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 generally relates to the field of coating inspection.

[0002] Statement Regarding Federal Rights The United States Government has 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 Cooperative Research Agreement The research work described herein was performed under a Cooperative Research and Development Agreement (CRADA), CRADA No. LA05C10518, between Los Alamos National Laboratory (LANL) and Chevron under the LANL-Chevron Alliance.

Background Art

[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. If there is a break in the coating, the underlying structure may be exposed to damage. Identifying a break in the coating may allow corrective action to be taken before the underlying structure is damaged.

Summary of the Invention

[0005] This 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 the acoustic response of the substrate from the measurements. The filtered measurements of acoustic excitation within the structure may include the acoustic response of the coating. Based on the acoustic response of the coating and / or other information in the filtered measurements of acoustic excitation within the structure, one or more properties of the coating may be determined.

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

[0007] The processor(s) may consist of machine-readable instructions. After executing the machine-readable instructions, the processor(s) may be prompted to perform a coating check. The machine-readable instructions may include one or more computer program components. The computer program components may include one or more of the following: measurement components, filter components, characteristic components, and / or other computer program components.

[0008] The measuring component may be configured to acquire measurements of acoustic excitations within a structure. The structure may include a substrate and a coating on at least a portion of the substrate. In some embodiments, the measurements of acoustic excitations within the structure may include measurements of displacement response, velocity response, and / or acceleration response.

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

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

[0011] In some embodiments, the coating properties may be determined non-destructively and at a distance from the structure. In some embodiments, the coating properties may be determined by a line inspection of the structure. In some embodiments, one or more maintenance operations on the structure may be performed based on the coating properties.

[0012] In some embodiments, determining the properties of a coating based on the acoustic response of the coating in filtered measurements of acoustic excitations within a structure may include generating one or more defect maps of the coating based on the acoustic response of the coating in filtered measurements of acoustic excitations within a structure and / or other information, and determining the properties of the coating based on the defect map(s). In some embodiments, the defect map(s) may be superimposed on the structure or aligned with the structure.

[0013] In some embodiments, multiple defect maps of the coating may be generated based on the acoustic response of the coating at different times. The change or progression of defects within the coating may be determined based on multiple defect maps superimposed on or aligned with a structure.

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

[0015] The objectives, features, and properties of the systems and / or methods disclosed herein, as well as the operation and function of the relevant elements of the structures, the combination of parts, and the economics of manufacture, will become clearer upon consideration of the following description and the appended claims with reference to the accompanying drawings. All of these form part of this specification, and similar reference figures in various drawings indicate corresponding parts. However, it should be clearly understood that the drawings are for illustrative and explanatory purposes only and are not intended to define any limitations of the invention. Where used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. [Brief explanation of the drawing]

[0016] [Figure 1] This shows an example system for coating inspection. [Figure 2] Examples of methods for coating inspection are shown. [Figure 3] Examples of measured values ​​for acoustic excitation within a structure, and examples of measured values ​​for acoustic excitation within a structure after filtering, are shown. [Figure 4] Examples of measured values ​​for acoustic excitation within a structure, and examples of measured values ​​for acoustic excitation within a structure after filtering, are shown. [Figure 5] An example of generating a defect map is shown. [Figure 6] Examples of structural images and defect maps for those structures are shown. [Figure 7] Examples of structural images, relative velocity features for structures, and defect maps for structures are shown. [Figure 8] Examples of structural images and defect maps for those structures are shown. [Modes for carrying out the invention]

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

[0018] The methods and systems of this disclosure may be implemented by and / or in a computing system, such as System 10 shown in Figure 1. System 10 may include one or more of the following components: 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 within a structure may be acquired 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 within the structure may be filtered by the processor 11 to remove the acoustic response of the substrate from the measurements. The filtered measurements of acoustic excitation within the structure may include the acoustic response of the coating. Based on the acoustic response of the coating and / or other information in the filtered measurements of acoustic excitation within the structure, one or more properties of the coating may be determined by the processor 11.

[0019] The acoustic excitation device 14 may refer to a device that generates acoustic excitation within a structure. Acoustic excitation of a structure may refer to imparting energy to the structure in order 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 waves(s) within the structure. Mechanical waves may include waves within the audible range and / or waves beyond the audible range.

[0020] The acoustic excitation device 14 may generate acoustic excitation within the structure by applying energy to the structure mechanically (e.g., using one or more transducers, e.g., piezoelectric transducers (plural available)), thermally (e.g., using one or more lasers), and / or by other means. For example, energy (e.g., in the form of sound, heat, ultrasonic waves, vibrations) may be applied 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 a plate-like structure in response to ultrasonic excitation. Ultrasonic excitation / guided waves may be sensitive to different characteristics of the structure. For example, ultrasonic excitation / guided waves may be sensitive to defects (e.g., damage) within the coating of the structure, and the defects may change the nature of the ultrasonic excitation / guided waves at the location where the defects are located within the coating of the structure.

[0021] The acoustic excitation device 14 may be configured to generate acoustic excitation within the structure. The acoustic excitation device 14 may be configured to generate acoustic excitation within the structure for various purposes. For example, the acoustic excitation device 14 may use different frequencies to generate acoustic excitation within the structure to test the acoustic response of the coating of the structure to different frequencies. For example, the acoustic excitation device 14 may be used to sweep over a range of excitation frequencies, and the measured values of these acoustic excitations within the structure may be used to identify a subset of the 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 within the structure using a single excitation frequency at a time or using a plurality of excitation frequencies at a time. For example, the acoustic excitation device 14 may be configured to generate acoustic excitation within 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 within the structure using the excitation frequency, stop generating acoustic excitation within the structure using the excitation frequency, start generating acoustic excitation within the structure using a different excitation frequency, etc.). The acoustic excitation device 14 may generate acoustic excitation using a plurality of excitation frequencies simultaneously (for example, generate acoustic excitation within the structure using all of the excitation frequencies at once, generate acoustic excitation within the structure using two or more of the excitation frequencies at once). In some embodiments, the number of excitation frequencies used to generate acoustic excitation within the structure may depend on the maximum output of the acoustic excitation device 14. For example, generating acoustic excitation within the structure using a plurality of excitation frequencies at a time may require sharing the power of the acoustic excitation device 14 across the plurality of excitation frequencies. Generating acoustic excitation within the structure using a plurality of excitation frequencies at a time may require a trade-off between inspection time and signal level.

[0023] The acoustic measurement device 15 may refer to a device that measures acoustic excitation within the structure. The measured value of the acoustic excitation within the structure may include the acoustic response to the acoustic excitation within the structure. The acoustic measurement device 15 may refer to a device that measures the acoustic response (for example, displacement response, velocity response, acceleration response) within the structure. For example, the structure may be acoustically excited by the acoustic excitation device 14 to generate mechanical wave(s) within the structure, and the acoustic measurement device 15 may measure one or more properties of the mechanical wave(s) within the structure and / or one or more properties of the structure that reflect (for example, indicate, are affected by) the mechanical wave(s) within the structure.

[0024] The acoustic measuring device 15 may measure acoustic excitations within the structure mechanically (e.g., using one or more transducers), optically (e.g., using a scanning laser), and / or by other means. For example, acoustic excitations within the structure may be measured from one or more transducers coupled to the structure, a scanning laser Doppler vibrometer, and / or other acoustic measuring devices. For example, the acoustic measuring device 15 may measure the acoustic response within the structure (e.g., the whole-field surface velocity response). The acoustic response may include the response of vibrations / waves (e.g., the whole-wave field response) within and / or beyond the audible range (ultrasonic response).

[0025] In some embodiments, the acoustic measuring 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 within 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 laser beams to measure the acoustic response in different parts of the structure. The acoustic response may include the amplitude, velocity, and / or frequency of vibrations / waves within the structure. The scan path may refer to the path that the beam(s) of the vibrometer track and / or follow along the structure to perform the measurement. In some embodiments, the vibrometer may perform the measurement using a raster scan.

[0026] The acoustic measuring device 15 may be configured to measure acoustic excitations within a structure. The acoustic measuring device 15 may be configured to measure acoustic excitations within a structure for various purposes. For example, the acoustic measuring device 15 may measure acoustic excitations generated within a structure to test the acoustic response of the structure's coating to different frequencies. The acoustic measuring device 15 may measure acoustic excitations generated within a structure for a more comprehensive inspection of the structure's coating. The acoustic measuring device 15 may be configured to measure acoustic excitations within a structure in the same or different ways for various purposes. For example, the acoustic measuring device 15 may perform partial measurements of acoustic excitations within a structure to test different frequencies, or perform full measurements of acoustic excitations within a structure for a more comprehensive inspection of the coating. Partial measurements of acoustic excitations within a structure may include incomplete measurements of acoustic excitations within the structure, while full measurements of acoustic excitations within a structure may include complete measurements of acoustic excitations within the structure. For example, partial measurements of acoustic excitations within a structure may include measurements at fewer points and / or smaller areas than full measurements of acoustic excitations within a structure. Partial measurements of acoustic excitations within a structure may involve sampling of specific parts of the structure with the aim of determining to what extent (e.g., how efficiently) different parts of the structure were acoustically excited using different excitation frequencies. Full measurements of acoustic excitations within a structure may involve measurements across the structure with the aim of examining the properties of the structure's coatings using the measured acoustic excitations (acoustic excitations performed using selected excitation frequencies).

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

[0028] A structure may refer to the arrangement and / or organization of one or more objects. Objects may be arranged and / or organized in a structure to perform one or more functions. A structure may consist of a specific type of object, or a combination of different types of objects. For example, a structure may include a rigid metal structure and / or other structures. A structure may have a symmetrical or asymmetrical 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 hollow structures, support structures, movable structures, and / or other structures. A hollow structure may refer to a structure that contains one or more empty spaces within it. 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 container, a pipe, a pressure vessel, a tank, and / or other hollow structures. 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 structures. 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 structures. Non-limiting examples of structures include offshore floating production facilities (e.g., spars, semi-submersible vessels, tension-leg platforms), oil rigs, ship / barge hulls, offshore mobile drilling units, aircraft, space launchers, wind turbine blades, pressure vessels, piping systems, ballast tanks, empty tanks, and cargo tanks, one or more parts or all of these. Other types of structures are also intended.

[0030] In some embodiments, the structure may refer to a part of a larger structure. For example, the structure may refer to a region 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, the structure may refer to a component of a larger structure; the coating on the component / the coating on a portion of the component may be inspected.

[0031] A coating may refer to one or more materials covering the surface of a structure. A coating may refer to one or more materials applied to the surface of a structure. A substrate may refer to one or more materials of a structure to which a coating may be applied. A coating on a structure may cover all or part of a substrate. A structure may be coated using one or more application of a coating. A coating on a structure may consist of a single coating of one or more materials or multiple coatings of one or more materials. The inner and / or outer surfaces of a structure may be covered with one or more coatings. For example, a coating on a steel panel may cover the outer surface of the steel panel. A coating on a pipe (e.g., a liner) may cover the inner diameter of the pipe. A hollow structure (e.g., a tank) may have a coating on both its inner and outer surfaces, or a coating on either the inner or outer surface. A coating on the inner surface may be the same as or different from a coating on the outer surface. The same or different types of coatings may be applied to different parts of a structure. Other types of coatings are also intended.

[0032] A coating may be applied to a structure to protect the structure and / or materials in contact with the structure. For example, a coating may be applied to a storage structure (e.g., a container) to protect the structure from accelerated deterioration by either the contents of the stored material or the external environment. If the coating is damaged, the structure may no longer be protected, and the integrity of the structure may be reduced. This may result in safety risks and a loss of capital. For example, if the coating is damaged, the underlying structure (substrate) may be exposed to potentially harsh conditions, which may result in substantial damage to the structure (e.g., corrosion). Repairing a damaged structure may be far more expensive and time-consuming than repairing the coating. It is very important to perform regular inspections of coated structures to identify and repair damaged coatings and maintain the integrity of the coating before evidence of structural damage appears.

[0033] Conventional coating inspections include manual testing by technicians. Technicians may use visual inspection to identify areas with visual signs of damage and then remove portions of the coating. They may also use electric current to determine coating thickness and identify areas where the coating is thinning. These inspection methods are time-consuming, can be destructive to the coating, and are susceptible to the technician's subjectivity. Furthermore, these methods do not predict areas where failure is imminent. Additionally, when using these methods, technicians may need to be in undesirable environments, such as enclosed spaces (e.g., inside hollow spaces, e.g., tanks or containers), and around potentially hazardous materials (e.g., open water, gas, oil). Even in the case of external inspections, when using these methods, technicians may need to be in hazardous locations and / or areas with restricted access.

[0034] This disclosure uses measured acoustic excitations within a structure having a coating to determine the properties of the coating, such as the location, size, and / or type of defects within the coating. The acoustic response of the structure is removed from the measured acoustic excitations within the structure to obtain the acoustic response of the coating, and this acoustic response of the coating is used to determine the properties of the coating.

[0035] In some embodiments, acoustic excitations within a structure having a coating may be measured to obtain a temporal surface velocity response. The complex surface velocity response may be calculated at the steady-state excitation frequency. Rather than using local wavenumber estimates from the complex velocity response, this disclosure utilizes relative velocity calculations to identify indicators of defects within the coating. The use of the velocity response in this disclosure may involve using velocity measurements and / or other temporal properties of the response. For example, the use of the velocity response may involve calculating / deriving displacement, acceleration, and / or other temporal derivatives from the velocity response, and these displacement, acceleration, and / or other temporal derivatives may be used in the analysis described herein (e.g., outlier analysis). For example, displacement and acceleration may be derived from a velocity response map, or they may be phase shifts of the velocity response map up to a constant multiplier. In some embodiments, 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 a certain frequency (e.g., a high frequency 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 the major structural modes, and the filtered response (including the response of the coating / defects within the coating) may be used to determine the coating properties(s). A poorly adhered coating may respond to these high frequencies, forming areas of high-response data indicating coating defects (e.g., bubbling, blistering, poor adhesion). Outlier analysis may be performed on the response data to identify areas of defects. For example, high-response pixels may indicate the presence of coating defects.

[0037] This disclosure enables faster and more efficient non-destructive testing of structural coatings. This disclosure may enable remote inspection of coatings without requiring technicians to be present at the coating site.

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

[0039] The processor 11 may be configured to provide information processing capabilities in the system 10. Therefore, the processor 11 may include one or more of the following: 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 to facilitate 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 the following: a measurement component 102, a filter component 104, a characteristic component 106, and / or other computer program components.

[0040] The measurement component 102 may be configured to acquire measurements of acoustic excitations within a structure. The structure may include a substrate and a coating on at least a portion of the substrate. The surface of the structure may be completely or partially covered with the coating. Acquiring measurements of acoustic excitations within a structure may include one or more of accessing, obtaining, analyzing, determining, inspecting, identifying, generating, loading, positioning, making, opening, receiving, searching, surveying, selecting, storing, taking in, and / or otherwise obtaining the measurements of acoustic excitations within the structure. Measurements of acoustic excitations within a structure may be acquired using acoustic measuring device 15 and / or other acoustic measuring devices. Measurements of acoustic excitations within a structure may be acquired from acoustic measuring device 15, other acoustic measuring devices, and / or other locations. For example, the acoustic measuring device 15 may generate information that characterizes, defines, identifies, and / or reflects the measured acoustic excitations within the structure, and this information may be obtained directly from the acoustic measuring device 15 and / or indirectly from the acoustic measuring device 15 (for example, from the electronic storage device of the acoustic measuring device 15).

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

[0042] In some embodiments, measurements of acoustic excitations within a structure may include measurements of displacement response, velocity response, and / or acceleration response within the structure. Measurement component 102 may acquire measurements of displacement response, velocity response, and / or acceleration response within the structure due to acoustic excitations. In some embodiments, measurements of displacement response, velocity response, and / or acceleration response within the structure may be acquired as a raw wave field image, the size of which reflects the type and / or quantity of the displacement response, velocity response, and / or acceleration response. In some embodiments, continuous area measurements of acoustic excitations / responses within the structure may be acquired. Other measurements of acoustic excitations within the structure are also intended.

[0043] In some embodiments, the measurement of acoustic excitations within a structure may include partial measurements of acoustic excitations within the structure. Partial measurements of acoustic excitations within a structure may include measurements that are less comprehensive than the total measurement. Partial measurements of acoustic excitations within a structure may include incomplete measurements of acoustic excitations within a structure. Partial measurements of acoustic excitations within a structure may include measurements at fewer points and / or smaller areas of the structure / coating compared to the total measurement of acoustic excitations within a structure. Partial measurements of acoustic excitations within a structure may include sampling of specific portions of the structure / coating with the aim of determining 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(s) to use to perform a full measurement of acoustic excitation within a structure. In some embodiments, the excitation frequency(s) selected to perform a coating inspection of a 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 defect to be identified, and / or other information. For example, frequencies of 400 kHz to 600 kHz may induce stronger excitation within the coating of a metal structure, revealing defects within the coating. Other frequencies are also intended to be used.

[0045] In some embodiments, the measurement of acoustic excitations within a structure may include a total measurement of acoustic excitations within the structure. A total measurement of acoustic excitations within a structure may include a more comprehensive measurement than a partial measurement. A total measurement of acoustic excitations within a structure may include a complete measurement of acoustic excitations within the structure. A total measurement of acoustic excitations within a structure may include measurements at more points and / or larger areas of the structure / coating compared to a partial measurement of acoustic excitations within a structure. A total measurement of acoustic excitations within a structure may include sampling of different parts of the structure / coating for the purpose of determining one or more properties of the coating. For example, acoustic excitations may be measured throughout the structure to generate a total wavefield measurement that shows the acoustic response of the entire coating / area of ​​interest. The total wavefield measurement may be used to identify (e.g., visualize) defects within the coating / area of ​​interest.

[0046] Acoustic excitations may be generated within a structure using a single excitation frequency at a time, or using multiple excitation frequencies at a time. Acoustic excitations within a structure may include steady-state acoustic excitations (acoustic steady-state wave field excitations). Acoustic excitations within a structure may also include quasi-steady-state acoustic excitations. Steady-state / quasi-steady-state acoustic excitations may be generated within a 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 acoustic steady-state wave field excitations within a 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 generate steady-state multi-tone ultrasonic excitations of a structure, and the ultrasonic response at different parts of the structure may be measured and used to determine the characteristics of the coating at corresponding parts. Using steady-state multi-tone ultrasonic excitation, ultrasonic response measurements can be performed rapidly (e.g., scanning an area of ​​more than one square meter in seconds) from long distances (e.g., tens of meters away) without the need for repetition. Other types of acoustic excitation of structures are also intended.

[0047] In some embodiments, the complex response within the structure at the excitation frequency (e.g., the complex velocity response) may be obtained from measurements of acoustic excitation within the structure. Each individual pixel of the measurement may contain a segment of time-response data. The time response of a pixel may be converted to the frequency domain via a dot product with the complex exponent at the excitation frequency. For example, the complex numerical amplitude and phase response at the excitation frequency may be calculated using the following: where v(x,y,t) is the time response at the pixel position (x,y), f0 is the excitation frequency, and T is the time length of the sliding window (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 also be obtained from the above.

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

[0050] The filter component 104 may be configured to filter measurements of acoustic excitations within a structure. For example, measurements of wave field excitations in the acoustic steady state within a structure may be filtered. Filtering measurements of acoustic excitations within a structure may involve using one or more filters to remove one or more portions of the data from the measurements. Measurements of acoustic excitations within a structure may include (1) the acoustic response of the substrate and (2) the acoustic response of the coating. For example, the complex ultrasonic response of the structure (e.g., the complex velocity response of the ultrasonic) may include response modes from the substrate and the coating on the substrate. Structural responses may overwhelm the responses of subtle coatings / coating defects. Measurements of acoustic excitations within a 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 excitations within a structure. The filtered measurements of acoustic excitations within a structure may include the acoustic response of the coating. For example, the filtered measurements of acoustic excitations within a structure may include the acoustic spatial wave field response of the coating.

[0051] Figure 3 shows an example of measured values ​​310 of acoustic excitation within a structure and an example of filtered measured values ​​320 of acoustic excitation within a structure. Measured value 310 may represent the wavenumber response within the structure, which includes both the response from the substrate and the response from the coating of the structure. Filtered measured value 320 may represent the filtered wavenumber response within the structure. Filtered measured value 320 may be generated by removing the response from the substrate of the structure from measured value 310. Filtered measured value 320 may include the response from the coating of the structure, rather than the response from the substrate of the structure.

[0052] Figure 4 shows an example of measured acoustic excitations within a structure (410) and an example of filtered measured acoustic excitations within a structure (420). Measured value 410 may represent the actual wave-field response within the structure, which includes both the response from the substrate and the response from the coating. Filtered measured value 420 may represent the filtered actual wave-field response within the structure. Filtered measured value 420 may be generated by removing the response from the substrate from measured value 410. Filtered measured value 420 may include the response from the coating of the structure, rather than the response from the substrate. The coating of the structure may include blisters, which may become more apparent in filtered measured value 420 after the dominant structural response mode has been filtered out.

[0053] In some embodiments, filtering measurements of acoustic excitations within a structure to remove the substrate's acoustic response from the measurements may involve applying one or more spatial band rejection filters. For example, a series of spatial band rejection filters may be applied to remove the substrate's acoustic response from the measurements. Spatial band rejection filters(s) may be applied in the wavenumber domain and / or the time domain. The use of other types of filters is also intended.

[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 properties of the coating. The characteristics of the coating may include the properties of the coating itself and / or the 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 properties of defects within the coating. For example, the characteristics of the coating may include the location, size, and / or type of one or more defects within the coating. Defects within the coating may refer to imperfections or abnormalities within the coating. Defects within the coating may impair the quality, function, and / or usefulness of the coating. For example, defects within the coating may include reduced adhesion between the coating and the substrate. Reduced adhesion between the coating and the substrate may include attenuation and / or breakage 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 intended.

[0055] Determining the properties of a coating may include identifying properties, quantifying properties, and / or other determinations of the properties of the coating. For example, the property component 106 may determine the presence and / or absence of one or more defects in the coating, identify the type of defects in the coating, identify the location of defects in the coating, determine the size of defects in the coating, determine the shape of defects in the coating, quantify the defects in the coating (for example, by providing a specified number), and / or provide other determinations of the properties of the coating.

[0056] The properties of the coating may be determined by the characteristic 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 excitations within the structure and / or other information. The properties of the coating may also be determined using the acoustic response of the coating to excitation frequencies. For example, the characteristic component 106 may determine the properties of different parts of the coating using the amount and / or type of acoustic excitations in different parts of the coating.

[0057] Determining the coating properties(s) in this way may enable non-destructive evaluation of the coating. Determining the coating properties(s) in this way may enable evaluation of the coating from a distance away from the structure. Acoustic excitations within the structure may be measured from a distance away from the structure (e.g., 10 meters away). For example, the coating properties(s) may be determined in a line-of-sight inspection of a structure as disclosed herein. A line-of-sight inspection of a structure may include an inspection of the structure using an unobstructed line of sight of the structure. Rather than requiring being near and adjacent to the structure for inspection, a line-of-sight inspection may determine the coating properties(s) using measurements of acoustic excitations within the structure from a distance (e.g., from a single distance away from the structure, or from different distances away from the structure).

[0058] Such inspections may be less intrusive and / or less expensive than physical inspections of structures. For example, inspecting the coating of a tall structure may require raising scaffolding to allow inspectors to reach the coating. Line-of-sight inspections may allow the coating to be inspected without the need for such equipment. Another example is that physical inspections of structures may require taking physical samples from the structure / coating, thus requiring inspectors to visit the structure. Equipment for line-of-sight inspections (e.g., acoustic excitation devices, acoustic measurement devices, processors) may be set up at the structure's location and used without the presence of inspectors. The coating of a structure may also be inspected remotely.

[0059] In some embodiments, one or more maintenance tasks on a structure may be performed based on the characteristics of the coating. Maintenance tasks may refer to tasks that repair the structure / coating. For example, maintenance tasks may be performed to repair defects in the coating. The characteristics of the coating as determined herein may be used to determine where to direct maintenance tasks on the structure. The characteristics of the coating may be used to determine the overall health of the coating on the structure (e.g., an overall health index). The characteristics 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 the 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 defects in the coating. For example, pinhead-sized defects in the coating may be identified for monitoring, while fingernail-sized defects 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 embodiments, one or more outlier detections (e.g., anomaly detections) may be performed on the acoustic response of the coating to determine the character(s) of the coating. For example, outlier analysis of the acoustic response of the coating may be used to determine the character(s) of defects 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 the rest of the acoustic response of the coating. In some embodiments, the degree to which a portion of the acoustic response of the coating must deviate from the rest of the acoustic response in order to be considered statistically / significantly different from the rest of the acoustic response may be determined based on the use of one or more thresholds, criteria, and / or other factors. In some embodiments, the degree to which a portion of the acoustic response of the coating must deviate from the rest of the acoustic response in order to be considered statistically / significantly different from the rest of the acoustic response may be set by the user of system 10.

[0061] Outliers in the acoustic response of a coating may indicate the presence of defects within the coating. The quantity and / or type of outliers in the acoustic response of a coating may be used to identify / determine the characteristics of defects. For example, outlier detection may be used on the response of a coating to identify regions of the coating with higher relative strain energy, as described later, and then used to identify / determine the characteristics of defects within the coating. Other outlier detection methods are also intended.

[0062] In some embodiments, determining the properties of a coating based on the acoustic response of the coating in filtered measurements of acoustic excitations within a 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 excitations within a structure and / or other information, and (2) determining the properties of the coating based on the defect map and / or other information.

[0063] A defect map may refer to an image that visually represents defects within a coating. A defect map may also refer to an image that visually represents different properties of a coating. For example, a defect map may visually represent different acoustic responses within a coating using different pixel values ​​(e.g., different colors, different intensities). A defect map may visually represent outliers in the acoustic response within a coating using different pixel values. It is intended that other statistics and other types of defect maps of the acoustic response within a coating may be used.

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

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

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

[0067] In some embodiments, generating a defect map(s) of the coating based on the acoustic response of the coating in filtered measurements of acoustic excitations within a structure may include outlier analysis of the coating's acoustic response and / or determination of pixel values ​​in the defect map(s) based on other information. For example, outlier analysis of the coating's acoustic response may include calculation of changes in displacement response, velocity response, and / or acceleration response within the structure / coating, and these changes in displacement response, velocity response, and / or acceleration response may be used to determine the pixel values ​​in the defect map(s). Outlier analysis of the coating's acoustic response may also utilize other properties of the acoustic response (e.g., other time derivatives).

[0068] For example, relative velocity features within a structure / coating may be used to identify changes in strain energy (U), where changes in strain energy indicate the presence / characterization of defects(s) within the coating. The rate of change in strain energy is the difference in relative velocity.

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[0069] Relative velocity features may be calculated within the submatrix (pixel grouping), and the central pixel

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[0070] Value of the center pixel

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

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

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[0073] Relative velocity features may be used to quantify / identify central pixels that deviate from their surrounding pixels. This technique can identify small defects (e.g., defects covered by one or a few pixels in the defect map), which may be missed by conventional methods. The computational submatrix width may be set to the distance between small defects (e.g., bubbling or blistering of coatings). Relative velocity features can highlight pixels that are significantly different from other pixels in the computational submatrix.

[0074] Relative velocity values ​​may be used as pixel values ​​in the defect map. Relative velocity values ​​may be used to determine the pixel values ​​in the defect map. In some embodiments, 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 ordinal statistics filter, a disk filter, and / or other filters may be applied. The width of the ordinal statistics filter may be fixed (e.g., 4 mm). The width of the ordinal statistics filter may be set to include clusters of defects to highlight areas with a high density of small defects. The ordinal statistics filter may sort the values ​​in the calculation matrix in ascending order. Pixels in the calculation matrix may be assigned as values ​​in the reference index. For example, the reference index may be selected as the 99.6th percentile of the position.

[0075] A disk-shaped filter may be used to reshape the results of the ordinal statistics filter. The shape of the ordinal statistics filter may be square, and as a result, the filtered data may appear as overlapping squares. The disk-shaped filter may blend the squares together to form a continuous defect map. Since many coating defects are circular in shape, a disk shape may be used. The use of other shapes is also intended.

[0076] The width of the disk filter may be fixed (e.g., radius 3 mm), and its diameter may extend beyond the edges of a square ordered statistical filter. The disk filter may create a 2D predefined filter by generating a correlation kernel and apply it to a matrix. The output of the disk filter may be used as a defect map.

[0077] Figure 5 shows an example of defect map generation. The left side is image A510, which shows the relative velocity feature values ​​for the coating region. The center is image B520, which shows the result of processing image A510 through an ordinal statistics filter. The right side is image C530, which shows the result of processing image B520 through a disk-type filter. Image C530 may be used as a defect map for the coating. The shapes shown in image C530 may correspond to the shapes of defects in the coating. The pixel values ​​of defects in image C530 may correspond to different types / severities of defects in the coating.

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

[0079] Figure 7 shows an example of a structural image 710, an example of a relative velocity feature 720 for a structural, and an example of a defect map 730 for a structural. The structural image 710 may show visible blistering within the structural coating. The relative velocity feature 720 for a structural may provide a fine-resolution view of defects within the coating. The relative velocity feature 720 for a structural may show individual blisters within the structural coating. The defect map 730 for a structural may highlight areas of the coating containing defects.

[0080] Figure 8 shows an example image of a structure 810 and an example defect map 820 for the structure. The image of the structure 810 may show visible defects within the coating of the structure. The defect map 820 for the structure may show both visible and invisible defects within the coating of the structure.

[0081] Embodiments of the Disclosure may be in the form of hardware, firmware, software, or any preferred combination thereof. The embodiment of the Disclosure shown in Figure 1 may be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. The 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, a tangible (non-temporary) machine-readable storage medium may include read-only memory, random-access memory, magnetic disk storage medium, optical recording medium, flash memory device, etc., and a machine-readable transmission medium may include the form of a propagating signal, such as a carrier wave, infrared signal, digital signal, etc. Firmware, software, routines, or instructions may be described herein in terms of specific typical embodiments and models of the Disclosure and the execution of certain operations.

[0082] In some embodiments, some or all of the functions attributed to System 10 in Figure 1 in this specification may be provided by external resources not included in System 10. These external resources may include hosts / sources of information, computing, and / or processing, and / or other providers of information, computing, and / or processing outside of System 10.

[0083] The processor 11, the electronic memory device 13, the acoustic excitation device 14, and the acoustic measurement device 15 are connected to the interface 12 in Figure 1, but any communication medium may be used to facilitate direct and / or indirect communication between any 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 memory device 13. In non-limiting examples, wireless communication may include one or more of the following: wireless communication, Bluetooth communication, Wi-Fi communication, cellular communication, infrared communication, or other wireless communication. Other types of communication are also intended by this disclosure.

[0084] Although the processor 11 is shown as a single entity in Figure 1, this is for illustrative purposes only. In some embodiments, the processor 11 may include multiple processing units. These processing units may be physically located within the same device, or the processor 11 may represent a processing function in which multiple devices work together. The processor 11 may be separate from and / or part of one or more components of the system 10. The processor 11 may be configured to execute one or more components by software, hardware, firmware; any combination of software, hardware, and / or firmware; and / or other mechanisms for configuring processing capabilities on the processor 11.

[0085] Although the computer program components are shown in Figure 1 as being located in the same place within a single processing unit, it should be understood that in embodiments in which the processor 11 includes multiple processing units, one or more computer program components may be located separately from other computer program components. Although the computer program components are described as performing or being configured to perform an operation, the computer program components may include instructions that can be programmed to perform an operation on the processor 11 and / or the system 10.

[0086] Although 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 limit them. In some embodiments, one or more functions of the computer program components described herein may be implemented via hardware (e.g., a dedicated chip, a field-programmable gate array) rather than software. One or more functions of the computer program components described herein may be implemented in software, in hardware, or in both software and hardware.

[0087] The descriptions of the functions provided by the various computer program components described herein are for illustrative purposes only and are not intended to limit any of the computer program components, as any of them may provide more or fewer functions than those described herein. For example, one or more computer program components may be removed, and some or all of their functions may be provided by other computer program components. As another example, the processor 11 may be configured to execute one or more further computer program components that can perform some or all of the functions belonging to one or more of the computer program components described herein.

[0088] The electronic storage medium of the electronic storage device 13 may be provided integrally with (i.e., substantially inremovably) one or more components of the system 10, and / or as a removable storage device that can be connected to one or more components of the system 10, for example, via a port (e.g., a USB port, a FireWire port, etc.) or a drive (e.g., a disk drive, etc.). The electronic storage device 13 may include one or more of the following: optically readable storage media (e.g., optical discs, etc.), magnetically readable storage media (e.g., magnetic tape, magnetic hard drives, floppy drives, etc.), charge-based storage media (e.g., EPROM, EEPROM, RAM, etc.), solid-state storage media (e.g., flash drives, etc.), and / or other electronically readable storage media. The electronic storage device 13 may be a separate component within the system 10, or it may be provided integrally with one or more other components of the system 10 (e.g., a processor 11). In Figure 1, the electronic storage device 13 is shown as a single entity, but this is for illustrative purposes only. In some embodiments, the electronic storage device 13 may include multiple storage units. These storage units may be physically located within the same device, or the electronic storage device 13 may represent the storage functions of multiple devices working together.

[0089] Figure 2 shows method 200 for coating inspection. The operation of method 200 described below is intended to be illustrative. In some embodiments, method 200 may be achieved using one or more further operations not described and / or without using one or more of the operations described. In some embodiments, two or more operations may be performed substantially simultaneously.

[0090] In some embodiments, one or more operations of Method 200 may be performed in one or more processing units (e.g., digital processors, analog processors, digital circuits designed to process information, central processing units, graphics processing units, microcontrollers, analog circuits designed to process information, state machines, and / or other mechanisms for electronically processing information). One or more processing units 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. One or more processing units 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] Referring to Figure 2 and Method 200, in operation 202, measurements of acoustic excitation within the structure may be obtained. The structure may include a substrate and a coating on at least a portion of the substrate. In some embodiments, operation 202 may be performed by the same or similar components as the measurement component 102 (shown in Figure 1 and described herein).

[0092] In operation 204, the measured values ​​of acoustic excitations within the structure may be filtered to remove the acoustic response of the substrate from the measurements. The filtered measured values ​​of acoustic excitations within the structure may include the acoustic response of the coating. In some embodiments, operation 204 may be performed by the same or similar components as the filter component 104 (shown in Figure 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 and / or other information in filtered measurements of acoustic excitations within the structure. In some embodiments, operation 206 may be performed by the same or similar components as the characteristic component 106 (shown in Figure 1 and described herein).

[0094] While the systems and / or methods of this disclosure have been described in detail for illustrative purposes, based on what is considered to be the most practical and preferred embodiment at present, it should be understood that such details are solely for that purpose, and this disclosure is not limited to the disclosed embodiments, but rather intended to cover modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it should be understood that, wherever possible, this disclosure is intended to allow one or more features of any embodiment to be combined with one or more features of any other embodiment.

Claims

1. A method for inspecting coatings, wherein the method is The acquisition of measurements of acoustic excitation within a structure, wherein the structure includes a substrate and a coating on at least a portion of the substrate. The method involves filtering the measured values ​​of acoustic excitations within the structure to remove the acoustic response of the substrate from the measured values, wherein the filtered measured values ​​of acoustic excitations within the structure include the acoustic response of the coating. The process includes determining one or more properties of the coating based on the acoustic response of the coating in the filtered measurements of acoustic excitations within the structure, Determining one or more properties of the coating based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure is: Based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure, a defect map of the coating is generated. A method comprising determining one or more properties of the coating based on the defect map.

2. The method according to claim 1, wherein filtering the measured values ​​of acoustic excitations within the structure to remove the acoustic response of the substrate from the measured values ​​includes applying one or more spatial band rejection filters.

3. The method according to claim 1, wherein the one or more properties of the coating include the location, size, and / or type of defects within the coating.

4. The method according to claim 3, wherein the defect in the coating includes a decrease in adhesion between the coating and the substrate.

5. The method according to claim 1, wherein the defect map is superimposed on the structure or aligned with the structure.

6. The method according to claim 5, wherein a plurality of defect maps of the coating are generated based on the acoustic response of the coating at different times, and the change or progression of defects in the coating is determined based on the plurality of defect maps superimposed on or aligned with the structure.

7. The method according to claim 6, wherein generating the defect map of the coating based on the acoustic response of the coating in the filtered measured values ​​of acoustic excitations within the structure comprises determining the pixel values ​​of the defect map based on outlier analysis of the acoustic response of the coating.

8. The method according to claim 7, wherein the measured values ​​of acoustic excitation within the structure include measured values ​​of displacement response, velocity response, and / or acceleration response.

9. The method according to claim 8, wherein the outlier analysis of the acoustic response of the coating includes calculating the changes in the displacement response, the velocity response, and / or the acceleration response.

10. The method according to claim 9, wherein one or more properties of the coating are determined non-destructively and at a distance from the structure.

11. The method according to claim 10, wherein the one or more properties of the coating are determined by a line inspection of the structure.

12. The method according to claim 11, wherein one or more maintenance operations on the structure are performed based on one or more properties of the coating.

13. A system for coating inspection, wherein the system is It includes one or more physical processors, and the one or more physical processors, by machine-readable instructions, The acquisition of measurements of acoustic excitation within a structure, wherein the structure includes a substrate and a coating on at least a portion of the substrate. The method involves filtering the measured values ​​of acoustic excitations within the structure to remove the acoustic response of the substrate from the measured values, wherein the filtered measured values ​​of acoustic excitations within the structure include the acoustic response of the coating. Based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure, one or more characteristics of the coating are determined. It is configured to do the following: Determining one or more properties of the coating based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure is: Based on the acoustic response of the coating in the filtered measurements of acoustic excitation within the structure, a defect map of the coating is generated. A system comprising determining one or more properties of the coating based on the defect map.

14. The system according to claim 13, wherein filtering the measured values ​​of acoustic excitations within the structure to remove the acoustic response of the substrate from the measured values ​​includes applying one or more spatial band rejection filters.

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