Coating Inspection Using Steady State Excitation

Abstract

A structure including a substrate and a coating on the substrate is acoustically excited to measure an acoustic response within the structure, the measured acoustic response within the structure is filtered to remove the acoustic response of the substrate and to determine the acoustic response of the coating, and the acoustic response of the coating is used to inspect the coating for damage.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of coating inspection.

[0002] Federal Rights Statement The U.S. Government owns certain rights in this invention pursuant to Contract No. 89233218CNA000001 between the United States Department of Energy and TRIAD National Security, LLC for the operation of Los Alamos National Laboratory.

[0003] Parties to the Joint Research Agreement The research work described here was performed under a Cooperative Research and Development Agreement (CRADA) between Los Alamos National Laboratory (LANL) and Chevron under the LANL-Chevron Alliance, CRADA number LA05C10518. [Background technology]

[0004] Structures may have coatings to protect the underlying structure (substrate). For example, a protective coating may be applied to a steel panel to protect the steel panel from damage. Any damage in the coating may expose the underlying structure to damage. Identifying damage in the coating may allow corrective action to be taken before the underlying structure is damaged. Summary of the Invention

[0005] The present disclosure relates to coating inspection. Measurements of acoustic excitation within a structure may be obtained. The structure may include a substrate and a coating on at least a portion of the substrate. The measurements of acoustic excitation within the structure may be filtered to remove an acoustic response of the substrate from the measurements. The filtered measurements of acoustic excitation within the structure may include an acoustic response of the coating. One or more properties of the coating may be determined based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure and / or other information.

[0006] A system for coating inspection may include one or more electronic storage devices, one or more processors, and / or other components. The electronic storage devices may store information about the structure, information about the coating on the structure, information about acoustic excitation in the structure, information about the acoustic response of the structure, information about the acoustic response of the coating, information about properties of the coating, and / or other information.

[0007] The processor(s) may be configured with machine-readable instructions. The machine-readable instructions, when executed, may cause the processor(s) to facilitate coating inspection. The machine-readable instructions may include one or more computer program components. The computer program components may include one or more of a measurement component, a filter component, a characterization component, and / or other computer program components.

[0008] The measurement component may be configured to obtain measurements of acoustic excitation in a structure. The structure may include a substrate and a coating on at least a portion of the substrate. In some implementations, the measurements of acoustic excitation in the structure may include measurements of displacement response, velocity response, and / or acceleration response.

[0009] The filter component may be configured to filter the measurements of the acoustic excitation within the structure. The measurements of the acoustic excitation within the structure may be filtered to remove an acoustic response of the substrate from the measurements. The filtered measurements of the acoustic excitation within the structure may include an acoustic response of the coating. In some embodiments, filtering the measurements of the acoustic excitation within the structure to remove an acoustic response of the substrate from the measurements may include applying one or more spatial band reject filters.

[0010] The characteristic component may be configured to determine one or more characteristics of the coating. The characteristic(s) of the coating may be determined based on an acoustic response of the coating in filtered measurements of acoustic excitation within the structure and / or other information. In some embodiments, the characteristic(s) of the coating may include a location, size, and / or type of one or more defects in the coating. In some embodiments, the defect(s) in the coating may include a reduction in adhesion between the coating and the substrate.

[0011] In some embodiments, the property(ies) of the coating may be determined non-destructively and at a distance from the structure. In some embodiments, the property(ies) of the coating may be determined upon line-of-sight inspection of the structure. In some embodiments, one or more maintenance actions on the structure may be performed based on the property(ies) of the coating.

[0012] In some embodiments, determining the property(ies) of the coating based on the acoustic response of the coating in the filtered measurements of the acoustic excitation within the structure may include generating one or more defect maps of the coating based on the acoustic response of the coating in the filtered measurements of the acoustic excitation within the structure and / or other information, and determining the property(ies) of the coating based on the defect map(s). In some embodiments, the defect map(s) may be overlaid on or registered to the structure.

[0013] In some implementations, multiple defect maps of the coating may be generated based on the acoustic response of the coating at different times, and changes or progression of defects in the coating may be determined based on the multiple defect maps superimposed on or aligned to the structure.

[0014] In some embodiments, generating a defect map(s) of the coating based on the acoustic response of the coating in the filtered measurements of the acoustic excitation within the structure may include determining pixel values ​​of the defect map(s) based on an outlier analysis of the acoustic response of the coating and / or other information, In some embodiments, the outlier analysis of the acoustic response of the coating may include calculating a change in displacement response, velocity response, and / or acceleration response.

[0015] These and other objects, features, and properties of the systems and / or methods disclosed herein, as well as the method of operation and function of the associated elements of structure, combination of parts, and economies of manufacture will become more apparent from a consideration of the following description and appended claims, taken in conjunction with the accompanying drawings, all of which form a part of this specification and in which like reference numerals indicate corresponding parts in the various views. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. [Brief description of the drawings]

[0016] [Figure 1] 1 shows an example system for coating inspection. [Diagram 2] 1 illustrates an example method for coating inspection. [Diagram 3] 1 shows example measurements of acoustic excitation within a structure and example filtered measurements of acoustic excitation within a structure. [Figure 4] 1 shows example measurements of acoustic excitation within a structure and example filtered measurements of acoustic excitation within a structure. [Diagram 5] 1 shows an example of generating a defect map. [Figure 6] 1 shows an example image of a structure and an example defect map for the structure. [Figure 7] 1 shows an example image of a structure, an example relative velocity signature for the structure, and an example defect map for the structure. [Figure 8] 1 shows an example image of a structure and an example defect map for the structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present disclosure relates to coating inspection. A structure including a substrate and a coating on the substrate is acoustically excited to measure an acoustic response in the structure. The measured acoustic response in the structure is filtered to remove the acoustic response of the substrate to determine the acoustic response of the coating. The acoustic response of the coating is used to inspect the coating for damage.

[0018] Methods and systems of the present disclosure may be implemented by and / or in a computing system, such as the system 10 shown in FIG. 1. The system 10 may include one or more of a processor 11, an interface 12 (e.g., a bus, a wireless interface), an electronic storage device 13, an acoustic excitation device 14, an acoustic measurement device 15, and / or other components. Measurements of acoustic excitation in a structure may be obtained by the processor 11. The structure may include a substrate and a coating on at least a portion of the substrate. The measurements of acoustic excitation in the structure may be filtered by the processor 11 to remove an acoustic response of the substrate from the measurements. The filtered measurements of acoustic excitation in the structure may include an acoustic response of the coating. One or more properties of the coating may be determined by the processor 11 based on the acoustic response of the coating and / or other information in the filtered measurements of acoustic excitation in the structure.

[0019] Acoustic excitation device 14 may refer to a device that generates acoustic excitation within a structure. Acoustic excitation of a structure may refer to the application of energy to the structure to generate an acoustic response within the structure. The acoustic response may refer to the presence and / or propagation of one or more mechanical waves within the structure. That is, the structure may be acoustically excited to generate mechanical wave(s) within the structure. The mechanical waves may include waves within the audible range and / or waves above the audible range.

[0020] The acoustic excitation device 14 may impart energy to the structure to generate acoustic excitation within the structure mechanically (e.g., using one or more transducers, e.g., piezoelectric transducer(s)), thermally (e.g., using one or more lasers), and / or by other methods. For example, energy (e.g., in the form of sound, heat, ultrasound, vibration) may be imparted to the structure through one or more transducers coupled to the structure, one or more pulsed lasers, and / or other acoustic excitation devices. For example, guided waves may be generated within the plate-like structure in response to ultrasonic excitation. The ultrasonic excitation / guided waves may be sensitive to different properties of the structure. For example, the ultrasonic excitation / guided waves may be sensitive to defects (e.g., damage) in the coating of the structure, which may change the nature of the ultrasonic excitation / guided waves where the defect is located in the coating of the structure.

[0021] The acoustic excitation device 14 may be configured to generate acoustic excitations within the structure. The acoustic excitation device 14 may be configured to generate acoustic excitations within the structure for a variety of purposes. For example, the acoustic excitation device 14 may generate acoustic excitations within the structure using different frequencies to test the acoustic response of the coating of the structure to the different frequencies. For example, the acoustic excitation device 14 may be used to sweep across a range of excitation frequencies, and measurements of these acoustic excitations within the structure may be used to identify a subset of tested excitation frequencies for use in a more comprehensive coating inspection of the structure.

[0022] The acoustic excitation device 14 may be configured to generate acoustic excitation in the structure using a single excitation frequency at a time, or using multiple excitation frequencies at a time. For example, the acoustic excitation device 14 may be configured to generate acoustic excitation in the structure using different excitation frequencies. The acoustic excitation device 14 may generate acoustic excitation using a single excitation frequency at a time (start generating acoustic excitation in the structure using the excitation frequency, stop generating acoustic excitation in the structure using the excitation frequency, start generating acoustic excitation in the structure using a different excitation frequency, etc.). The acoustic excitation device 14 may generate acoustic excitation using multiple excitation frequencies simultaneously (e.g., generate acoustic excitation in the structure using all of the excitation frequencies at a time, generate acoustic excitation in the structure using two or more of the excitation frequencies at a time). In some implementations, the number of excitation frequencies used to generate acoustic excitation in the structure may depend on the maximum power of the acoustic excitation device 14. For example, generating acoustic excitation in the structure using multiple excitation frequencies at a time may require sharing the power of the acoustic excitation device 14 across multiple excitation frequencies. Generating acoustic excitation in the structure using multiple excitation frequencies at a time may require a trade-off between inspection time and signal level.

[0023] Acoustic measurement device 15 may refer to a device that measures acoustic excitation in a structure. Measurements of acoustic excitation in a structure may include acoustic responses to the acoustic excitation in the structure. Acoustic measurement device 15 may refer to a device that measures acoustic responses (e.g., displacement response, velocity response, acceleration response) in a structure. For example, a structure may be acoustically excited by acoustic excitation device 14 to generate mechanical wave(s) in the structure, and acoustic measurement device 15 may measure one or more properties of the mechanical wave(s) in the structure and / or one or more properties of the structure that reflect (e.g., indicative of, affected by) the mechanical wave(s) in the structure.

[0024] The acoustic measurement device 15 may measure acoustic excitation within the structure mechanically (e.g., using one or more transducers), optically (e.g., using a scanning laser), and / or by other methods. For example, the acoustic excitation within the structure may be measured from one or more transducers coupled to the structure, a scanning laser Doppler vibrometer, and / or other acoustic measurement device. For example, the acoustic measurement device 15 may measure an acoustic response within the structure (e.g., a full-field surface velocity response). The acoustic response may include vibration / wave responses (e.g., a full wave field response) within the audible range and / or above the audible range (ultrasonic response).

[0025] In some embodiments, the acoustic measurement device 15 may include a vibrometer. The vibrometer may include one or more vibration recorders and / or other devices that measure the amplitude, velocity, and / or frequency of vibrations in the structure. In some embodiments, the vibrometer may measure the acoustic response using one or more beams. For example, the vibrometer may include one or more laser Doppler vibrometers that use a laser beam to measure the acoustic response at different parts of the structure. The acoustic response may include the amplitude, velocity, and / or frequency of vibrations / waves in the structure. A scan path may refer to the path that the beam(s) of the vibrometer traces and / or follows along the structure to make measurements. In some embodiments, the vibrometer may use a raster scan to make measurements.

[0026] The acoustic measurement device 15 may be configured to measure the acoustic excitation in the structure. The acoustic measurement device 15 may be configured to measure the acoustic excitation in the structure for various purposes. For example, the acoustic measurement device 15 may measure the acoustic excitation generated in the structure to test the acoustic response of the coating of the structure to different frequencies. The acoustic measurement device 15 may measure the acoustic excitation generated in the structure for a more comprehensive coating inspection of the structure. The acoustic measurement device 15 may be configured to measure the acoustic excitation in the structure in the same or different ways for various purposes. For example, the acoustic measurement device 15 may perform a partial measurement of the acoustic excitation in the structure to test different frequencies and a full measurement of the acoustic excitation in the structure for a more comprehensive coating inspection. A partial measurement of the acoustic excitation in the structure may include an incomplete measurement of the acoustic excitation in the structure, while a full measurement of the acoustic excitation in the structure may include a complete measurement of the acoustic excitation in the structure. For example, a partial measurement of the acoustic excitation in the structure may include measurements at fewer points and / or a smaller area than a full measurement of the acoustic excitation in the structure. A partial measurement of acoustic excitation within a structure may include sampling of specific portions of the structure to determine to what extent (e.g., how efficiently) different portions of the structure were acoustically excited using different excitation frequencies. A full measurement of acoustic excitation within a structure may include measurements across the structure to inspect properties of a coating on the structure using measured acoustic excitation (acoustic excitation performed using a selected excitation frequency).

[0027] In some implementations, one or more components of system 10 may be separate from system 10. For example, acoustic excitation device 14 and / or acoustic measurement device 15 may be separate from system 10 and controlled by one or more processors separate from processor 11. Although the components of system 10 are shown as single components, this is by way of example only and is not intended to be limiting.

[0028] A structure may refer to an arrangement and / or organization of one or more objects. Object(s) may be arranged and / or organized in a structure to perform one or more functions. A structure may consist of a particular type of object or a combination of different types of objects. For example, a structure may include a metallic rigid structure and / or other structures. A structure may have a symmetric or asymmetric shape. A structure may include one or more simple geometric shapes, one or more arbitrary complex geometric shapes, and / or other geometric shapes.

[0029] In some embodiments, a structure may include a hollow structure, a support structure, a movable structure, and / or other structures. A hollow structure may refer to a structure that includes one or more empty spaces within the structure. The empty space(s) may be used to hold, carry, transport, and / or otherwise interact with one or more objects. For example, a hollow structure may include a vehicle, a vessel, a pipe, a pressure vessel, a tank, and / or other hollow structure. A support structure may refer to a structure that provides support for one or more objects. For example, a support structure may include equipment, a platform, a frame, a crane, a beam, and / or other support structure. A movable structure may refer to a structure that moves to perform its function. For example, a movable structure may include a turbine blade and / or other movable structure. Non-limiting examples of structures include one or more portions or all of an offshore floating production facility (e.g., spars, semi-submersibles, tension leg platforms), oil rigs, ship / barge hulls, offshore mobile drilling units, aircraft, space launch vehicles, wind turbine blades, pressure vessels, piping systems, ballast tanks, void tanks, and cargo tanks. Other types of structures are also contemplated.

[0030] In some implementations, a structure may refer to a portion of a larger structure. For example, a structure may refer to a target area of ​​a larger structure. That is, rather than inspecting the coating of the entire structure, a specific portion of the coating of the structure may be inspected. As another example, a structure may refer to a component of a larger structure. A coating on / a coating on a portion of a component may be inspected.

[0031] A coating may refer to one or more materials that cover a surface of a structure. A coating may refer to one or more materials that are applied to a surface of a structure. A substrate may refer to the material(s) of a structure to which a coating may be applied. A coating on a structure may cover all or a portion of the substrate. A structure may be coated using one or more applications of a coating. A coating on a structure may include a single coating of material(s) or multiple coatings of material(s). An interior and / or exterior surface of a structure may be covered with one or more coatings. For example, a coating on a steel panel may cover the exterior surface of the steel panel. A coating on a pipe (e.g., a liner) may cover the inside diameter of the pipe. A hollow structure (e.g., a tank) may have a coating on both the interior and exterior surfaces, or on either the interior or exterior surface. A coating on an interior surface may be the same or different from a coating on the exterior surface. The same or different types of coatings may be applied to different portions of a structure. Other types of coatings are also contemplated.

[0032] Coatings may be applied to structures to protect them and / or to protect materials in contact with the structure. For example, coatings may be applied to storage structures (e.g., containers) to protect the structure from accelerated degradation due to either the contents of the stored material and / or the external environment. If the coating is compromised, the structure may no longer be protected and the integrity of the structure may be compromised. This may result in safety risks and capital setbacks. For example, if the coating is broken, it may expose the underlying structure (substrate) to potentially harsh conditions, which may result in substantial damage (e.g., corrosion) to the structure. Repairing a damaged structure may be much more costly and time consuming than repairing a coating. It is very important to perform periodic inspections of coated structures to identify and repair damaged coatings and maintain the integrity of the coating before evidence of structural damage appears.

[0033] Traditional coating inspection involves manual testing by a technician. The technician may use visual inspection to identify areas with visual signs of damage and then remove portions of the coating. The technician may send an electric current through the coating to determine the coating thickness and identify areas where the coating is thinning. These inspection methods are time consuming, can be destructive to the coating, and are subject to the technician's subjectivity. Furthermore, these inspection methods do not predict areas where failure is imminent. Furthermore, when using these methods, the technician may need to be in undesirable environments, such as enclosed spaces (e.g., inside hollow spaces, e.g., tanks or vessels), and around potentially hazardous materials (e.g., open water, gas, oil). Even for exterior inspection, when using these methods, the technician may need to be in hazardous locations and / or locations with restricted access and egress.

[0034] In the present disclosure, measurements of acoustic excitation in a structure having a coating are utilized to determine a property(s) of the coating, such as the location, size, and / or type of defects in the coating. The acoustic response of the structure is subtracted from the measurements of acoustic excitation in the structure to obtain the acoustic response of the coating, which is used to determine the property(s) of the coating.

[0035] In some implementations, acoustic excitation may be measured within a structure having a coating to obtain a temporal surface velocity response. A complex surface velocity response may be calculated at a steady-state excitation frequency. Rather than using an estimate of the local wave number from the complex velocity response, the present disclosure utilizes relative velocity calculations to identify indicators of defects within the coating. Using the velocity response in the present disclosure may include using velocity measurements and / or other temporal properties of the response. For example, using the velocity response may include calculating / deriving displacement, acceleration, and / or other time derivatives from the velocity response, which may be used in the analysis (e.g., outlier analysis) described herein. For example, the displacement and acceleration may be derived from a velocity response map, or a phase shift of the velocity response map up to a constant multiplier. In some implementations, the displacement, acceleration, and / or other temporal properties of the response may be measured without using the velocity response.

[0036] For example, a structure may be acoustically excited at certain frequencies (e.g., high frequencies to which coating defects respond, e.g., above 300 kHz) and a coarse resolution scan of the structure may be performed to identify potentially problematic areas. A fine resolution scan of these areas may be performed to obtain the complex velocity surface response in these areas. The response may be filtered (e.g., using a series of band-reject filters) to remove major structural modes, and the filtered response (including the response of the coating / defects in the coating) may be used to determine the property(ies) of the coating. A poorly adherent coating may respond to these high frequencies to form areas of high response data indicative of a coating defect (e.g., bubbling, blistering, poor adhesion). An outlier analysis may be performed on the response data to identify areas of defects. For example, high response pixels may indicate the presence of a coating defect.

[0037] The present disclosure allows for faster and more efficient non-destructive inspection of structural coatings. The present disclosure may allow for remote inspection of coatings without the need for a technician to be present at the coating location.

[0038] 1, electronic storage 13 may be configured to include an electronic storage medium that electronically stores information. Electronic storage 13 may store software algorithms, information determined by processor 11, remotely received information, and / or other information that enables system 10 to function properly. For example, electronic storage 13 may store information about the structure, information about a coating on the structure, information about acoustic excitation within the structure, information about the acoustic response of the structure, information about the acoustic response of the coating, information about properties of the coating, and / or other information.

[0039] The processor 11 may be configured to provide information processing capabilities in the system 10. Thus, the processor 11 may include one or more of a digital processor, an analog processor, a digital circuit designed to process information, a central processing unit, a graphics processing unit, a microcontroller, an analog circuit designed to process information, a state machine, and / or other mechanisms for electronically processing information. The processor 11 may be configured to execute one or more machine-readable instructions 100 for facilitating coating inspection. The machine-readable instructions 100 may include one or more computer program components. The machine-readable instructions 100 may include one or more of a measurement component 102, a filter component 104, a characterization component 106, and / or other computer program components.

[0040] The measurement component 102 may be configured to obtain measurements of acoustic excitation within a structure. The structure may include a substrate and a coating on at least a portion of the substrate. A surface of the structure may be completely or partially covered with the coating. Obtaining measurements of acoustic excitation within the structure may include one or more of accessing, acquiring, analyzing, determining, inspecting, identifying, generating, loading, locating, making, opening, receiving, retrieving, reviewing, selecting, storing, capturing, and / or otherwise obtaining measurements of acoustic excitation within the structure. Measurements of acoustic excitation within the structure may be obtained using the acoustic measurement device 15 and / or other acoustic measurement device(s). Measurements of acoustic excitation within the structure may be obtained from the acoustic measurement device 15, other acoustic measurement device(s), and / or other locations. For example, acoustic measuring device 15 may generate information that characterizes, defines, identifies, and / or reflects the measured acoustic excitation within the structure, and that information may be obtained directly from acoustic measuring device 15 and / or indirectly from acoustic measuring device 15 (e.g., from electronic storage of acoustic measuring device 15).

[0041] In some embodiments, the scanning parameters of the acoustic measurement device 15 may be set / adjusted for different types of coating inspection. For example, a trade-off may exist between resolution and scan time. A fine resolution inspection (fine pixel pitch, slow scan speed) may take significantly longer to complete than a coarse resolution inspection. A slower scan speed may improve the signal-to-noise ratio in the measurements.

[0042] In some embodiments, the measurements of acoustic excitation within the structure may include measurements of displacement response, velocity response, and / or acceleration response within the structure. The measurement component 102 may obtain measurements of the displacement response, velocity response, and / or acceleration response within the structure due to the acoustic excitation. In some embodiments, the measurements of the displacement response, velocity response, and / or acceleration response within the structure may be obtained as raw wave field images, with the magnitude of the raw wave field images reflecting the type and / or amount of the displacement response, velocity response, and / or acceleration response. In some embodiments, continuous area measurements of the acoustic excitation / response within the structure may be obtained. Other measurements of acoustic excitation within the structure are also contemplated.

[0043] In some embodiments, the measurement of acoustic excitation within the structure may include a partial measurement of acoustic excitation within the structure. The partial measurement of acoustic excitation within the structure may include a less comprehensive measurement than a full measurement. The partial measurement of acoustic excitation within the structure may include an incomplete measurement of acoustic excitation within the structure. The partial measurement of acoustic excitation within the structure may include measurements at fewer points and / or smaller areas of the structure / coating as compared to a full measurement of acoustic excitation within the structure. The partial measurement of acoustic excitation within the structure may include sampling of specific portions of the structure / coating to determine to what extent (e.g., how efficiently) different portions of the structure / coating were acoustically excited using different excitation frequencies.

[0044] Different excitation frequencies may be tested to determine which frequency(es) to use to perform a full measurement of acoustic excitation within the structure. In some embodiments, the excitation frequency(es) selected to perform a coating inspection of the structure may depend on the type, composition, and / or thickness of the structure, the type, composition, and / or thickness of the coating, the type of defects to be identified, and / or other information. For example, a frequency of 400 kHz to 600 kHz may encourage stronger excitation within the coating of a metal structure to reveal defects within the coating. Use of other frequencies is also contemplated.

[0045] In some embodiments, the measurement of acoustic excitation within a structure may include a full measurement of acoustic excitation within the structure. The full measurement of acoustic excitation within a structure may include a more comprehensive measurement than a partial measurement. The full measurement of acoustic excitation within a structure may include a complete measurement of acoustic excitation within a structure. The full measurement of acoustic excitation within a structure may include measurements at more points and / or larger areas of the structure / coating as compared to a partial measurement of acoustic excitation within a structure. The full measurement of acoustic excitation within a structure may include sampling of different portions of the structure / coating for purposes of determining one or more properties of the coating. For example, acoustic excitation across the entire structure may be measured to generate a full wave field measurement indicative of the acoustic response of the entire coating / area of ​​interest. The full wave field measurement may be used to identify (e.g., visualize) defects within the coating / area of ​​interest.

[0046] Acoustic excitation may be generated in the structure using a single excitation frequency at a time or using multiple excitation frequencies at a time. Acoustic excitation in the structure may include steady-state acoustic excitation (acoustic steady-state wave field excitation) in the structure. Acoustic excitation in the structure may include quasi-steady-state acoustic excitation in the structure. Steady-state / quasi-steady-state acoustic excitation may be generated in the structure and the steady-state / quasi-steady-state response of the coating to one or more excitation frequencies may be used to inspect the coating of the structure. For example, measurements of the acoustic steady-state wave field excitation in the structure may be obtained. The excitation frequencies may include one or more ultrasonic frequencies and / or one or more non-ultrasonic frequencies. For example, an acoustic excitation device(s) may be used to create a steady-state multi-tone ultrasonic excitation of the structure and the ultrasonic response at different portions of the structure may be measured and used to determine properties of the coating of the structure at the corresponding portions. Using steady-state, multi-tone ultrasonic excitation, ultrasonic response measurements may be made quickly (e.g., scanning an area of ​​a square meter or more in a few seconds) from large distances (e.g., tens of meters away) without the need for repetition. Other types of acoustic excitation of structures are also contemplated.

[0047] In some implementations, a complex response (e.g., a complex velocity response) within a structure at an excitation frequency may be obtained from measurements of acoustic excitation within the structure. Each individual pixel of the measurement may include a segment of time response data. The time response of the pixel may be transformed to the frequency domain via a dot product with a complex exponential at the excitation frequency. For example, the complex-valued amplitude and phase response at the excitation frequency may be calculated using: where v(x,y,t) is the time response at pixel location (x,y), f0 is the excitation frequency, and T is the time length of the sliding window (the scan time divided by the number of pixels).

number

[0048] A complex-valued wavefield map of the steady-state response of the structure / coating may be obtained from above.

[0049] In some implementations, measurements of acoustic excitation within a structure may be adjusted based on the geometry of the structure. For example, for structures with non-uniform or complex geometric features, a distance measurement device (e.g., LiDAR, laser range finder) may be used to take distance measurements and generate a point cloud representation of the structure. The point cloud representation of the structure may be used to correct measurements of acoustic excitation for geometric distortions. For example, measurements of acoustic excitation within a structure may be modified to compensate for acoustic response measurements using a beam that is not perpendicular to the portion being scanned. That is, perspective correction may correct for beam incidence angles that deviate from a line perpendicular to that portion of the structure. For example, the orientation of the individual (planar) sections with respect to the scanning system may be determined / estimated using a least squares method, and the relative perspective of the individual sections may be corrected using this orientation so that the acoustic response of the individual sections approximates the acoustic response that would have been measured at normal incidence. Other geometric corrections are also contemplated for use.

[0050] The filter component 104 may be configured to filter the measurements of acoustic excitation in the structure. For example, the measurements of acoustic steady state wave field excitation in the structure may be filtered. Filtering the measurements of acoustic excitation in the structure may include removing one or more portions of data from the measurements using one or more filters. The measurements of acoustic excitation in the structure may include (1) an acoustic response of the substrate, and (2) an acoustic response of the coating. For example, the ultrasonic complex response (e.g., ultrasonic complex velocity response) of the structure may include response modes from the substrate and the coating on the substrate. The structural response may overwhelm the response of subtle coatings / coating defects. The measurements of acoustic excitation in the structure may be filtered to remove the acoustic response of the substrate from the measurements. A dominant structural response (dominant mode) may be identified and removed from the measurements of acoustic excitation in the structure. The filtered measurements of acoustic excitation in the structure may include the acoustic response of the coating. For example, the filtered measurements of acoustic excitation in the structure may include the acoustic spatial wave field response of the coating.

[0051] 3 illustrates an example measurement 310 of acoustic excitation within a structure and an example filtered measurement 320 of acoustic excitation within a structure. Measurement 310 may represent a wavenumber response within the structure, which includes both a response from the structure's substrate and a response from the structure's coating. Filtered measurement 320 may represent a filtered wavenumber response within the structure. Filtered measurement 320 may be generated by removing the response from the structure's substrate from measurement 310. Filtered measurement 320 may include a response from the structure's coating, but not the response from the structure's substrate.

[0052] FIG. 4 illustrates an example measurement 410 of acoustic excitation in a structure and an example filtered measurement 420 of acoustic excitation in a structure. Measurement 410 may represent an actual wave field response in the structure, which includes both a response from the structure's substrate and a response from the structure's coating. Filtered measurement 420 may represent a filtered actual wave field response in the structure. Filtered measurement 420 may be generated by removing a response from the structure's substrate from measurement 410. Filtered measurement 420 may include a response from the structure's coating, but not a response from the structure's substrate. The structure's coating may include blisters, which may be more apparent in filtered measurement 420 after the dominant structural response modes are filtered out.

[0053] In some implementations, filtering the measurements of the acoustic excitation in the structure to remove the acoustic response of the substrate from the measurements may include applying one or more spatial band-stop filters. For example, a series of spatial band-stop filters may be applied to remove the acoustic response of the substrate from the measurements. The spatial band-stop filter(s) may be applied in the wavenumber domain and / or the time domain. It is contemplated that other types of filters may be used.

[0054] The characteristic component 106 may be configured to determine one or more characteristics of the coating. The characteristics of the coating may refer to the physical attributes, quality, and / or nature of the coating. The characteristics of the coating may include properties of the coating itself and / or properties of the interface / interaction between the coating and the substrate. The characteristics of the coating may refer to the physical attributes, quality, and / or nature of defects in the coating. For example, the characteristics of the coating may include the location, size, and / or type of one or more defects in the coating. The defects in the coating may refer to imperfections or anomalies in the coating. The defects in the coating may impair the quality, function, and / or usefulness of the coating. For example, the defects in the coating may include a reduction in adhesion between the coating and the substrate. The reduction in adhesion between the coating and the substrate may include a weakening and / or failure of adhesion between the coating and the substrate. Other examples of defects include coating blistering, corrosion creep, and corrosion seepage. Other types of defects are also contemplated.

[0055] Determining a characteristic of the coating may include identifying a characteristic, quantifying a characteristic, and / or other determination of a characteristic of the coating. For example, the characterization component 106 may determine the presence and / or absence of one or more defects in the coating, identify a type of defect(s) in the coating, identify a location of the defect(s) in the coating, determine a size of the defect(s) in the coating, determine a shape of the defect(s), quantify (e.g., provide a number defining) the defect(s) in the coating, and / or provide other determination of a characteristic of the coating.

[0056] The property(ies) of the coating may be determined by the property component 106 based on the acoustic response of the coating (e.g., the acoustic spatial wave field response of the coating) in filtered measurements of acoustic excitation within the structure and / or other information. The acoustic response of the coating to the excitation frequency(ies) may be used to determine the property(ies) of the coating. For example, the property component 106 may use the amount and / or type of acoustic excitation in different portions of the coating to determine the property(ies) of different portions of the coating.

[0057] Determining the property(ies) of the coating in this manner may allow for non-destructive evaluation of the coating. Determining the property(ies) of the coating in this manner may allow for evaluation of the coating from a distance away from the structure. Acoustic excitation within the structure may be measured at a distance away from the structure (e.g., 10 meters away). For example, the property(ies) of the coating may be determined as disclosed herein in a line-of-sight inspection of the structure. Line-of-sight inspection of the structure may include inspection of the structure with an unobstructed view of the structure. Rather than having to be near and next to the structure for inspection, the line-of-sight inspection may use measurements of acoustic excitation within the structure from a distance (e.g., from a single distance away from the structure, from different distances away from the structure) to determine the property(ies) of the coating.

[0058] Such inspection may be less intrusive and / or less costly than a physical inspection of the structure. For example, inspecting a coating on a tall structure may require scaffolding to be raised to allow an inspector to reach the coating. Line-of-sight inspection may allow the coating to be inspected without the need for such equipment. As another example, a physical inspection of a structure may require taking physical samples from the structure / coating, which may require the inspector to visit the structure. Equipment for line-of-sight inspection (e.g., acoustic excitation device, acoustic measurement device, processor(s)) may be set up at the structure's location and used without the inspector being present. A coating on a structure may be inspected remotely.

[0059] In some implementations, one or more maintenance actions may be performed on the structure based on the characteristic(s) of the coating. A maintenance action may refer to an action to repair the structure / coating. For example, a maintenance action may be performed to repair a defect in the coating. The characteristic(s) of the coating determined herein may be used to determine where to direct a maintenance action on the structure. The characteristic(s) of the coating may be used to determine an overall health (e.g., an overall health index) of the coating on the structure. The characteristic(s) of the coating may be used to determine when and where the coating on the structure needs to be repaired. For example, defects in the coating may be classified based on the extent of damage and / or the need for repair. The timing of maintenance on the structure to repair the coating may be determined based on the nature of the defect in the coating. For example, a pinhead-sized defect in the coating may be identified for monitoring, while a fingernail-sized defect in the coating may be identified for repair. As another example, defects in non-critical areas of the structure may be identified for monitoring, while defects in critical areas of the structure may be identified for repair.

[0060] In some implementations, one or more outlier detections (e.g., anomaly detection) may be performed on the acoustic response of the coating to determine a characteristic(s) of the coating. For example, outlier analysis of the acoustic response of the coating may be used to determine a characteristic of a defect(s) in the coating. An outlier in the acoustic response of the coating may refer to a portion of the acoustic response of the coating that is statistically / significantly different from other portions of the acoustic response of the coating. In some implementations, the degree to which a portion of the acoustic response of the coating must deviate from other portions of the acoustic response for the portion to be considered statistically / significantly different from the other portions may be determined based on using one or more thresholds, criteria, and / or other factors. In some implementations, the degree to which a portion of the acoustic response of the coating must deviate from other portions of the acoustic response for the portion to be considered statistically / significantly different from the other portions may be set by a user of the system 10.

[0061] Outliers in the acoustic response of the coating may indicate the presence of defects in the coating. The amount and / or type of outliers in the acoustic response of the coating may be used to identify / determine the characteristics of the defects. For example, outlier detection may be used on the response of the coating to identify areas of the coating that have higher relative strain energy, as described below, which may then be used to identify / determine the characteristics of defects in the coating. Other outlier detection uses are also contemplated.

[0062] In some embodiments, determining a characteristic(s) of the coating based on the acoustic response of the coating in filtered measurements of acoustic excitation within the structure (e.g., the acoustic spatial wave field response of the coating) may include (1) generating one or more defect maps of the coating based on the acoustic response of the coating in filtered measurements of acoustic excitation within the structure and / or other information; and (2) determining a characteristic(s) of the coating based on the defect map(s) and / or other information.

[0063] A defect map may refer to an image that visually represents defects in a coating. A defect map may refer to an image that visually represents different properties of a coating. For example, a defect map may use different values ​​of pixels (e.g., different colors, different intensities) to visually represent different acoustic responses in a coating. A defect map may use different values ​​of pixels to visually represent outliers in the acoustic response in a coating. Other statistics of acoustic responses in a coating and other types of defect maps are contemplated for use.

[0064] In some embodiments, separate defect maps may be generated using separate excitation frequencies. The degree of excitation within the defect may depend on the excitation frequency and the size and / or type of the defect. The separate defect maps from the separate excitation frequencies may be combined to provide a combined defect map. The combined defect map may provide a more comprehensive view of the defects within the coating as compared to the individual defect maps.

[0065] In some embodiments, the defect map(s) may be presented in one or more graphical user interfaces. In some embodiments, the defect map(s) may be presented on one or more displays. In some embodiments, the defect map(s) may be overlaid on or aligned to the structure (e.g., reference). For example, the defect map may be presented on an image of the structure (e.g., using an overlay combined with an image of the structure) and / or projected onto the actual structure. The defect map and the structure (structure in image, actual structure) may be aligned such that defects in the defect map are presented over defects in the coating of the structure.

[0066] In some embodiments, multiple defect maps of the coating may be generated based on the acoustic response of the coating at different times. Acoustic excitation in the structure may be measured over time, and the acoustic response of the coating at different times may be used to generate separate defect maps of the coating. The defect maps for different times may indicate changes or progression of defects in the coating over time. For example, the defect maps for different times may indicate changes in appearance and / or size / shape of defects in the coating over time. The changes or progression of defects in the coating may be determined by comparing the defect maps for different times. The changes or progression of defects in the coating may be determined based on multiple defect maps superimposed on or aligned to the structure. The defect maps for different times may be used to determine how the coating ages over time.

[0067] In some implementations, generating the defect map(s) of the coating based on the acoustic response of the coating in the filtered measurements of the acoustic excitation in the structure may include determining pixel values ​​of the defect map(s) based on an outlier analysis of the acoustic response of the coating and / or other information. For example, the outlier analysis of the acoustic response of the coating may include calculating a change in the displacement response, velocity response, and / or acceleration response in the structure / coating, and the change in the displacement response, velocity response, and / or acceleration response may be used to determine pixel values ​​of the defect map(s). The outlier analysis of the acoustic response of the coating may utilize other properties of the acoustic response (e.g., other time derivatives).

[0068] For example, the relative velocity characteristics within a structure / coating may be used to identify changes in strain energy (U), which indicates the presence / characteristics of a defect(s) within the coating. The rate of change of strain energy is determined by the difference in the relative velocities.

number

number

[0069] The relative velocity features may be calculated within a sub-matrix (grouping of pixels), with the central pixel

number

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[0070] Value of the central pixel

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number

number

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number

[0071] The relative velocity signature may be used to quantify / identify the boundaries of defects in the coating. Assuming that the normalized relative velocity (change in relative velocity between two points) is proportional to the change in strain energy, and that the strain energy changes when there is a discontinuity in the acoustic wave propagating across the coating, such as due to a defect in the coating, a large change in the relative velocity signature between pixels may indicate / quantify a defect in the coating. A large normalized difference between adjacent pixels may indicate / quantify a defect in the coating.

[0072] The pixel value is the complex relative velocity submatrix

number

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[0073] The relative velocity feature may be used to quantify / identify the center pixel that deviates from the surrounding pixels. This technique may be used to identify defects of small size (e.g., defects covered by one or a few pixels in the defect map), where traditional processing methods may drop such small details from the analysis. The computational submatrix width may be set to the distance between small defects (e.g., bubbling or blistering in the coating). The relative velocity feature may highlight pixels that are significantly different from other pixels in the computational submatrix.

[0074] The relative velocity values ​​may be used as pixel values ​​of the defect map. The relative velocity values ​​may be used to determine pixel values ​​of the defect map. In some implementations, one or more filters may be applied to the defect map to highlight areas with a large number of high relative velocity pixels. For example, an order statistics filter, a disk-shaped filter, and / or other filters may be applied. The width of the order statistics filter may be fixed (e.g., 4 mm). The width of the order statistics filter may be set to include a cluster of defects to highlight areas with a high concentration of small defects. The order statistics filter may sort the values ​​in the computation matrix in ascending order. The pixels in the computation matrix may be assigned as values ​​in a reference index. For example, the reference index may be selected as the 99.6th percentile of the location.

[0075] A disk-shaped filter may be used to reshape the results of the order statistics filter. The order statistics filter may be square in shape, so that the filtered data may look like overlapping squares. The disk-shaped filter may blend the squares together to form a continuous defect map. A disk shape may be used since many coating defects are circular in shape. Other shapes are contemplated.

[0076] The width of the disk filter may be fixed (e.g., 3 mm radius) and the diameter extends beyond the edge of the square order statistics filter. The disk filter may create a 2D predefined filter by generating a correlation kernel and applying it to the matrix. The output of the disk filter may be used as a defect map.

[0077] An example of generating a defect map is shown in FIG. 5. On the left is image A 510 showing values ​​of relative velocity features for areas of a coating. In the middle is image B 520 showing the result of processing image A 510 through an order statistics filter. On the right is image C 530 showing the result of processing image B 520 through a disk-shaped filter. Image C 530 may be used as a defect map for the coating. The shapes shown in image C 530 may correspond to the shapes of defects in the coating. The pixel values ​​of the defects in image C 530 may correspond to different types / severities of defects in the coating.

[0078] As shown in Figures 6-8, the present disclosure enables identification of both visible and non-visible defects in a coating of a structure. Figure 6 shows an example image 610 of a structure and an example defect map 620 for the structure. The image 610 of the structure may not show any visible defects in the coating of the structure. The defect map 620 may show small defects scattered throughout the coating.

[0079] 7 illustrates an example image 710 of a structure, an example relative velocity feature for the structure 720, and an example defect map 730 for the structure. The image 710 of the structure may show visible blistering in the coating of the structure. The relative velocity feature 720 for the structure may provide a fine resolution view of defects in the coating. The relative velocity feature 720 for the structure may show individual blisters in the coating of the structure. The defect map 730 for the structure may highlight areas of the coating that contain defects.

[0080] 8 illustrates an example image 810 of a structure and an example defect map for the structure 820. The image 810 of the structure may show visible defects in the coating of the structure. The defect map 820 for the structure may show both visible and non-visible defects in the coating of the structure.

[0081] The embodiments of the present disclosure may be implemented in hardware, firmware, software, or any suitable combination thereof. The embodiments of the present disclosure illustrated in FIG. 1 may be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, tangible (non-transitory) machine-readable storage media may include read-only memory, random-access memory, magnetic disk storage media, optical recording media, flash memory devices, and the like, and machine-readable transmission media may include forms of propagated signals, such as carrier waves, infrared signals, digital signals, and the like. The firmware, software, routines, or instructions may be described herein in terms of certain exemplary aspects and implementations of the present disclosure and performing certain operations.

[0082] 1 may be provided by external resources not included in system 10. External resources may include hosts / sources of information, computing, and / or processing, and / or other providers of information, computing, and / or processing external to system 10.

[0083] Although the processor 11, the electronic storage device 13, the acoustic excitation device 14, and the acoustic measurement device 15 are illustratively connected to an interface 12 in FIG. 1, any communication medium may be used to facilitate direct and / or indirect intercommunication between any of the components of the system 10. One or more components of the system 10 may communicate with each other through wired communication, wireless communication, or both. For example, one or more components of the system 10 may communicate with each other through a network. For example, the processor 11 may communicate wirelessly with the electronic storage device 13. By way of non-limiting example, the wireless communication may include one or more of radio communication, Bluetooth communication, Wi-Fi communication, cellular communication, infrared communication, or other wireless communication. Other types of communication are also contemplated by the present disclosure.

[0084] Although processor 11 is shown as a single entity in FIG. 1, this is for illustrative purposes only. In some implementations, processor 11 may include multiple processing units. These processing units may be physically located within the same device, or processor 11 may represent the processing functionality of multiple devices working in conjunction. Processor 11 may be separate from and / or part of one or more components of system 10. Processor 11 may be configured to execute one or more components by software, hardware, firmware; some combination of software, hardware, and / or firmware; and / or other mechanisms for configuring processing power on processor 11.

[0085] 1 as being co-located within a single processing unit, it should be understood that in embodiments in which processor 11 includes multiple processing units, one or more of the computer program components may be located remotely from the other computer program components. Although the computer program components are described as performing or configured to perform operations, the computer program components may include instructions that can program processor 11 and / or system 10 to perform operations.

[0086] Although the computer program components are described herein as being implemented via the processor 11 through machine-readable instructions 100, this is merely for ease of reference and is not intended to be limiting. In some embodiments, one or more functions of the computer program components described herein may be implemented via hardware (e.g., dedicated chips, field programmable gate arrays) rather than software. One or more functions of the computer program components described herein may be software implemented, hardware implemented, or software and hardware implemented.

[0087] The description of the functionality provided by the various computer program components described herein is for illustrative purposes and is not intended to be limiting, as any of the computer program components may provide more or less functionality than described. For example, one or more of the computer program components may be deleted and some or all of its functionality may be provided by other computer program components. As another example, the processor 11 may be configured to execute one or more additional computer program components that may perform some or all of the functionality attributed to one or more of the computer program components described herein.

[0088] The electronic storage media of electronic storage 13 may be provided integrally (i.e., substantially non-removably) with one or more components of system 10 and / or may be provided as a removable storage device connectable to one or more components of system 10, for example, via a port (e.g., USB port, Firewire port, etc.) or drive (e.g., disk drive, etc.). Electronic storage 13 may include one or more of an optically readable storage medium (e.g., optical disk, etc.), a magnetically readable storage medium (e.g., magnetic tape, magnetic hard drive, floppy drive, etc.), a charge-based storage medium (e.g., EPROM, EEPROM, RAM, etc.), a solid-state storage medium (e.g., flash drive, etc.), and / or other electronically readable storage medium. Electronic storage 13 may be a separate component within system 10, or electronic storage 13 may be provided integrally with one or more other components of system 10 (e.g., processor 11). Although electronic storage 13 is shown as a single entity in FIG. 1, this is for illustrative purposes only. In some implementations, electronic storage 13 may include multiple storage units, which may be physically located within the same device, or electronic storage 13 may represent the storage functionality of multiple devices working in conjunction.

[0089] 2 illustrates a method 200 for coating inspection. The operations of method 200 described below are intended to be exemplary. In some embodiments, method 200 may be accomplished with one or more additional operations not described and / or without one or more of the operations described. In some embodiments, two or more of the operations may occur substantially simultaneously.

[0090] In some implementations, one or more operations of method 200 may be implemented in one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed to process information, a central processing unit, a graphics processing unit, a microcontroller, an analog circuit designed to process information, a state machine, and / or other mechanisms for electronically processing information). The one or more processing devices may include one or more devices that perform some or all of the operations of method 200 in response to instructions electronically stored on one or more electronic storage media. The one or more processing devices may include one or more devices configured through hardware, firmware, and / or software to be specifically designed to perform one or more of the operations of method 200.

[0091] 2 and method 200, in operation 202, measurements of acoustic excitation within a structure may be obtained. The structure may include a substrate and a coating on at least a portion of the substrate. In some implementations, operation 202 may be performed by a component the same as or similar to measurement component 102 (shown in FIG. 1 and described herein).

[0092] In operation 204, the measurements of the acoustic excitation in the structure may be filtered to remove the acoustic response of the substrate from the measurements. The filtered measurements of the acoustic excitation in the structure may include the acoustic response of the coating. In some implementations, operation 204 may be performed by a component the same as or similar to filter component 104 (shown in FIG. 1 and described herein).

[0093] In operation 206, one or more properties of the coating may be determined based on the acoustic response of the coating in the filtered measurements of the acoustic excitation within the structure and / or other information. In some implementations, operation 206 may be performed by a component the same as or similar to characterization component 106 (shown in FIG. 1 and described herein).

[0094] While the system(s) and / or method(s) of the present disclosure have been described in detail for purposes of illustration based on what are presently considered to be the most practical and preferred embodiments, it is to be understood that such detail is for such purposes only and that the present disclosure is not limited to the disclosed embodiments, but on the contrary, is intended to cover modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it is to be understood that the present disclosure contemplates, to the extent possible, the combination of one or more features of any embodiment with one or more features of any other embodiment.

Claims

1. 1. A method for coating inspection, the method comprising: obtaining measurements of acoustic excitation within a structure, the structure including a substrate and a coating on at least a portion of the substrate; filtering the measurements of acoustic excitation in the structure to remove an acoustic response of the substrate from the measurements, the filtered measurements of acoustic excitation in the structure including an acoustic response of the coating; and determining one or more properties of the coating based on the acoustic response of the coating to the filtered measurements of acoustic excitation within the structure.

2. The method of claim 1 , wherein filtering the measurements of acoustic excitation within the structure to remove an acoustic response of the substrate from the measurements comprises applying one or more spatial band-reject filters.

3. The method of claim 1 , wherein the one or more characteristics of the coating include a location, a size, and / or a type of defect in the coating.

4. The method of claim 3 , wherein the defects in the coating comprise a loss of adhesion between the coating and the substrate.

5. Determining the one or more properties of the coating based on the acoustic response of the coating to the filtered measurements of acoustic excitation within the structure includes: generating a defect map of the coating based on the acoustic response of the coating to the filtered measurements of acoustic excitation within the structure; and determining the one or more characteristics of the coating based on the defect map.

6. The method of claim 5 , wherein the defect map is overlaid on or registered to the structure.

7. 7. The method of claim 6, wherein multiple defect maps of the coating are generated based on the acoustic response of the coating at different times, and a change or progression of defects in the coating is determined based on the multiple defect maps superimposed on or aligned to the structure.

8. 8. The method of claim 7, wherein generating the defect map of the coating based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure comprises determining pixel values ​​of the defect map based on an outlier analysis of the acoustic response of the coating.

9. The method of claim 8 , wherein the measurements of acoustic excitation within the structure include measurements of displacement response, velocity response, and / or acceleration response.

10. The method of claim 9 , wherein the outlier analysis of the acoustic response of the coating comprises calculating a change in the displacement response, the velocity response, and / or the acceleration response.

11. The method of claim 10 , wherein the one or more properties of the coating are determined non-destructively and at a distance from the structure.

12. The method of claim 11 , wherein the one or more properties of the coating are determined upon line-of-sight inspection of the structure.

13. The method of claim 12 , wherein one or more maintenance actions are performed on the structure based on the one or more properties of the coating.

14. 1. A system for coating inspection, comprising: one or more physical processors, the one or more physical processors configured by machine-readable instructions to: obtaining measurements of acoustic excitation within a structure, the structure including a substrate and a coating on at least a portion of the substrate; filtering the measurements of acoustic excitation in the structure to remove an acoustic response of the substrate from the measurements, the filtered measurements of acoustic excitation in the structure including an acoustic response of the coating; determining one or more properties of the coating based on the acoustic response of the coating to the filtered measurements of acoustic excitation within the structure; A system configured to:

15. The system of claim 14 , wherein filtering the measurements of acoustic excitation within the structure to remove an acoustic response of the substrate from the measurements comprises applying one or more spatial band-reject filters.

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