Surface roughness analysis system and method for analyzing the surface roughness of a workpiece - Patents.com

Abstract

To provide a surface roughness analysis system and methods of analyzing surface roughness of a workpiece.SOLUTION: The surface roughness analysis system comprises a number of wave generators, a number of wave sensors, and an ultrasonic analysis system. The ultrasonic analysis system is configured to receive material mechanical parameters for a workpiece, determine incident surface wave signal parameters for a source signal to be sent by the number of wave generators, and determine a cut-off wavelength using the material mechanical parameters, where the cut-off wavelength is a ratio of a surface wavelength to an incident wavelength.SELECTED DRAWING: None

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to non-destructive testing, and more particularly to a system and method for analyzing the surface roughness of a workpiece. [Background technology]

[0002] Surface roughness is a component of surface texture. Surface roughness is a product of the manufacturing process. In surface metrology, " Roughness The term "roughness" is typically applied to the high and low frequency parameters of a finished surface. Surface roughness can be described as a series of irregularities on a surface.

[0003] Surface roughness may be directly related to manufacturing characteristics and control. For some articles, surface roughness only affects aesthetics. For mechanical components, roughness is often a predictor of component performance. Roughness is associated with the propagation of mismatches. Therefore, roughness is often undesirable.

[0004] Current methods of roughness analysis include visual inspection or contact probes. Visual inspection is performed by comparing representative specimens with various known roughnesses to the workpiece being analyzed. Visual inspection has limited precision.

[0005] A contact probe makes contact with the surface being analyzed. The contact probe measures roughness by quantifying the distance the tip of the probe moves vertically as it moves across the surface of the workpiece. Contact probes are speed limited and only quantify the roughness of the surface traversed by the contact probe.

[0006] It would therefore be desirable to have a method and apparatus that takes into account at least some of the above issues, as well as possible other issues. Summary of the Invention

[0007] An embodiment of the present disclosure provides a surface roughness analysis system comprising a number of wave generators, a number of wave generators, and an ultrasonic analysis system configured to receive material mechanical parameters for a workpiece, determine incident surface wave signal parameters for source signals transmitted by the number of wave generators, and determine a predetermined distance of the number of wave sensors from the number of wave generators such that the number of wave sensors receiving a threshold surface wave indicates a surface roughness within a roughness threshold.

[0008] Another embodiment of the present disclosure provides a method of analyzing a surface roughness of a workpiece, wherein a material machine parameter of the workpiece is received, wherein a signal parameter for a source signal transmitted into the workpiece is determined using the material machine parameter, and wherein a predetermined distance of a number of wave sensors from a number of wave generators is determined such that a number of wave sensors receiving a threshold surface wave indicate a surface roughness within a roughness threshold.

[0009] Yet another embodiment of the present disclosure provides a method for analyzing a surface roughness of a workpiece. Signal parameters are determined for source signals transmitted into the workpiece by a number of wave generators to analyze the surface roughness of the workpiece. A cutoff wavelength is determined using material mechanical parameters of the workpiece. The cutoff wavelength is a ratio of the surface wavelength to the incident wavelength. A predetermined distance of a number of wave sensors from a number of wave generators is determined using the cutoff wavelength such that a number of wave sensors receiving a threshold surface wave indicates a surface roughness within a roughness threshold.

[0010] Another embodiment of the present disclosure provides a surface roughness analysis system. The surface roughness analysis system includes an ultrasonic analysis system, a number of wave generators, a number of wave sensors, and a roughness evaluator. The ultrasonic analysis system is configured to receive material mechanical parameters for the workpiece, determine incident surface wave signal parameters for source signals transmitted by the number of wave generators, and determine a predetermined distance of the number of wave sensors from the number of wave generators such that the number of wave sensors receiving a threshold surface wave indicates a surface roughness within a roughness threshold. The number of wave generators are configured to transmit source signals having the signal parameters into the workpiece. The number of wave sensors are positioned at least a predetermined distance from the number of wave generators. The roughness evaluator is configured to determine whether a surface roughness of the workpiece is below a roughness threshold based on the surface waves sensed by the number of wave sensors.

[0011] Another embodiment of the present disclosure provides a surface roughness analysis system. The surface roughness analysis system includes a number of wave generators, a number of wave sensors, and a roughness evaluator. The number of wave generators are configured to transmit source signals having signal parameters into a workpiece, and the signal parameters are calculated to generate surface waves at the workpiece. The number of wave sensors are configured to be oriented to receive surface waves from the workpiece and positioned at least a predetermined distance from the number of wave generators, where the predetermined distance is such that receiving a threshold surface wave at the number of wave sensors is indicative of a surface roughness within a roughness threshold. The roughness evaluator is configured to determine whether a surface roughness of the workpiece is below the roughness threshold based on the presence or absence of surface waves sensed by the number of wave sensors.

[0012] The features and functions can be achieved alone in various embodiments of the present invention or can be combined in other embodiments, further details of which can be seen with reference to the following description and drawings.

[0013] The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims, however, the illustrative embodiments, preferred modes of use, as well as further objects and features thereof, will be best understood by reading the following detailed description of the illustrative embodiments of the present disclosure when read in conjunction with the accompanying drawings. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 depicts a block diagram of an inspection environment in which an illustrative embodiment may be implemented; [Diagram 2] 1 is a perspective view of a workpiece having a surface roughness according to an illustrative embodiment; [Diagram 3] 1 is a side view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece according to an exemplary embodiment; [Figure 4] 1 is a side view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece according to an exemplary embodiment; [Diagram 5] 1 is a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece according to an exemplary embodiment; [Figure 6] 1 is a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece according to an exemplary embodiment; [Figure 7] 1 is a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece according to an exemplary embodiment; [Figure 8] 1 is a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece according to an exemplary embodiment; [Figure 9] FIG. 1 is a block diagram of a surface roughness analysis system associated with a surface of a workpiece in accordance with an illustrative embodiment. [Figure 10A-B] 1 illustrates a flow diagram of a method for analyzing the surface roughness of a workpiece in accordance with an illustrative embodiment. [Figure 11A-B] 1 illustrates a flow diagram of a method for analyzing the surface roughness of a workpiece in accordance with an illustrative embodiment. [Figure 12] 1 is an illustration of an aircraft manufacturing and service method in block diagram form in accordance with an illustrative embodiment; [Figure 13] 1 is an illustration of an aircraft in block diagram form in which an illustrative embodiment may be implemented; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The exemplary embodiments recognize and take into account one or more different considerations. The exemplary embodiments recognize and take into account that roughness is a predictor of mechanical components in both subtractive and additive manufacturing. The exemplary embodiments recognize and take into account that irregularities in surface finishes can form nucleation sites for cracks and corrosion. The exemplary embodiments recognize and take into account that fatigue is a surface phenomenon and that high surface roughness can increase the likelihood of crack growth initiation.

[0016] The illustrative examples recognize and take into account that roughness can also play a role in the interaction of a material with its environment, for example, roughness affects corrosion.

[0017] The illustrative examples recognize and take into account that surface roughness can be a challenge in the manufacture of three-dimensional printed parts. The illustrative examples recognize and take into account that many additive manufacturing methods form the shape of a part by layer-by-layer deposition of material. Surface roughness can be particularly important in high fatigue cycle components.

[0018] In an exemplary embodiment, ultrasonic surface guided waves are used to characterize the amplitude and period of surface roughness during the manufacturing process. Surface acoustic waves are generated by several transducers and propagate along the rough surface. In an exemplary embodiment, a cut-off threshold for Rayleigh wave propagation is predefined to indicate the type of surface roughness. This cut-off occurs for a specific ratio of spatial surface waviness to acoustic waves. Detection of the resulting wave attenuation and decay characterizes the surface roughness.

[0019] Exemplary embodiments can be used in-line in manufacturing processes. Exemplary embodiments can signal adjustments in material deposition rates in additive manufacturing when shown to achieve desired product quality. Exemplary embodiments indicate when rework or additional surface processing is desired.

[0020] 1, a block diagram of an inspection environment in which an exemplary embodiment may be implemented is shown. In the inspection environment 100, a surface roughness analysis system 102 is used to analyze a surface roughness 104 of a surface 106 of a workpiece 108. The surface roughness 104 may result from a process 110 applied to the workpiece 108. The process 110 may include any desired type of manufacturing, maintenance, cleaning, operating, or other process. The process 110 may be used to add material to or remove material from the workpiece 108.

[0021] In some demonstrative embodiments, the process 110 may include a surface treatment 112. The surface treatment 112 affects the surface roughness 104 of the workpiece 108. The surface treatment 112 is selected from one of mechanical 114 or chemical 116. In some demonstrative embodiments, the mechanical 114 surface treatment 112 is selected from polishing, sanding, grinding, sandblasting, or any other desired form of mechanical 114 surface treatment 112.

[0022] In some illustrative examples, when the process 110 includes a surface treatment 112 that affects the surface roughness 104, the surface 106 is part of a substrate 118 of the workpiece 108. In other illustrative examples, when the process 110 includes a surface treatment 112 that affects the surface roughness 104, the surface 106 is a coating 120 that covers the substrate 118. In some illustrative examples, the coating 120 is applied directly onto the substrate 118. In other illustrative examples, there is an intermediate layer between the coating 120 and the substrate 118.

[0023] In some illustrative examples, the process 110 includes a surface coating application 122. The surface coating application 122 includes applying any desired thickness or type of material to the workpiece 108. In some illustrative examples, the surface coating application 122 includes one of a paint, a wax treatment, an anti-icing layer application, a hydrophobic layer application, a thermal protection layer application, or any other surface coating application 122.

[0024] In some exemplary embodiments, the surface roughness analysis system 102 may be a pitch-catch ultrasonic roughness analysis system. In some exemplary embodiments, the surface roughness analysis system 102 includes a number of wave generators 124, a number of wave sensors 126, and an ultrasonic analysis system 128. The ultrasonic analysis system 128 is configured to receive material mechanical parameters 130 for the workpiece 108, determine signal parameters 132 for source signals 134 transmitted by the number of wave generators 124, and determine a predetermined distance 160 of the number of wave sensors 126 from the number of wave generators 124 such that the number of wave sensors 126 receiving a threshold surface wave 164 indicate a surface roughness 104 within a roughness threshold 165. In some exemplary embodiments, the ultrasonic analysis system 128 is further configured to determine a cut-off wavelength 136 using the material mechanical parameters 130, the cut-off wavelength 136 being a ratio of a surface wavelength 138 to an incident wavelength 140. The predetermined distance 160 is determined based on the cutoff wavelength 136. In some exemplary embodiments, the cutoff wavelength 136 is approximately 0.5.

[0025] A cutoff threshold for Rayleigh wave propagation is predefined to indicate the surface roughness 104. This cutoff wavelength 136 occurs for a particular ratio of the surface wavelength 138 to the incident wavelength 140. In some illustrative examples, this ratio is described as the ratio of the spatial surface waviness to the acoustic wavelength. Detection of the resulting wave attenuation and attenuation characterizes the surface roughness 104. The surface roughness analysis system 102 can be used in-line in a manufacturing process. In additive manufacturing, the surface roughness analysis system 102 can be used in conjunction with signal adjustment of the material deposition rate to achieve the desired surface roughness.

[0026] Rayleigh waves propagate across the surface of a solid medium, such as surface 106 of workpiece 108, gradually losing energy due to surface roughness 104. For a perfectly smooth surface, the Rayleigh waves would have no discernible energy loss.

[0027] The attenuation of a surface wave (e.g., surface wave 164) is related to the surface profile parameters. The wavefront of a rough surface is attenuated by interference from the roughness pattern. R max and λ surface Depending on the roughness profile and magnitude of R, immediate or partial attenuation of the surface waves can occur. max If the height distance R / 2 is greater than the length of the Rayleigh wave, no surface wave is formed and the wave front is immediately reflected. max <λ surface In the frequency spectrum below one wavelength, where , surface waves form and propagate, but eventually decay over a certain distance along the rough surface.

[0028] The cutoff wavelength 136 is the ratio of the surface wavelength 138 to the incident wavelength 140, i.e., λ , at which no Rayleigh waves are formed. surface / λ wave The surface wave is attenuated at any point beyond the cutoff wavelength 136. The surface wavelength 138, or λ surface The higher the magnitude of , the greater the attenuation of the wave. If the ratio is 0.1, there is complete attenuation, if the ratio is 1, there is no attenuation. 0.1<λ surface / λ wave Within the range of λ<1, there is partial attenuation of the Rayleigh wave. The cutoff wavelength can be customized for different roughness profiles. In some example embodiments, the cutoff threshold is λ surface / λ wave =0.5.

[0029] The number of wave generators 124 generate the number of source signals 150 using signal parameters 132 that are determined by an ultrasonic analysis system 128 and take into account material mechanical parameters 130 and cutoff wavelengths 136.

[0030] A number of wave generators 124 includes any desired quantity of wave generators. As used herein, "a number of," when used in reference to an item, means one or more of the item. For example, "a number of wave generators 124" includes one or more wave generators.

[0031] In some exemplary embodiments, some of the wave generators 124 are acoustically coupled to the surface 106 via contact with the surface 106. In some exemplary embodiments, some of the wave generators 124 are acoustically coupled to the surface 106 via a coupling fluid. In some exemplary embodiments, some of the wave generators 124 are non-contact 142.

[0032] The number of wave sensors 126 may include any desired quantity of wave sensors. The number of wave sensors 126 may include one or more wave sensors.

[0033] In some illustrative embodiments, some of the wave sensors 126 are acoustically coupled to the surface 106 via contact with the surface 106. In some illustrative embodiments, some of the wave sensors 126 are acoustically coupled to the surface 106 via a coupling fluid. In some illustrative embodiments, some of the wave sensors 126 are non-contact 144.

[0034] If a surface wave such as surface wave 164 is completely attenuated or not formed before some wave sensors 126, some wave sensors 126 will not receive surface wave 164. Some wave sensors 126 generate an electrical signal output indicative of any surface wave sensed by some wave sensors 126. An output of some wave sensors 126 above a signal threshold indicates the detection of a surface wave. The signal threshold is set to distinguish between signal and noise.

[0035] When the surface waves 164 are completely attenuated, some of the wave sensors 126 will not sense the surface waves 164. When some of the wave sensors 126 do not sense the surface waves 164, the output of some of the wave sensors 126 will be below the signal threshold. The output of some of the wave sensors 126 below the signal threshold indicates that the surface roughness 104 is outside the roughness threshold 165. The roughness threshold 165 is a predetermined undesirable level of the surface roughness 104 for the workpiece 108 and its intended use. For example, the roughness threshold 165 is a maximum level based on a maximum desired roughness height or a maximum desired roughness width. The maximum desired roughness height or maximum desired roughness width is based on the desired use of the workpiece 108, the material, and the type of part.

[0036] In some illustrative embodiments, the number of wave generators 124 includes a wave generator 146. In some illustrative embodiments, the number of wave generators 124 includes a wave generator 148. The number of wave generators 124 are configured to transmit multiple source signals 150 into the surface 106 of the workpiece 108. The multiple source signals 150 may be transmitted simultaneously or sequentially into the surface 106. The wave generator 146 transmits a source signal 134 into the workpiece 108. The wave generator 146 transmits a source signal 134 into the workpiece 108 at a source location 152 on the surface 106.

[0037] The number of wave sensors 126 are configured to sense a plurality of surface waves 154 traveling through the surface 106. The number of wave sensors 126 are positioned at least a predetermined distance 160 from the number of wave generators 124 to detect surface waves from the workpiece 108, the predetermined distance 160 being selected based on a cutoff wavelength 136 calculated by the ultrasonic analysis system 128.

[0038] In some demonstrative embodiments, some wave sensors 126 include only the wave sensor 156 distance 158 from the wave generator 146. When some wave generators 124 have only the wave generator 146 and some wave sensors 126 have only the wave sensor 156, the distance 158 is at least the predetermined distance 160. The distance 158 is measured in a second direction 162 on the surface 106 of the workpiece 108. The predetermined distance 160 is selected based on the cutoff wavelength 136 calculated by the ultrasonic analysis system 128. The predetermined distance 160 is selected such that receiving a threshold surface wave indicates a surface roughness within a roughness threshold 165.

[0039] When the distance 158 between the wave sensor 156 and the wave generator 146 is at least the predetermined distance 160, receiving a surface wave 164 at the wave sensor 156 indicates that the surface roughness 104 is within a roughness threshold 165. In these illustrative examples, the surface wave 164 is generated by a source signal 134 transmitted at a source location 152 to the workpiece 108.

[0040] If the wave sensor 156 senses a surface wave 164, then the surface roughness 104 between the wave generator 146 and the wave sensor 156 is within the roughness threshold 165. If the wave sensor 156 does not sense a surface wave 164, then the surface wave 164 has either attenuated due to the surface roughness 104 or is not forming at all due to the surface roughness 104. If the wave sensor 156 does not sense a surface wave 164, then the surface roughness 104 between the wave generator 146 and the wave sensor 156 is outside the roughness threshold 165.

[0041] In some demonstrative embodiments, the number of wave sensors 126 includes a series of wave sensors 166. Each wave sensor in the series of wave sensors 166 has a different distance from a wave generator 146 of the number of wave generators 124 in the second direction 162 of the surface 106 of the workpiece 108. The series of wave sensors 166 includes a wave sensor 156 and a wave sensor 168. The wave sensor 168 has a distance 170 from the wave generator 146. The distance 158 and the distance 170 are different values.

[0042] A single wave sensor, such as wave sensor 156, is used to analyze the surface roughness 104 at a single location. A series of wave sensors 166 can be used in combination to evaluate various locations between the wave generator 146 and the series of wave sensors 166.

[0043] In some illustrative embodiments, distance 158 is less than distance 170. In some illustrative embodiments, wave sensor 156 senses surface waves 164 and wave sensor 168 does not sense surface waves 164. In these illustrative embodiments, surface roughness 104 between wave sensor 156 and wave generator 146 is within roughness threshold 165. In these illustrative embodiments, surface roughness 104 between wave sensor 168 and wave sensor 156 is outside roughness threshold 165.

[0044] In some illustrative embodiments, neither wave sensor 156 nor wave sensor 168 senses surface waves 164. In these illustrative embodiments, the surface roughness 104 between wave sensor 156 and wave generator 146 is outside roughness threshold 165.

[0045] In some illustrative embodiments, both wave sensor 156 and wave sensor 168 sense surface waves 164. In these illustrative embodiments, the surface roughness 104 between wave generator 146 and wave sensor 168 is within a roughness threshold 165.

[0046] In some illustrative embodiments, the number of wave generators 124 comprises a plurality of wave generators, wave generator 146 and wave generator 148, spaced across the surface 106 of the workpiece 108 in a first direction 172. The first direction 172 is perpendicular to the second direction 162. In these illustrative embodiments, the number of wave generators transmit a number of source signals 150 into the surface 106 at a number of source locations.

[0047] In some illustrative embodiments, wave sensor 156 is positioned at least a predetermined distance 160 from wave generator 146 and wave sensor 174 is positioned at least a predetermined distance 160 from wave generator 148. Output from wave sensor 156 and wave sensor 174 is used to analyze the local surface roughness 104 in a first direction 172. Output from wave sensor 156 is used to analyze the surface roughness 104 between wave generator 146 and wave sensor 156. Output from wave sensor 174 is used to analyze the surface roughness 104 between wave generator 148 and wave sensor 174.

[0048] The controller 176 is configured to control the generation of the number of source signals 150 having the signal parameters 132 by the number of wave generators 124. The controller 176 may be implemented in at least one of hardware and software. The controller 176 may be a processor unit in a computer system or a dedicated circuit, depending on the particular implementation.

[0049] In some exemplary embodiments, the controller 176 is configured to send electrical control signals to the number of pulsers 178. The electrical control signals instruct the number of pulsers 178 as to which pulsing scheme to utilize. In response to these electrical control signals, the number of pulsers 178 output electrical signals to the number of wave generators 124 that are representative of the ultrasonic waves to be generated.

[0050] The surface roughness analysis system 102 includes a roughness evaluator 180 configured to determine whether the surface roughness 104 of the workpiece 108 is below a roughness threshold 165 based on the surface waves sensed by the number of wave sensors 126. The roughness evaluator 180 determines whether the surface roughness 104 is within the roughness threshold 165 from the outputs of the number of wave sensors 126. If a wave sensor of the number of wave sensors 126 outputs a signal equal to or greater than the signal threshold, the wave sensor has detected a surface wave, such as the surface wave 164. If the roughness evaluator 180 receives an output from the number of wave sensors 126 that is less than the signal threshold, the roughness evaluator 180 determines that the surface roughness 104 is outside the roughness threshold 165.

[0051] The number of wave sensors 126 convert the impinging ultrasonic waves into electrical signals. In some illustrative embodiments, these electrical signals are transmitted to the number of receivers 182. In these illustrative embodiments, the number of receivers 182 output electrical signals representing the acquired ultrasonic inspection data from the number of wave sensors 126 to the roughness evaluator 180.

[0052] In some illustrative examples, the surface roughness analysis system 102 includes an ultrasonic analysis system 128 configured to receive material mechanical parameters 130 for the workpiece 108, determine incident surface wave signal parameters 132 for source signals 134 transmitted by the number of wave generators 124, and determine a predetermined distance 160 of the number of wave sensors 126 from the number of wave generators 124 such that the number of wave sensors 126 receiving the threshold surface waves 164 indicate a surface roughness 104 within a roughness threshold 165, the number of wave generators 124 configured to transmit source signals having the signal parameters 132 into the workpiece, the number of wave sensors 126 positioned at least the predetermined distance 160 from the number of wave generators 124, and a roughness evaluator 180 configured to determine whether the surface roughness 104 of the workpiece 108 is below a roughness threshold 165 based on the surface waves 164 sensed by the number of wave sensors 126.

[0053] In some demonstrative examples, the surface roughness analysis system 102 includes a number of wave generators 124 configured to transmit a source signal 134 having signal parameters 132 into the workpiece 108, the signal parameters 132 being calculated to generate surface waves 164 at the workpiece 108, a number of wave sensors 126 oriented to receive surface waves 154 from the workpiece 108 and positioned at least a predetermined distance 160 from the number of wave generators 124, the predetermined distance 160 being such that receiving a threshold surface wave 164 at the number of wave sensors 126 indicates a surface roughness 104 within a roughness threshold 165, and a roughness evaluator 180 configured to determine whether the surface roughness 104 of the workpiece 108 is below the roughness threshold 165 based on the presence or absence of the surface waves 164 sensed by the number of wave sensors 126. It is equipped with:

[0054] The illustration of the surface roughness analysis system 102 and inspection environment 100 in FIG. 1 is not meant to imply physical or architectural limitations to the manner in which an example embodiment may be implemented. Other components in addition to or in place of the illustrated components may be used. Some components may not be required. Moreover, blocks are illustrated to illustrate some functional components. When implemented in an example embodiment, one or more of these blocks may be combined, divided, or combined and divided into different blocks.

[0055] For example, although some wave generators 124 have only been described as having one or two wave generators, some wave generators 124 may have any desired quantity of wave generators. For example, some wave generators 124 may have more than two wave generators.

[0056] As another example, although the series of wave sensors 166 are illustrated as being associated with the wave generator 146, in some illustrative embodiments some wave generators 124 include more than one wave generator, each associated with its own series of wave sensors. As yet another example, although the series of wave sensors 166 are illustrated as including only two wave sensors, in some illustrative embodiments the series of wave sensors 166 include more than two wave sensors.

[0057] As another example, although the controller 176 is shown as a separate component from the ultrasonic analysis system 128, in some not shown embodiments the ultrasonic analysis system 128 and the controller 176 are part of the same processor unit or computer system. As yet another example, although the controller 176 is shown as a separate component from the roughness estimator 180, in some not shown embodiments the roughness estimator 180 and the controller 176 are part of the same processor unit or computer system.

[0058] 2, a perspective view of a workpiece having a surface roughness is shown in accordance with an exemplary embodiment. Workpiece 200 is a physical implementation of workpiece 108 of FIG. 1. Surface roughness analysis system 102 of FIG. 1 can be used to analyze surface roughness 202 of workpiece 200.

[0059] The workpiece 200 has a surface 204 having a surface roughness 202. The surface roughness 202 has a roughness height 206 and a roughness width 208.

[0060] The surface roughness 202 consists of surface irregularities resulting from the manufacturing process. These irregularities combine to form the surface texture. This is illustrated in FIG. 2. The roughness width 208 is the distance parallel to the nominal surface between successive peaks or ridges that make up the main pattern roughness. The roughness height 206 is often known as the height of the irregularity. The roughness height 206 is the height of the irregularity relative to a reference mean-line.

[0061] Roughness lay 210 represents the direction of the main surface pattern produced and reflects the manufacturing process used to produce it. Waviness refers to widely spaced irregularities outside the roughness width cutoff range and can be the result of workpiece or tool deflection during machining, vibration, or tool run-out. Waviness height is the distance from peak to valley of the surface profile measured in millimeters.

[0062] 3, a side view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is shown according to an example embodiment. The components of the surface roughness analysis system 300 are associated with the workpiece 302. The surface roughness analysis system 300 is a physical implementation of the surface roughness analysis system 102 of FIG. 1. The workpiece 302 may be a physical implementation of the workpiece 108 of FIG. 1. In some example embodiments, a diagram 304 is a cross-sectional view of the workpiece 200.

[0063] Components of the surface roughness analysis system 300 include a wave generator 306 and a wave sensor 308. The wave generator 306 is acoustically coupled to the surface 310 of the workpiece 302. The wave sensor 308 is acoustically coupled to the surface 310 of the workpiece 302 and detects surface waves from the workpiece 302.

[0064] In some exemplary embodiments, the wave generator 306 is acoustically coupled to the surface 310 via contact with the surface 310. In some exemplary embodiments, the wave generator 306 is acoustically coupled to the surface 310 via a coupling fluid. In some exemplary embodiments, the wave generator 306 is a non-contact ultrasonic generator.

[0065] The wave generator 306 transmits a source signal having signal parameters into a surface 310 of the workpiece 302. The signal parameters are determined by an ultrasonic analysis system and take into account material mechanical parameters of the workpiece 302.

[0066] In some illustrative embodiments, the wave sensor 308 is acoustically coupled to the surface 310 via contact with the surface 310. In some illustrative embodiments, the wave sensor 308 is acoustically coupled to the surface 310 via a coupling fluid. In some illustrative embodiments, the wave sensor 308 is a non-contact ultrasonic sensor.

[0067] The surface 310 has a surface roughness 312. As shown, the surface roughness 312 interrupts the propagation of surface waves along the surface 310 of the workpiece 302. The surface roughness 312 can cause immediate attenuation or partial attenuation of the waves.

[0068] The wave sensor 308 is positioned at least a predetermined distance from the wave generator 306 in the second direction 314. The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The predetermined distance is selected such that receiving surface waves within a threshold indicates acceptable surface roughness. The predetermined distance is a distance beyond which surface waves will not propagate if the surface roughness 312 is outside the roughness threshold.

[0069] A source signal having signal parameters transmitted by the wave generator 306 to the surface 310 of the workpiece 302 generates a Rayleigh wave propagation 316. In FIG. 304, the Rayleigh wave propagation 316 is shown. The Rayleigh wave propagation 316 originates from a source location where the source signal transmitted by the wave generator 306 enters the surface 310. In FIG. 304, due to surface roughness 312, a surface wave does not propagate from the Rayleigh wave propagation 316 to the wave sensor 308. The surface roughness 312 has at least one of an undesirable roughness width or an undesirable roughness height.

[0070] Because no surface waves propagate from the Rayleigh wave propagation 316 to the wave sensor 308, a signal with sufficient strength is not received by the wave sensor 308. In diagram 304, the wave sensor 308 does not receive a signal.

[0071] Data output from the wave sensor 308 is directed to an associated roughness evaluator (not shown). In some illustrative examples, a receiver (not shown) outputs an electrical signal representative of the acquired ultrasonic inspection data from the wave sensor 308 to the roughness evaluator (not shown). When the wave sensor 308 does not receive a signal, the associated roughness evaluator determines that the surface 310 has a surface roughness 312 that is outside a roughness threshold.

[0072] 4, a side view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is shown according to an example embodiment. The surface roughness analysis system 400 is a physical implementation of the surface roughness analysis system 102 of FIG. 1. The workpiece 402 may be a physical implementation of the workpiece 108 of FIG. 1. In some example embodiments, a diagram 404 is a cross-sectional view of the workpiece 200.

[0073] The components of the surface roughness analysis system 400 include a number of wave generators 406 and a number of wave sensors 408. The number of wave generators 406 has only one wave generator, wave generator 410. The wave generator 410 is acoustically coupled to a surface 412 of the workpiece 402.

[0074] The number of wave sensors 408 includes a series of wave sensors 414, where each wave sensor in the series of wave sensors 414 has a different distance from a wave generator 410 of the number of wave generators 406 in a second direction 416 of the surface 412 of the workpiece 402. The number of wave sensors 408 includes a wave sensor 418, a wave sensor 420, and a wave sensor 422.

[0075] A number of wave sensors 408 are acoustically coupled to a surface 412 of the workpiece 402 to detect surface waves from the workpiece 402. The surface 412 has a surface roughness 424. As shown, the surface roughness 424 interrupts the propagation of surface waves along the surface 412 of the workpiece 402. The surface roughness 424 may cause immediate or partial attenuation of the waves.

[0076] In some exemplary embodiments, the number of wave generators 406 are acoustically coupled to the surface 412 via contact with the surface 412. In some exemplary embodiments, the number of wave generators 406 are acoustically coupled to the surface 412 via a coupling fluid. In some exemplary embodiments, the number of wave generators 406 are non-contact ultrasonic generators.

[0077] A number of wave generators 406 transmit source signals having signal parameters into a surface 412 of the workpiece 402. The signal parameters are determined by an ultrasonic analysis system and take into account material mechanical parameters of the workpiece 402.

[0078] In some illustrative examples, at least one of the number of wave sensors 408 is acoustically coupled to the surface 412 via contact with the surface 412. In some illustrative examples, at least one of the number of wave sensors 408 is acoustically coupled to the surface 412 via a coupling fluid. In some illustrative examples, at least one of the number of wave sensors 408 is a non-contact ultrasonic sensor.

[0079] The wave generator 410 is positioned relative to the workpiece 402 to transmit a source signal to the workpiece 402 at a source location 426. Some of the wave sensors 408 are oriented relative to the workpiece 402 such that some of the wave sensors 408 are oriented to sense waves at at least two different locations from the source location 426. In this illustrative example, some of the wave sensors 408 are oriented to sense waves at three different distances from the source location 426.

[0080] Each of the several wave sensors 408 is positioned a different distance from the wave generator 410. Wave sensor 418 is separated from the wave generator 410 by a distance 428. Wave sensor 420 is separated from the wave generator 410 by a distance 430. Wave sensor 422 is separated from the wave generator 410 by a distance 432.

[0081] In this illustrative example, determining whether the surface roughness 424 of the workpiece 402 is within a roughness threshold includes determining whether the surface roughness 424 at multiple locations of the workpiece 402 is within a roughness threshold for at least one of a roughness width or a roughness height based on the output of several wave sensors 408.

[0082] By positioning several wave sensors 408, different distances from the wave generator 410 and different locations of the surface 412 in the second direction 416 are analyzed. For example, the surface roughness 424 at a location 434 between the wave generator 410 and the wave sensor 418 is analyzed using data from the wave sensor 418. If the wave sensor 418 produces an output indicative of a surface wave, then the surface roughness 424 at the location 434 is within a roughness threshold. For example, an output of the wave sensor 418 above a signal threshold indicates the detection of a surface wave. The signal threshold is set to distinguish between signal and noise. If a surface wave propagates to the wave sensor 418, then the surface roughness 424 is within a roughness threshold.

[0083] As another example, surface roughness 424 at location 436 between wave sensor 418 and wave sensor 420 is analyzed using data from wave sensor 420. If wave sensor 420 produces an output indicative of a surface wave, then surface roughness 424 at location 436 is within the roughness threshold. For example, an output of wave sensor 420 above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor 420, the surface wave propagates to location 434 and location 436. When a surface wave propagates to wave sensor 420, surface roughness 424 at location 434 and location 436 is within the roughness threshold.

[0084] As yet another example, the surface roughness 424 at a location 438 between the wave sensor 420 and the wave sensor 422 is analyzed using data from the wave sensor 422. If the wave sensor 422 produces an output indicative of a surface wave, then the surface roughness 424 at the location 438 is within the roughness threshold. For example, an output of the wave sensor 422 above a signal threshold indicates the detection of a surface wave. When a surface wave propagates to the wave sensor 422, the surface wave propagates through the locations 434, 436, and 438. When the surface wave propagates to the wave sensor 420, the surface roughness 424 at the locations 434, 436, and 438 is within the roughness threshold. If the surface wave does not reach the wave sensor 420, then the surface roughness 424 before the wave sensor 420 may be outside the roughness threshold.

[0085] By using several wave sensors 408 in combination, the surface roughness 424 at each of the locations 434, 436, and 438 can be analyzed individually. By using several wave sensors 408 in combination, the surface roughness 424 at each of the locations 434, 436, and 438 can be detected locally outside the roughness threshold. For example, if a surface wave is detected by the wave sensor 420, but no surface wave is detected by the wave sensor 422, then the surface roughness 424 at the location 436 is within the roughness threshold, but the surface roughness 424 at the location 438 is not within the roughness threshold. As another example, for example, if a surface wave is detected by the wave sensor 418, but no surface wave is detected by the wave sensor 420, then the surface roughness 424 at the location 434 is within the roughness threshold, but the surface roughness 424 at the location 436 is not within the roughness threshold. If no surface wave is detected by the wave sensor 418, then the surface roughness 424 at the location 434 is outside the roughness threshold. If no surface waves are detected by the wave sensor 418, the surface roughness 424 at locations 436 and 438 is not analyzed.

[0086] A number of wave sensors 408 are positioned at least a predetermined distance from the number of wave generators to detect surface waves from the workpiece, the predetermined distance being selected based on a cutoff wavelength calculated by the ultrasonic analysis system such that receiving a threshold surface wave indicates an acceptable surface roughness.

[0087] A source signal having signal parameters transmitted by wave generator 406 to surface 412 of workpiece 402 generates a Rayleigh wave propagation 440. In diagram 404, Rayleigh wave propagation 440 is shown. Rayleigh wave propagation 440 originates from a source location where the source signal transmitted by wave generator 406 enters surface 412. In diagram 404, due to surface roughness 424, a surface wave does not propagate from Rayleigh wave propagation 440 to any of wave sensor 418, wave sensor 420, or wave sensor 422. Surface roughness 424 has at least one of an undesirable roughness width or an undesirable roughness height.

[0088] Data output from the number of wave sensors 408 is directed to an associated roughness evaluator (not shown). In some illustrative examples, the number of receivers (not shown) output electrical signals representative of the acquired ultrasonic inspection data from the number of wave sensors 408 to the roughness evaluator (not shown). If a wave sensor of the number of wave sensors 408 does not receive a signal, the associated roughness evaluator determines that the surface 412 has a surface roughness 424 that is outside a roughness threshold.

[0089] 5, a perspective view of a workpiece with components of a surface roughness analysis system associated with the surface of the workpiece is shown in accordance with an exemplary embodiment. Surface roughness analysis system 500 is a physical implementation of surface roughness analysis system 102 of FIG. 1. In some exemplary embodiments, workpiece 502 is a physical implementation of workpiece 108 of FIG. 1. In some exemplary embodiments, view 504 is a perspective view of workpiece 200. In some exemplary embodiments, view 504 is a perspective view of surface roughness analysis system 300 and workpiece 302 of FIG. 3.

[0090] The components of the surface roughness analysis system 500 include a number of wave generators 506 and a number of wave sensors 508. The number of wave sensors 506 include a wave sensor 510, a wave sensor 511, and a wave generator 512. The wave generator 510, the wave generator 511, and the wave generator 512 are acoustically coupled to a surface 514 of the workpiece 502.

[0091] In some exemplary embodiments, the number of wave generators 506 are acoustically coupled to the surface 514 via contact with the surface 514. In some exemplary embodiments, the number of wave generators 506 are acoustically coupled to the surface 514 via a coupling fluid. In some exemplary embodiments, the number of wave generators 506 are a number of non-contact ultrasonic generators.

[0092] In some illustrative examples, at least one of the number of wave sensors 508 is acoustically coupled to the surface 514 via contact with the surface 514. In some illustrative examples, at least one of the number of wave sensors 508 is acoustically coupled to the surface 514 via a coupling fluid. In some illustrative examples, at least one of the number of wave sensors 508 is a non-contact ultrasonic sensor.

[0093] Each wave sensor of number of wave sensors 508 is positioned in a second direction 516 of a surface 514 of the workpiece 502 at least a predetermined distance from one of number of wave generators 506. Number of wave sensors 508 include wave sensor 518, wave sensor 520, and wave sensor 522.

[0094] Several wave sensors 508 are acoustically coupled to a surface 514 of the workpiece 502 to detect surface waves from the workpiece 502. The surface 514 has a surface roughness 524. The surface roughness 524 interrupts the propagation of surface waves along the surface 514 of the workpiece 502. The surface roughness 524 may cause immediate or partial attenuation of the waves.

[0095] Determining whether the surface roughness 524 of the workpiece 502 is within the roughness threshold includes determining whether the surface roughness 524 at each of a plurality of locations on the workpiece 502 is within the roughness threshold based on the outputs of several wave sensors, wave sensor 518, wave sensor 520, and wave sensor 522.

[0096] Having wave sensor 518, wave sensor 520, and wave sensor 522 makes it possible to analyze surface roughness 524 at several locations. Wave sensor 518, wave sensor 520, and wave sensor 522 are separated from each other in a first direction 526. In FIG. 5, several locations are spread across first direction 526.

[0097] The wave sensor 518 is positioned at least a predetermined distance from the wave generator 510 in a second direction 516 on the surface 514 of the workpiece 502 to detect surface waves from the workpiece 502. The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The predetermined distance is selected such that receiving a threshold surface wave indicates an acceptable surface roughness.

[0098] The wave sensor 520 is positioned at least a predetermined distance from the wave generator 511 in the second direction 516 of the surface 514 of the workpiece 502 to detect surface waves from the workpiece 502. The wave sensor 522 is positioned at least a predetermined distance from the wave generator 512 in the second direction 516 of the surface 514 of the workpiece 502 to detect surface waves from the workpiece 502.

[0099] The several wave generators 506 are separated in a first direction 526 of the workpiece 502. In FIG. 504, wave generator 510, wave generator 511, and wave generator 512 are equally spaced across the first direction 526. In other illustrative embodiments, the several wave generators 506 have different spacings.

[0100] In this illustrative embodiment, the surface roughness analysis system 500 analyzes the surface roughness 524 of the surface 514 between the number of wave generators 506 and the number of wave sensors 508. As shown, the number of wave generators 506 and the number of wave sensors 508 are separated from substantially all of the surface 514 in the second direction 516.

[0101] 6, a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is shown in accordance with an illustrative embodiment. Surface roughness analysis system 600 is a physical implementation of surface roughness analysis system 102 of FIG. 1. Workpiece 602 may be a physical implementation of workpiece 108 of FIG. 1. In some illustrative examples, view 604 is a perspective view of workpiece 200.

[0102] The components of the surface roughness analysis system 600 include a number of wave generators 606 and a number of wave sensors 608. The number of wave sensors 606 include a wave generator 610, a wave generator 611, and a wave generator 612. The wave generators 610, 611, and 612 are acoustically coupled to a surface 614 of the workpiece 602.

[0103] In some exemplary embodiments, the number of wave generators 606 are acoustically coupled to the surface 614 via contact with the surface 614. In some exemplary embodiments, the number of wave generators 606 are acoustically coupled to the surface 614 via a coupling fluid. In some exemplary embodiments, the number of wave generators 606 are non-contact ultrasonic generators.

[0104] In some demonstrative embodiments, at least one of the number of wave sensors 608 is acoustically coupled to the surface 614 via contact with the surface 614. In some demonstrative embodiments, at least one of the number of wave sensors 608 is acoustically coupled to the surface 614 via a coupling fluid. In some demonstrative embodiments, at least one of the number of wave sensors 608 is a non-contact ultrasonic sensor.

[0105] Each wave sensor of the number of wave sensors 608 is positioned in a second direction 616 on the surface 614 of the workpiece 602 at least a predetermined distance from one of the number of wave generators 606. The number of wave sensors 608 include a series of wave sensors 618, a series of wave sensors 620, and a series of wave sensors 622.

[0106] Several wave sensors 608 are acoustically coupled to a surface 614 of the workpiece 602 to detect surface waves from the workpiece 602. The surface 614 has a surface roughness 624. The surface roughness 624 may interrupt the propagation of surface waves along the surface 614 of the workpiece 602. The surface roughness 624 may cause immediate or partial attenuation of the waves.

[0107] The series of wave sensors 618, the series of wave sensors 620, and the series of wave sensors 622 form a network of wave sensors 625. The network of wave sensors 625 spans the surface 614 and analyzes the surface roughness 624 of the surface 614. Having a network of wave sensors 625 makes it possible to analyze the surface roughness 624 at multiple locations. Having a network of wave sensors 625 makes it possible to identify local surface roughness 624 outside of a roughness threshold. Having a network of wave sensors 625 makes it possible to analyze the surface roughness 624 at multiple locations. In FIG. 6, the network of wave sensors 625 spans in a first direction 634 and a second direction 616. In FIG. 6, multiple locations span across the first direction 634 and the second direction 616.

[0108] A series of wave sensors 618 are positioned at multiple distances from the wave generator 610 in the second direction 616 to detect surface waves from the workpiece 602. The series of wave sensors 618 includes a wave sensor 626, a wave sensor 628, a wave sensor 630, and a wave sensor 632.

[0109] By positioning a series of wave sensors 618, different locations of the surface 614 at different distances from the wave generator 610 and in the second direction 616 are analyzed. For example, the surface roughness 624 at a location between the wave generator 610 and the wave sensor 626 is analyzed using data from the wave sensor 626. If the wave sensor 626 produces an output indicative of a surface wave, then the surface roughness 624 at a location between the wave generator 610 and the wave sensor 626 is within a roughness threshold. For example, an output of the wave sensor 626 above a signal threshold indicates the detection of a surface wave. The signal threshold is set to distinguish between signal and noise. If a surface wave propagates to the wave sensor 626, then the surface roughness 624 is within a roughness threshold.

[0110] As another example, the surface roughness 624 at a location between the wave sensor 626 and the wave sensor 628 is analyzed using data from the wave sensor 628. If the wave sensor 628 generates an output indicative of a surface wave, then the surface roughness 624 at a location between the wave generator 626 and the wave sensor 628 is within a roughness threshold. For example, an output of the wave sensor 628 above a signal threshold indicates the detection of a surface wave. If a surface wave propagates to the wave sensor 628, then the surface wave has propagated through the surface 614 between the wave generator 610 and the wave sensor 626, and then through the surface 614 between the wave sensor 626 and the wave sensor 628. If a surface wave propagates to the wave sensor 628, then the surface roughness 624 between the wave generator 610 and the wave sensor 628 is within a roughness threshold.

[0111] As yet another example, the surface roughness 624 at a location between the wave sensor 628 and the wave sensor 630 is analyzed using data from the wave sensor 630. If the wave sensor 630 generates an output indicative of a surface wave, then the surface roughness 624 at that location is within the roughness threshold. For example, an output of the wave sensor 630 above a signal threshold indicates the detection of a surface wave. If a surface wave propagates to the wave sensor 630, then the surface wave propagates from the wave generator 610 through the surface 614, through a location between the wave sensor 626 and the wave generator 610, through a location between the wave sensor 626 and the wave sensor 628, and through a location between the wave sensor 628 and the wave sensor 630. If a surface wave propagates to the wave sensor 630, then the surface roughness 624 between the wave generator 610 and the wave sensor 630 is within the roughness threshold. If a surface wave does not reach the wave sensor 630, then the surface roughness 624 before the wave sensor 630 may be outside the roughness threshold.

[0112] As yet another example, the surface roughness 624 at a location between the wave sensor 630 and the wave sensor 632 is analyzed using data from the wave sensor 632. If the wave sensor 632 generates an output indicative of a surface wave, then the surface roughness 624 at that location is within the roughness threshold. For example, an output of the wave sensor 632 above a signal threshold indicates the detection of a surface wave. If a surface wave propagates to the wave sensor 632, then the surface wave has propagated from the wave generator 610 through the surface 614, through a location between the wave sensor 626 and the wave generator 610, through a location between the wave sensor 626 and the wave sensor 628, through a location between the wave sensor 628 and the wave sensor 630, and through a location between the wave sensor 630 and the wave sensor 632. If a surface wave propagates to the wave sensor 632, then the surface roughness 624 between the wave generator 610 and the wave sensor 632 is within the roughness threshold. If the surface waves do not reach the wave sensor 632, the surface roughness 624 before the wave sensor 632 may be outside the roughness threshold.

[0113] Several wave sensors 618 can be used in combination to detect surface roughness 624 at locations between the wave sensors. A series of wave sensors 618 can be used in combination to detect local surface roughness 624 outside of a roughness threshold.

[0114] Series of wave sensors 618, series of wave sensors 620, and series of wave sensors 622 are spaced apart in a first direction 634. Series of wave sensors 618 are spaced apart from series of wave sensors 620 in the first direction 634. Series of wave sensors 620 are spaced apart from series of wave sensors 622 in the first direction 634.

[0115] Several wave generators 606 are separated in a first direction 634 of the workpiece 602. In diagram 604, wave generator 610, wave generator 611, and wave generator 612 are equally spaced across the first direction 634. In other illustrative embodiments, several wave generators 606 have different spacing. Wave generator 610 is spaced from wave generator 611 in the first direction 634. A series of wave sensors 620 are positioned to sense surface waves generated from wave generator 611. The series of wave sensors 620 are positioned to sense surface waves at multiple locations between wave generator 610 and each of the series of wave sensors 620.

[0116] Surface waves propagating from wave generator 611 across surface 614 encounter wave sensor 636, wave sensor 638, wave sensor 640, and then wave sensor 642. As some illustrative examples, wave sensor 636 is positioned at least a predetermined distance from wave generator 611. The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The predetermined distance is selected such that receiving a threshold surface wave indicates acceptable surface roughness.

[0117] If a surface wave is received at wave sensor 636, then the surface roughness 624 between wave generator 611 and wave sensor 636 is within the roughness threshold. If a surface wave is received at a subsequent wave sensor in the series of wave sensors 620, then each subsequent location is within the roughness threshold. For example, if wave sensor 638 receives a surface wave, then the location between wave sensor 636 and wave sensor 638 has a surface roughness 624 within the roughness threshold. As another example, if wave sensor 640 receives a surface wave, then the location between wave sensor 638 and wave sensor 640 has a surface roughness 624 within the roughness threshold. As yet another example, if wave sensor 642 receives a surface wave, then the location between wave sensor 640 and wave sensor 642 has a surface roughness 624 within the roughness threshold.

[0118] Series of wave sensors 620 are spaced apart in a first direction 634 from series of wave sensors 622. Series of wave sensors 622 are positioned to sense surface waves generated by wave generator 612 in surface wave 614. The wave sensors in series of wave sensors 622 span a second direction 616. Series of wave sensors 622 include wave sensor 644, wave sensor 646, wave sensor 648, and wave sensor 650.

[0119] If a surface wave is received at wave sensor 644, then the surface roughness 624 between wave generator 612 and wave sensor 644 is within the roughness threshold. If a surface wave is received at a subsequent wave sensor in series of wave sensors 622, then each subsequent location is within the roughness threshold. For example, if wave sensor 646 receives a surface wave, then the location between wave sensor 644 and wave sensor 646 has a surface roughness 624 within the roughness threshold. As another example, if wave sensor 648 receives a surface wave, then the location between wave sensor 646 and wave sensor 648 has a surface roughness 624 within the roughness threshold. As yet another example, if wave sensor 650 receives a surface wave, then the location between wave sensor 648 and wave sensor 650 has a surface roughness 624 within the roughness threshold.

[0120] 7, a perspective view of a workpiece with components of a surface roughness analysis system associated with the surface of the workpiece is shown in accordance with an illustrative embodiment. Surface roughness analysis system 700 is a physical implementation of surface roughness analysis system 102 of FIG. 1. Workpiece 702 may be a physical implementation of workpiece 108 of FIG. 1. In some illustrative examples, view 704 is a perspective view of workpiece 200. In some illustrative examples, view 704 is a perspective view of surface roughness analysis system 400 and workpiece 402 of FIG. 4.

[0121] The components of the surface roughness analysis system 700 include a number of wave generators 706 and a number of wave sensors 708. The number of wave generators 706 has only one wave generator, wave generator 710. The wave generator 710 is acoustically coupled to a surface 712 of the workpiece 702.

[0122] The number of wave sensors 708 comprises a series of wave sensors 714, where each wave sensor of the series of wave sensors 714 has a different distance from a wave generator 710 of the number of wave generators 706 in the second direction 716 of the surface 712 of the workpiece 402. The number of wave sensors 708 includes a wave sensor 718, a wave sensor 720, and a wave sensor 722. Each wave sensor of the number of wave sensors 708 is positioned at least a predetermined distance from one of the number of wave generators 706 in the second direction 716 of the surface 712 of the workpiece 702. The number of wave sensors 708 includes a wave sensor 718, a wave sensor 720, and a wave sensor 722.

[0123] Several wave sensors 708 are acoustically coupled to a surface 712 of the workpiece 702 to detect surface waves from the workpiece 702. The surface 712 has a surface roughness 724. The surface roughness 724 may interrupt the propagation of surface waves along the surface 712 of the workpiece 702. The surface roughness 724 may cause immediate or partial attenuation of the waves.

[0124] In some exemplary embodiments, the number of wave generators 706 are acoustically coupled to the surface 712 via contact with the surface 712. In some exemplary embodiments, the number of wave generators 706 are acoustically coupled to the surface 712 via a coupling fluid. In some exemplary embodiments, the number of wave generators 706 are non-contact ultrasonic generators.

[0125] In some demonstrative embodiments, at least one of the number of wave sensors 708 is acoustically coupled to the surface 712 via contact with the surface 712. In some demonstrative embodiments, at least one of the number of wave sensors 708 is acoustically coupled to the surface 712 via a coupling fluid. In some demonstrative embodiments, at least one of the number of wave sensors 708 is a non-contact ultrasonic sensor.

[0126] The wave sensor 718 is positioned at least a predetermined distance from the wave generator 710 in a second direction 716 of the surface 712 of the workpiece 702 to detect surface waves from the workpiece 702. The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The predetermined distance is selected such that receiving a threshold surface wave indicates an acceptable surface roughness.

[0127] The wave sensor 720 is positioned at least a predetermined distance from the wave generator 710 in the second direction 716 of the surface 712 of the workpiece 702 to detect surface waves from the workpiece 702. The wave sensor 720 is further away from the wave generator 710 than the wave sensor 718.

[0128] Wave sensor 722 is positioned at least a predetermined distance from wave generator 710 in the second direction 716 of the surface 712 of workpiece 702 to detect surface waves from workpiece 702. Wave sensor 722 is further away from wave generator 710 than both wave sensor 718 and wave sensor 720.

[0129] By positioning several wave sensors 708, different positions of the surface 712 at different distances from the wave generator 710 and in the second direction 716 are analyzed. For example, the surface roughness 724 at a position between the wave generator 710 and the wave sensor 718 is analyzed using data from the wave sensor 718. If the wave sensor 718 produces an output indicative of a surface wave, then the surface roughness 724 at a position between the wave generator 710 and the wave sensor 718 is within a roughness threshold. For example, an output of the wave sensor 718 above a signal threshold indicates the detection of a surface wave. The signal threshold is set to distinguish between signal and noise. If a surface wave propagates to the wave sensor 718, then the surface roughness 724 is within a roughness threshold.

[0130] As another example, the surface roughness 724 at a location between the wave sensor 718 and the wave sensor 720 is analyzed using data from the wave sensor 720. If the wave sensor 720 generates an output indicative of a surface wave, then the surface roughness 724 at a location between the wave generator 718 and the wave sensor 720 is within the roughness threshold. For example, an output of the wave sensor 720 above a signal threshold indicates the detection of a surface wave. When a surface wave propagates to the wave sensor 720, the surface wave is propagating through the surface 712 from the wave generator 710 to the wave sensor 720. If the surface wave propagates to the wave sensor 720, then the surface roughness 724 between the wave generator 710 and the wave sensor 720 is within the roughness threshold. If the surface wave does not reach the wave sensor 720, then the surface roughness 724 before the wave sensor 720 may be outside the roughness threshold.

[0131] As yet another example, the surface roughness 724 at a location between the wave sensor 720 and the wave sensor 722 is analyzed using data from the wave sensor 722. If the wave sensor 722 generates an output indicative of a surface wave, then the surface roughness 724 at a location between the wave generator 720 and the wave sensor 722 is within the roughness threshold. For example, an output of the wave sensor 722 above a signal threshold indicates the detection of a surface wave. When a surface wave propagates to the wave sensor 722, the surface wave is propagating through the surface 712 from the wave generator 710 to the wave sensor 722. If the surface wave propagates to the wave sensor 722, then the surface roughness 724 at a location between the wave generator 710 and the wave sensor 722 is within the roughness threshold. If the surface wave does not reach the wave sensor 722, then the surface roughness 724 before the wave sensor 722 may be outside the roughness threshold.

[0132] By using several wave sensors 708 in combination, the surface roughness 724 at each location can be analyzed individually. By using several wave sensors 708 in combination, local surface roughness 724 outside the roughness threshold can be detected. For example, if a surface wave is detected by wave sensor 720 but not by wave sensor 722, then the surface roughness 724 at a location in front of wave sensor 720 is within the roughness threshold, but the surface roughness 724 at a location between wave sensor 720 and wave sensor 722 is not within the roughness threshold. As another example, if a surface wave is detected by wave sensor 718 but not by wave sensor 720, then the surface roughness 724 at a location in front of wave sensor 718 is within the roughness threshold, but the surface roughness 724 at a location between wave sensor 718 and wave sensor 720 is not within the roughness threshold. If no surface waves are detected by the wave sensor 718, then the surface roughness 724 at the location between the wave generator 710 and the wave sensor 718 is outside the roughness threshold. If no surface waves are detected by the wave sensor 718, then the surface roughness 724 at the location after the wave sensor 718 is not analyzed.

[0133] 8, a perspective view of a workpiece with components of a surface roughness analysis system associated with the surface of the workpiece is shown in accordance with an illustrative embodiment. Surface roughness analysis system 800 is a physical implementation of surface roughness analysis system 102 of FIG. 1. Workpiece 802 may be a physical implementation of workpiece 108 of FIG. 1. In some illustrative examples, view 804 is a perspective view of workpiece 200. In some illustrative examples, view 804 is a perspective view of surface roughness analysis system 300 and workpiece 302 of FIG. 3.

[0134] The components of the surface roughness analysis system 800 include a number of wave generators 806 and a number of wave sensors 808. The number of wave generators 806 has only one wave generator, wave generator 810. The wave generator 810 is acoustically coupled to a surface 812 of the workpiece 802.

[0135] The number of wave sensors 808 includes only one wave sensor, wave sensor 814. The wave sensor 814 is positioned at least a predetermined distance from the wave generator 810 in a second direction 816 of the surface 812 of the workpiece 802. The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The predetermined distance is selected such that receiving a threshold surface wave indicates an acceptable surface roughness.

[0136] Several wave sensors 808 are acoustically coupled to a surface 812 of the workpiece 802 to detect surface waves from the workpiece 802. The surface 812 has a surface roughness 818. The surface roughness 818 may interrupt the propagation of surface waves along the surface 812 of the workpiece 802. The surface roughness 818 may cause immediate or partial attenuation of the waves.

[0137] In some exemplary embodiments, the number of wave generators 806 are acoustically coupled to the surface 812 via contact with the surface 812. In some exemplary embodiments, the number of wave generators 806 are acoustically coupled to the surface 812 via a coupling fluid. In some exemplary embodiments, the number of wave generators 806 are a number of non-contact ultrasonic generators.

[0138] In some illustrative examples, at least one of the number of wave sensors 808 is acoustically coupled to the surface 812 via contact with the surface 812. In some illustrative examples, at least one of the number of wave sensors 808 is acoustically coupled to the surface 812 via a coupling fluid. In some illustrative examples, at least one of the number of wave sensors 808 is a non-contact ultrasonic sensor.

[0139] In diagram 804, a wave generator 810 and a wave sensor 814 are used to analyze the surface roughness 818 across a surface 812. In diagram 804, the wave sensor 814 is separated from the wave generator 810 by more than half the area of ​​the surface 812 in a second direction 816.

[0140] The illustrations of surface roughness analysis system 300 in FIG. 3 , surface roughness analysis system 400 in FIG. 4 , surface roughness analysis system 500 in FIG. 5 , surface roughness analysis system 600 in FIG. 6 , surface roughness analysis system 700 in FIG. 7 , and surface roughness analysis system 800 in FIG. 8 are not intended to imply physical or architectural limitations to the manner in which the example embodiments may be implemented. Other components may be used in addition to or in place of the illustrated components. Some components may not be required. For example, the number of wave generators in any of the surface roughness analysis systems is merely illustrative. The number of wave generators may include any desired quantity of wave generators positioned relative to the workpiece in any desired position and in any desired pattern to transmit at least one source signal into the workpiece. As another example, the number of wave sensors in any of the surface roughness analysis systems is merely illustrative. The number of wave generators may include any desired quantity of wave sensors positioned relative to the workpiece in any desired position and in any desired pattern to sense surface waves in the workpiece.

[0141] 9, a block diagram of a surface roughness analysis system associated with a surface of a workpiece is shown, according to an exemplary embodiment. Surface roughness analysis system 900 is a pictorial representation of surface roughness analysis system 102 of FIG. 1. Surface roughness analysis system 900 may be used to analyze workpiece 200 of FIG. 2. Workpiece 902 may be identical to workpiece 200 of FIG. 2. Surface roughness analysis system 900 includes a wave generator 904 and a wave sensor 906. In some exemplary embodiments, wave generator 904 is a pictorial representation of wave generator 306 and wave sensor 906 is a pictorial representation of wave sensor 308 of FIG. 3. In some exemplary embodiments, wave generator 904 is a pictorial representation of wave generator 410 of FIG. 4 and wave sensor 906 is a pictorial representation of wave sensor 418, wave sensor 420, or wave sensor 422 of FIG. 4. In some illustrative examples, the wave generator 904 is a pictorial representation of one of the number of wave generators 506 of FIG. 5 and the wave sensor 906 is a pictorial representation of one of the number of wave sensors 508 of FIG. 5. In some illustrative examples, the wave generator 904 is a pictorial representation of one of the number of wave generators 606 of FIG. 6 and the wave sensor 906 is a pictorial representation of one of the number of wave sensors 608 of FIG. 6. In some illustrative examples, the wave generator 904 is a pictorial representation of one of the number of wave generators 706 of FIG. 7 and the wave sensor 906 is a pictorial representation of one of the number of wave sensors 708 of FIG. 7. In some illustrative examples, the wave generator 904 is a pictorial representation of one of the number of wave generators 806 of FIG. 8 and the wave sensor 906 is a pictorial representation of one of the number of wave sensors 808 of FIG. 8.

[0142] The wave generator 904 is acoustically coupled to the workpiece 902. In some exemplary embodiments, the wave generator 904 is acoustically coupled to the workpiece 902 through contact with the workpiece 902. In some exemplary embodiments, the wave generator 904 is acoustically coupled to the workpiece 902 through a coupling fluid. In some exemplary embodiments, the wave generator 904 is a non-contact ultrasonic generator.

[0143] The wave generator 904 transmits a source signal having signal parameters into the surface 310 of the workpiece 302 of Figure 3. The signal parameters are determined by an ultrasonic analysis system and take into account material mechanical parameters of the workpiece 302.

[0144] The wave generator 906 is acoustically coupled to the workpiece 902. In some illustrative embodiments, the wave generator 906 is acoustically coupled to the workpiece 902 via contact with the workpiece 902. In some illustrative embodiments, the wave sensor 906 is acoustically coupled to the workpiece 902 via a coupling fluid. In some illustrative embodiments, the wave sensor 906 is a non-contact ultrasonic sensor.

[0145] 9, an ultrasonic analysis system 908 receives material mechanical parameters 910 for a workpiece 902. The ultrasonic analysis system 908 determines signal parameters 912 for simulating Rayleigh wave propagation in the workpiece 902. The ultrasonic analysis system 908 transmits the signal parameters 912 to a controller 914.

[0146] The controller 914 is configured to send electrical control signals to the pulser 916. In response to these electrical control signals, the pulser 916 outputs electrical signals representative of the ultrasonic waves to be generated to the wave generator 904. The wave generator 904 may include one or more ultrasonic transducer elements. The wave generator 904 transmits the electrical signals from the pulser 916 into ultrasonic waves. More specifically, the electrical signals sent to the pulser 916 are configured to cause the pulser 916 to generate bursts of ultrasonic waves having wave characteristics that are the same as or similar to the simulated ultrasonic waves used in the simulation. In some illustrative examples, the wave generator 904 is activated using a sinusoidal signal.

[0147] A wave generator 904 is acoustically coupled to the workpiece 902. The wave generator 904 is activated to generate ultrasonic waves that propagate through the material of the workpiece 902.

[0148] A wave generator 906 is also acoustically coupled to the workpiece 902, but at a different location. The wave generator 906 may include one or more ultrasonic transducer elements. The distance that the Rayleigh waves travel as they propagate from the wave generator 904 to the wave sensor 906 is selected such that the distance equals or exceeds a specified distance. The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The cutoff wavelength is the ratio of the surface wavelength to the incident wavelength.

[0149] The wave sensor 906 converts the incident ultrasonic waves into an electrical signal that is transmitted to a receiver 918. The receiver 918 receives an electrical signal from the controller 914 that is representative of the source signal transmitted by the wave generator 904. The receiver 918 then outputs an electrical signal that is representative of the acquired ultrasonic inspection data to a roughness evaluator 920.

[0150] The roughness evaluator 920 is a computer system configured to analyze the acquired ultrasonic inspection data from the wave sensor 906 and determine if the surface roughness of the workpiece 902 is within a roughness threshold. The roughness evaluator 920 is configured to compare the data from the wave sensor 906 to a signal threshold. The signal threshold is set to distinguish between signal and noise. In some example embodiments, the roughness evaluator 920 is configured to generate a flag in response to the surface roughness being outside the roughness threshold. The flag may be any of an analog signal, a digital code, a report, a notice, a warning, or a notice. The flag may be displayed on a display device. Alternatively, the flag may be in the form of an audible warning.

[0151] 10A and 10B, a flow diagram of a method for analyzing the surface roughness of a workpiece is shown, according to an exemplary embodiment. The method 1000 may be implemented using the surface roughness analysis system 102 of FIG. 1. The method 1000 may be used to analyze the surface roughness 104 of the surface 106 of the workpiece 108 of FIG. 1. The method 1000 may be used to analyze the surface roughness 202 of the surface 204 of the workpiece 200 of FIG. 2. The method 1000 may be used to analyze the surface roughness 312 of the workpiece 302 of FIG. 3. The method 1000 may be used to analyze the surface roughness 424 of the workpiece 402 of FIG. 4. The method 1000 may be used to analyze the surface roughness 524 of the workpiece 502 of FIG. 5. The method 1000 may be used to analyze the surface roughness 624 of the workpiece 602 of FIG. 6. The method 1000 may be used to analyze the surface roughness 724 of the workpiece 702 of Figure 7. The method 1000 may be used to analyze the surface roughness 818 of the workpiece 802 of Figure 8. The method 1000 may be implemented to analyze the surface roughness of the workpiece 902 of Figure 9 using the surface roughness analysis system 900.

[0152] The method 1000 receives material machine parameters of the workpiece (operation 1002). The material machine parameters include any desired material machine parameters (e.g., shear modulus, density, elastic modulus, or any other desired material machine parameter). The method 1000 uses the material machine parameters to determine signal parameters for a source signal transmitted into the workpiece (operation 1004). To determine the signal parameters, the material machine parameters are used to determine effective wave propagation. An incident wave frequency for the workpiece is determined. The incident wavelength is a function of the incident wave frequency.

[0153] The method 1000 determines a predetermined distance of the number of wave sensors from the number of wave generators such that the number of wave sensors receiving the threshold surface waves indicate a surface roughness within the roughness threshold (operation 1005). The method 1000 then ends.

[0154] In some example embodiments, the method 1000 determines a cutoff wavelength using the material mechanical parameters, the cutoff wavelength being a ratio of the surface wavelength to the incident wavelength, and the predetermined distance is determined based on the cutoff wavelength (Operation 1007). In some example embodiments, the method 1000 transmits a source signal having the signal parameters into the workpiece using a pulser and wave generator (Operation 1006). The method 1000 determines whether the surface roughness of the workpiece is within a roughness threshold for at least one of the roughness width or the roughness height based on the output of the number of wave sensors (Operation 1008).

[0155] In some exemplary embodiments, the method 1000 orients a wave generator relative to the workpiece to transmit a source signal into the workpiece at a source location (operation 1010). The source location is at any desired location on the surface of the workpiece. In some exemplary embodiments, orienting the wave generator includes acoustically coupling the wave generator to the surface. In some exemplary embodiments, the wave generator is in contact with the surface of the workpiece. In some exemplary embodiments, the wave generator is a non-contact ultrasonic generator.

[0156] In some example embodiments, the method 1000 orients at least one wave sensor of the number of wave sensors relative to the workpiece to sense waves at a predetermined distance from the source location (operation 1012). The predetermined distance is selected based on a cutoff wavelength calculated by the ultrasonic analysis system. The cutoff wavelength is the ratio of the surface wavelength to the incident wavelength. The cutoff wavelength can be customized for different roughness profiles. In some example embodiments, λ surface / λ wave If = 0.5, it is the cut-off threshold.

[0157] In some exemplary embodiments, method 1000 orients several wave sensors relative to the workpiece such that several wave sensors are oriented to sense waves at at least two different distances from the source location (operation 1014). In some exemplary embodiments, the series of wave sensors are at various distances from the wave generator. When several wave sensors are oriented to sense waves at at least two different distances, surface roughness may be located on the surface. In one exemplary embodiment, operation 1014 is performed in FIG. 4 using series of wave sensors 414. In another exemplary embodiment, operation 1014 is performed in FIG. 6 using at least one of series of wave sensors 618, series of wave sensors 620, or series of wave sensors 622. In yet another exemplary embodiment, operation 1014 is performed in FIG. 7 using series of wave sensors 714.

[0158] In some exemplary embodiments, determining whether the surface roughness of the workpiece is within the roughness threshold includes determining whether the surface roughness at the plurality of locations of the workpiece is within a roughness threshold for at least one of a roughness width or a roughness height based on the output of the number of wave sensors (Operation 1018). In some exemplary embodiments, determining whether the surface roughness at the plurality of locations of the workpiece is within a roughness threshold includes determining whether the surface roughness at a plurality of locations of the workpiece extending in a second direction is within the roughness threshold, the second direction extending over at least two different distances (Operation 1020). In these exemplary embodiments, each of the number of locations is associated with a respective wave sensor of a series of wave sensors separated in the second direction.

[0159] In some exemplary embodiments, the method 1000 uses multiple pulsers and multiple wave generators to transmit multiple source signals having signal parameters into the workpiece at multiple source locations of the workpiece, where the transmitting a source signal into the workpiece is one of the multiple source signals transmitted into the workpiece (Operation 1016). In some exemplary embodiments, Operation 1016 is performed by wave generator 510, wave generator 511, and wave generator 512 in FIG. 5 to transmit a source signal into the workpiece 502. In these exemplary embodiments, wave generator 510, wave generator 511, and wave generator 512 transmit multiple source signals at multiple source locations spaced apart in a first direction 526. In some exemplary embodiments, Operation 1016 is performed by wave generator 610, wave generator 611, and wave generator 612 in FIG. 6 to transmit a source signal into the workpiece 602. In these illustrative examples, wave generator 610, wave generator 611, and wave generator 612 transmit multiple source signals at multiple source locations spaced apart in first direction 634. In some illustrative examples, determining whether the surface roughness of the workpiece is within a roughness threshold includes determining whether the surface roughness at the multiple locations of the workpiece is within a roughness threshold for at least one of a roughness width or a roughness height based on outputs of the number of wave sensors (OPERATION 1022).

[0160] In some example embodiments, the plurality of locations are spread across the workpiece in a first direction and the plurality of source signals are spread across the workpiece in the first direction (Operation 1024). In some example embodiments, the plurality of locations are spread across the surface in the first direction of the surface. In some of these example embodiments, the plurality of wave generators and associated plurality of wave sensors are separated in the first direction.

[0161] In some illustrative examples, the plurality of locations are spread across the surface in a first direction and a second direction of the surface. In some of these illustrative examples, some of the wave generators are spread across the first direction and some of the wave sensors are spread across both the first direction and the second direction, forming a network of wave sensors. In these illustrative examples, the network of wave sensors is also referred to as a grid of wave sensors.

[0162] 11A and 11B, a flow diagram of a method for analyzing the surface roughness of a workpiece is shown, according to an exemplary embodiment. The method 1000 may be implemented using the surface roughness analysis system 102 of FIG. 1. The method 1100 may be used to analyze the surface roughness 104 of the surface 106 of the workpiece 108 of FIG. 1. The method 1100 may be used to analyze the surface roughness 202 of the surface 204 of the workpiece 200 of FIG. 2. The method 1100 may be used to analyze the surface roughness 312 of the workpiece 302 of FIG. 3. The method 1100 may be used to analyze the surface roughness 424 of the workpiece 402 of FIG. 4. The method 1100 may be used to analyze the surface roughness 524 of the workpiece 502 of FIG. 5. The method 1100 may be used to analyze the surface roughness 624 of the workpiece 602 of FIG. 6. The method 1100 may be used to analyze the surface roughness 724 of the workpiece 702 of Figure 7. The method 1100 may be used to analyze the surface roughness 818 of the workpiece 802 of Figure 8. The method 1100 may be implemented to analyze the surface roughness of the workpiece 902 of Figure 9 using the surface roughness analysis system 900.

[0163] Method 1100 determines signal parameters for source signals transmitted by a number of wave generators into a workpiece to analyze the surface roughness of the workpiece (operation 1101). Method 1100 determines a cutoff wavelength using material mechanical parameters of the workpiece, the cutoff wavelength being a ratio of the surface wavelength to the incident wavelength (operation 1102). Method 1100 uses the cutoff wavelength to determine a predetermined distance of a number of wave sensors from a number of wave generators such that a number of wave sensors receiving a threshold surface wave indicate a surface roughness within a roughness threshold (operation 1103). Method 1100 then ends.

[0164] In some exemplary embodiments, the method 1100 positions a number of wave sensors relative to the workpiece to sense waves at least a predetermined distance from each of the number of wave generators based on the cutoff wavelength (OPERATION 1104). In some exemplary embodiments, the method 1100 transmits a number of source signals having signal parameters at a number of source locations into the workpiece using the number of wave generators (OPERATION 1108). In some exemplary embodiments, the method 1100 senses surface waves with the number of wave sensors to generate a sensor output (OPERATION 1110). In some exemplary embodiments, the method 1100 determines whether a surface roughness of the workpiece is within a roughness threshold based on the sensor output (OPERATION 1112).

[0165] If the surface waves sensed by some of the wave sensors meet a minimum intensity value, the surface roughness is within a roughness threshold (operation 1118). If the surface waves meet a minimum intensity value, the signals generated by some of the wave sensors in response meet a signal threshold. A signal threshold is set to distinguish between signal and noise.

[0166] In some demonstrative examples, determining whether the surface roughness is within the roughness threshold includes determining whether the surface roughness at a plurality of locations on the workpiece is within a roughness threshold for at least one of a roughness width or a roughness height based on outputs of the number of wave sensors (Operation 1120).

[0167] In some illustrative examples, positioning the number of wave sensors includes positioning the number of wave sensors relative to the workpiece such that the number of wave sensors are oriented to sense waves at at least two different distances from the wave generators of the number of wave generators (OPERATION 1114). In these illustrative examples, the number of wave sensors includes a series of wave sensors positioned at multiple distances from the wave generators. When a series of wave sensors is present, the multiple locations can be analyzed for surface roughness. In some illustrative examples, determining whether the surface roughness of the multiple locations of the workpiece is within a roughness threshold includes determining whether the surface roughness of the multiple locations extending in a second direction of the workpiece is within a roughness threshold, the second direction extending over at least two different distances (OPERATION 1122).

[0168] In some exemplary embodiments, the method 1100 transmits a plurality of source signals having signal parameters into the workpiece at a plurality of source locations of the workpiece using a plurality of pulsers and a plurality of wave generators, the transmitting a source signal into the workpiece being one of the plurality of source signals transmitted into the workpiece (OPERATION 1116). In some exemplary embodiments, determining whether the surface roughness of the workpiece is within a roughness threshold includes determining whether the surface roughness at the plurality of locations of the workpiece is within a roughness threshold for at least one of a roughness width or a roughness height based on the output of the plurality of wave sensors (OPERATION 1124). In some exemplary embodiments, the plurality of locations span a first direction of the workpiece, and the plurality of source signals span across the workpiece in the first direction (OPERATION 1126).

[0169] As used herein, the terms "approximately," "about," and "substantially" refer to an amount close to a specified amount that may still perform a desired function or achieve a desired result. For example, the terms "approximately," "about," and "substantially" may refer to an amount within less than 10%, less than 5%, less than 1%, less than 0.1%, and less than 0.01% of a specified amount.

[0170] As used herein, the phrase "at least one of" used in conjunction with enumerated items means that various combinations of one or more of the enumerated items may be used and only one of each enumerated item may be required. For example, without limitation, "at least one of item A, item B, and item C" may include item A, item A and item B, or item B. This example may also include item A, item B, and item C, or item B and item C. Of course, any combination of these items may be present. In other examples, "at least one of" may be, for example, without limitation, "2 items A, 1 item B, and 10 items C," "4 items B and 7 items C," or other suitable combinations. An item may be a particular object, object, or category. In other words, "at least one of" means that any combination of items or some items from the enumeration may be used, but not all of the enumerated items are required.

[0171] The flow diagrams and block diagrams in the various depicted embodiments illustrate the structure, functionality, and operation of some possible implementations of the apparatus and methods of the example embodiments. In this regard, each block in the flow diagrams or block diagrams may represent at least one of a module, a segment, a function, or a portion of an operation or step.

[0172] In some alternative implementations of the exemplary embodiments, one or more functions described in the blocks may occur out of the order described in the figures. For example, in some cases, two blocks shown in succession may be executed substantially simultaneously or in the reverse order, depending on the functionality involved. Furthermore, other blocks may be added in addition to the blocks shown in the flow diagram or block diagram. Some blocks may be optional. For example, operations 1010 to 1024 may be optional. As another example, operations 1114 to 1126 may be optional.

[0173] An example embodiment of the disclosure may be described with reference to aircraft manufacturing and service method 1200 shown in Figure 12 and aircraft 1300 shown in Figure 13. With reference initially to Figure 12, an aircraft manufacturing and service method is illustrated in accordance with an example embodiment. During pre-production, aircraft manufacturing and service method 1200 may include specification and design 1202 of aircraft 1300 in Figure 13, and material procurement 1204.

[0174] During production, component and subassembly manufacturing 1206 and system integration 1208 of the aircraft 1300 takes place. The aircraft 1300 then undergoes certification and delivery 1210 and is placed into service 1212. While in customer service 1212, the aircraft 1300 is scheduled for routine maintenance and service 1214, which may include modifications, reconfigurations, refurbishment, and other maintenance and maintenance.

[0175] Each process of aircraft manufacturing and service method 1200 may be performed or carried out by a system integrator, a third party, and / or an operator. In these examples, the operator may be a customer. For purposes of this specification, a system integrator may include, but is not limited to, any number of aircraft manufacturers and subcontractors of major systems, a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers, and an operator may include an airline, a leasing company, a military entity, a service organization, etc.

[0176] Referring now to Figure 13, an illustration of an aircraft in which an illustrative embodiment may be implemented is shown. In this example, aircraft 1300 may be manufactured by aircraft manufacturing and service method 1200 in Figure 12 and may include an airframe 1302 having a number of systems 1304 and an interior 1306. Example systems 1304 include one or more of propulsion system 1308, electrical system 1310, hydraulic system 1312, and environmental system 1314. Any number of other systems may also be included.

[0177] Apparatus and methods embodied herein may be used during at least one of the stages of aircraft manufacturing and service method 1200. One or more exemplary embodiments may be used during component and subassembly manufacturing 1206, system integration 1208, service 1212, or maintenance and service 1214 of FIG. 12. Method 1300 may include a structure analyzed using surface roughness analysis system 102 of FIG. 1. Surface roughness analysis system 102 of FIG. 1 may be used during component and subassembly manufacturing 1206 to analyze the surface roughness of a workpiece manufactured during component and subassembly manufacturing 1206. As an example, method 1000 or method 1100 may be used during component and subassembly manufacturing 1206 to analyze the surface roughness of a structure. In some exemplary examples, surface roughness analysis system 102 of FIG. 1 may be used during service 1212 or maintenance and service 1214 of FIG. 12 to analyze any surface roughness that occurs during service 1212. In some illustrative examples, the structure inspected using surface roughness analysis system 102 in FIG. 1 is a component of aircraft 1300 .

[0178] An illustrative embodiment provides a method for inspecting a surface for roughness after a manufacturing application. Surface acoustic waves are generated by an array of transducers and propagate along the surface. A surface roughness analysis system determines a predefined cutoff threshold for Rayleigh wave propagation, which is indicative of a type of surface roughness. This cutoff occurs for a particular ratio of spatial surface waviness to acoustic wavelength. Detection of the resulting wave attenuation and attenuation characterizes the surface roughness.

[0179] The exemplary embodiments may be used in-line in a manufacturing process. By using the exemplary embodiments in-line, results from the surface roughness analysis system may be used to adjust manufacturing equipment or processes. For example, the exemplary embodiments may be used in-line to identify times for maintenance or cleaning of manufacturing equipment. The exemplary embodiments are particularly effective approaches in measuring the quality of 3D printed components formed with additive manufacturing techniques. As another example, the exemplary embodiments may be used to signal adjustments to the material deposition rate of an additive manufacturing process to achieve a required product quality. As yet another example, the exemplary embodiments may be used to identify workpieces for rework or cleaning prior to further manufacturing processes.

[0180] The illustrative examples show a novel in-line ultrasonic inspection technique using high frequency ultrasonic Rayleigh waves to characterize surface roughness parameters during the manufacturing process. The frequency of incident wave excitation used for roughness measurement is adjusted based on the mechanical properties of the structure. The method uses surface wave energy loss and attenuation to characterize the roughness of the surface. In some illustrative examples, other wave parameters such as rate of change of wave velocity may be used to measure the surface roughness profile.

[0181] The transmission of Rayleigh waves can be used to measure the quality of rough surfaces of structures having various material properties. The rate of attenuation and decay of the surface wave propagation is used to determine the cutoff ratio at which no corrugations are formed due to the roughness intensity. In some exemplary embodiments, λ surface / λwave = 0.5, the cut-off ratio is at the threshold. The cut-off wavelength and effective frequency of inspection can be customized for different roughness profiles.

[0182] Furthermore, the present disclosure includes embodiments according to the following clauses:

[0183] Clause 1 1. A surface roughness analysis system (102) comprising an ultrasonic analysis system (128) configured to receive material machine parameters (130) for a workpiece (108), determine incident surface wave signal parameters (132) for source signals (134) transmitted by a number of wave generators (124), and determine a predetermined distance (160) of a number of wave sensors (126) from a number of wave generators (124) such that a number of wave sensors (126) receiving a threshold surface wave (164) is indicative of a surface roughness (104) within a roughness threshold (165).

[0184] Clause 2 The surface roughness analysis system (102) of claim 1, wherein the ultrasonic analysis system (128) is further configured to determine a cutoff wavelength (136) using the material mechanical parameters (130), the cutoff wavelength (136) being a ratio of a surface wavelength (138) to an incident wavelength (140), and the predetermined distance (160) being determined based on the cutoff wavelength (136).

[0185] Clause 3 3. The surface roughness analysis system (102) of claim 2, wherein the cutoff wavelength (136) is about 0.5.

[0186] Clause 4 the number of wave generators (124) configured to transmit a source signal (134) having the signal parameters (132) into a workpiece (108); and the number of wave sensors (126) positioned at least the predetermined distance (160) from the number of wave generators (124); 4. The surface roughness analysis system of any one of clauses 1 to 3, further comprising:

[0187] Clause 5 The surface roughness analysis system (102) of clause 4, wherein the number of wave sensors (126) comprises a series of wave sensors (166), each wave sensor (156, 168) of the series of wave sensors (166) having a different distance (158, 170) from a wave generator (146) of the number of wave generators (124) in a second direction (162) of the surface (106) of the workpiece (108).

[0188] Clause 6 The surface roughness analysis system (102) of claim 4, wherein the number of wave generators (124) comprises a plurality of wave generators (146, 148) spaced across the surface (106) of the workpiece (108) in a first direction (172).

[0189] Clause 7 The surface roughness analysis system (102) of clause 4, wherein the number of wave sensors (126) are positioned at least a predetermined distance (160) from the number of wave generators (124) to detect surface waves (154) from the workpiece (108), the predetermined distance (160) being selected based on a cutoff wavelength (136) calculated by the ultrasonic analysis system (128).

[0190] Clause 8 The surface roughness analysis system (102) of clause 4, further comprising a roughness evaluator (180) configured to determine whether the surface roughness (104) of the workpiece (108) is less than a roughness threshold (165) based on the surface waves (164) sensed by the number of wave sensors (126).

[0191] Clause 9 A method (1000) for analyzing a surface roughness of a workpiece (108), comprising: receiving (1002) material-mechanical parameters (130) of the workpiece (108); determining (1004) signal parameters (132) for a source signal (134) transmitted into a workpiece (108) using the material machine parameters (130); determining (1005) a predetermined distance (160) of a number of wave sensors (126) from a number of wave generators (124) such that a number of the wave sensors (126) receiving a threshold surface wave (164) indicate a surface roughness (104) within a roughness threshold (165); The method includes:

[0192] Clause 10 10. The method of claim 9, further comprising: determining (1007) a cutoff wavelength (136) using the material mechanical parameters (130), the cutoff wavelength (136) being a ratio of a surface wavelength (138) to an incident wavelength (140), and the predetermined distance (160) being determined based on the cutoff wavelength (136).

[0193] Clause 11 transmitting a plurality of source signals (150) having the signal parameters (132) into the workpiece (108) at a plurality of source locations on the workpiece (108) using a plurality of pulsers (178) and a plurality of wave generators (146, 148); transmitting the source signal (134) into the workpiece (108) is one of the plurality of source signals (150) transmitted into the workpiece (108); The method (1000) of clause 10, wherein determining whether the surface roughness (104) of the workpiece (108) is within a roughness threshold (165) comprises determining whether the surface roughness (104) at multiple locations of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on the output of the several wave sensors (126).

[0194] Clause 12 12. The method (1000) of claim 11, wherein the plurality of locations spans a first direction (172) of the workpiece (108) and the plurality of source signals (150) spans across the workpiece (108) in the first direction (172).

[0195] Clause 13 transmitting (1006) the source signal (134) having the signal parameters (132) into the workpiece (108) using a pulser (178) and a wave generator (146); determining (1008) whether the surface roughness (104, 202) of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on outputs of the number of wave sensors (126); 13. The method of any one of clauses 9 to 12, further comprising:

[0196] Clause 14 orienting (1010) the wave generator (146) relative to the workpiece (108) to transmit the source signal (134) to the workpiece (108) at a source location (152); orienting (1012) at least one wave sensor of the number of wave sensors (126) relative to the workpiece (108) to sense waves at a predetermined distance (160) from the source location (152); 14. The method (1000) of claim 13, further comprising:

[0197] Clause 15 15. The method (1000) of claim 14, further comprising orienting (1014) the number of wave sensors (126) relative to the workpiece (108) such that the number of wave sensors (126) are oriented to sense waves at at least two different distances from the source location (152).

[0198] Clause 16 The method (1000) of clause 15, wherein determining whether the surface roughness (104, 202) of the workpiece (108) is within a roughness threshold (165) comprises determining (1018) whether the surface roughness (104, 202) at multiple positions of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on the output of the several wave sensors (126).

[0199] Clause 17 The method (1000) of clause 16, wherein determining whether the surface roughness (104, 202) at a plurality of locations (434, 436, 438) of the workpiece (108) is within a roughness threshold (165) comprises determining whether the surface roughness (104, 202) at a plurality of locations (434, 436, 438) extending in a second direction (162, 416) of the workpiece (108) is within the roughness threshold (165), wherein the second direction (162, 416) extends (1020) over at least two different distances (428, 430, 432).

[0200] Clause 18 A method (1100) for analyzing a surface roughness of a workpiece (108), comprising: determining (1101) signal parameters (132) for source signals (134) transmitted into a workpiece (108) by a number of wave generators (124) for the surface roughness (104) of the workpiece (108); determining (1102) a cutoff wavelength (136) using material mechanical parameters (130) of the workpiece (108), the cutoff wavelength (136) being a ratio of a surface wavelength (138) to an incident wavelength (140); determining (1103) a predetermined distance (160) of the number of wave sensors (126) from the number of wave generators (124) such that the number of wave sensors (126) receiving a threshold surface wave (164) indicate a surface roughness (104) within a roughness threshold (165); A method (1100) comprising:

[0201] Clause 19 positioning (1104) a number of wave sensors (126) relative to the workpiece (108) to sense waves at least a predetermined distance (160) from each wave generator (146) of the number of wave generators (124) based on the cutoff wavelength (136); transmitting (1108) a number of source signals (134) having the signal parameters (132) into the workpiece (108) at a number of source locations (152) using the number of wave generators (124); sensing (1110) surface waves with the number of wave sensors (126) to generate a sensor output; determining (1112) whether the surface roughness (104) of the workpiece (108) is within a roughness threshold (165) based on the sensor output; 20. The method (1100) of claim 18, further comprising:

[0202] Clause 20 The method (1100) of any one of clauses 18 to 19, wherein the surface roughness (104) is within (1118) a roughness threshold (165) if the surface waves sensed by the number of wave sensors (126) meet a minimum intensity value.

[0203] Clause 21 The method (1100) of any one of clauses 18 to 20, wherein determining whether the surface roughness (104) is within a roughness threshold (165) comprises determining (1120) whether the surface roughness (104) at multiple locations on the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on the output of the several wave sensors (126).

[0204] Clause 22 22. The method (1100) of any one of claims 18 to 21, wherein positioning the number of wave sensors (126) includes positioning (1114) the number of wave sensors (126) relative to the workpiece (108) such that the number of wave sensors (126) are oriented to sense waves at at least two different distances from a wave generator (146) of the number of wave generators (124).

[0205] Clause 23 The method (1100) of clause 22, wherein determining whether the surface roughness (104) at a plurality of locations on the workpiece (108) is within a roughness threshold (165) comprises determining whether the surface roughness (104) at a plurality of locations extending in a second direction (162) of the workpiece (108) is within a roughness threshold (165), the second direction (162) extending over at least two different distances (1122).

[0206] Clause 24 transmitting (1116) a plurality of source signals (150) having the signal parameters (132) into the workpiece (108) at a plurality of source locations of the workpiece (108) using a plurality of pulsers (178) and a plurality of wave generators (146, 148); transmitting the source signal (134) into the workpiece (108) is one of the plurality of source signals (150) transmitted into the workpiece (108); The method (1100) of any one of clauses 18 to 23, wherein determining whether the surface roughness (104) of the workpiece (108) is within a roughness threshold (165) comprises determining (1124) whether the surface roughness (104, 202) at multiple positions of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on the output of the several wave sensors (126).

[0207] Clause 25 The method (1100) of claim 24, wherein the plurality of locations spans a first direction (172) of the workpiece (108) and the plurality of source signals (150) spans (1126) across the workpiece (108) in the first direction (172).

[0208] Clause 26 A surface roughness analysis system (102), comprising: an ultrasonic analysis system (128) configured to receive material machine parameters (130) for the workpiece (108), determine incident surface wave signal parameters (132) for source signals (134) transmitted by a number of wave generators (124), and determine a predetermined distance (160) of the number of wave sensors (126) from the number of wave generators (124) such that a number of wave sensors (126) receiving a threshold surface wave (164) is indicative of a surface roughness (104) within a roughness threshold (165); the number of wave generators (124) configured to transmit a source signal (134) having the signal parameters (132) into a workpiece (108); the number of wave sensors (126) positioned at least the predetermined distance (160) from the number of wave generators (124); and a roughness evaluator (180) configured to determine whether the surface roughness (104) of the workpiece (108) is less than a roughness threshold (165) based on the surface waves (164) sensed by the number of wave sensors (126). A surface roughness analysis system (102) comprising:

[0209] Clause 27 The surface roughness analysis system (102) of clause 26, wherein the number of wave sensors (126) comprises a series of wave sensors (166), each wave sensor (156, 168) of the series of wave sensors (166) having a different distance (158, 170) from a wave generator (146) of the number of wave generators (124) in a second direction (162) of the surface (106) of the workpiece (108).

[0210] Clause 28 28. The surface roughness analysis system (102) of claim 26 or 27, wherein the number of wave generators (124) comprises a plurality of wave generators (146, 148) spaced across the surface (106) of the workpiece (108) in a first direction (172).

[0211] Clause 29 The surface roughness analysis system (102) of any one of clauses 26 to 28, wherein the number of wave sensors (126) are positioned at least a predetermined distance (160) from the number of wave generators (124) to detect surface waves (154) from the workpiece (108), the predetermined distance (160) being selected based on a cutoff wavelength (136) calculated by the ultrasonic analysis system (128).

[0212] Clause 30 30. The surface roughness analysis system (102) of claim 29, wherein the cutoff wavelength (136) is about 0.5.

[0213] Clause 31 A surface roughness analysis system (102), comprising: a number of wave generators (124) configured to transmit a source signal (134) having signal parameters (132) into a workpiece (108), the signal parameters (132) being calculated to generate a surface wave at the workpiece (108); a number of wave sensors (126) oriented to receive surface waves from the workpiece (108) and positioned at least a predetermined distance (160) from the number of wave generators (124), the predetermined distance (160) being such that receiving a threshold surface wave (164) at the number of wave sensors (126) indicates a surface roughness (104) within a roughness threshold (165); and a roughness evaluator (180) configured to determine whether the surface roughness (104) of the workpiece (108) is below a roughness threshold (165) based on the presence or absence of surface waves (164) sensed by the number of wave sensors (126). A surface roughness analysis system (102) comprising:

[0214] The description of the various exemplary embodiments is for the purpose of illustration and explanation, and is not intended to be exhaustive or to limit the embodiments to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, various exemplary embodiments may provide different features as compared to other exemplary embodiments. The selected embodiment or embodiments have been selected and described in order to best explain the principles and practical applications of the embodiments, and to facilitate understanding by others skilled in the art of the disclosure of the various embodiments and various modifications suitable for the particular application under consideration.

Claims

1. A surface roughness analysis system (102), comprising: an ultrasound analysis system (128) comprising: receiving material machine parameters (130) for the workpiece (108); determining incident surface wave signal parameters (132) for a source signal (134) transmitted by a number of wave generators (124) using the material mechanical parameters (130); determining a cutoff wavelength (136) using said material mechanical parameters (130), which is the ratio of the surface wavelength (138) to the incident wavelength (140); determining a predetermined distance (160) of the number of wave sensors (126) from the number of wave generators (124) based on the cutoff wavelength (136) such that the number of wave sensors (126) receiving a threshold surface wave (164) indicate a surface roughness (104) within a roughness threshold (165); It is structured as follows: the number of wave generators (124) configured to transmit the source signal (134) having the signal parameters (132) into the workpiece (108); the number of wave sensors (126) are positioned at least the predetermined distance (160) from the number of wave generators (124); the surface roughness analysis system (102) further comprises a roughness evaluator (180) configured to determine whether the surface roughness (104) of the workpiece (108) is less than the roughness threshold (165) based on the surface waves (164) sensed by the number of wave sensors (126). A surface roughness analysis system (102).

2. The surface roughness analysis system (102) of claim 1, wherein the cutoff wavelength (136) is about 0.

5.

3. 3. The surface roughness analysis system (102) of claim 1 or 2, wherein the number of wave sensors (126) comprises a series of wave sensors (166), each wave sensor (156, 168) of the series of wave sensors (166) having a different distance (158, 170) from one wave generator (146) of the number of wave generators (124) in a second direction (162) of the surface (106) of the workpiece (108).

4. A surface roughness analysis system (102) as described in any one of claims 1 to 3, wherein the number of wave generators (124) comprises a plurality of wave generators (146, 148) spaced across the surface (106) of the workpiece (108) in a first direction (172).

5. 5. The surface roughness analysis system (102) of claim 1, wherein the number of wave sensors (126) are positioned at least the predetermined distance (160) from the number of wave generators (124) to detect surface waves (154) from the workpiece (108), the predetermined distance (160) being selected based on a cutoff wavelength (136) calculated by the ultrasonic analysis system (128).

6. A method (1000) for analyzing a surface roughness of a workpiece (108), comprising: receiving (1002) material-mechanical parameters (130) of the workpiece (108); determining (1004) signal parameters (132) for a source signal (134) transmitted into a workpiece (108) using the material machine parameters (130); determining (1007) a cutoff wavelength (136) using said material mechanical parameters (130), the cutoff wavelength being the ratio of a surface wavelength (138) to an incident wavelength (140); determining (1005) a predetermined distance (160) of a number of wave sensors (126) from a number of wave generators (124) based on the cutoff wavelength (136) such that a number of the wave sensors (126) receiving a threshold surface wave (164) indicate a surface roughness (104) within a roughness threshold (165); positioning said number of wave sensors (126) at least said predetermined distance (160) from said number of wave generators (124); transmitting the source signal (134) having the signal parameters (132) from the number of wave generators (124) into the workpiece (108); determining whether the surface roughness (104) of the workpiece (108) is within the roughness threshold (165) based on the surface waves (164) sensed by the number of wave sensors (126); The method includes:

7. transmitting a plurality of source signals (150) having the signal parameters (132) into the workpiece (108) at a plurality of source locations of the workpiece (108) using a plurality of pulsers (178) and a plurality of wave generators (146, 148); transmitting the source signal (134) into the workpiece (108) is one of the plurality of source signals (150) transmitted into the workpiece (108); 7. The method (1000) of claim 6, wherein determining whether the surface roughness (104) of the workpiece (108) is within the roughness threshold (165) comprises determining whether the surface roughness (104) at multiple locations of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on the output of the several wave sensors (126).

8. 8. The method (1000) of claim 7, wherein the plurality of locations span a first direction (172) of the workpiece (108) and the plurality of source signals (150) span across the workpiece (108) in the first direction (172).

9. transmitting (1006) the source signal (134) having the signal parameters (132) into the workpiece (108) using a pulser (178) and a wave generator (146); determining (1008) whether the surface roughness (104, 202) of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on outputs of the number of wave sensors (126); The method of any one of claims 6 to 8, further comprising:

10. orienting (1010) the wave generator (146) relative to the workpiece (108) to transmit the source signal (134) to the workpiece (108) at a source location (152); orienting (1012) at least one wave sensor of the number of wave sensors (126) relative to the workpiece (108) to sense waves at the predetermined distance (160) from the source location (152).

10. The method of claim 9, further comprising:

11. The method (1000) of claim 10, further comprising orienting (1014) the number of wave sensors (126) relative to the workpiece (108) so that the number of wave sensors (126) are oriented to sense waves at at least two different distances from the source position (152).

12. The method (1000) of claim 11, wherein determining whether the surface roughness (104, 202) of the workpiece (108) is within the roughness threshold (165) includes determining (1018) whether the surface roughness (104, 202) at multiple locations of the workpiece (108) is within a roughness threshold (165) for at least one of a roughness width (208) or a roughness height (206) based on the output of the several wave sensors (126).

13. 13. The method (1000) of claim 12, wherein determining whether the surface roughness (104, 202) of the plurality of locations (434, 436, 438) of the workpiece (108) is within the roughness threshold (165) comprises determining whether the surface roughness (104, 202) of a plurality of locations (434, 436, 438) extending in a second direction (162, 416) of the workpiece (108) is within the roughness threshold (165), the second direction (162, 416) extending over the at least two different distances (428, 430, 432) (1020).

14. A method (1000) according to any one of claims 6 to 13, wherein the workpiece (108) has a surface coating.

15. The method (1000) of claim 14, wherein the surface coating comprises one of a paint, a wax, an anti-icing layer, a hydrophobic layer, or a thermal protection layer.

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