Method and apparatus for detecting layer inconsistencies within a composite object

Abstract

The title of the invention is a method and apparatus for detecting layer inconsistencies within a composite object. A plurality of plate pairs including at least three pairs of plates (116-122, 604-608, 704-714) are positioned on a surface (110) of a composite object (104). The electrical resistance of a plurality of layers (103) in the composite object is measured in at least three different fiber orientations. Each of the at least three different fiber orientations is measured by a corresponding one of the at least three pairs of plates.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to testing composite objects, and more particularly to methods and apparatus for non-destructive testing of layers in a composite object using pairs of capacitive plates. BACKGROUND

[0002] Carbon fiber reinforced polymers (CFRP) are an example of a type of composite material. The carbon fibers in carbon fiber reinforced polymers provide both mechanical strength and electrical conductivity. Composite parts can be made from multiple layers of carbon fiber reinforced polymers. Non-destructive inspection (NDI) testing can be used to test the layers in such composite parts. But conventional, currently available non-destructive inspection testing techniques, such as those involving the propagation of ultrasonic waves, can only reveal areas of delamination of the layers. These testing techniques can not provide information about carbon fiber discontinuities in the layers. For example, these testing techniques can not be sensitive enough to provide information about fiber conductivity or fiber continuity within the composite object.

[0003] Carbon fiber continuity within a composite object is related to the mechanical tensile strength of the composite object. For example, broken or discontinuous carbon fibers can reduce the mechanical tensile strength of the composite object. Further, broken or discontinuous carbon fibers can reduce the ability of the composite object to conduct electrical current, such as lightning. Thus, it is important to have a method of detecting carbon fiber discontinuities in a composite object during the manufacturing and servicing of the composite. Accordingly, it can be desirable to provide methods and apparatus that address at least some of the above issues. SUMMARY

[0004] In one illustrative example, an apparatus includes a plurality of pairs of plates attached to a base. The plurality of pairs of plates includes at least three pairs of plates, each pair of plates including two capacitive plates aligned to measure electrical resistance of a plurality of layers in different fiber orientations.

[0005] In another illustrative example, a method for testing a composite object is provided. A plurality of pairs of plates including at least three pairs of plates is positioned on a surface of the composite object. Electrical resistance of a plurality of layers in the composite object in at least three different fiber orientations is measured. Each of the at least three different fiber orientations is measured via a respective one of the at least three pairs of plates.

[0006] In yet another illustrative example, a testing apparatus includes a base and a plurality of pairs of plates attached to the base. Each pair of plates includes two capacitive plates aligned to measure electrical resistance of layers in different fiber directions in a composite object. An area between the plurality of pairs of plates defines a target area. When the plurality of pairs of plates is positioned on a surface of the composite object, a voltage measurement generated at each of a plurality of different locations on the surface indicates whether a fiber discontinuity exists in the composite object.

[0007] These features and functionalities can be implemented independently of one another or in combination in various embodiments of the present disclosure, as will be apparent upon reference to the following descriptions and attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0008] The novel features described herein are set forth with particularity in the claims that follow. These embodiments, however, are exemplary and do not limit the application, as the scope thereof is best determined by reference to the appended claims, when read in light of the foregoing description and attached drawings.

[0009] Figure 1 is a diagram of a test device according to an example embodiment.

[0010] Figure 2 is a diagram of a top view of a pair of plates on a surface of a composite object from Figure 1

[0011] Figure 3 is a diagram of a top view of a test device positioned on a composite object according to an example embodiment.

[0012] Figure 4 is a circuit diagram according to an example embodiment.

[0013] Figure 5 is a circuit diagram according to an example embodiment.

[0014] Figure 6 is a diagram of a top view of a test device according to an example embodiment.

[0015] Figure 7 is a diagram of a top view of a test device according to an example embodiment.

[0016] Figure 8 is a flowchart of a method for testing a composite object according to an example embodiment.

[0017] Figure 9 is a flowchart of a method for testing a composite object according to an example embodiment.

[0018] Figure 10 is a flowchart of processing voltage measurements according to an example embodiment.

[0019] Figure 11 is an example of a two-dimensional plot set according to an example embodiment.

[0020] Figure 12 is an example of a two-dimensional standard deviation plot set according to an example embodiment. DETAILED DESCRIPTION

[0021] ​The example implementations described below provide methods, apparatuses, and systems for easily and effectively detecting certain types of layer inconsistencies. In particular, the example implementations provide methods, apparatuses, and systems for detecting fiber discontinuities in composite objects composed of carbon fiber reinforced polymers (CFRP). Fiber resistance is measured using capacitive coupling and the application of alternating current (AC). These measurements can be used to create a two-dimensional map or atlas of areas of fiber discontinuity. This type of map or atlas can be very helpful for the manufacture and repair of composite materials.

[0022] In one or more examples, the composite object can have layers of fibers extending in multiple directions. In one or more examples, pairs of plates are capacitively coupled on a surface of the composite object, each pair for measuring an effective series resistance of a different fiber orientation. In particular, a voltage difference between a reference branch and each of at least three measurement branches is measured. Each of these measurement branches can include a pair of plates capacitively coupled to the composite object corresponding to a particular fiber orientation. The voltage difference provides an indication of the effective series resistance in each fiber orientation and can be used to identify areas of the composite object that potentially include layer inconsistencies, such as fiber discontinuities.

[0023] This type of system and method for non-destructively testing composite objects makes the identification of layer inconsistencies simple, fast, and effective. In particular, a system and method similar to the system and method described above can help ensure that a composite object has a desired mechanical strength (e.g., mechanical tensile strength) and a desired electrical conductivity (e.g., the ability to conduct and thus dissipate lightning currents).

[0024] Referring now to the drawings, Figure 1 is a diagram of a testing apparatus according to example implementations. The testing apparatus 100 can be used to test a composite object, such as composite object 101. In some cases, the testing apparatus 100 can be referred to as a testing system or a non-destructive testing apparatus or system. The composite object 101 includes multiple layers 103 of composite material. In particular, the layers 103 can be composed of carbon fibers. For example, each layer of composite material can be a layer of carbon fiber reinforced polymer (CFRP).

[0025] The testing apparatus 100 is used to detect areas of the composite object 101 that have undesirable layer inconsistencies. Undesirable layer inconsistencies can be, for example and without limitation, fiber discontinuities or some other type of layer defect. In one or more illustrative examples, the composite object 101 can be an aircraft composite structure. For example, the composite object 101 can be a composite fuselage panel, a composite wing panel, or some other type of composite structure.

[0026] The testing device 100 includes a base 102, a plate system 104, a control box 106, and a handle 108. In this illustrative example, the plate system 104 and the control box 106 are both attached to the base 102, while the handle 108 is attached to the control box 106. The base 102 has an opening 109. In some cases, the opening 109 corresponds to a target area. In one or more illustrative examples, the base 102 is a printed circuit board that has circuitry that is in communication or otherwise connected to circuitry inside the control box 106. For example, each of the base 102 and the control box 106 can include any number of electrical components, such as inductors, capacitors, resistors, switches, other types of electrical components, or combinations thereof. In some examples, the control box 106 can also be referred to as a housing. The handle 108 can be used by an operator to move the testing device 100 over a surface of an object, such as a surface 110 of a composite object 101. The operator can be a human operator or a machine operator (e.g., a robotic arm or an end effector).

[0027] In this illustrative example, the plate system 104 includes a plurality of pairs of plate pairs 112. The plate pairs 112 can be symmetrically aligned with respect to a central axis 114 through the opening 109. For example, each of the plate pairs 112 can include two plates that are aligned facing each other. In other words, each of the plate pairs 112 can include two plates that are positioned on opposite sides of the base 102. In this example, each of the plate pairs 112 can include two plates that are positioned on opposite sides of the opening 109. The plates in each of the plate pairs 112 are capacitive plates and can be spaced apart by the same distance.

[0028] The plate pairs 112 include at least three pairs of plate pairs. In this illustrative example, the plate pairs 112 include four pairs of plate pairs. Specifically, the plate pairs 112 include a first plate pair 116, a second plate pair 118, a third plate pair 120, and a fourth plate pair 122. In other examples, the plate pairs 112 can include some other number of plate pairs, such as, for example, three pairs of plate pairs or six pairs of plate pairs.

[0029] The first plate pair 116 includes a plate 124 and a plate 126. The second plate pair 118 includes a plate 128 and a plate 130. The third plate pair 120 includes a plate 132 and a plate 134. The fourth plate pair 122 includes a plate 136 and a plate 138. The plates 124, 126, 128, 130, 132, 134, 136, and 138 can be capacitive plates. In these illustrative examples, each of the plates 124, 126, 128, 130, 132, 134, 136, and 138 includes a metal layer and an insulating layer. In other illustrative examples, each plate can include only a metal layer.

[0030] As described above, the pairs of plates 112 are symmetrically aligned about the opening 109. In this illustrative example, the pairs of plates 112 are arranged in a symmetric octagonal configuration with respect to the central axis 114. The test device 100 can be positioned on the composite object 101 such that the alignment of the pairs of plates 112 can be used to provide measurements of electrical resistance in particular fiber orientations (i.e., fiber directions). More specifically, each of the aligned pairs of plates 112 is used to measure electrical resistance of a different fiber orientation. This electrical resistance can be an effective series resistance (ESR) of that fiber orientation.

[0031] As one illustrative example, the first pair of plates 116 is used to measure electrical resistance in a 0 degree fiber orientation. The second pair of plates 118 is used to measure electrical resistance in a 45 degree fiber orientation. The third pair of plates 120 is used to measure electrical resistance in a 90 degree fiber orientation. The fourth pair of plates 122 is used to measure electrical resistance in a -45 degree fiber orientation.

[0032] In some illustrative examples, the measurements generated by the test device 100 can be processed by the computer system 140. In these examples, the test device 100 is in wireless communication with the computer system 140. However, in other examples, the test device 100 can be in communication with the computer system 140 through one or more wired communication lines, wireless communication lines, optical communication lines, or a combination thereof.

[0033] Figure 2 is from a surface of a composite object 101 according to example implementations Figure 1 A diagram of a top view of the test device 100 on a surface of a composite object 101. The area 200 between the plates of the pairs of plates 112 is an area in which measurements can be taken. When the test device 100 is placed on the composite object 101, the area 200 overlaps a corresponding area or surface area of the composite object 101. The area 200 includes a first measurement area 202, a second measurement area 204, a third measurement area 206, and a fourth measurement area 208.

[0034] The first measurement area 202, the second measurement area 204, the third measurement area 206, and the fourth measurement area 208 correspond to the first pair of plates 116, the second pair of plates 118, the third pair of plates 120, and the fourth pair of plates 122, respectively. More specifically, the first measurement area 202 indicates an area on the composite object 101 that will be most sensitive to fibers in an orientation (e.g., a 0 degree fiber orientation) corresponding to the first pair of plates 116, the second measurement area 204 indicates an area on the composite object 101 that will be most sensitive to fibers in an orientation (e.g., a 45 degree fiber orientation) corresponding to the second pair of plates 118. The third measurement area 206 indicates an area on the composite object 101 that will be most sensitive to fibers in an orientation (e.g., a 90 degree fiber orientation) corresponding to the third pair of plates 120. The fourth measurement area 208 indicates an area on the composite object 101 that will be most sensitive to fibers in an orientation (e.g., a -45 degree fiber orientation) corresponding to the fourth pair of plates 122.

[0035] The area where all four measurement regions (i.e., the first measurement region 202, the second measurement region 204, the third measurement region 206, and the fourth measurement region 208) overlap defines a target region 210. The target region 210 is centrally disposed relative to the pairs of plates 112. The target region 210 is a portion of the area 200 that provides the best measurement of the electrical resistance (e.g., effective series resistance) of a composite object (such as the composite object 101) for all different fiber orientations. The target region 210 can also be referred to as a target test region, a test region, or a target test region.

[0036] Figure 3 is positioned on a composite object according to example implementations from Figure 1 a top view of the test device 100. In Figure 3 the test device 100 is used to test a composite object 300. Similar to the composite object 101 in Figure 1 the composite object 300 includes a plurality of layers, each layer composed of carbon fibers (e.g., CFRP).

[0037] The layers can include fibers extending in four different directions. For example, the layers can include one or more layers of fibers having a 0-degree fiber orientation, one or more layers of fibers having a 45-degree fiber orientation, one or more layers of fibers having a 90-degree fiber orientation, and one or more layers of fibers having a -45-degree fiber orientation.

[0038] In this example, the test device 100 is positioned on and contacts a surface 302 of the composite object 300. As previously discussed, the test device 100 has a target region 210 that provides the best measurement of the electrical resistance of the composite object for all different fiber orientations of the composite object 300.

[0039] The test device 100 can move in any of a variety of different patterns across the surface 302 of the composite object 300 to test the composite object 300. In this illustrative example, the test device 100 moves across the surface 302 in the direction of the arrow 304 to follow a raster pattern. A raster pattern is a scanning pattern in which an area is scanned from side to side in lines from top to bottom (the directions indicated are relative). In these illustrative examples, the vertical “pitch” between the scanning lines is set to the diameter of the target region 210 to ensure that all portions of the surface 302 overlap the target region 210 of the test device 100 at some point as the test device 100 moves across the surface 302.

[0040] Figure 4is a circuit diagram according to example implementations. Circuit 400 represents an example of a system that can be used to non-destructively test a composite object. Circuit 400 includes components that represent a combination of electronic components and physical components or structures.

[0041] In this illustrative example, circuit 400 includes a ground 401 and an alternating current (AC) voltage source 402 set at a frequency that is set to a resonant frequency, where:

[0042]

[0043] Circuit 400 further includes a reference branch 404, a branch 406 (which can also be referred to as a circuit branch or a measurement branch), a voltage output 408, and a voltage output 409. Reference branch 404 includes an inductor 410, a capacitor 412, a resistor 414, a capacitor 416, and a resistor 418. Branch 406 includes an inductor 420, a capacitor 422, a resistor 424, a capacitor 426, and a resistor 428.

[0044] In circuit 400, alternating current voltage source 402, inductor 410, capacitor 412, resistor 414, capacitor 416, resistor 418, inductor 420, and resistor 428 represent electronic components. Capacitor 422 and capacitor 426 represent physical capacitive components. For example, each of capacitor 422 and capacitor 426 can represent a capacitive plate. In particular, capacitor 422 and capacitor 426 represent capacitive plates that are to be positioned and aligned on a composite object to measure the resistance of fibers in one orientation, which can be an effective series resistance. Resistor 424 represents the effective series resistance of the physical fibers of the composite object being tested.

[0045] In this illustrative example, resistor 414, resistor 418, and resistor 428 are set to resistance values that are based on an expected effective series resistance of the composite object. The value of the expected effective series resistance depends on the number of layers in the composite object, the thickness of each layer, and the layer density. In these illustrative examples, the layer density refers to the percentage of layers of each different fiber orientation in the layer. For example, the layer density can indicate a percentage of layers with fibers in a first orientation, a percentage of layers with fibers in a second orientation, a percentage of layers with fibers in a third orientation, and so on. The difference between voltage output 408 and voltage output 409 (i.e., the voltage difference) provides an indication of the difference between the effective series resistance of the composite object and the expected effective series resistance. A voltage difference that exceeds a selected tolerance can indicate a fiber discontinuity.

[0046] Thus, circuit 400 represents a component of a test apparatus for testing a composite object having fibers extending in a single direction. This component can be constructed to test composite objects having fibers extending in different directions. For example, multiple branches (such as branch 406) can be daisy-chained together by a daisy-chain switching system to enable measurements for different fiber directions or orientations.

[0047] Figure 5 is a circuit diagram showing circuitry included in test apparatus 100 from Figures 1-3 FIG. 1, according to example embodiments. In this illustrative example, circuit 500 represents the electronic components and physical structure of test apparatus 100 capable of testing a composite object, such as composite object 101 in Figures 1-3 FIG. 1. Circuit 500 includes ground 502, AC voltage source 504, reference branch 506, first branch 508, second branch 510, third branch 512, and fourth branch 514. First branch 508, second branch 510, third branch 512, and fourth branch 514 can also be referred to as measurement branches.

[0048] Reference branch 506 includes inductor 515, capacitor 516, resistor 518, capacitor 520, and resistor 522. The components of the reference branch represent electronic components that can be present, for example, in control box 106 in Figure 1 FIG. 1. Resistors 518 and 522 are set to an expected effective series resistance of composite object 101, which is within a selected tolerance range, based on the number of layers 103 in composite object 101, the thickness of each of layers 103, and the layer density of layers 103.

[0049] First branch 508, second branch 510, third branch 512, and fourth branch 514 represent portions of circuitry in test apparatus 100 that are involved in measurements using first plate pair 116, second plate pair 118, third plate pair 120, and fourth plate pair 122, respectively. First branch 508 includes switch 524, inductor 526, capacitor 528, resistor 530, capacitor 532, and resistor 534. Second branch 510 includes switch 536, inductor 538, capacitor 540, resistor 542, capacitor 544, and resistor 546. Third branch 512 includes switch 548, inductor 550, capacitor 552, resistor 554, capacitor 556, and resistor 558. Fourth branch 514 includes switch 560, inductor 562, capacitor 564, resistor 566, capacitor 568, and resistor 570.

[0050] Capacitors 528 and 532 represent Figure 1The first pair of plates 116. Resistor 530 represents the effective series resistance along the fiber direction corresponding to the first pair of plates 116 (i.e., 0 degree fiber orientation). Resistor 534 represents the expected reference resistance in the fiber direction corresponding to the first pair of plates 116 (i.e., 0 degree fiber orientation). In these examples, the reference resistance (e.g., expected effective series resistance) is set to the same value as resistor 518 and resistor 522 within a selected tolerance limit.

[0051] Capacitors 540 and 544 represent the capacitance of the second pair of plates 118. Resistor 542 represents the effective series resistance along the fiber direction corresponding to the second pair of plates 118 (i.e., 45 degree fiber orientation). Resistor 546 represents the expected reference resistance in the fiber direction corresponding to the second pair of plates 118 (i.e., 45 degree fiber orientation). In these examples, the reference resistance (e.g., expected effective series resistance) is set to the same value as resistor 518 and resistor 522 within a selected tolerance limit. Figure 1

[0052] Capacitors 552 and 556 represent the capacitance of the third pair of plates 120. Resistor 554 represents the effective series resistance along the fiber direction corresponding to the third pair of plates 120 (i.e., 90 degree fiber orientation). Resistor 558 represents the expected reference resistance in the fiber direction corresponding to the third pair of plates 120 (i.e., 90 degree fiber orientation). In these examples, the reference resistance (e.g., expected effective series resistance) is set to the same value as resistor 518 and resistor 522 within a selected tolerance limit. Figure 1

[0053] Capacitors 564 and 568 represent the capacitance of the fourth pair of plates 122. Resistor 566 represents the effective series resistance along the fiber direction corresponding to the fourth pair of plates 122 (i.e., -45 degree fiber orientation). Resistor 570 represents the expected reference resistance in the fiber direction corresponding to the fourth pair of plates 122 (i.e., -45 degree fiber orientation). In these examples, the reference resistance (e.g., expected effective series resistance) is set to the same value as resistor 518 and resistor 522 within a selected tolerance limit. Figure 1

[0054] Circuit 500 includes a voltage output 571 of the reference branch 506, a voltage output 572 of the first branch 508, a voltage output 574 of the second branch 510, a voltage output 576 of the third branch 512, and a voltage output 578 of the fourth branch 514. A daisy chain network is formed between switches 524, 536, 548, and 560, which enables the voltage difference between the reference branch 506 and each of the measurement branches to be measured.

[0055] ​​​For example, the difference between voltage output 572 and voltage output 571 is used to indicate whether there is a difference between the effective series resistance of the fibers in a 0 degree fiber orientation and the expected effective series resistance of that fiber orientation. The difference between voltage output 574 and voltage output 571 is used to indicate whether there is a difference between the effective series resistance of the fibers in a 45 degree fiber orientation and the expected effective series resistance of that fiber orientation. The difference between voltage output 576 and voltage output 571 is used to indicate whether there is a difference between the effective series resistance of the fibers in a 90 degree fiber orientation and the expected effective series resistance of that fiber orientation. The difference between voltage output 578 and voltage output 571 is used to indicate whether there is a difference between the effective series resistance of the fibers in a -45 degree fiber orientation and the expected effective series resistance of that fiber orientation. These measurements can be generated at multiple locations on the composite object to fully test the composite object.

[0056] In some illustrative examples, voltage output 572, voltage output 574, voltage output 576, and voltage output 578 can be used to determine the layer density of the composite object. For example, the composite object can have four fiber orientations with the following layer densities: 40% of the layers in a 0 degree orientation, 20% of the layers in a 45 degree orientation, 20% of the layers in a -45 degree orientation, and 10% of the layers in a 90 degree orientation. When the reference resistors (resistor 534, resistor 546, resistor 558, and resistor 570, and optionally resistor 518 and resistor 522) are set to zero, the ratio between voltage output 572, voltage output 574, voltage output 576, and voltage output 578 can provide an indication of the layer density of the composite object.

[0057] Figure 6 is a diagram of another testing device according to example implementations. Testing device 600 includes base 602 and first pair of plates 604, second pair of plates 606, and third pair of plates 608. Although not shown in this example, testing device 600 can also include a control box similar to control box 106 in Figure 1 , a handle similar to handle 108 in Figure 1 , or both.

[0058] First pair of plates 604 includes plate 610 and plate 612. Second pair of plates 606 includes plate 614 and plate 616. Third pair of plates 608 includes plate 618 and plate 620. First pair of plates 604, second pair of plates 606, and third pair of plates 608 are symmetrically aligned around target area 622. In particular, the three pairs of plates have a symmetric hexagonal configuration. First pair of plates 604 can be used to measure the resistance (e.g., effective series resistance) in a 0 degree fiber orientation. Second pair of plates 606 can be used to measure the resistance in a 60 degree fiber orientation. Third pair of plates 608 can be used to measure the resistance in a -60 degree fiber orientation.

[0059] Figure 7 is an illustration of yet another test device according to example implementations. The test device 700 includes a base 702 and a first pair of plates 704, a second pair of plates 706, a third pair of plates 708, a fourth pair of plates 710, a fifth pair of plates 712, and a sixth pair of plates 714. Although not shown in this example, the test device 700 can further include a control box similar to the control box 106 in Figure 1 , a handle similar to the handle 108 in Figure 1 , or both.

[0060] The first pair of plates 704 includes a plate 716 and a plate 718. The second pair of plates 706 includes a plate 720 and a plate 722. The third pair of plates 708 includes a plate 724 and a plate 726. The fourth pair of plates 710 includes a plate 728 and a plate 730. The fifth pair of plates 712 includes a plate 732 and a plate 734. The sixth pair of plates 714 includes a plate 736 and a plate 738.

[0061] The first pair of plates 704, the second pair of plates 706, the third pair of plates 708, the fourth pair of plates 710, the fifth pair of plates 712, and the sixth pair of plates 714 are symmetrically aligned about a target area 740. In particular, the six pairs of plates have a symmetric dodecagon configuration. The first pair of plates 704 can be used to measure resistance (e.g., effective series resistance) at a 0-degree fiber orientation. The second pair of plates 706 can be used to measure resistance at a 30-degree fiber orientation. The third pair of plates 708 can be used to measure resistance at a 60-degree fiber orientation. The fourth pair of plates 710 can be used to measure resistance at a 90-degree fiber orientation. The fifth pair of plates 712 can be used to measure resistance at a -60-degree fiber orientation. The sixth pair of plates 714 can be used to measure resistance at a -30-degree fiber orientation.

[0062] Figures 1-7 The illustrations in

[0063] Figure 8 is a flowchart of a method for testing a composite object according to example implementations. Figure 8 The method 800 in Figures 1-2 may be used to test a composite object, such as Figure 3 the composite object 101 in Figures 1-3 or Figure 6 the composite object 300 in Figure 7 . Furthermore, the method 800 can be performed using a test device such as the test device 100 described in

[0064] The method 800 can begin by positioning a plurality of plate pairs (operation 802) including at least three plate pairs on a surface of a composite object. Each of these plate pairs includes two capacitive plates for capacitively coupling with the composite object.

[0065] The resistances of the plurality of layers of the composite object are measured in at least three different fiber orientations, each of the at least three different fiber orientations being measured by a corresponding one of the at least three plate pairs (operation 804). The measured resistances can be effective series resistances. In one or more examples, in operation 804, the resistances of the fiber orientations are measured by measuring a voltage output from a circuit branch that includes the plate pair designed to measure that fiber orientation. Thus, in operation 804, the measured values of resistance can actually be measured values of voltage indicative of resistance.

[0066] It is then determined whether any layer discontinuities exist on the composite object based on the measured values (operation 806), after which the method terminates. Operation 806 can be performed by, for example, processing the measured values using one or more mathematical analysis tools or computer programs.

[0067] Figure 9 is a flowchart of a method for testing a composite object according to example embodiments. Figure 9 The method 900 in can be used to test composite objects such as Figures 1-2 the composite object 101 in or Figure 3 the composite object 300 in. Furthermore, the method 900 can be performed using a test apparatus such as Figures 1-3 the test apparatus 100 described in, Figure 6 the test apparatus 600 in, Figure 7 the test apparatus 700 in, or some other type of similarly implemented test apparatus.

[0068] The method 900 can begin by identifying a scan pattern for testing a composite object that includes a plurality of layers having at least three different fiber orientations (operation 902). For example, the composite object can have a first plurality of layers having a first fiber orientation, a second plurality of layers having a second fiber orientation, a third plurality of layers having a third fiber orientation, and a fourth plurality of layers having a fourth fiber orientation. One of these fiber orientations is a 0-degree fiber orientation, which is considered to be a primary fiber orientation. In some examples, the scan pattern identified in operation 902 can be a raster pattern.

[0069] The test device, including the plurality of pairs of plates, is then oriented with respect to the composite object such that the primary pair of plates is aligned with a primary fiber orientation of the composite object (operation 904). For example, the test device can include a pair of plates for each of a first plurality of layers, a second plurality of layers, a third plurality of layers, and a fourth plurality of layers of the composite object. In one illustrative example, the primary pair of plates can be the pair of plates designed to align with the primary fiber orientation, which is a 0 degree fiber orientation.

[0070] Thereafter, the test device is moved to an initial position on the surface of the composite object, the initial position determined based on the identified scan pattern (operation 906). Voltage measurements for each of the plurality of pairs of plates are collected at the current position of the test device (operation 908). For each pair of plates, operation 908 can include generating a voltage output from a measurement branch of the electrical circuit, the measurement branch including at least the pair of plates, the composite object (and thus the effective series resistance of the layers corresponding to the fiber direction of the pair of plates), and a reference resistance.

[0071] In some illustrative examples, operation 908 optionally includes generating a voltage measurement for a reference branch of the electrical circuit, the reference branch including various electronic components including at least two resistors set to an expected effective series resistance of the composite object. As previously discussed, the expected effective series resistance depends on the number of layers in the composite object, the thickness of each layer (and / or the thickness of the composite object), and the layer density. In other illustrative examples, the voltage measurement for the pair of plates generated in operation 908 is a voltage difference, the voltage difference being the difference between a first voltage output from the measurement branch corresponding to the pair of plates and a second voltage output from the reference branch.

[0072] Thereafter, it is determined whether there is a next position to test according to the scan pattern (operation 910). If there is a next position, the test device is moved to the next position (operation 912). The collected voltage measurements are then processed to determine whether there is a layer inconsistency in the composite object (operation 914), after which the method terminates. Again, with reference to operation 910, if there is no next position to scan, the method 900 proceeds directly to operation 914 as described above.

[0073] Figure 10 is a flowchart for processing voltage measurements according to example implementations. The method 1000 can be an example of one way in which the operation 914 in Figure 9 may be implemented. The method 1000 can be implemented using a computer system, such as the computer system 140 in Figure 1 , or other type of processor.

[0074] The method 1000 can begin by plotting the voltage measurements collected for each fiber orientation in a two-dimensional atlas (operation 1002). The two-dimensional atlas can include, for example, a two-dimensional plot for each different fiber orientation. In one or more instances, the two-dimensional plot for a given fiber orientation is a contour plot that provides a visual indication of whether a layer inconsistency was detected in the layer of that fiber orientation.

[0075] In some cases, the method 1000 further includes plotting the standard deviation of the voltage measurements in a two-dimensional standard deviation atlas (operation 1004), after which the method terminates. The two-dimensional standard deviation atlas includes a two-dimensional standard deviation plot for each fiber orientation. The two-dimensional standard deviation plot for a given fiber orientation provides an indication of how reliably and accurately a layer inconsistency was detected.

[0076] The flow and block diagrams in the various depicted embodiments illustrate the architecture, functionality, and operations of some possible implementations of apparatuses and methods in example implementations. In this regard, each block in the flow or block diagrams can represent a part of a module, segment, function, and / or operation.

[0077] In some optional implementations of example implementations, one or more of the functions mentioned in the blocks can occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may, sometimes, be executed in the reverse order, depending upon the involved functions. Also, other blocks can be added.

[0078] Figure 11 is an example of a two-dimensional atlas according to example implementations. The two-dimensional atlas set 1100 is generated in operation 1002 in Figure 10 is an example of an implementation of a two-dimensional atlas set generated in operation 1002 in

[0079] The two-dimensional atlas set 1100 includes atlas 1102, atlas 1104, atlas 1106, and atlas 1108, each of which is a two-dimensional atlas for a different fiber orientation of the composite object. In particular, each of these plots is a contour plot of voltage measurements collected with respect to the composite object. These voltage measurements are voltage differences. Further, each of these plots has an M-N coordinate system that matches a coordinate system of the surface of the composite object.

[0080] Map 1102 is a two-dimensional map of a layer of a composite object with fibers having a 0 degree fiber orientation. Map 1102 includes a line 1110 of voltage measurements. In this illustrative example, a layer inconsistency is visually indicated (or detected) at location 1112. Map 1104 is a two-dimensional map of a layer of a composite object with fibers having a 45 degree fiber orientation. Map 1104 includes a line 1114 of voltage measurements. In this illustrative example, a layer inconsistency is visually indicated (or detected) at location 1116.

[0081] Map 1106 is a two-dimensional map of a layer of a composite object with fibers having a -45 degree fiber orientation. Map 1106 includes a curve 1118 of voltage measurements. In this example, a layer inconsistency is visually indicated (or detected) at location 1120. Map 1108 is a two-dimensional map of a layer of a composite object with fibers having a 90 degree fiber orientation. Map 1108 includes a line 1122 of voltage measurements. In this example, a layer inconsistency is visually indicated (or detected) at location 1124.

[0082] Figure 11 The lines 1110, 1114, 1118, and 1122 are shown in the maps 1102, 1104, 1106, and 1108 as patterned lines. Each different patterned line in the lines 1110, 1114, 1118, and 1122 represents a different voltage measurement value. For example, one pattern can be used to plot voltage measurements within a certain range of values, while another pattern can be used to plot voltage measurements within a different range of values. In other illustrative examples, the lines 1110, 1114, 1118, and 1122 can use different colors instead of different line patterns.

[0083] Figure 12 is an example of a set of two-dimensional standard deviation maps according to an example implementation. The set of two-dimensional standard deviation maps 1200 is generated by taking the standard deviation of the voltage measurement data provided in the set of two-dimensional standard deviation maps 1200 in Figure 10 is an example of one implementation of the set of two-dimensional standard deviation maps generated in operation 1004 in

[0084] The set of two-dimensional standard deviation maps 1200 is generated by taking the standard deviation of the voltage measurement data provided in the set of two-dimensional standard deviation maps 1200 in Figure 12 The set of two-dimensional standard deviation maps 1200 includes maps 1202, 1204, 1206, and 1208. Each of these maps is a two-dimensional standard deviation map. In particular, each of these maps is a contour map of standard deviation.

[0085] Map 1202 includes a line 1210, which is a line of standard deviation values for the layer of the composite object with fibers having a 0 degree fiber orientation. In this example, a layer inconsistency is visually indicated (or detected) at location 1212. Figure 12contours of the standard deviation of the voltage measurements of the map 1202. The line 1210 indicates that there is some noise in the voltage measurement data at the 0 degree fiber orientation, in addition to a layer inconsistency detected at location 1212. The map 1204 includes a line 1214, which is a Figure 12 contours of the standard deviation of the voltage measurements of the map 1204. The line 1214 indicates that there is little noise in the voltage measurement data at the 45 degree orientation, in addition to a layer inconsistency detected at location 1216.

[0086] The map 1206 includes a line 1218, which is a Figure 12 contours of the standard deviation of the voltage measurements of the map 1206. The line 1218 indicates that there is little noise in the voltage measurement data at the -45 degree orientation, in addition to a layer inconsistency detected at location 1220. The map 1208 includes a line 1222, which is a Figure 12 contours of the standard deviation of the voltage measurements of the map 1208. The line 1222 indicates that there is little noise in the voltage measurement data at the 90 degree orientation, in addition to a layer inconsistency detected at location 1224.

[0087] Accordingly, the different example embodiments described above provide systems and methods for non-destructive testing of composite objects to easily, quickly, and effectively detect, for example, fiber discontinuities. For example, Figures 1-3 The testing device 100 described in FIG. 1 can be used to test composite objects for fiber discontinuities during manufacturing and repair to ensure that these composite objects have the desired mechanical strength and the desired electrical conductivity.

[0088] Further, the present disclosure includes embodiments in accordance with the following clauses:

[0089] Clause 1. An apparatus comprising:

[0090] a plurality of pairs of plates (112, 604-608, 704-714), including at least three pairs of plates (116-122, 604-608, 704-714), each pair of plates including two capacitive plates (124-138, 610-620, 716-738) aligned to measure electrical resistance of a layer (103) at different fiber orientations; and

[0091] a base (102, 602, 702) to which the plurality of pairs of plates (112) are attached.

[0092] Clause 2. The apparatus of clause 1, wherein the plurality of pairs of plates (112) includes:

[0093] a first pair of plates (116) to measure electrical resistance at a 0 degree fiber orientation;

[0094] a second pair of plates (118) for measuring resistance at a 45 degree fiber orientation;

[0095] a third pair of plates (120) for measuring resistance at a 90 degree fiber orientation; and

[0096] a fourth pair of plates (122) for measuring resistance at a -45 degree fiber orientation.

[0097] Clause 3. The apparatus of clause 1, wherein the plurality of pairs of plates (112) comprises:

[0098] a first pair of plates (604) for measuring resistance at a 0 degree fiber orientation;

[0099] a second pair of plates (606) for measuring resistance at a 60 degree fiber orientation; and

[0100] a third pair of plates (608) for measuring resistance at a -60 degree fiber orientation.

[0101] 4. The apparatus of clause 1, wherein the plurality of pairs of plates (112) comprises:

[0102] a first pair of plates (704) for measuring resistance at a 0 degree fiber orientation;

[0103] a second pair of plates (706) for measuring resistance at a 30 degree fiber orientation;

[0104] a third pair of plates (708) for measuring resistance at a 60 degree fiber orientation;

[0105] a fourth pair of plates (710) for measuring resistance at a 90 degree fiber orientation;

[0106] a fifth pair of plates (712) for measuring resistance at a -60 degree fiber orientation; and

[0107] a sixth pair of plates (714) for measuring resistance at a -30 degree fiber orientation.

[0108] Clause 5. The apparatus of clause 1, wherein the plurality of pairs of plates (112) are arranged in a symmetric octagonal configuration, the symmetric octagonal configuration defining a test region disposed centrally with respect to the plurality of pairs of plates (112).

[0109] Clause 6. The apparatus of clause 1, wherein the two capacitive plates of each pair of the plurality of pairs of plates (112) are separated by the same distance.

[0110] Clause 7. The apparatus of clause 1, further comprising:

[0111] a circuit (400) comprising a plurality of branches (404-406, 506-514),

[0112] wherein the branches (406, 508-514) of the plurality of branches include plate pairs of the plurality of plate pairs (112);

[0113] wherein the plate pairs are designed for a particular fiber orientation;

[0114] wherein the resistance of the particular fiber orientation is measured using the voltage output (409) from the branch.

[0115] Clause 8. The apparatus of clause 7, wherein the circuit (400) further comprises:

[0116] a reference branch (404, 506) comprising at least one reference resistor (534, 546, 558, 570) having an expected effective series resistance.

[0117] Clause 9. The apparatus of clause 1, wherein the base (102, 602, 702) is a printed circuit board.

[0118] Clause 10. The apparatus of clause 9, wherein the base and the plurality of plate pairs (112) form a test apparatus (100, 600, 700), the test apparatus further comprising:

[0119] a housing (106) attached to the base (102), wherein the housing (106) houses the circuit connected to the printed circuit board.

[0120] Clause 11. The apparatus of clause 10, wherein the test apparatus (100, 600, 700) further comprises:

[0121] a handle (108) attached to the housing (106), wherein the handle (108) allows an operator to move the test apparatus (100, 600, 700) along a surface (110) of the composite object (101).

[0122] Clause 12. The apparatus of clause 1, wherein the capacitive plate of the two capacitive plates comprises:

[0123] a metal layer.

[0124] Clause 13. The apparatus of clause 13, wherein the capacitive plate further comprises:

[0125] an insulating layer.

[0126] Clause 14. A method of testing a composite object (101), the method comprising:

[0127] positioning a plurality of plate pairs (112) comprising at least three plate pairs (116-122, 604-608, 704-714) on a surface (110) of the composite object (101); and

[0128] measuring the electrical resistance of a plurality of layers (103) in the composite object (101) in at least three different fiber orientations, each of the at least three different fiber orientations being measured by a respective one of the at least three pairs of plates (116-122, 604-608, 704-714).

[0129] Clause 15. The method of clause 14, wherein measuring the electrical resistance includes:

[0130] measuring the electrical resistance in the 0-degree fiber orientation by a first pair of plates (116) of the plurality of pairs of plates (112);

[0131] measuring the electrical resistance in the 45-degree fiber orientation by a second pair of plates (118) of the plurality of pairs of plates (112);

[0132] measuring the electrical resistance in the -45-degree fiber orientation by a third pair of plates (120) of the plurality of pairs of plates (112); and

[0133] measuring the electrical resistance in the 90-degree fiber orientation by a fourth pair of plates (122) of the plurality of pairs of plates (112).

[0134] Clause 16. The method of clause 14, wherein measuring the electrical resistance includes:

[0135] measuring the electrical resistance in the 0-degree fiber orientation by a first pair of plates (604) of the plurality of pairs of plates (112);

[0136] measuring the electrical resistance in the 60-degree fiber orientation by a second pair of plates (606) of the plurality of pairs of plates (112); and

[0137] measuring the electrical resistance in the -60-degree fiber orientation by a third pair of plates (608) of the plurality of pairs of plates (112).

[0138] Clause 17. The method of clause 14, wherein measuring the electrical resistance includes:

[0139] measuring the electrical resistance in the 0-degree fiber orientation by a first pair of plates (704) of the plurality of pairs of plates (112);

[0140] measuring the electrical resistance in the 30-degree fiber orientation by a second pair of plates (706) of the plurality of pairs of plates (112);

[0141] measuring the electrical resistance in the -30-degree fiber orientation by a third pair of plates (708) of the plurality of pairs of plates (112);

[0142] measuring the electrical resistance in the 60-degree fiber orientation by a fourth pair of plates (710) of the plurality of pairs of plates (112);

[0143] measuring the electrical resistance in the -60-degree fiber orientation by a fifth pair of plates (712) of the plurality of pairs of plates (112); and

[0144] measuring the resistance in the 90 degree fiber orientation by a sixth pair of plates (714) in the plurality of pairs of plates (112).

[0145] Clause 18. The method of clause 17, further comprising:

[0146] moving the testing device (100, 600, 700) including the plurality of pairs of plates (112) in a raster pattern along the surface (110) of the composite object (101).

[0147] Clause 19. The method of clause 14, wherein measuring the resistance comprises:

[0148] at each of the plurality of locations along the surface (110) of the composite object (101), generating a voltage measurement for each of at least three pairs of plates (116-122, 604-608, 704-714).

[0149] Clause 20. A testing device (100, 600, 700) comprising:

[0150] a base (102, 602, 702);

[0151] a plurality of pairs of plates (112) attached to the base (102, 602, 702),

[0152] wherein each pair of plates includes two capacitive plates (124-138, 610-620, 716-738) to measure the resistance of the layer (103) in the composite object (101) at different fiber orientations;

[0153] wherein an area between the plurality of pairs of plates (112) defines a target area (210, 622, 740); and

[0154] wherein, when the plurality of pairs of plates (112) are positioned on the surface (110) of the composite object (101), the voltage measurements generated at each of a plurality of different locations on the surface (110) provide an indication of whether there is a fiber discontinuity in the composite object (101).

[0155] The description of the different example implementations has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the implementations disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Moreover, different example implementations can provide different features to those described above. The chosen embodiments were described to best explain the principles of the embodiments and the practical application, and to thereby enable others skilled in the art to best exploit the embodiments for their own purposes, considering any permutations and the foregoing description being encompassed within the general scope of the disclosure.

Claims

1. An apparatus comprising: Multiple pairs of plates (112, 604-608, 704-714), comprising at least three pairs of plates (116-122, 604-608, 704-714), each pair of plates comprising two capacitor plates (124-138, 610-620, 716-738), the capacitor plates (124-138, 610-620, 716-738) being aligned to measure the resistance of the layer (103) of the composite body on the corresponding fiber orientation; and Base (102, 602, 702), the plurality of pairs of plates (112) are attached to the base (102, 602, 702); Each of the plurality of plate pairs (112, 604-608, 704-714) forms at least a portion of a measurement branch in a circuit for a corresponding fiber orientation, the measurement branch being configured to generate a first voltage output. The circuit further includes a reference branch (404, 506) comprising at least one reference resistor (534, 546, 585, 570) representing the expected effective series resistance, the reference branch being configured to generate a second voltage output; and The voltage difference between the first voltage output and the second voltage output represents the difference between the effective series resistance of the fiber in the corresponding fiber orientation and the expected effective series resistance of the fiber in the corresponding fiber orientation.

2. The apparatus according to claim 1, wherein the plurality of pairs of plates (112) comprises: The first plate pair (116) is used to measure the resistance on the fiber orientation at 0 degrees; The second plate pair (118) is used to measure the resistance at a 45-degree fiber orientation relative to a 0-degree fiber orientation. The third plate pair (120) is used to measure the resistance at a 90-degree fiber orientation relative to a 0-degree fiber orientation; and The fourth plate pair (122) is used to measure the resistance at a -45 degree fiber orientation relative to a 0 degree fiber orientation.

3. The apparatus according to claim 1, wherein the plurality of pairs of plates (112) comprises: The first plate pair (604) is used to measure the resistance on the fiber orientation at 0 degrees; The second plate pair (606) is used to measure the resistance at a 60-degree fiber orientation relative to a 0-degree fiber orientation. and The third plate pair (608) is used to measure the resistance at a fiber orientation of -60 degrees relative to a fiber orientation of 0 degrees.

4. The apparatus of claim 1, wherein the plurality of pairs of plates (112) comprises: The first plate pair (704) is used to measure the resistance on the fiber orientation at 0 degrees; The second plate pair (706) is used to measure the resistance at a 30-degree fiber orientation relative to a 0-degree fiber orientation; The third plate pair (708) is used to measure the resistance at a 60-degree fiber orientation relative to a 0-degree fiber orientation; The fourth plate pair (710) is used to measure the resistance at a 90-degree fiber orientation relative to a 0-degree fiber orientation; The fifth plate pair (712) is used to measure the resistance at a fiber orientation of -60 degrees relative to a fiber orientation of 0 degrees; and The sixth plate (714) is used to measure the resistance at a fiber orientation of -30 degrees relative to a fiber orientation of 0 degrees.

5. The apparatus according to any one of claims 1-2, wherein the plurality of pairs of plates (112) are arranged in a symmetrical octagonal configuration, the symmetrical octagonal configuration defining a test area centrally located relative to the plurality of pairs of plates (112).

6. The apparatus according to any one of claims 1-2, wherein the two capacitor plates of each of the plurality of pairs of plates (112) are spaced apart by the same distance.

7. The apparatus according to any one of claims 1-2, wherein the measuring branch and the reference branch are connected in parallel with each other.

8. The apparatus of claim 7, wherein the measuring branch and the reference branch are connected in parallel with each other and in parallel with an AC voltage source.

9. The apparatus according to any one of claims 1-2, wherein the base (102, 602, 702) is a printed circuit board, and wherein the base and the plurality of board pairs (112) form a test apparatus (100, 600, 700), further comprising: A control box (106) is attached to the base (102), wherein the control box (106) houses circuitry connected to the printed circuit board.

10. A method for testing a complex (101), the method comprising: Multiple pairs of plates (112) comprising at least three pairs of plates (116-122, 604-608, 704-714) are positioned on the surface (110) of the composite body (101); and The resistance of multiple layers (103) in the composite body (101) is measured at at least three different fiber orientations, each of the at least three different fiber orientations being measured by a corresponding pair of the at least three pairs of plate pairs (116-122, 604-608, 704-714); Each of the plurality of plate pairs forms at least a portion of a measurement branch in a circuit for a corresponding fiber orientation, the measurement branch being configured to generate a first voltage output; The circuit further includes a reference branch comprising at least one reference resistor representing the expected effective series resistance, the reference branch being configured to generate a second voltage output; and The voltage difference between the first voltage output and the second voltage output represents the difference between the effective series resistance of the fiber in the corresponding fiber orientation and the expected effective series resistance of the fiber in the corresponding fiber orientation.

11. The method of claim 10, wherein measuring the resistance comprises: The resistance at 0 degrees fiber orientation is measured by the first plate pair (116) in a plurality of plate pairs (112); The resistance at a 45-degree fiber orientation relative to a 0-degree fiber orientation is measured by the second plate pair (118) of the multiple plate pairs (112); The resistance at a fiber orientation of -45 degrees relative to a fiber orientation of 0 degrees is measured by the third plate pair (120) in a multi-plate pair (112); and The resistance at a 90-degree fiber orientation relative to a 0-degree fiber orientation is measured by the fourth plate pair (122) of the multiple plate pairs (112).

12. The method of claim 10, wherein measuring the resistance comprises: The resistance at 0 degrees fiber orientation is measured by the first plate pair (604) in a plurality of plate pairs (112); The resistance at a 60-degree fiber orientation relative to a 0-degree fiber orientation is measured by the second plate pair (606) in a plurality of plate pairs (112); and The resistance at -60 degrees fiber orientation relative to 0 degrees fiber orientation is measured by the third plate pair (608) in a multi-plate pair (112).

13. The method of claim 10, wherein measuring the resistance comprises: The resistance at 0 degrees fiber orientation is measured by the first plate pair (704) in a plurality of plate pairs (112); The resistance at a 30-degree fiber orientation relative to a 0-degree fiber orientation is measured by the second plate pair (706) in a multi-plate pair (112); The resistance at a fiber orientation of -30 degrees relative to a fiber orientation of 0 degrees is measured by the third plate pair (708) in a multi-plate pair (112); The resistance at a 60-degree fiber orientation relative to a 0-degree fiber orientation is measured by the fourth plate pair (710) in a multi-plate pair (112); The resistance at a fiber orientation of -60 degrees relative to a fiber orientation of 0 degrees is measured by the fifth plate pair (712) in a multi-plate pair (112); and The resistance at a 90-degree fiber orientation relative to a 0-degree fiber orientation is measured by the sixth plate pair (714) of the multiple plate pairs (112).

14. The method of claim 13, further comprising: The test apparatus (100, 600, 700) comprising the multiple pairs of plates (112) is moved along the surface (110) of the composite body (101) in a grating pattern.

15. The method according to any one of claims 10-11, wherein measuring the resistance comprises: Voltage measurements are generated at each of a plurality of locations along the surface (110) of the composite body (101) for each of the at least three pairs of plate pairs (116-122, 604-608, 704-714).

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