist von einer Unregelmäßigkeitsdicke (290, 480), einer Unregelmäßigkeitsbreite (300, 490), einer Unregelmäßigkeitslänge, einer Unregelmäßigkeitsstelle und einer Unregelmäßigkeitsform;

    Definieren wenigstens eines Verbundstrukturparameters;

    Erzeugen wenigstens eines Modells (400) basierend auf dem wenigstens einen Unregelmäßigkeits- (270, 450) -Parameter, wobei das Modell (400) eine grafische Darstellung des wenigstens einen Unregelmäßigkeits- (270, 450) -Parameters ist;

    Durchführen einer ersten simulierten Überprüfung, um einen ersten Wellenformdatensatz bereitzustellen, der zu dem wenigstens einen Unregelmäßigkeits- (270, 450) -Parameter gehört, wobei die erste simulierte Überprüfung unter Verwendung einer ersten Evaluierungseinstellung zur Verwendung bei der Überprüfung der Verbundstruktur (200) durchgeführt wird, wobei die erste Evaluierungseinstellung zu einem Stimulierungsmechanismus zum Stimulieren der Verbundstruktur gehört;

    Erzeugen eines ersten Bilds (572) basierend auf dem ersten Wellenformdatensatz;

    Ermitteln, ob eine Qualität des ersten Bilds (572) einen vorgegebenen Schwellenwert erfüllt; und

    wobei, wenn die Qualität des ersten Bilds den vorgegebenen Schwellenwert erfüllt, das Verfahren des Weiteren aufweist:

    Identifizieren der ersten Evaluierungseinstellung als gewünschte Evaluierungseinstellung zur Verwendung bei der Überprüfung der Verbundstruktur (200); oder

    wenn die Qualität des ersten Bilds den vorgegebenen Schwellenwert nicht erfüllt, das Verfahren des Weiteren aufweist:

    Durchführen einer zweiten simulierten Überprüfung, um einen zweiten Wellenformdatensatz bereitzustellen, der zu dem wenigstens einen Unregelmäßigkeits- (270, 450) -Parameter gehört, wobei die zweite simulierte Überprüfung unter Verwendung einer zweiten Evaluierungseinstellung durchgeführt wird, die sich von der ersten Evaluierungseinstellung unterscheidet, wobei die Qualität des ersten Bilds (572) den vorgegebenen Schwellenwert nicht erfüllt;

    Erzeugen eines zweiten Bilds (572) basierend auf dem zweiten Wellenformdatensatz;

    Ermitteln, dass eine Qualität des zweiten Bilds (572) einen vorgegebenen Schwellenwert erfüllt; und

    Identifizieren der zweiten Evaluierungseinstellung als gewünschte Evaluierungseinstellung zur Verwendung bei der Überprüfung der Verbundstruktur (200).


     
    2. Computerimplementiertes Verfahren nach Anspruch 1, wobei der wenigstens eine Verbundstrukturparameter wenigstens eines aufweist von einer äußeren Lagendicke (210), einer inneren Lagendicke (240), einer Anzahl von Lagen, einer Lagenlaminierung, einer Verbundstruktur- (200) -Dicke, einem Material, das zum Herstellen wenigstens eines Abschnitts der wenigstens einen Verbundstruktur (200) verwendet wird, einer Anzahl von Elementschichten pro Lage, einer Harzdicke (242, 422) und einer Harzdichte.
     
    3. Computerimplementiertes Verfahren nach einem der Ansprüche 1-2, das des Weiteren das Definieren wenigstens eines Stimulierungsparameters aufweist, der zu dem Stimulierungsmechanismus zum Stimulieren der Verbundstruktur (200) gehört, wobei der wenigstens eine Stimulierungsparameter wenigstens eines aufweist von einem Typ von Stimulierungsmechanismus, einer Strahlbreite, einem Wellenmodus, einer relativen Orientierung wenigstens eines Stimulierungsmechanismus bezüglich der Verbundstruktur (200), einem Abstand zwischen dem wenigstens einen Stimulierungsmechanismus und der Verbundstruktur (200), einem Abstand zwischen dem wenigstens einen Stimulierungsmechanismus und einem Sensor, einer Impulsform und Mittenfrequenz, einem Kopplungsmittel und einer Kopplungsmitteldicke.
     
    4. Computerlesbare Speichervorrichtung, auf der computerlesbare Befehle codiert sind, die von einem Prozessor (520) ausführbar sind, um Funktionen durchzuführen, die aufweisen:

    Definieren wenigstens eines Unregelmäßigkeits- (270, 450) - Parameters, wobei das Definieren wenigstens eines Unregelmäßigkeits- (270, 450) -Parameters das Definieren wenigstens eines aufweist von einer Unregelmäßigkeitsdicke (290, 480), einer Unregelmäßigkeitsbreite (300, 490), einer Unregelmäßigkeitslänge, einer Unregelmäßigkeitsstelle und einer Unregelmäßigkeitsform;

    Definieren wenigstens eines Verbundstrukturparameters;

    Erzeugen wenigstens eines Modells (400) basierend auf dem wenigstens einen Unregelmäßigkeits- (270, 450) -Parameter, wobei das Modell (400) eine grafische Darstellung des wenigstens einen Unregelmäßigkeits- (270, 450) -Parameters ist;

    Durchführen einer ersten simulierten Überprüfung einer Verbundstruktur (200), um einen ersten Wellenformdatensatz bereitzustellen, der zu dem wenigstens einen Unregelmäßigkeits- (270, 450) -Parameter gehört, wobei die erste simulierte Überprüfung unter Verwendung einer ersten Evaluierungseinstellung zur Verwendung bei der Überprüfung der Verbundstruktur (200) durchgeführt wird, wobei die erste Evaluierungseinstellung zu einem Stimulierungsmechanismus zum Stimulieren der Verbundstruktur gehört;

    Erzeugen eines ersten Bilds (572) basierend auf dem ersten Wellenformdatensatz; und

    Ermitteln, ob eine Qualität des ersten Bilds (572) einen vorgegebenen Schwellenwert erfüllt; und

    wobei, wenn die Qualität des ersten Bilds den vorgegebenen Schwellenwert erfüllt, die von dem Prozessor (520) durchgeführten Funktionen des Weiteren das Identifizieren der ersten Evaluierungseinstellung als gewünschte Evaluierungseinstellung zur Verwendung bei der Überprüfung der Verbundstruktur (200) aufweisen; und

    wobei, wenn die Qualität des ersten Bilds den vorgegebenen Schwellenwert nicht erfüllt, die von dem Prozessor (520) durchgeführten Funktionen des Weiteren aufweisen:

    Durchführen einer zweiten simulierten Überprüfung, um einen zweiten Wellenformdatensatz bereitzustellen, der zu dem wenigstens einen Unregelmäßigkeits- (270, 450) -Parameter gehört, wobei die zweite simulierte Überprüfung unter Verwendung einer zweiten Evaluierungseinstellung durchgeführt wird, die sich von der ersten Evaluierungseinstellung unterscheidet, wobei die Qualität des ersten Bilds (572) den vorgegebenen Schwellenwert nicht erfüllt;

    Erzeugen eines zweiten Bilds (572) basierend auf dem zweiten Wellenformdatensatz;

    Ermitteln, dass eine Qualität des zweiten Bilds (572) einen vorgegebenen Schwellenwert erfüllt; und

    Identifizieren der zweiten Evaluierungseinstellung als gewünschte Evaluierungseinstellung zur Verwendung bei der Überprüfung der Verbundstruktur (200).


     
    5. Computerlesbare Speichervorrichtung nach Anspruch 4, wobei der wenigstens eine Verbundstrukturparameter wenigstens eines aufweist von einer äußeren Lagendicke (210), einer inneren Lagendicke (240), einer Anzahl von Lagen, einer Lagenlaminierung, einer Verbundstruktur- (200) - Dicke, einem Material, das zum Herstellen wenigstens eines Abschnitts der wenigstens einen Verbundstruktur (200) verwendet wird, einer Anzahl von Elementschichten pro Lage, einer Harzdicke (242, 422) und einer Harzdichte.
     
    6. Computerlesbare Speichervorrichtung nach einem der Ansprüche 4-5, wobei die von dem Prozessor (520) durchgeführten Funktionen des Weiteren das Definieren wenigstens eines Stimulierungsparameters aufweisen, der zu dem Stimulierungsmechanismus zum Stimulieren der Verbundstruktur (200) gehört, wobei der wenigstens eine Stimulierungsparameter wenigstens eines aufweist von einem Typ von Stimulierungsmechanismus, einer Strahlbreite, einem Wellenmodus, einer relativen Orientierung wenigstens eines Stimulierungsmechanismus bezüglich der Verbundstruktur (200), einem Abstand zwischen dem wenigstens einen Stimulierungsmechanismus und der Verbundstruktur (200), einem Abstand zwischen dem wenigstens einen Stimulierungsmechanismus und einem Sensor, einer Impulsform und Mittenfrequenz, einem Kopplungsmittel und einer Kopplungsmitteldicke.
     


    Revendications

    1. Procédé mis en œuvre par un ordinateur destiné à une utilisation pour inspecter une structure composite (200), ledit procédé comprenant :

    la définition d'au moins un paramètre d'irrégularité (270, 450), dans lequel la définition de l'au moins un paramètre d'irrégularité (270, 450) comprend en outre la définition de l'au moins un paramètre d'irrégularité (270, 450) incluant au moins un paramètre parmi une épaisseur (290, 480) d'irrégularité, une largeur (300, 490) d'irrégularité, une longueur d'irrégularité, un emplacement d'irrégularité, et une forme d'irrégularité ;

    la définition d'au moins un paramètre de structure composite ;

    la génération d'au moins un modèle (400) sur la base de l'au moins un paramètre d'irrégularité (270, 450), dans lequel le modèle (400) est une représentation graphique de l'au moins un paramètre d'irrégularité (270, 450) ;

    la réalisation d'une première inspection simulée pour fournir un premier ensemble de données de formes d'onde associé à l'au moins un paramètre d'irrégularité (270, 450), dans lequel la première inspection simulée est réalisée à l'aide d'un premier réglage d'évaluation destiné à une utilisation pour inspecter la structure composite (200), dans lequel le premier réglage d'évaluation est associé à un mécanisme de stimulation pour la stimulation de la structure composite ;

    la production d'une première image (572) sur la base du premier ensemble de données de formes d'ondes ;

    la détermination si une qualité de la première image (572) satisfait à un seuil prédéterminé ; et

    dans lequel, si la qualité de la première image satisfait au seuil prédéterminé, le procédé comprend en outre :

    l'identification du premier réglage d'évaluation sous la forme d'un réglage d'évaluation souhaité destiné à une utilisation pour inspecter la structure composite (200) ; ou

    si la qualité de la première image ne satisfait pas au seuil prédéterminé, le procédé comprend en outre :

    la réalisation d'une seconde inspection simulée pour fournir un second ensemble de données de formes d'onde associé à l'au moins un paramètre d'irrégularité (270, 450), dans lequel la seconde inspection simulée est réalisée à l'aide d'un second réglage d'évaluation qui est différent du premier réglage d'évaluation, dans lequel la qualité de la première image (572) ne satisfait pas au seuil prédéterminé ;

    la production d'une seconde image (572) sur la base du second ensemble de données formes d'ondes ;

    la détermination qu'une qualité de la seconde image (572) satisfait à un seuil prédéterminé ; et

    l'identification du second réglage d'évaluation sous la forme d'un réglage d'évaluation souhaité destiné à une utilisation pour inspecter la structure composite (200).


     
    2. Procédé mis en œuvre par un ordinateur selon la revendication 1, dans lequel l'au moins un paramètre de structure composite inclut au moins un paramètre parmi une épaisseur (210) de pli extérieure, une épaisseur (240) de pli intérieure, un nombre de plis, une configuration de plis, une épaisseur de structure composite (200), un matériau utilisé pour fabriquer au moins une partie de l'au moins une structure composite (200), un nombre de couches d'éléments par pli, une épaisseur de résine (242, 422), et une densité de résine.
     
    3. Procédé mis en œuvre par un ordinateur selon une quelconque des revendications 1 à 2, comprenant en outre la définition d'au moins un paramètre de stimulation associé au mécanisme de stimulation pour la stimulation de la structure composite (200), dans lequel l'au moins un paramètre de stimulation inclut au moins un paramètre parmi un type de mécanisme de stimulation, une largeur de faisceau, un mode d'onde, une orientation relative d'au moins un mécanisme de stimulation par rapport à la structure composite (200), une distance entre l'au moins un mécanisme de stimulation et la structure composite (200), une distance entre l'au moins un mécanisme de stimulation et un capteur, une forme d'impulsion et une fréquence centrale, un couplant, et une épaisseur de couplant.
     
    4. Dispositif de stockage lisible par un ordinateur ayant codées dessus des instructions lisibles par un ordinateur qui peuvent être exécutées par un processeur (520) pour mettre en œuvre des fonctions comprenant :

    la définition d'au moins un paramètre d'irrégularité (270, 450), dans lequel la définition d'au moins un paramètre d'irrégularité (270, 450) inclut la définition d'au moins un paramètre parmi une épaisseur (290, 480) d'irrégularité, une largeur (300, 490) d'irrégularité, une longueur d'irrégularité, un emplacement d'irrégularité, et une forme d'irrégularité ;

    la définition d'au moins un paramètre de structure composite ;

    la génération d'au moins un modèle (400) sur la base de l'au moins un paramètre d'irrégularité (270, 450), dans lequel le modèle (400) est une représentation graphique de l'au moins un paramètre d'irrégularité (270, 450) ;

    la réalisation d'une première inspection simulée d'une structure composite (200) pour fournir un premier ensemble de données de formes d'onde associé à au moins un paramètre d'irrégularité (270, 540), dans lequel la première inspection simulée est réalisée à l'aide d'un premier réglage d'évaluation destiné à une utilisation pour inspecter la structure composite (200), dans lequel le premier réglage d'évaluation est associé à un mécanisme de stimulation pour la stimulation de la structure composite ;

    la production d'une première image (572) sur la base du premier ensemble de données de formes d'ondes ; et

    la détermination si une qualité de la première image (572) satisfait à un seuil prédéterminé ;

    dans lequel, si la qualité de la première image satisfait au seuil prédéterminé, les fonctions mises en œuvre par le processeur (520) comprennent en outre l'identification du premier réglage d'évaluation sous la forme d'un réglage d'évaluation souhaité destiné à une utilisation pour inspecter la structure composite (200) ; et

    dans lequel, si la qualité de la première image ne satisfait pas au seuil prédéterminé, les fonctions mises en œuvre par le processeur (520) comprennent en outre :

    la réalisation d'une seconde inspection simulée pour fournir un second ensemble de données de formes d'onde associé à l'au moins un paramètre d'irrégularité (270, 450), dans lequel la seconde inspection simulée est réalisée à l'aide d'un second réglage d'évaluation qui est différent du premier réglage d'évaluation, dans lequel la qualité de la première image (572) ne satisfait pas au seuil prédéterminé ;

    la production d'une seconde image (572) sur la base du second ensemble de données de formes d'ondes ;

    la détermination qu'une qualité de la seconde image (572) satisfait à un seuil prédéterminé ; et

    l'identification du second réglage d'évaluation sous la forme d'un réglage d'évaluation souhaité destiné à une utilisation pour inspecter la structure composite (200).


     
    5. Dispositif de stockage lisible par un ordinateur selon la revendication 4, dans lequel l'au moins un paramètre de structure composite inclut au moins un paramètre parmi une épaisseur (210) de pli extérieure, une épaisseur (240) de pli intérieure, un nombre de plis, une configuration de plis, une épaisseur de structure composite (200), un matériau utilisé pour fabriquer au moins une partie de l'au moins une structure composite (200), un nombre de couches d'éléments par pli, une épaisseur de résine (242, 422), et une densité de résine.
     
    6. Dispositif de stockage lisible par un ordinateur selon une quelconque des revendications 4 à 5, dans lequel les fonctions mises en œuvre par le processeur (520) comprennent en outre la définition d'au moins un paramètre de stimulation associé au mécanisme de stimulation pour la stimulation de la structure composite (200), dans lequel l'au moins un paramètre de stimulation inclut au moins un paramètre parmi un type de mécanisme de stimulation, une largeur de faisceau, un mode d'onde, une orientation relative d'au moins un mécanisme de stimulation par rapport à la structure composite (200), une distance entre l'au moins un mécanisme de stimulation et la structure composite (200), une distance entre l'au moins un mécanisme de stimulation et un capteur, une forme d'impulsion et une fréquence centrale, un couplant, et une épaisseur de couplant.
     




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    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description