Advanced model of flexible corrosion mechanism

Abstract

To determine the corrosion tendency of a material system of an aircraft before a material is determined to be suitable for usage in the material system.SOLUTION: A material test device includes a housing for controlling at least one of humidity, pressure, and temperature. The housing includes a jaw, a plate, a first flat wall on the plate, and a second flat wall parallel to the first flat wall across a vertical wall. One of the motor and the device is arranged in the exterior of the housing. In that case, the motor includes a drive shaft connected to a plurality of guide rods in contact with the vertical wall.SELECTED DRAWING: None

Description

Technical Field

[0001]

[0001] Aspects of the present disclosure generally relate to apparatuses and methods for determining the operating performance of a material system.

Background Art

[0002]

[0002] Aircraft experience repeated harsh conditions over the life of their operation. These repeated harsh conditions can result in the degradation of some of the aircraft's component parts. Such degradation can take the form of, for example, coating damage and / or corrosion. Corrosion can contribute to a reduction in the integrity and strength of aircraft components. Specifically, a material system such as an aircraft component can include a fuselage or outer panel, a coated lap joint between two metal panels, or an assembly of a wing and fuselage of an aircraft exterior. The material system can corrode over time due to exposure to mechanical and chemical stresses while the aircraft is in use.

[0003]

[0003] Before a material is determined to be suitable for use as an aircraft material system, it would be desirable to determine the corrosion tendency of that material system. However, the performance of an aircraft material system such as a panel while the aircraft is actually in use in the real world may not correlate with coating and / or corrosion test data.

[0004]

[0004] Accordingly, there is a need in the art for improved apparatuses and methods for determining the operating performance of a material system.

Summary of the Invention

[0005]

[0005] In one aspect, the present disclosure provides an apparatus including a housing configured to control one or more of humidity, pressure, or temperature. The housing includes a joist, a plate, a first planar wall disposed on the plate, and a second planar wall parallel to the first planar wall separated by a vertical wall. A motor or actuator is disposed on the exterior of the housing. In that case, the motor includes a drive shaft coupled to a plurality of guide rods in contact with the vertical wall.

[0006]

[0006] In another aspect, the present disclosure provides an apparatus including a housing configured to control one or more of humidity, pressure, or temperature. The housing includes a joist having one or more fixing screws symmetrically oriented along the joist. The apparatus includes a plate. A motor or apparatus is disposed on the exterior of the housing. In that case, the motor includes a drive shaft coupled to a plurality of guide rods in contact with the vertical wall.

[0007]

[0007] In another aspect, the present disclosure provides a method for determining the performance of a material. The method includes exposing a material system to a relative humidity of 0% to 100% within an apparatus and flexing the material system using a joist within the housing of the apparatus at a first temperature within the housing. A motor or actuator is disposed on the exterior of the housing. The motor includes a drive shaft coupled to a plurality of guide rods in contact with a vertical wall connecting the first planar wall and the second planar wall. The motor or actuator operates at a second temperature different from the first temperature during the flexing. The apparatus includes a joist fixed to the vertical wall. In that case, one or more fixing screws are symmetrically oriented along the joist and configured to clamp the material system within the joist.

[0008]

[0008] To better understand the above-described features of the present disclosure, a more specific description of the present disclosure, briefly summarized above, is provided by reference to the embodiments, some of which are shown in the accompanying drawings. It should be noted, however, that the present disclosure may recognize other equally effective aspects, and the accompanying drawings merely illustrate typical aspects of the present disclosure and should not be considered as limiting the scope of the present disclosure.

Brief Description of the Drawings

[0009]

Figure 1

[0009] A top cross-sectional view of a material testing apparatus for accelerating and controlling the coating failure mode and / or corrosion-related failure mode of a material system according to one aspect of the present disclosure.

Figure 2

[0010] A side cross-sectional view of a material testing apparatus for accelerating and controlling the coating failure mode and / or corrosion-related failure mode of a material system according to one aspect of the present disclosure.

Figure 3

[0011] A perspective view of a flexure device according to one aspect of the present disclosure.

Figure 4

[0012] A perspective view of a motor according to one aspect of the present disclosure.

Figure 5

[0013] A side view of a material system according to one aspect of the present disclosure.

Figure 6

[0014] A side view of a material system according to one aspect of the present disclosure.

Figure 7A

[0015] A plan view of a material system according to one aspect of the present disclosure.

Figure 7B

[0016] A plan view of a material system according to one aspect of the present disclosure.

Figure 7C

[0017] A plan view of a material system according to one aspect of the present disclosure.

Modes for Carrying Out the Invention

[0010]

[0018] For ease of understanding, the same reference numbers are used to denote the same elements common to the figures, where possible. The drawings are not drawn to scale and may be simplified for clarity. Elements and features of one aspect are believed to be advantageously incorporated into other aspects without further elaboration.

[0011]

[0019] The description of the various aspects of the present disclosure is presented for purposes of illustration and is not intended to be exhaustive or limited to the disclosed aspects. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described aspects. The terms used herein are chosen to best explain the principles of the aspects, the practical application, or technical improvement in technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the aspects disclosed herein.

[0012]

[0020] Conventional chambers used to obtain coating and / or corrosion data are unable to apply a uniform force to the material. For example, the chamber may apply a greater mechanical force at a particular location on the material, resulting in simulated corrosion and mechanical data that may not be correlated to real-world use. Accordingly, there is a need for improved apparatus and methods for determining the operating performance of material systems.

[0013]

[0021] Multiple aspects of the present disclosure generally relate to apparatuses and methods for determining the performance of a materials system. The materials system may be an aircraft component and typically includes a substrate, such as a metal, and one or more coatings, such as an epoxy, disposed on the substrate. One or more electrodes, such as an electrode pair, may be disposed on or within the surface of the materials system to electrochemically detect the performance of the materials system, such as corrosion or coating impedance. Determination of the performance of the materials system may be performed by an operator or manufacturer in a laboratory or on an aircraft before, during (in situ), or after the materials system is exposed to flexure processing and / or moisture processing. For example, the materials system may be energized with a spectrometer to provide impedance data for one or more surfaces of the materials system to assist in determining the performance of the materials system during flexure and exposure to moisture.

[0014]

[0022] In one aspect, a materials testing apparatus includes a chamber configured to control one or more environmental parameters, such as humidity, pressure, or temperature. In at least one aspect, the chamber is configured to control humidity, pressure, and temperature. The materials testing apparatus further includes a jaw configured to flex the materials system. The jaw provides a uniform load distribution across the material by clamping the top and bottom of the material. The chamber includes a drive shaft disposed on the exterior of the chamber at a first end and a motor or actuator coupled to a first wall of the chamber at a second end. The motor can be any suitable electric motor, gas-powered motor, pneumatic motor, or hydraulic motor. The actuator can be any suitable electric actuator, gas-powered actuator, pneumatic actuator, or hydraulic actuator. A plurality of guide rods coupled to the drive shaft extend through the chamber and contact a moving beam to provide a uniform tensile force across the material.

[0015]

[0023] The devices and methods of the present disclosure provide a humidity-controlled environment suitable for cryogenic and high-temperature conditions, and monitor material performance such as corrosion or coating impedance for various material systems such as aircraft material systems such as panels, coated lap joints between two or more panels, wing and fuselage assemblies, or combinations thereof. The material systems, devices, and methods of the present disclosure provide the function of reproducing real-world failure modes and failure mechanisms during operation in a controlled exposure environment such as cryogenic conditions and high-temperature conditions.

[0016]

[0024] The mechanical flexure of the material system within the material test device of the present disclosure can apply a uniform force. Thereby, a smoother and more uniform load distribution of the material is generated by applying a symmetric force to the material system within the joe. The combined effect of mechanical and chemical stresses is combined to cause degradation that more accurately reproduces the corrosion and coating failure experienced by material systems such as aircraft panels in the real-world environment. As a result, the coating failure and corrosion found in aircraft material systems during use in the real world of aircraft, such as cryogenic conditions and high-temperature conditions, are more accurately simulated by the methods and devices of the present disclosure. The material systems, methods, and devices of the present disclosure enable testing of coating degradation and corrosion of stand-alone material systems and the interface between coating layers. Thereby, the degradation experienced by material systems such as panels while the material system is actually being used as part of an aircraft is more accurately represented. The material systems, methods, and devices of the present disclosure further provide the reproduction of strain profiles specific to irregular flight. Thereby, improved predictive and forensic investigations of aircraft material systems can be performed.

[0017] Material test device

[0025] Material systems, such as panels, can have one or more surface layers, such as surface finishes, primers, and / or topcoats. Corrosion can occur in one or more of these layers during use due to mechanical and chemical stresses. The material systems, devices, and methods of the present disclosure provide in-situ electrochemical monitoring of impedance to determine corrosion in a situation that mimics the corrosion experienced by a material system under actual use conditions. The material system is subjected to mechanical as well as chemical stresses without degradation of the electrochemical monitoring system. The material systems, devices, and methods of the present disclosure provide electrochemical monitoring of impedance to determine corrosion at one or more of the material system surface, finish surface, primer surface, and / or topcoat surface.

[0018]

[0026] FIG. 1 is a top view of a material testing apparatus 100 for accelerating and controlling coating failure modes and / or corrosion-related failure modes of a material system according to one aspect of the present disclosure. FIG. 2 is a side view of the material testing apparatus 100 of FIG. 1. One or more components of the material testing apparatus 100 are made of a material that exhibits resistance to a corrosive environment, such as an environment containing moisture (e.g., salt spray), an environment containing acidity and / or alkalinity (e.g., acid spray or alkali spray), or a combination thereof. As shown in FIGS. 1 and 2, the material testing apparatus 100 includes a housing 160 having one or more spray nozzles 102 (one is shown) disposed therein and configured to spray a treatment liquid, such as salt spray, within the housing 160. A fixed support is disposed within the housing to support the material system for being exposed and flexed internally. The material testing apparatus 100 includes a liquid reservoir 104 for supplying the treatment liquid to the spray nozzles 102. The spray nozzles 102 may be nozzles such as atomizing nozzles, nozzles calibrated for air consumption, BETE full cone nozzles, hollow cone nozzles, fan mist nozzles, tank cleaning spray nozzles, air assist nozzles, for example, NASA Mod1 nozzles for water spray atomization and droplet control, mist spray nozzles, for example, Q-Lab OEM atomizing nozzles, spray applicator nozzles, for example, Cool Clean ChilAire™ Lite, or combinations thereof. The spray nozzles 102 may be made of a material such as hard rubber, plastic, or other inert materials.

[0019]

[0027] The fixed support includes joists 124a - f configured to flex the material system. The joists 124a - f can be configured to flex, e.g., bend, the material system from a first position to a second position. During the flexing process, the second position can be from above 0° to about 180° from the starting position, e.g., from about 5° to about 90°, e.g., from about 5° to about 45°. The plate 146 is configured to support the moving beam 180 and the stationary beam 182. The stationary beam 182 supports the joists 124a - f. The plate 146 is disposed between the spray nozzle 102 and the joists 124a - f (shown in FIGS. 1 and 2) and allows the treatment liquid to enter the housing without directly impinging on the material system held by one or more of the joists 124a - f. This configuration mimics a typical humid atmospheric condition as compared to direct rainfall on an aircraft's material system. This enables accurate modeling of the various environments to which an aircraft's materials can be exposed during operation. Alternatively, the joists 124a - f are disposed between the spray nozzle 102 and the plate 146 (this configuration is not shown) and provide a direct flow of the treatment liquid towards the material system held by one or more of the joists 124a - f. This configuration mimics direct rainfall or aerosol on an aircraft's material system. The spray nozzle 102 can be configured to adjust the flow angle and allow the treatment liquid to flow at one or more angles relative to the material system surface. In at least one aspect, the surface of the material system can be parallel to the main direction of the liquid flow through the material testing apparatus 100 based on the main surface being tested. This reduces liquid accumulation on the material system during the corrosion test performed within the material testing apparatus 100. In such aspects, the spray nozzle 102 can be directed or adjusted by a baffle plate so that the liquid does not directly impinge on the material system. (The spray nozzle 102, the discharge port 122, the guide rod 168, the outer housing 136, and the legs 148a - f are shown in dashed lines in FIG. 1 to indicate that these components are disposed behind the plate 146 in one aspect shown in FIG. 1.)

[0020]

[0028] The spray pump 108 is configured to assist the flow of liquid from the liquid reservoir 104 to the spray nozzle 102 via the first fluid line 106 and the second fluid line 110. The first fluid line 106 is connected to the liquid reservoir 104 at a first end and to the spray pump 108 at a second end, coupling the two and providing liquid communication between the liquid reservoir 104 and the spray pump 108. The second fluid line 110 is connected to the spray pump 108 at a first end and to the spray nozzle 102 at a second end, coupling the two and providing liquid communication between the spray pump 108 and the spray nozzle 102.

[0021]

[0029] A compressed air source 112 and a bubble tower 114 are configured to provide humidified air to the spray nozzle 102. In at least one aspect, the pressure within the chamber can be adjusted to mimic the pressures that an aircraft experiences at various altitudes during real-world use. Thus, the compressed air source 112 is configured to flow air at pressures in the range of from about 2 pounds per square inch (PSI) to about 50 PSI, from about 5 PSI to about 30 PSI, from about 12 PSI to about 18 PSI. In these ranges, the lower pressure value side mimics the pressure that an aircraft experiences at higher altitudes, while the higher pressure value side mimics the pressure that an aircraft experiences at lower altitudes closer to sea level. The air may contain a mixture of gases similar to those found in the atmosphere, including, among other gases, for example, about 78% N2, about 21% O2, and about 0.039% CO2. A third fluid line 116 is connected to and couples the bubble tower 114 at a first end and the spray nozzle 102 at a second end, providing liquid communication between the bubble tower 114 and the spray nozzle 102. A compressed air line 118 is connected to and couples the compressed air source 112 at a first end and the bubble tower 114 at a second end, providing liquid communication between the compressed air source 112 and the bubble tower 114. The bubble tower 114 may contain a liquid such as an aqueous fluid or an organic fluid. For example, the valve tower 114 may contain a hydraulic fluid, a hydrocarbon fluid, water, or any other fluid suitable for providing humidification. The bubble tower 114 may provide initial or further humidification to the air flowing from the compressed air source 112 via the compressed air line 118.

[0022]

[0030] The discharge port 122 can be coupled to the first wall 130, the second wall 132, or the third wall 152 (FIG. 2) to adjust the pressure inside the material testing apparatus 100. A heater 120 can be provided and configured to adjust the temperature inside the material testing apparatus 100, such as the housing 160. The heater 120 is disposed adjacent to the first wall 130 of the material testing apparatus 100 and can be coupled to the third wall 152 (FIG. 2). The heater 120 can be attached to the third wall 152 by any suitable attachment element, such as a rivet. The heater 120 can be coupled to and controlled by a controller 138.

[0023]

[0031] A fixed support including one or more joists is configured to support and flex a material system disposed within a housing for testing. The joists 124a, 124b, 124c, 124d, and 124e support the material system by clamping the upper and lower portions of the material system to ensure a uniform pressure along the sides of the material. Without being bound by theory, the uniform pressure can enable the joists 124a, 124b, 124c, 124d, and 124e to uniformly flex the material system, such as a panel, a coated lap joint between two metal panels, a wing and fuselage assembly, or combinations thereof. The material system can be an aircraft material system, such as a panel, like a flat panel of an outer skin or fuselage. The material system can have a width, for example, of about 4 inches and a length, for example, of from about 6 inches to about 14.5 inches. The fixed support can flex the material system to impart a strain in the range of from about 0.05% to about 50%, from about 0.1% to about 30%, from about 0.3% to about 5%, for example, about 0.37%.

[0024]

[0032] Jaws 124a - f are configured to bend the material system from a first starting position to a second position that is fully or partially bent. Jaws 124a - f are configured to bend the material system from the first position to the second position. During the bending process, the second position ranges from greater than 0° to about 180° from the starting position, for example, from about 5° to about 90°, for example, from about 5° to about 45°. Jaws 124a - e can be of the same size or different sizes. For example, jaw 124a may be the same size as jaw 124b, but can be a different size from jaw 124d (as shown in FIG. 1). Further, jaws 124a - e can be positioned from each other by the same or different distances as the distances between different pairs of jaws 124a - f. For example, the first distance between jaws 124a and 124b may be different from the second distance between jaws 124d and 124e. During the process of exposure and bending within the material testing apparatus 100, the various sizes of the jaws and the various distances between the jaws provide for the simultaneous testing of material systems of various sizes, such as panels. In at least one aspect, one or more of jaws 124a - f include steel. In at least one aspect, one or more of jaws 124a - f include a corrosion - resistant material (e.g., titanium). In at least one aspect, one or more of jaws 124a - f are anodized. In at least one aspect, one or more of jaws 124a - f include an inert material such as hard rubber and / or plastic. One or more of jaws 124a - f may include an insulating material such as polyethylene (e.g., a density of 0.94 g / cm 3 ³ or greater) and / or fiberglass to provide for the maintenance of the temperature of the jaws (and the material system) independent of the temperature of the motor 126. In such multiple aspects, the temperature of jaws 124a - f can be maintained at a desired temperature, for example, from about - 196°C to about 100°C, while the motor 126 is also maintained at a desired temperature, for example, from about - 30°C to about 50°C.

[0025]

[0033] In at least one aspect, jaws 124a - f are configured to support a material system, such as a panel, at an angle of about 15° to about 30° with respect to the first wall 130 and / or the second wall 132. Thereby, during a corrosion test performed within the material testing apparatus 100, the accumulation of liquid on the material system is reduced, and by mimicking the direction used during operation, an enhanced modeling of the material system can be provided. In at least one aspect, jaw 124a is configured to grip the material system at a first end of the material system, and jaw 124a is configured to grip the material system at a second end of the material system. In at least one aspect, jaws 124a - f are configured to flex the material system simultaneously and / or alternately. Thereby, additional modeling parameters of the material system can be provided.

[0026]

[0034] The motor 126 operates the jaws 124a - f. The motor 126 is disposed on the exterior of the first wall 130. In that case, as described below, the drive shaft 402 is coupled to the guide rod 168. The guide rod 168 extends through one or more chamber walls and is coupled to the jaws 124a - f. The guide rod 168 can apply one or more tensile or compressive forces to the jaws 124a - f. The guide rod can be a material resistant to environmental - based corrosion, such as humidity, salt, pressure, or combinations thereof. For example, the guide rod 168 can be titanium. The guide rod 168 extends through one or more chamber walls and couples to the jaws 124a - f. Thereby, the moving parts of the motor 126, such as actuators, drive shafts, or bearings, are disposed outside the chamber. Thereby, the corrosion of the moving parts of the motor can be reduced. Without being bound by theory, this allows for less maintenance and fewer chamber malfunctions, as the moving parts, such as the drive shaft, are not exposed to the corrosive environment.

[0027]

[0035] Jaws 124a - f are supported by a plate 146. The plate 146 is supported by legs 148a, 148b, 148c, 148d, 148e, and 148f. The legs 148a - f are coupled to the plate 146 at a first end and are coupled to a chamber, a rack 150a, or a rack 150b at a second end. The plate 146 can be disposed between the housing 136 and the jaws 124a - f. The plate 146 can be made of an insulating material such as polyethylene (e.g., high - density polyethylene) and / or fiberglass to provide a temperature control barrier between the motor 126 and the jaws 124a - f. In such a plurality of embodiments, the temperature of the jaws 124a - f can be maintained at a desired temperature inside the chamber while the motor 126 is also maintained at a desired temperature outside the chamber.

[0028]

[0036] The motor 126 uses a drive shaft 402 to convert into a bending motion inside the chamber via a guide rod 168. The drive shaft 402 can include a screw such as a ball screw, an acme screw, a lead screw, a roller screw, and a screw mount, or a shaft coupled to the jaws 124a - f. As will be described in more detail below, the guide rod 168 maintains the spacing between the stationary beam 182 and the moving beam 180 while being deflected.

[0029]

[0037] The apparatus and material system of the present disclosure include one or more electrodes, such as one or more electrode pairs. The electrodes may be coupled to a substrate (to form the material system), and then a material testing apparatus 100 is used to test the operating performance of the material system. During deflection, the central portion of the material system will experience more strain than the ends of the material system. Thus, electrode pairs disposed on the same side of the material system detect impedance across the same side of the material system.

[0030]

[0038] As shown in FIGS. 1 and 2, the material testing apparatus 100 includes electrode pairs 156 and 158. Although electrode pairs are shown in FIGS. 1 and 2, in an alternative aspect, the apparatus 100 comprises a single electrode. The electrode pair 156 is configured to be coupled to a first side (not shown) of the material system, and the electrode pair 158 is configured to be coupled to a second side (not shown) of the material system. The electrodes can be made of conductive epoxy, nickel, gold, silver, copper, platinum, palladium, or a mixture thereof. In at least one aspect, at least one electrode is a conductive epoxy such as electrode pairs 156 and / or 158. In at least one aspect, the conductive epoxy is a conductive silver epoxy, providing enhanced conduction compared to other transition metals. The electrode pair 156 is coupled to the spectrometer 164 via an electrical line 162 to provide energization between the electrode pair 156 and the spectrometer 164. Further, the electrode pair 158 is coupled to the spectrometer 164 via an electrical line 166 to provide energization between the electrode pair 158 and the spectrometer 164. The electrical lines 162, 166 can be insulated wires (e.g., insulated steel wires) or wires having insulated conductive tape. As will be described in more detail below, the electrode pair 156 is configured to be coupled to a first side of the material system, and the electrode pair 158 is configured to be coupled to a second side of the material system. In at least one aspect, the spectrometer 164 includes a potentiostat, a galvanostat, and / or a zero-resistance ammeter. The spectrometer 164 can be an electrochemical impedance spectrometer such as the Reference 600 from Gamry Instruments or the VMP300 from Bio-Logic Science Instruments. The electrodes (e.g., electrode pairs 156 and 158), when coupled to the material system, detect an electrical signal from the material system and transmit this electrical signal to a spectrometer such as the spectrometer 164. The spectrometer 164 is configured to interpret the electrical signal and provide electrical data such as impedance regarding the state of the material system, such as corrosion. Electrochemical impedance is typically measured by applying an AC potential to an electrochemical cell and then measuring the current passing through this cell. The response to this potential, for example, a sinusoidal potential, is an alternating current signal.This current signal can be analyzed as a sum of sine functions (Fourier series). Electrochemical impedance is usually measured using a small excitation signal. This is done to make the response of the cell pseudo-linear. In a linear (or pseudo-linear) system, the current response to a sinusoidal potential will be a sine curve with the same frequency but a phase shift. Data from electrochemical impedance spectroscopy (EIS) is typically analyzed from the perspective of an equivalent circuit model. Echem Analyst (a German software product) finds a model that matches the data where the impedance was measured.

[0031]

[0039] The components of the material testing apparatus 100 described herein may include materials that are suitably inert with respect to the conditions within the material testing apparatus 100 during the cyclic flexure spray process. Suitably inert materials may include polyethylene (e.g., high density polyethylene), fiberglass, plastic, glass, stone, metal, rubber, and / or epoxy. Other materials that may be used to fabricate components of one or more of the components of apparatus 100 include high density polypropylene, commercially available grades of titanium (II) with polyethylene inserts, stainless steel with polyethylene inserts, and combinations thereof.

[0032]

[0040] The material testing apparatus 100 can be controlled by a processor-based system controller such as a controller 138. For example, the controller 138 can be configured to control the components of the material testing apparatus 100 and the processing parameters associated with the cyclic flexure spray process. The controller 138 includes a programmable central processing unit (CPU) 140 that operates with a memory 142, a mass storage device, an input control unit, and a display unit (not shown), such as a power supply, a clock, a cache, input / output (I / O) circuits, etc., coupled to various components of the material testing apparatus 100 to facilitate control of the cyclic flexure spray process. The controller 138 can be energized, for example, with the outlet tube 134, the outlet 122, the heater 120, and / or the jaws 124a - f.

[0033]

[0041] To facilitate the control of the above-described material testing apparatus 100, the CPU 140 may be one of any form of general-purpose computer processor that can be used in industrial settings, such as a programmable logic controller (PLC) for controlling various chambers and sub-processors. The memory 142 is coupled to the CPU 140, and the memory 142 is non-transitory and may be one or more of readily available memories such as random access memory (RAM), read-only memory (ROM), floppy disk drive, hard disk, or any other form of local or remote digital storage. To support the processor in a conventional manner, a support circuit 144 is coupled to the CPU 140. Information obtained from the cyclic flexure spray process using the material testing apparatus 100 may typically be stored in the memory 142 as software routines. The software routines may also be stored and / or executed by a second CPU (not shown) located remotely from the hardware controlled by the CPU 140. The memory 142 takes the form of a computer-readable storage medium containing instructions that facilitate the operation of the apparatus 100 when executed by the CPU 140. The instructions in the memory 142 take the form of a program product, such as a program implementing the processes of the present disclosure. The program code may conform to any one of a number of different programming languages. In at least one aspect, the present disclosure may be implemented as a program product stored on a computer-readable storage medium for use in a computer system. The program of the program product defines the functions of a plurality of aspects (including the methods described herein). Exemplary computer-readable storage media include, but are not limited to, the following.(i) A non-writable storage medium in which information is permanently stored (e.g., a read-only memory device inside a computer, such as a CD-ROM disk readable by a CD-ROM drive, a flash memory, a ROM chip, or any type of solid-state non-volatile semiconductor memory), and (ii) A writable storage medium in which alternative information is stored (e.g., a floppy disk or a hard disk drive inside a disk drive, or any type of solid-state random access semiconductor memory). When such a computer-readable storage medium holds computer-readable instructions for managing the functions of the methods and apparatuses of the present disclosure, such a computer-readable storage medium is an aspect of the present disclosure.

[0034]

[0042] FIG. 3 is a perspective view of a bender 300 configured to perform periodic flexure, according to one aspect of the present disclosure. The bender 300 can be disposed inside a material performance chamber, such as the material testing apparatus 100, as described with reference to FIG. 1. As shown in FIG. 3, the bender 300 includes a moving beam 180 and a stationary beam 182. The stationary beam 182 can be attached to the plate 146 by one or more mounting bolts. The moving beam 180 is slidably disposed on the plate 146 adjacent to the stationary beam 182. Without being bound by theory, the bender 300 having the moving beam 180 and the stationary beam 182 applies a uniform force to the material fixed between the beams. The linear movement between the stationary beam 182 and the moving beam 180 is maintained by guide rods 168a and 168b. The guide rods 168a and 168b can include titanium, stainless steel, high density polypropylene, high density polyethylene, chromium (such as Armoloy® coating), and combinations thereof. Each of the guide rods 168a and 168b is coupled to the stationary beam 182 and the moving beam 180. The guide rods 168a and 168b are parallel to each other. Only two guide rods 168a and 168b are shown in FIG. 1, but any suitable number of guide rods can be implemented, for example, from about 1 guide rod to about 10 guide rods, such as from about 1 to about 3, from about 3 to about 5, from about 5 to about 7, or from about 7 to about 10 guide rods. Without being bound by theory, two or more guide rods can reduce the bending of the moving beam or the stationary beam, thereby generating a smoother and more uniform load distribution between the test stages as compared to an apparatus having a single guide rod. Without being bound by theory, longer guide rods 168a and 168b can provide a more uniform force distribution across a plurality of materials disposed within the jaws 124a-f. Alternatively, shorter guide rods 168a and 168b can provide a uniform load across a plurality of materials disposed within the jaws 124a-f.

[0035]

[0043] The stationary beam 182 and the moving beam 180 attach or otherwise support the jaws 124a - f. The stationary beam 182 attaches the first sides of the jaws 124a - f to a stationary position while being deflected, while the moving beam 180 attaches the second sides of the jaws 124a - f and enables movement of the second sides of the jaws 124a - f while being deflected. The stationary beam 182 and the moving beam 180 may include high - density polyethylene. While being deflected, the moving beam is laterally shifted relative to the stationary beam from a starting point to an end point, resulting in deflection of the material system disposed within the jaws 124a - f. The starting point, the end point, and the shift distance may be controlled by the user of the deflector 300 based on the mechanical boundary limits of the test fixture, mechanical stop blocks, or the control of the drive system software of the fixture.

[0036]

[0044] Each of the stationary beam 182 and the moving beam 180 includes a second planar wall 312 separated from the first planar wall 310 by the perpendicular wall 308. These can form an I-beam structure, such as an I-beam, joist, truss, rafter, or T-beam. The first planar wall 310 and the second planar wall 312 can be parallel to each other. Without being bound by theory, the I-beam structure can enhance rigidity and result in a uniform distribution of stress to each test material. The perpendicular wall 308 includes a plurality of attachment positions 314a - f, where each attachment position can enable each of the jaws 124a - f to be attached to the perpendicular wall 308. The attachment positions can be at right angles, angled, or a combination thereof, and can provide angles at which each of the jaws 124a - f can be attached. The attachment positions 314a - f can be centered with respect to two or more guide rods. Thereby, torque in the Y-axis associated with the position can be minimized, providing uniform bending of the material system. Further, the attachment positions 314a - f can be symmetric with respect to the center of the stationary beam or the moving beam to reduce any torque in the Z-axis. The positions of the attachment positions 314a - f are centered with respect to two or more guide rods, and when the moving beam 180 moves towards the stationary beam 182, a uniform force can be applied to the jaws 124a - f, making it possible to generate compression of the material.

[0037]

[0045] Jaws 124a - f include one or more fixing screws 310 that clamp the ends of the material within Jaws 124a - f. The one or more fixing screws 310 apply a uniform force across the material. Thereby, the material is uniformly fixed within Jaws 124a - f. Without being bound by theory, by using the fixing screws 310 at both the top and bottom of the material to fix the material, a uniform force will be applied to both the top and bottom of the material. One side of the material will be prevented from having a greater force applied to it. Otherwise, an inappropriate simulation of the material could result. Jaws 124a - f can be hinged. This allows for bending of the material system while compressing the material system. For example, Jaws 124a - f can be attached on one side of each attachment position on the vertical wall 308 and can be arranged at an angle, for example, from 15° to 30° with respect to a line perpendicular to the base. Other angles are considered in comparison to vertical to achieve the desired test conditions for the material panel. The angle of Jaws 124a - f determines the angular position of the material system. In at least one aspect, the material system is arranged at an angle, for example, from 15° to 30° with respect to a line perpendicular to the base.

[0038]

[0046] In at least one aspect, the joes 124a - f are non - conductive and non - metallic so as to have little or no galvanic effect on the material system. One or more of the joes 124a - f can include high - density polyethylene, a commercially available grade of titanium (II) with a polyethylene insert, sacrificial 316SS with a polyethylene insert, or combinations thereof. This prevents (partial or complete) galvanic corrosion of the joe and the material system during testing. One or more of the joes 124a - f can be provided with, for example, a sleeve cover including polyethylene. This further prevents galvanic corrosion of the joe and the material system during testing. The electrode pair 158 of the material testing apparatus 100 is disposed directly on the first side of the material system disposed within the joe 124f. Also, an electrode pair 156 (not shown) of the material testing apparatus 100 is disposed on the second side of the material system opposite the first side. As will be described below, while the material testing apparatus 100 is in use (e.g., while testing the material system), a non - conductive protective coating 512 can be disposed on the electrode pairs 158 and 156 to protect the electrodes from the corrosive environment. The non - conductive protective coating includes a non - conductive epoxy, tape, adhesive, sealant, or mixtures thereof. For example, the non - conductive epoxy can be a two - part waterproof epoxy.

[0039]

[0047] FIG. 3 shows the electrodes 156 and 158 disposed directly on the material system disposed within the joe 124f, but it should be understood that the material system (and apparatus) of the present disclosure includes a plurality of aspects as follows. That is, one or more electrodes and / or electrode pairs are not disposed directly on the material system disposed within one or more of the joes 124a - f, and the electrodes and / or electrode pairs can be energized to a spectrometer 164 via electrical lines similar to or the same as the electrical lines 162, 166. Such a plurality of aspects provides in - situ monitoring of a plurality of material systems within a material performance chamber such as the material testing apparatus 100. Further, as will be described below, a non - conductive protective coating can be disposed on the electrodes and / or electrode pairs.

[0040]

[0048] A flexer, such as flexer 300, can provide various movements of the moving beam and the material system at a variable frequency that can be adjusted in real time. The flexer can also apply tensile and compressive forces to the material system while exposing the material to one or more environmental conditions. Without being bound by theory, flexer 300 can increase the stiffness of the moving beam and the stationary beam compared to previous material systems while simplifying the assembly and reducing costs. Further, without significant bending of the beam and without having moving parts of the motor inside the chamber that exposes the material to one or more environmental conditions, the symmetry of the panel position can distribute a uniform load. Thus, a reduction in the risk of wear and corrosion can be achieved. This can reduce the maintenance and downtime of the device.

[0041]

[0049] In at least one aspect of the present disclosure, a material performance chamber includes two or more flexers 300. In at least one aspect where the material performance chamber includes two or more flexers 300, guide rods 168a and 168b extend through the plurality of flexers 300.

[0042]

[0050] FIG. 4 is a perspective view of a motor 400 configured to provide a tensile or compressive force to the flexer 300, according to one aspect of the present disclosure. A support structure 401 is disposed adjacent to the chamber. The support structure 401 may be configured to support one or more inlets or outlets coupled to the chamber without applying a load to the chamber. Two or more guide rods 168a and 168b are disposed between the support structure and the motor 126. The two or more guide rods 168 may extend or retract along a first axis. Thereby, the guide rod applies a tensile or compressive force to a flexer (not shown). The guide rod 168 is extended or retracted by a motor 126 that operates a drive shaft 402. The drive shaft 402 may convert the rotation of the motor into linear motion, for example, longitudinal motion that extends or retracts the guide rod 168. In some embodiments, a plurality of drive shafts 402 may be incorporated to facilitate smooth linear motion of the guide rod 168. The motor 126 may be coupled to an aligner 403. The aligner 403 may provide easier alignment of the guide rod 168 passing through the chamber.

[0043]

[0051] Without being bound by theory, reduced corrosion and damage to the motor and / or the movable parts of the motor can be reduced because the movable parts of the motor are located outside the chamber. Thereby, maintenance, wear, and downtime can be reduced.

[0044] Material system

[0052] In at least one aspect, the material system includes a metal panel including a coating disposed on the material panel. The coating may include an epoxy coating, as described below. The metal panel may be flat. The material properties of the flat panel, such as the properties of the metal panel, the properties of the coating, the adhesion of the coating to the metal panel, or combinations thereof, are tested by periodically flexing the material system while exposing the panel to at least one cycle of humidity, such as salt spray. Before, during, and / or after the exposure and flexing, the material system is evaluated for the onset of corrosion, propagation rate, and performance.

[0045]

[0053] In at least one aspect, prior to being exposed to at least one cycle of salt spray, a substrate is provided having two flat metal panels that are connected, joined, welded, or fastened together using metal fasteners, screws, bolts, or other hardware, in order for a material system to provide an evolved modeling and improved design of areas of an aircraft that are susceptible to wear and damage.

[0046]

[0054] In at least one aspect, a material system includes a mechanical joint or knuckle joint that is made of a metallic material or a composite material and can be coated prior to being exposed to one cycle of salt spray and / or prior to being evaluated for corrosion initiation, propagation rate, and performance, in order for the material system to provide an evolved modeling and improved design of areas of an aircraft that are susceptible to wear and damage.

[0047]

[0055] In at least one aspect, a material system includes a structural system that can reproduce aircraft components representative of fuselage side joins, stringer-fuselage assemblies, fuselage panels, or wing spar-fuselage assemblies. The manufactured assembly can be operated or flexed while being exposed to at least one cycle of salt spray, as described herein, prior to / during being evaluated for corrosion initiation, propagation rate, and performance, in order for the material system to provide an evolved modeling and improved design of areas of an aircraft that are susceptible to wear and damage.

[0048]

[0056] FIG. 5 is a side view of a material system 500 showing a conductive metal component 502 and a coating layer 504 disposed on the component 502. The metal substrate 502 can be made of titanium, aluminum, copper, or alloys thereof. The metal substrate 502 may be coated with one or more primer agents such as a chromate-containing primer, a surface finishing agent, and / or a top coating agent. For example, the coating layer 504 can be made of a chromate-containing primer, an epoxy primer, a urethane primer, or a mixture thereof. An electrode 506 (which can be part of an electrode pair such as electrode pair 158) is disposed directly on the coating layer 504 and is a reference electrode. An electrode 508 (which can be part of an electrode pair such as electrode pair 156) is disposed directly on the metal substrate 502 and is a working electrode. In at least one aspect, an insulating adhesive such as a non-conductive epoxy is disposed between the electrode 508 and the metal substrate 502. For spectroscopic measurements during testing, the working electrode 508 is attached to the conductive metal substrate 502 and an electrical signal is transmitted through the working electrode (or electrode pair). This signal then travels through the coating layer 504 and is received by the electrode 506 (of electrode pair 158) and transmitted to the spectrometer 164. In an alternative aspect, the working electrode 508 and the reference electrode 506 are each disposed (e.g., directly) on the coating layer 504.

[0049]

[0057] In a plurality of embodiments where a coating layer, such as coating layer 504, is made of epoxy and the electrodes disposed on the coating layer are made of conductive epoxy, it has been found that the epoxy materials of the coating layer and the electrodes absorb into each other. Alternatively, the electrodes are nickel or include nickel. Thereby, conduction of electrons across the electrodes can be increased. It is optional to use an adhesive to bond the two materials such that the electrodes are disposed directly on the coating layer. In such embodiments, the surface of the coating layer can be lightly polished and then the electrodes can be added directly onto the polished surface. In the case of epoxy electrodes, this "like-on-like" interaction between the coating layer and the electrodes improves the compatibility of the interface between the electrodes and the coating layer. The improved compatibility between the electrodes and the coating layer improves the thermal and mechanical properties between the coating layer and the electrodes. Conventional electrodes are operably connected to a substrate surface by a non-conductive adhesive. These adhesives inhibit the flow of electricity between the electrodes and the substrate, such as the coating layer, and produce inaccurate spectroscopic data. Using such adhesives causes the electrical properties of the material system to be affected by a component (the adhesive) that is not a component likely to be used in a commercial use of the material system. The adhesives introduce a sharp gradient in the mechanical, chemical, and thermal performance of the material system where the electrodes are disposed. The improved compatibility between the electrodes and the coating layer of the material system of the present disclosure results in homogeneity between the electrodes and the coating layer, thereby reducing the noise observed in the spectroscopic signal.

[0050]

[0058] As a comparative example with a material system having an epoxy electrode, a material system having a metal electrode deposited on the coating layer was tested. Electrochemical monitoring of the material system having a metal electrode deposited on the coating layer results in an EIS spectrum showing only the "air" curve. This indicates that the interaction between the metal electrode and the coating layer is insufficient. As used herein, the "air curve" represents an open lead experiment. In this experiment, an EIS spectrum in which no cell adheres at all is recorded. The spectrum from the open lead experiment appears very similar to a noisy spectrum for a parallel RC network. Therefore, when an air curve is observed in the data, the leads from the spectrometer are not in any electrical contact with the coating, and an EIS spectrum of open air (i.e., the "air curve") is being collected.

[0051]

[0059] Furthermore, it has been discovered that the thickness of the electrodes of the material system can affect the spectroscopic results of the electrochemical monitoring. A plurality of electrodes of the present disclosure, such as electrodes 506 and 508 of electrode pairs 156 and / or 158, can have a thickness of 20 micrometers (μm) or less, such as about 12 micrometers. For example, an electrode having a thickness of about 12 μm or less provides flexibility to the electrodes disposed on and / or within the material system and provides a material system operable to have electrodes disposed on one or more layers of the material system. This is for more accurately electrochemically monitoring each of one or more layers of the material system. In at least one aspect, the electrodes of the present disclosure have a thickness of from about 1 μm to about 12 μm, such as from about 2 μm to about 11 μm, such as from about 3 μm to about 10 μm. In at least one aspect, the coating layer of the present disclosure has a thickness of from about 1 μm to about 500 μm, such as from about 2 μm to about 250 μm, such as from about 3 μm to about 100 μm, such as from about 4 μm to about 15 μm. Further, compared to conventional wires that are too large to be embedded within multiple layers of a multilayer material system, the reduced size of the electrodes of the present disclosure provides smaller / thinner wires (coupled to the electrodes at a first end and to a spectrometer at a second end) for use in the material systems of the present disclosure.

[0052]

[0060] In comparison, electrodes having a thickness of 13 μm or more (such as interlocking electrodes) are more rigid than thinner electrodes and tend to become disconnected from the material system during a flexure test. The rigidity of the thick electrodes impairs the ability of the electrodes to conform to the surface of the material system. Further, when a coating layer of conventional thickness (such as an assembly primer, an interior primer, a fuel tank primer, etc.) is deposited on the electrodes, electrodes having a thickness of 13 μm or more tend to have defects in the upper layer, and then these defects are accentuated during the flexure test. Further, some conventional electrode designs involve piercing through the substrate to create holes for embedding the electrodes within the layer. Such embedded electrodes have the same drawbacks as described for thick electrodes.

[0053]

[0061] In at least one aspect, the electrodes of the material system of the present disclosure are offset from each other. For example, as shown in FIG. 5, electrodes 506 and 508 are offset from each other by a distance (d). By offsetting the electrodes of the material system of the present disclosure, the influence of moisture is reduced. This is because an electrical signal flows where the electrons have the lowest resistance. If the electrodes are not offset from each other, the area under the reference electrode is protected from absorbing electrolyte from moisture. As the water content inside the coating (e.g., inside cracks / fissures) increases during testing, the accuracy of the electrical data also improves. This is because the dielectric constants of water and saline are relatively high compared to that of the least damaged coating. For example, if the electrodes themselves are not protected from moisture, the electrical signals can be inaccurate. Protection of the electrodes from moisture can be achieved by sealing the electrodes with a protective coating 512 such as a non-conductive epoxy.

[0054]

[0062] FIG. 6 is a side view of a material system 600 according to one aspect of the present disclosure. As shown in FIG. 6, the material system 600 is a multi-layer material system including a metal substrate 502, a first coating layer 602, and a second coating layer 504. Electrodes 608 (which can be an electrode pair) are disposed on the metal substrate 502 and are energized with a spectrometer such as spectrometer 164 via an electrical line 610. Further, electrodes 604 (which can be an electrode pair) are disposed on the first coating layer 602 and are energized with a spectrometer such as spectrometer 164 via an electrical line 606. A protective coating (not shown) can be disposed on one or both of electrodes 608 and 604 before depositing subsequent coating layers on the electrodes and equipment. As shown in FIG. 6, electrodes 608 and 604 are inside (e.g., embedded) the material system. The internal electrodes provide in-situ electrochemical monitoring of the individual layers of the material system at the coating / substrate interface of the multi-layer material system to identify corrosion. In at least one aspect, an insulating adhesive such as a non-conductive epoxy is disposed between electrode 608 and the metal substrate 502.

[0055]

[0063] As shown in FIG. 6, electrode 608 and electrode 508 are offset by a distance (d1). Electrodes 508 and 506 are offset by a distance (d2). In that case, electrodes 508 and 506 are protected by a protective coating 512. The protective coating 512 is also disposed on electrical line 166 and / or electrical line 162 to further protect electrical line 166 and / or 162 during flexure and / or salt spray exposure. Electrode 506 and electrode 604 are offset by a distance (d3). (d1), (d2), and (d3) are sized to prevent polarization of the electrodes. Otherwise, it would deviate from the pseudo-linear portion of the voltage-current response curve. In at least one aspect, (d1) = (d2) = (d3). In at least one aspect, (d1), (d2), and / or (d3) is between about 0.3 cm and about 10 cm, for example, between about 0.5 cm and about 3 cm, for example, about 1 cm.

[0056]

[0064] Further, the electrochemical interaction between the electrode and the surface of the underlying layer is affected by variations in the surface area of the surface of the electrode that contacts the surface of the underlying layer. One way to utilize variations in surface area for a desired application is to change the shape of one or more electrodes. This is because, assuming other parameters are equal, different shapes result in different surface areas of the contact surface of the electrode, as will be explained in more detail below. The electrodes of the material system of the present disclosure can have various shapes. For example, the electrodes of the present disclosure are square in shape. Alternatively, the electrodes of the present disclosure have a circular, star-shaped, rectangular, or polygonal shape such as pentagonal, hexagonal, heptagonal, or octagonal. Further, the electrodes of the present disclosure may have one or more spokes protruding (e.g., outwardly) from their shape.

[0057]

[0065] The electrodes of the present disclosure have a surface area that contacts the underlying layer (i.e., the contact surface area, including spokes if present). This is appropriate for the desired application. In at least one aspect, the electrode is about 0.2 cm 2 to about 10 cm 2, for example, about 0.5 cm 2 to about 5 cm 2 , for example, about 1 cm 2 to about 2 cm 2 and have a contact surface area such as this. For specific test applications of the present disclosure, the overall shape, spokes, and surface area can affect the method of electrochemical monitoring.

[0058]

[0066] Figures 7A, 7B, and 7C are plan views of a material system according to one aspect of the present disclosure. As shown in Figure 7A, the material system 500 (of Figure 5) includes an electrode pair 158 having a circular-shaped electrode 506. A protective coating 512 can be disposed on the electrode 506. In at least one aspect, the protective coating 512 is also disposed on an electrical line 166 (not shown) to further protect the electrical line 166 during bending and / or salt spray exposure. As shown in Figure 7B, the material system 700 includes an electrode pair 706 having a rectangular-shaped electrode 702. Each of the electrodes 702 is disposed on a material layer 704. A protective coating 720 (shown transparently for clarity) is disposed on the electrode 702. In at least one aspect, the protective coating 720 is also disposed on a wire 708 (not shown) to further protect the wire 708 during bending and / or salt spray exposure. Each of the electrodes 702 can be energized to a spectrometer via the wire 708. As shown in Figure 7C, the material system 710 includes an electrode pair 714 having a pentagonal-shaped electrode 712. Each of the electrodes 712 has five spokes 712a extending outwardly from the pentagonal shape of the electrode 712. Each of the electrodes 712 is disposed on a material layer 718. A protective coating 722 (shown transparently for clarity) is disposed on the electrode 712 / 712a. In at least one aspect, the protective coating 722 is also disposed on a wire 716 to further protect the wire 716 during bending and / or salt spray exposure. The electrode 702 can be energized to the spectrometer via the wire 716.

[0059]

[0067] Further or alternatively, the degree of corrosion of the material system of the present disclosure may be determined by a mass loss method by weighing the material system after a cyclic flexing process and subtracting that weight from the weight of the material system before the cyclic flexing process. The mass loss method is advantageous in embodiments where electrodes are not disposed on the material system of the present disclosure.

[0060] Manufacture of the Material System

[0068] Manufacturing the material system of the present disclosure may include lightly polishing the area of the coating layer to which the electrodes are to be added. The polished area can be washed with any solvent and dried. Manufacturing further includes disposing electrodes on the coating layer, such as the polished area of the coating layer. The insulating ends of wires, such as electrical line 166, may be removed to form the exposed portions of the wires. The exposed portions are then contacted to the electrodes, after which non-conductive tape and / or a protective coating (such as protective coating 512) is added.

[0061]

[0069] The electrodes (and coating layer) of the present disclosure may be disposed on a metal substrate or layer by any suitable deposition process. Deposition processes include screen printing and three-dimensional printing. Additionally, photolithography may be applied to the coating layer, followed by depositing the electrodes within the photolithographically processed regions of the layer.

[0062]

[0070] The electrodes can be deposited, for example, using any suitable screen printing apparatus (e.g., supplied by ASM Assembly Systems of Munich, Germany). Screen printing can be carried out using a screen having one or more openings shaped in the desired shape and dimensions for electrode formation. The deposition material may be placed on part of the screen and subsequently squeegeed across the openings. Specifically, the screen is placed above and directly above the printing surface, whereby the ink can be accurately deposited at the desired position. As the squeegee moves across the screen, the mesh of the screen is brought into contact with the surface by the squeegee. The ink is pushed out into the empty area and a pattern is formed. The excess is removed by the blade of the squeegee. The mesh should be peeled off the surface immediately after the squeegee passes so that all the ink that was in the mesh remains deposited on the printing surface. Next, the screen can be lifted and released. The recommended screen tension is the tension required to stretch the mesh enough to peel the screen from the substrate after printing but not so much as to cause damage. The applied tension depends on the material of the screen. For example, the tension used for nylon mesh is usually 6% and for polyester it is 3%. It is common practice for the squeegee to be held at an angle of 45° with respect to the frame area.

[0063]

[0071] The electrodes can be deposited, for example, using any suitable 3D printing device (e.g., supplied by nScrypt, Inc. of Orlando, Florida). The nScript device dispenses a conductive ink, such as DuPont CB230 silver-coated copper conductive ink or DuPont CB028 flexible silver ink, at a material flow rate adjusted by backpressure on the nozzle. The movement speed of the nozzle and the backpressure of the material within the nozzle are directly proportional to the flow rate while the patterning is constant. The nScript printing device has a backpressure in the range from 0 psi to about 30 psi. A backpressure of 18 psi can be used to deposit the conductive ink on the coated panel. This backpressure corresponds to a flow rate of about 0.052 grams per minute. After deposition of the electrodes by the nScript device, the ink is baked at an elevated temperature for a certain period of time, for example, from about 150 °C to about 170 °C for about 10 to 30 minutes to promote curing.

[0064]

[0072] The coating layer may be photolithographically processed, for example, using any suitable photolithography device. Electrodes formed by photolithography are typically interdigitated electrodes.

[0065]

[0073] Suitable interdigitated electrodes can be obtained, for example, from Synkera Technologies, Inc. of Longmont, Colorado, or Micrux Technologies, S.L. of Oviedo, Spain.

[0066] Test method

[0074] For example, a materials testing process such as a cyclic flexure spraying process within a materials testing apparatus 100 can be performed by exposing a materials system such as a panel to a treatment fluid such as salt spray and flexing the materials system. The exposure can be performed over a period of from about 1 hour to about 4500 hours, for example, from about 200 hours to about 2000 hours, for example, from about 500 hours to about 1000 hours. In at least one aspect, an exposure zone such as housing 160 has a relative humidity of from about 0% to about 100%, for example, from about 30% to about 95%, for example, ambient humidity. Exposing the materials system to a relative humidity of 30% or less for about 1 hour mimics, for example, the salt spray exposure that a materials system as part of an aircraft experiences in a dry climate. Exposing the materials system to a relative humidity of 80% or more for about 4500 hours mimics, for example, the salt spray exposure that a materials system as part of an aircraft experiences in a very wet climate or a moderately wet climate over a very long period. The liquid can include water which is reagent grade water. The liquid can be salt water. The salt water can include sodium chloride. The salt water can contain from about 2 parts sodium chloride in 98 parts water to about 6 parts sodium chloride in 94 parts water, for example, about 5 parts sodium chloride in 95 parts water. A liquid such as salt water can contain less than about 0.1% bromide, fluoride, and iodide. A liquid such as salt water can contain less than about 1 mass ppm, for example, about 0.3 mass ppm of copper. A liquid such as salt water may not contain an antifreeze agent because such chemicals can serve as corrosion inhibitors. Materials systems that can be tested include, for example, aircraft panels that can form the outer skin or fuselage of an aircraft, coated lap joints between two metal panels, wing-to-fuselage assemblies, and combinations thereof. The liquid can be atomized to form a treatment fluid such as salt spray. This salt spray can have a pH in the range of from about 3 to about 11, for example, from about 5 to about 8, for example, from about 6.5 to about 7.2. The pH can be measured using a suitable glass pH sensing electrode, reference electrode, and pH measurement system. It may be desirable to adjust the pH of the liquid. For example, a treatment fluid having a low pH can mimic a polluted atmosphere containing, for example, acid rain.Furthermore, the pH of the liquid atomized in the treatment liquid may be adjusted to readjust the liquid during the exposure process. The pH may be adjusted, for example, by adding hydrochloric acid (HCl) to lower the pH or by adding sodium hydroxide (NaOH) to raise the pH. The liquid such as salt spray is 80 cm. 2 Per horizontal accumulation area of, from about 0.5 milliliters per hour (mL / h) to about 5 mL / h, for example, 80 cm 2 Per horizontal accumulation area of, may be flowed at a flow rate of from about 1 milliliter per hour (mL / h) to about 2 mL / h.

[0067]

[0075] In at least one aspect, a material system such as a panel can be flexed by a fixed support using one of Joe 124a - f or by a plurality of Joe 124a - f. Flexing can be performed at varying frequencies to mimic the effects of mechanical stress under corrosion conditions experienced by aircraft materials under real - world conditions. For example, the material system may be flexed at frequencies from about 0.1 Hertz (Hz) to about 150 Hz, from about 0.1 Hz to about 100 Hz, from about 0.1 Hz to about 60 Hz. The number of cycles during periodic flexing may be from about 1 cycle to about 10,000 cycles, for example, from about 500 cycles to about 5000 cycles, for example, from about 500 cycles to about 3000 cycles.

[0068]

[0076] Furthermore, the greater the curvature of the material system being deflected, the greater the degradation of the material system using the apparatus and method of the present disclosure. For example, a flat panel having a length of 6 inches may be gripped by two jaws, and the distance between the two jaws may be 6 inches. The panel can be deflected at a rate of 0.33 Hz during exposure to a salt spray solution. In another example, a flat panel having a length of 7.5 inches may be gripped by two jaws, where the distance between the jaws is similarly 6 inches. The panel can be deflected at a rate of 0.33 Hz during exposure to a salt spray solution. The panel having a length of 7.5 inches has a greater curvature and will experience further degradation compared to a panel having a length of 6 inches and all other conditions being the same. Without being bound by theory, mechanical stress results in curvature in the material system, causing cracks to form in the material system, thereby allowing corrosive fluids such as spray salt water to penetrate into the cracks of the material system. After penetrating into the cracks of the material system, the corrosive fluid can further penetrate between various additional layers (such as a coating layer below) if they are present. As a result, the corrosive fluid can cause corrosion in one or more of the material system and / or further layers of the material system. These conditions mimic the conditions experienced by aircraft material systems such as panels during real-world use.

[0069]

[0077] In at least one aspect, an exposure zone, such as the housing 160 of the material testing apparatus 100, can be maintained at a temperature in the range of about -196°C to about 100°C, such as about -50°C to about 95°C, such as about 0°C to about 50°C, such as about 33°C to about 37°C, such as 35°C, during exposure of the material system to a treatment fluid (such as salt water atomized into salt spray) and / or while flexing the material system. For example, the temperature can be maintained at cryogenic temperatures such as about -70°C to about -20°C, such as about -55°C. Alternatively, the temperature can be maintained at high temperatures such as about 50°C to about 80°C, such as about 60°C. The temperature can be monitored by a recording device or thermometer (not shown) that can be read from the outer surface of the apparatus such as the material testing apparatus 100. In at least one aspect, exposing a material system, such as a panel, to a liquid such as salt spray and flexing the material system can be performed simultaneously. In at least one aspect, exposing a material system, such as a panel, to a liquid such as salt spray and flexing the material system can be performed sequentially. In at least one aspect, the material system can be exposed to salt spray and flexed both simultaneously and sequentially. This results in the reproduction of irregular or variable flight-specific strain profiles that an in-service material system can experience. In at least one aspect, the exposure of the material system to the liquid and / or flexing the material system can be interrupted for visual inspection, repositioning, or removal of the material system and / or for replenishment of a solution such as the solution in the liquid reservoir 104. In a process that uses a low humidity atmosphere within the exposure zone, a vacuum can be used to remove air from the exposure zone and / or dry air (such as with a relative humidity of less than 30%) can be provided to the exposure zone without introducing a liquid such as salt spray. A gas such as air can be introduced into the apparatus at a pressure in the range of about 15 PSI to about 200 PSI, such as about 15 PSI to about 60 PSI, such as about 60 PSI.During a cyclic flexure process (e.g., from about -70°C to about -20°C) or during a high-temperature cyclic flexure process (e.g., from about 50°C to about 80°C), the gas provided to the chamber and / or housing can have a temperature from about -30°C to about 50°C, such as from about -10°C to about 25°C, such as from about 0°C to about 20°C, such as from about 10°C to about 25°C. Without being bound by theory, the temperature within the device independent of the temperature conditions of the motor can potentially extend the life of the motor. Further or alternatively, the temperature of the motor can be controlled using any suitable temperature control device (e.g., a heater) coupled to the motor. For example, the surface of the motor can have a temperature from about -30°C to about 50°C, such as from about -10°C to about 25°C, such as from about 0°C to about 20°C, such as from about 10°C to about 25°C, as determined by a thermocouple coupled to the surface of the motor.

[0070]

[0078] Before, during (in-situ), and / or after the flexure and spraying of the present disclosure, an electrochemical impedance spectrometer can be used to measure the impedance of one or more layers of the material system. Electrochemical impedance spectroscopy (EIS) provides in-situ measurement of the impedance of one or more layers of the material system. The measurements can provide information for determining coating characteristics such as coating degradation over a period of time, corrosion at the substrate / coating interface, and absorbed moisture, by analyzing the coating of the material system before and after exposure within the material test apparatus 100. The electrochemical impedance spectroscopy process of the present disclosure can be performed at an excitation potential from about 5 mV to about 150 mV, such as from about 10 mV to about 20 mV. The electrical frequency for EIS can be from about 0.1 Hz to 10000 Hz, such as from about 1 Hz to about 5000 Hz, such as from about 1 Hz to about 100 Hz, such as from about 0.01 Hz to about 10 Hz, or from about 100 Hz to about 4000 Hz. In at least one aspect, EIS is performed continuously at fixed intervals at a frequency from about 0.5 Hz to about 100 Hz, such as from about 1 Hz to about 10 Hz.

[0071] Furthermore, the present disclosure includes the following examples. E1. A material testing device, a housing configured to control one or more of humidity, pressure, or temperature, a joist, a plate, a first planar wall disposed on the plate, and a housing comprising a second planar wall parallel to the first planar wall and separated by a vertical wall, and a motor or actuator disposed on the exterior of the housing, the motor comprising a drive shaft coupled to a plurality of guide rods in contact with the vertical wall, the material testing device. E2. The device of Example E1, wherein the housing is configured to control each of humidity, pressure, and temperature using a spray nozzle. E3. a first guide rod coupled to the vertical wall at a first end and coupled to a block at a second end, and The device of Example E1 or E2, further comprising a second guide rod coupled to the vertical wall at a first end and coupled to the block at a second end. E4. The device of any one of Examples E1 to E3, wherein the vertical wall comprises a plurality of joists fixed at a plurality of attachment positions on the surface of the vertical wall. E5. The device of Example E4, wherein each attachment position of the plurality of attachment positions is configured to attach each joist of the plurality of joists. E6. The device of any one of Examples E1 to E5, wherein the joist comprises one or more fixing screws disposed at an upper portion and a lower portion of the joist. E7. The device of Example E6, wherein the fixing screws are directed symmetrically along the joist. E8. The device according to Example 6, wherein the first planar wall, the second planar wall, and the vertical wall form an I-beam. E9. An apparatus according to any one of Examples E1 to E8, further comprising a spectrometer and an electrode, wherein the electrode is configured to be coupled to the spectrometer at a first end and to a material system at a second end. E10. The apparatus according to Example E9, wherein the spectrometer is an electrochemical impedance spectrometer. E11. A material testing apparatus, a housing configured to control one or more of humidity, pressure, and temperature, the joist comprising one or more fixed screws oriented symmetrically along the joist, a plate, and a motor or actuator disposed on an exterior of the housing, the motor comprising a drive shaft coupled to a plurality of guide rods in contact with a vertical wall. E12. The apparatus according to Example E11, wherein the housing is configured to control each of humidity, pressure, and temperature using a spray nozzle. E13. a first guide rod coupled to the vertical wall at a first end and to a block at a second end, and The apparatus according to Example E11 or E12, further comprising a second guide rod coupled to the vertical wall at a first end and to the block at a second end. E14. The apparatus according to any one of Examples E11 to E13, wherein the housing further comprises a first planar wall disposed on the plate. E15. The apparatus according to Example E14, further comprising a second planar wall parallel to the first planar wall, the second planar wall and the first planar wall being separated by the vertical wall. E16. The apparatus according to Example E15, wherein the vertical wall comprises a plurality of joists fixed at a plurality of attachment positions on a surface of the vertical wall. E17. The device of Example E16, wherein each of the plurality of attachment positions is configured to attach the jaw. E18. The device according to any one of Examples E11 to E17, further comprising a spectrometer and an electrode, wherein the electrode is configured to be coupled to the spectrometer at a first end and to a material system at a second end. E19. The device of Example E18, wherein the spectrometer is an electrochemical impedance spectrometer. E20. A method for determining material performance, exposing a material system in a material testing device to a relative humidity from 0% to 100%, and flexing the material system using a jaw within the device and a motor or actuator disposed on an exterior of the housing at a first temperature within the housing of the device, wherein the motor comprises a drive shaft coupled to a plurality of guide rods in contact with a vertical wall connecting a first planar wall and a second planar wall disposed within the housing, flexing the material system, and operating the motor or the actuator at a second temperature different from the first temperature while flexing. The device The method further comprising the jaw fixed to the vertical wall, the jaw having one or more fixing screws symmetrically oriented along the jaw and configured to clamp the material system within the jaw. E21. The method of Example E20, wherein a first guide rod and a second guide rod are in direct contact with the vertical wall connecting the first planar wall and the second planar wall. E22. The method of Example E21, wherein a first guide rod is coupled to the vertical wall at a first end and to a block at a second end, and a second guide rod is coupled to the vertical wall at a first end and to the block at a second end. E23. Any one of the methods from E20 to E22, wherein the joe is configured to apply a uniform pressure to the material system. E24. Any one of the methods from E20 to E23, wherein the fixing screws are arranged at the upper and lower parts of the material system.

[0072]

[0079] Generally, the devices and methods of the present disclosure provide a materials testing apparatus having a chamber configured to control one or more environmental parameters, such as humidity, pressure, or temperature. The materials testing apparatus further includes a joe configured to flex a material system. The joe provides a uniform load distribution across the material by clamping the upper and lower portions of the material. The chamber includes a drive shaft disposed on the exterior of the chamber at a first end and a motor or actuator coupled to a first wall of the chamber at a second end. A plurality of guide rods coupled to the drive shaft extend through the chamber and into the chamber to provide a uniform tensile force across the material.

[0073]

[0080] The mechanical flexing of the material system within the materials testing apparatus of the present disclosure can provide a uniform force. Thereby, a smoother and more uniform load distribution of the material is produced by applying symmetric forces to the material system. The combined effect of mechanical stress and chemical stress is coupled to cause a reduction that more accurately reproduces the corrosion and coating damage experienced by a materials system, such as an aircraft panel, in a real-world environment. As a result, the methods and apparatus of the present disclosure more accurately simulate the coating damage and corrosion found in an aircraft's materials system during its use in the real world, such as cryogenic and high-temperature conditions.

[0074]

[0081] Although the above is directed to multiple aspects of the present disclosure, other aspects and further multiple aspects of the present disclosure may be devised without departing from its basic scope. Further, while the above is directed to material systems such as aircraft material systems, including panels, covered lap joints between two or more panels, and wing and fuselage assemblies, aspects of the present disclosure may be directed to other material systems not associated with aircraft, such as multi-element material systems used in the aerospace industry, automotive industry, marine industry, energy industry, etc.

Claims

1. An apparatus (100) comprising: a housing (160) configured to control one or more of humidity, pressure, or temperature, a joist (124), a plate (146), a first planar wall (310) disposed on the plate, and a housing (160) comprising a second planar wall (312) parallel to the first planar wall (310) and separated by a vertical wall (308), and a motor (126) or actuator disposed on an exterior of the housing (160), the motor (126) comprising a drive shaft (402) coupled to a plurality of guide rods (168) in contact with the vertical wall (308).

2. The apparatus (100) according to claim 1, wherein the housing (160) is configured to control each of humidity, pressure, and temperature using a spray nozzle (102).

3. A first guide rod (168a) coupled to the vertical wall (308) at a first end and to a block at a second end, and a second guide rod (168b) coupled to the vertical wall (308) at a first end and to the block at a second end, the apparatus (100) according to claim 1.

4. The apparatus (100) according to claim 1, wherein the vertical wall (308) comprises a plurality of joists (124a - e) fixed at a plurality of attachment positions on a surface of the vertical wall (308).

5. The apparatus (100) according to claim 4, wherein each attachment position of the plurality of attachment positions is configured to attach each joist (124) of the plurality of joists (124a - e).

6. The apparatus (100) according to claim 1, wherein each joist (124) comprises one or more fixing screws disposed at an upper and a lower portion of the joist.

7. The apparatus (100) according to claim 6, wherein the fixing screws (310) are symmetrically oriented along the joist (124).

8. The apparatus (100) according to claim 6, wherein the first planar wall (310), the second planar wall (312), and the vertical wall (308) form an I-beam.

9. An apparatus (100) comprising: a housing (160) configured to control one or more of humidity, pressure, temperature, the joist (124) comprising one or more fixing screws (310) symmetrically oriented along the joist (124), a plate (146), and An apparatus (100) comprising a motor (126) or an actuator disposed on an exterior of the housing (160), the motor (126) comprising a drive shaft (402) coupled to a plurality of guide rods (168a - b) in contact with a vertical wall (308).

10. The apparatus (100) according to claim 9, wherein the housing (160) is configured to control each of humidity, pressure, and temperature using a spray nozzle (102).

11. A first guide rod (168a) coupled to the vertical wall (308) at a first end and coupled to a block at a second end, and The apparatus (100) according to claim 9, further comprising a second guide rod (168b) coupled to the vertical wall (308) at a first end and coupled to the block at a second end.

12. The apparatus (100) according to claim 11, wherein the housing (160) further comprises a first planar wall (310) disposed on the plate (146).

13. The apparatus (100) according to claim 12, further comprising a second planar wall (312) parallel to the first planar wall (310), the second planar wall (312) and the first planar wall (310) being separated by the vertical wall (308).

14. The apparatus (100) according to claim 13, wherein the vertical wall (308) comprises a plurality of joists (124a - e) fixed at a plurality of attachment positions on a surface of the vertical wall (308).

15. The apparatus (100) according to claim 14, wherein each of the plurality of attachment positions is configured to attach the joist (124a - e).

16. A method for determining material properties, comprising Exposing a material system in an apparatus (100) to a relative humidity of 0% to 100%, and flexing the material system using a joist (124) within the apparatus (100) and a motor (126) or an actuator disposed on an exterior of the housing (160) at a first temperature within the housing (160) of the apparatus (100), the motor (126) comprising a drive shaft (402) coupled to a plurality of guide rods (168a - b) in contact with a vertical wall (308) connecting a first planar wall (310) and a second planar wall (312) disposed within the housing (160), flexing the material system, and including operating the motor (126) or the actuator at a second temperature different from the first temperature while being deflected, the apparatus (100) is, the method further comprising the jaw (124) fixed to the vertical wall (308), the jaw (124) being symmetrically oriented along the jaw (124) and comprising one or more fixing screws (310) configured to clamp the material system within the jaw (124).

17. The method according to claim 16, wherein the first guide rod (168a) and the second guide rod (168b) are in direct contact with the vertical wall (308) connecting the first planar wall (310) and the second planar wall (312).

18. The method according to claim 17, wherein the first guide rod (168a) is coupled to the vertical wall (308) at a first end and to a block at a second end, and the second guide rod (168b) is coupled to the vertical wall (308) at a first end and to the block at a second end.

19. The method according to claim 16, wherein the jaw (124) is configured to apply a uniform pressure to the material system.

20. The method according to claim 16, wherein the fixing screws (310) are disposed at an upper and a lower portion of the material system.

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