Patent Description:
Surface roughness is a component of surface texture. Surface roughness is a product of manufacturing processes. In surface metrology, the term "roughness" is typically applied to the high-frequency and short-wavelength parameters of a finished surface. Surface roughness can be described as a series of peaks and valleys of the surface.

Surface roughness can be directly associated with the properties and control of the manufacturing. For some goods, surface roughness only affects aesthetics. For mechanical components, roughness is often a predictor for the performance of the components. Roughness is associated with the propagation of inconsistencies. Thus, roughness is often undesirable.

Current methods of roughness analysis include visual inspection or a contact probe. Visual inspection is performed by comparing example specimens with various known roughnesses to a workpiece being analyzed. Visual inspection is limited in its accuracy.

A contact probe makes contact with a surface to be analyzed. The contact probe measures roughness by quantifying a distance the probe tip moves vertically as the contact probe moves across the surface of the workpiece. A contact probe is limited in speed and only quantifies the roughness of the surface the contact probe has traversed.

<CIT> describes, in a machine translation of its abstract: "a method for detecting the surface roughness of an object, in particular to a method for detecting the surface roughness of an object by using ultrasonic waves. Ultrasonic waves are generated and received by an ultrasonic transducer. During roughness detection, the ultrasonic transducer emits surface acoustic waves at a frequency F1, and the surface waves are received by the ultrasonic transducer after being propagated along a detected surface. When the surface roughness is different, the surface acoustic wave received by the ultrasonic transducer is different, and the output electrical signal is different. The surface roughness of an object is detected according to different electrical signals".

An embodiment of the present disclosure as defined in independent claim <NUM> provides a method of analyzing surface roughness of a workpiece. Material mechanical parameters of the workpiece are received.

A cut-off wavelength is determined using material mechanical parameters of the workpiece. The cut-off wavelength is a ratio of surface wavelength over incident wavelength. A designated distance for a number of wave sensors from the number of wave generators is determined using the cut-off wavelength such that the number of wave sensors receiving a surface wave of a threshold value indicates a surface roughness within a roughness threshold.

Another embodiment of the present disclosure as defined in the independent claim <NUM> provides a surface roughness analysis system. The surface roughness analysis system comprises 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 a workpiece, determine incident surface wave signal parameters for a source signal to be sent by the number of wave generators, and determine a designated distance for a number of wave sensors from the number of wave generators such that the number of wave sensors receiving a surface wave of a threshold value indicates a surface roughness within a roughness threshold. The number of wave generators is configured to send a source signal having the signal parameters into a workpiece. The number of wave sensors is positioned at least the designated distance from the number of wave generators. The roughness evaluator is configured to determine if the surface roughness of the workpiece is below a roughness threshold based on a surface wave sensed by number of wave sensors.

The illustrative examples recognize and take into account one or more different considerations. The illustrative examples recognize and take into account that roughness is often a predictor for performance of mechanical components in both subtractive and additive manufacturing processes. The illustrative examples recognize and take into account that irregularities on a surface finish may form nucleation sites for cracks and corrosion. The illustrative examples recognize and take into account that fatigue is a surface phenomenon and high surface roughness can increase crack growth initiation possibility.

The illustrative examples recognize and take into account that roughness also plays a role in material interaction with the environment. For example, roughness affects corrosion.

The illustrative examples recognize and take into account that surface roughness can be a challenge in manufacturing of three-dimensionally printed parts. The illustrative examples recognize and take into account that many additive manufacturing methods construct a part's geometry by layered deposition of the material. Surface roughness can be especially important to high fatigue cycle components.

The illustrative embodiments use ultrasonic surface guided waves to characterize the surface roughness amplitude and frequency during the manufacturing process. Surface acoustic waves are produced by a number of transducers and propagate along a rough surface. The illustrative embodiments predefine a cut-off threshold for Rayleigh wave propagation, which is indicative of the surface roughness description. This cut-off occurs for a particular ratio of the spatial surface waviness and the acoustic wavelength, and the detection of the resulting wave attenuation and decay characterizes the surface roughness.

The illustrative embodiments can be used in-line with the production process. The illustrative embodiments could signal adjustment of the material deposition rate in additive manufacturing when indicated to achieve the desired product quality. The illustrative embodiments indicate when rework or additional surface processing is desirable.

Turning now to <FIG>, an illustration of a block diagram of an inspection environment is depicted in which an illustrative embodiment may be implemented. In inspection environment <NUM>, surface roughness analysis system <NUM> is used to analyze surface roughness <NUM> of surface <NUM> of workpiece <NUM>. Surface roughness <NUM> can be due to processes <NUM> applied to workpiece <NUM>. Processes <NUM> include any desirable type of manufacturing, maintenance, cleaning, operation, or other process. Processes <NUM> may be used to add or subtract material to workpiece <NUM>.

In some illustrative examples, processes <NUM> include surface treatment <NUM>. Surface treatment <NUM> affects surface roughness <NUM> of workpiece <NUM>. Surface treatment <NUM> is selected from one of mechanical <NUM> or chemical <NUM>. In some illustrative examples, mechanical <NUM> surface treatment <NUM> is selected from at least one of polishing, sanding, grinding, sand blasting, or any other desirable form of mechanical <NUM> surface treatment <NUM>.

In some illustrative examples, when processes <NUM> include surface treatment <NUM> that affects surface roughness <NUM>, surface <NUM> is part of substrate <NUM> of workpiece <NUM>. In other illustrative examples, when processes <NUM> include surface treatment <NUM> that affects surface roughness <NUM>, surface <NUM> is coating <NUM> over substrate <NUM>. In some illustrative examples, coating <NUM> is applied directly over substrate <NUM>. In other illustrative examples, intermediate layers are present between coating <NUM> and substrate <NUM>.

In some illustrative examples, processes <NUM> include surface coating application <NUM>. Surface coating application <NUM> includes adding any desirable thickness or type of material to workpiece <NUM>. In some illustrative examples, surface coating application <NUM> includes one of painting, waxing, applying an anti-icing layer, applying a hydrophobic layer, applying a heat protective layer, or any other surface coating application <NUM>.

In some illustrative examples, surface roughness analysis system <NUM> may be described as a pitch-catch ultrasonic roughness analysis system. In some illustrative examples, surface roughness analysis system <NUM> comprises number of wave generators <NUM>, number of wave sensors <NUM>, and ultrasonic analysis system <NUM>. Ultrasonic analysis system <NUM> is configured to receive material mechanical parameters <NUM> for workpiece <NUM>, determine signal parameters <NUM> for source signal <NUM> to be sent by number of wave generators <NUM>, and determine designated distance <NUM> for number of wave sensors <NUM> from number of wave generators <NUM> such that number of wave sensors <NUM> receiving surface wave <NUM> of a threshold value indicates surface roughness <NUM> within roughness threshold <NUM>. In some illustrative examples, ultrasonic analysis system <NUM> is further configured to determine cut-off wavelength <NUM> using material mechanical parameters <NUM>, wherein cut-off wavelength <NUM> is a ratio of surface wavelength <NUM> over incident wavelength <NUM>. Designated distance <NUM> is determined based on cut-off wavelength <NUM>. In some illustrative examples, cut-off wavelength <NUM> is approximately <NUM>.

A cut-off threshold for Rayleigh wave propagation exists, which is indicative of surface roughness <NUM>. This cut-off wavelength <NUM> occurs for a particular ratio of surface wavelength <NUM> and incident wavelength <NUM>. In some illustrative examples, this ratio is described as a ratio of the spatial surface waviness and the acoustic wavelength. Detection of the resulting wave attenuation and decay characterizes surface roughness <NUM>. Surface roughness analysis system <NUM> can be used in-line with the production process. For additive manufacturing, surface roughness analysis system <NUM> can be used in-line to signal adjustment of the material deposition rate to achieve the desired surface roughness.

The Rayleigh wave propagates over the surface of solid media, such as surface <NUM> of workpiece <NUM>, and gradually loses its energy due to surface roughness <NUM>. A Rayleigh wave would have no discernable energy loss for an entirely smooth surface.

Attenuation of a surface wave, such as surface wave <NUM>, is related to the surface profile parameters. A wave front on a rough surface decays by interference from the roughness pattern. The roughness profile and the magnitude of Rmax and λsurface can cause immediate or partial attenuation of a surface wave. If the height distance of Rmax / <NUM> is higher than a Rayleigh wavelength, then the surface wave will not form at all and the wave front reflects immediately. For the frequency spectrum ranging less than one wavelength where Rmax < λsurface, the surface wave forms and propagates but is eventually damped at a certain distance along the rough surface.

Cut-off wavelength <NUM> can be described as a ratio between surface wavelength <NUM> over incident wavelength <NUM>, λsurface / λwave at which the Rayleigh wave does not form. The surface waves attenuate at any point beyond cut-off wavelength <NUM>. The higher the magnitude of surface wavelength <NUM>, λsurface, the greater the wave attenuation. There is total attenuation if the ratio is <NUM> and no attenuation if the ratio is <NUM>. There is a partial attenuation of the Rayleigh wave in the range of <NUM> < λsurface / λwave < <NUM>. The cut-off wavelength can be customized for different roughness profiles. In some illustrative examples, the cut-off threshold is when λsurface / λwave = <NUM>.

Number of wave generators <NUM> generates plurality of source signals <NUM> using signal parameters <NUM>. Signal parameters <NUM> are determined by ultrasonic analysis system <NUM> and take into account material mechanical parameters <NUM> and cut-off wavelength <NUM>.

Number of wave generators <NUM> includes any desirable quantity of wave generators. As used herein, "a number of," when used with reference to items, means one or more items. For example, "number of wave generators <NUM>" includes one or more wave generators.

In some illustrative examples, number of wave generators <NUM> is acoustically coupled to surface <NUM> through contact with surface <NUM>. In some illustrative examples, number of wave generators <NUM> is acoustically coupled to surface <NUM> through a coupling fluid. In some illustrative examples, number of wave generators <NUM> is non-contact <NUM>.

Number of wave sensors <NUM> includes any desirable quantity of wave sensors. Number of wave sensors <NUM> includes one or more wave sensors.

In some illustrative examples, number of wave sensors <NUM> is acoustically coupled to surface <NUM> through contact with surface <NUM>. In some illustrative examples, number of wave sensors <NUM> is acoustically coupled to surface <NUM> through a coupling fluid. In some illustrative examples, number of wave sensors <NUM> is non-contact <NUM>.

When a surface wave, such as surface wave <NUM>, is completely attenuated prior to number of wave sensors <NUM> or does not form, number of wave sensors <NUM> does not receive surface wave <NUM>. Number of wave sensors <NUM> produce output of electrical signals indicative of any surface waves sensed by number of wave sensors <NUM>. Output of number of wave sensors <NUM> above a signal threshold indicates detection of a surface wave. The signal threshold is set to differentiate signal from noise.

When surface wave <NUM> completely attenuates, number of wave sensors <NUM> does not sense surface wave <NUM>. When number of wave sensors <NUM> does not sense surface wave <NUM>, output of number of wave sensors <NUM> is below a signal threshold. Output of number of wave sensors <NUM> below a signal threshold indicates surface roughness <NUM> is outside of roughness threshold <NUM>. Roughness threshold <NUM> is a predetermined level at which surface roughness <NUM> is undesirable for workpiece <NUM> and its intended use. For example, roughness threshold <NUM> is a predetermined maximum level based on a largest desirable roughness height or largest desirable roughness width. The largest desirable roughness height and largest desirable roughness width are based on a desired use, material, and part type of workpiece <NUM>.

In some illustrative examples, number of wave generators <NUM> includes wave generator <NUM>. In some illustrative examples, number of wave generators <NUM> includes wave generator <NUM>. Number of wave generators <NUM> is configured to send plurality of source signals <NUM> into surface <NUM> of workpiece <NUM>. Plurality of source signals <NUM> may be sent into surface <NUM> simultaneously or consecutively. Wave generator <NUM> sends source signal <NUM> into workpiece <NUM>. Wave generator <NUM> sends source signal <NUM> into workpiece <NUM> at source location <NUM> of surface <NUM>.

Number of wave sensors <NUM> is configured to sense plurality of surface waves <NUM> traveling through surface <NUM>. Number of wave sensors <NUM> is positioned at least a designated distance from number of wave generators <NUM> to detect surface waves from workpiece <NUM>, wherein designated distance <NUM> is selected based on cut-off wavelength <NUM> calculated by ultrasonic analysis system <NUM>.

In some illustrative examples, number of wave sensors <NUM> includes only wave sensor <NUM> distance <NUM> from wave generator <NUM>. When number of wave generators <NUM> has only wave generator <NUM> and number of wave sensors <NUM> has only wave sensor <NUM>, distance <NUM> is at least designated distance <NUM>. Distance <NUM> is measured in second direction <NUM> on surface <NUM> of workpiece <NUM>. Designated distance <NUM> is selected based on cut-off wavelength <NUM> calculated by ultrasonic analysis system <NUM>. Designated distance <NUM> is selected such that receiving a surface wave of a threshold value indicates a surface roughness within a roughness threshold <NUM>.

When distance <NUM> between wave sensor <NUM> and wave generator <NUM> is at least designated distance <NUM>, receiving surface wave <NUM> at wave sensor <NUM> indicates surface roughness <NUM> is within roughness threshold <NUM>. In these illustrative examples, surface wave <NUM> is generated by source signal <NUM> sent into workpiece <NUM> at source location <NUM>.

If wave sensor <NUM> senses surface wave <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensors <NUM> is within roughness threshold <NUM>. If wave sensor <NUM> does not sense surface wave <NUM>, surface wave <NUM> has attenuated due to surface roughness <NUM> or not formed at all due to surface roughness <NUM>. If wave sensor <NUM> does not sense surface wave <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensors <NUM> is outside roughness threshold <NUM>.

In some illustrative examples, number of wave sensors <NUM> comprises series of wave sensors <NUM>. Each wave sensor of series of wave sensors <NUM> has a different distance from wave generator <NUM> of number of wave generators <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. Series of wave sensors <NUM> include wave sensor <NUM> and wave sensor <NUM>. Wave sensor <NUM> is distance <NUM> from wave generator <NUM>. Distance <NUM> and distance <NUM> are different values.

Using a single wave sensor, such as wave sensor <NUM>, surface roughness <NUM> of a single location is analyzed. Using series of wave sensors <NUM> in combination, different locations between wave generator <NUM> and series of wave sensors <NUM> can be evaluated.

In some illustrative examples, distance <NUM> is less than distance <NUM>. In some illustrative examples, wave sensor <NUM> senses surface wave <NUM> and wave sensor <NUM> does not sense surface wave <NUM>. In these illustrative examples, surface roughness <NUM> between wave sensor <NUM> and wave generator <NUM> is within roughness threshold <NUM>. In these illustrative examples, surface roughness <NUM> between wave sensor <NUM> and wave sensor <NUM> is outside roughness threshold <NUM>.

In some illustrative examples, neither wave sensor <NUM> nor wave sensor <NUM> sense surface wave <NUM>. In these illustrative examples, surface roughness <NUM> between wave sensor <NUM> and wave generator <NUM> is outside of roughness threshold <NUM>.

In some illustrative examples, both wave sensor <NUM> and wave sensor <NUM> sense surface wave <NUM>. In these illustrative examples, surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM> is within roughness threshold <NUM>.

In some illustrative examples, number of wave generators <NUM> comprises a plurality of wave generators, wave generator <NUM> and wave generator <NUM>, spaced across surface <NUM> of workpiece <NUM> in first direction <NUM>. First direction <NUM> is perpendicular to second direction <NUM>. In these illustrative examples, the plurality of wave generators sends plurality of source signals <NUM> into surface <NUM> in a plurality of source locations.

In some illustrative examples, wave sensor <NUM> is positioned at least designated distance <NUM> from wave generator <NUM> and wave sensor <NUM> is positioned at least designated distance <NUM> from wave generator <NUM>. Using output from wave sensor <NUM> and wave sensor <NUM>, localized surface roughness <NUM> in first direction <NUM> is analyzed. Output from wave sensor <NUM> is used to analyze surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM>. Output from wave sensor <NUM> is used to analyze surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM>.

Controller <NUM> is configured to control generation of plurality of source signals <NUM> having signal parameters <NUM> by number of wave generators <NUM>. Controller <NUM> may be implemented in at least one of hardware or software. Controller <NUM> may be a processor unit in a computer system or a specialist circuit depending on the particular implementation.

In some illustrative examples, controller <NUM> is configured to send electrical control signals to number of pulsers <NUM>. The electrical control signals instruct number of pulsers <NUM> which pulsing scheme to employ. In response to those electrical control signals, number of pulsers <NUM> outputs electrical signals representing the ultrasonic waves to be generated to number of wave generators <NUM>.

Surface roughness analysis system <NUM> includes roughness evaluator <NUM> configured to determine if surface roughness <NUM> of workpiece <NUM> is below roughness threshold <NUM> based on surface waves sensed by number of wave sensors <NUM>. Roughness evaluator <NUM> determines, from output of number of wave sensors <NUM>, if surface roughness <NUM> is within roughness threshold <NUM>. When a wave sensor of number of wave sensors <NUM> outputs a signal at or above a signal threshold, the wave sensor has detected a surface wave, such as surface wave <NUM>. When roughness evaluator <NUM> receives output from number of wave sensors <NUM> that below signal threshold, roughness evaluator <NUM> determines that surface roughness <NUM> is outside of roughness threshold <NUM>.

Number of wave sensors <NUM> converts impinging ultrasonic waves into electrical signals. In some illustrative examples, these electrical signals are sent to number of receivers <NUM>. In these illustrative examples, number of receivers <NUM> outputs electrical signals representing the acquired ultrasonic inspection data from number of wave sensors <NUM> to roughness evaluator <NUM>.

In some illustrative examples, surface roughness analysis system <NUM> comprises ultrasonic analysis system <NUM> configured to receive material mechanical parameters <NUM> for workpiece <NUM>, determine incident surface wave signal parameters <NUM> for a source signal <NUM> to be sent by a number of wave generators <NUM>, and determine a designated distance <NUM> for a number of wave sensors <NUM> from the number of wave generators <NUM> such that the number of wave sensors <NUM> receiving a surface wave <NUM> of a threshold value indicates a surface roughness <NUM> within roughness threshold <NUM>; number of wave generators <NUM> configured to send a source signal having signal parameters <NUM> into a workpiece; number of wave sensors <NUM> positioned at least designated distance <NUM> from number of wave generators <NUM>; and roughness evaluator <NUM> configured to determine if surface roughness <NUM> of workpiece <NUM> is below a roughness threshold <NUM> based on a surface wave <NUM> sensed by number of wave sensors <NUM>.

In some illustrative examples, surface roughness analysis system <NUM> comprises number of wave generators <NUM> configured to send source signal <NUM> having signal parameters <NUM> into workpiece <NUM>, signal parameters <NUM> calculated to generate surface wave <NUM> in workpiece <NUM>; number of wave sensors <NUM> is oriented to receive surface waves <NUM> from workpiece <NUM> and positioned at least designated distance <NUM> from the number of wave generators <NUM>, wherein designated distance <NUM> is such that receiving surface wave <NUM> of a threshold value at number of wave sensors <NUM> indicates a surface roughness <NUM> within roughness threshold <NUM>; and roughness evaluator <NUM> is configured to determine if surface roughness <NUM> of workpiece <NUM> is below roughness threshold <NUM> based on a presence or absence of surface wave <NUM> sensed by number of wave sensors <NUM>.

The illustrations of surface roughness analysis system <NUM> and inspection environment <NUM> in <FIG> are not meant to imply physical or architectural limitations to the manner in which an illustrative embodiment may be implemented. Other components in addition to or in place of the ones illustrated may be used. Some components may be unnecessary. Also, the blocks are presented to illustrate some functional components. One or more of these blocks may be combined, divided, or combined and divided into different blocks when implemented in an illustrative embodiment.

For example, although number of wave generators <NUM> is only discussed as having one or two wave generators, number of wave generators <NUM> can have any desirable quantity of wave generators. For example, number of wave generators <NUM> can have more than two wave generators.

As another example, although series of wave sensors <NUM> is discussed as associated with wave generator <NUM>, in some illustrative examples number of wave generators <NUM> has more than one wave generator, each associated with its own series of wave sensors. As yet another example, although series of wave sensors <NUM> is depicted as only having two wave sensors, in some illustrative examples series of wave sensors <NUM> has more than two wave sensors.

As another example, although controller <NUM> is shown as a separate component from ultrasonic analysis system <NUM>, in some non-depicted examples, ultrasonic analysis system <NUM> and controller <NUM> are part of the same processor unit or computer system. As yet another example, although controller <NUM> is shown as a separate component from roughness evaluator <NUM>, in some non-depicted examples, roughness evaluator <NUM> and controller <NUM> are part of the same processor unit or computer system.

Turning now to <FIG>, a perspective view of a workpiece having a surface roughness is depicted in accordance with an illustrative embodiment. Workpiece <NUM> is a physical implementation of workpiece <NUM> of <FIG>. Surface roughness analysis system <NUM> of <FIG> can be used to analyze surface roughness <NUM> of workpiece <NUM>.

Workpiece <NUM> has surface <NUM> with surface roughness <NUM>. Surface roughness <NUM> has roughness height <NUM> and roughness width <NUM>.

Surface roughness <NUM> consists of surface irregularities which result from manufacturing processes. These irregularities combine to form surface texture and are illustrated in <FIG>. Roughness width <NUM> is the distance parallel to the nominal surface between the successive peaks or ridges constituting the predominant pattern roughness. Roughness height <NUM> is sometimes also known as the height of unevenness. Roughness height <NUM> is the height of the irregularities with respect to a reference mean-line.

Roughness lay <NUM> represents the direction of predominant surface pattern produced and it reflects the manufacturing operation used to produce it. "Waviness" refers to widely spaced irregularities outside the roughness width cut off values, and which may be the result of work piece or tool deflection during machining, vibration, or tool run-out. Waviness height is the peak to valley distance of the surface profile, measured in millimeters.

Turning now to <FIG>, a cross-sectional side view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is depicted in accordance with an illustrative embodiment. Components of surface roughness analysis system <NUM> are associated with workpiece <NUM>. Surface roughness analysis system <NUM> is a physical implementation of surface roughness analysis system <NUM> of <FIG>. Workpiece <NUM> can be a physical implementation of workpiece <NUM> of <FIG>. In some illustrative examples, view <NUM> is a cross-sectional view of workpiece <NUM>.

Components of surface roughness analysis system <NUM> include wave generator <NUM> and wave sensor <NUM>. Wave generator <NUM> is acoustically coupled to surface <NUM> of workpiece <NUM>. Wave sensor <NUM> is acoustically coupled to surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>.

In some illustrative examples, wave generator <NUM> is acoustically coupled to surface <NUM> through contact with surface <NUM>. In some illustrative examples, wave generator <NUM> is acoustically coupled to surface <NUM> through a coupling fluid. In some illustrative examples, wave generator <NUM> is a non-contact ultrasonic wave generator.

Wave generator <NUM> sends source signals having signal parameters into surface <NUM> of workpiece <NUM>. The signal parameters are determined by an ultrasonic analysis system and take into account material mechanical parameters of workpiece <NUM>.

In some illustrative examples, wave sensor <NUM> is acoustically coupled to surface <NUM> through contact with surface <NUM>. In some illustrative examples, wave sensor <NUM> is acoustically coupled to surface <NUM> through a coupling fluid. In some illustrative examples, wave sensor <NUM> is a non-contact ultrasonic wave sensor.

Surface <NUM> has surface roughness <NUM>. As depicted, surface roughness <NUM> disrupts propagation of surface waves along surface <NUM> of workpiece <NUM>. Surface roughness <NUM> can cause immediate or partial attenuation of a wave.

Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM>. The designated distance is selected based on a cut-off wavelength calculated by an ultrasonic analysis system. The designated distance is selected such that receiving a surface wave within a threshold value indicates an acceptable surface roughness. The designated distance is a distance at which a surface wave would not propagate if surface roughness <NUM> is outside of a roughness threshold.

Source signals having signal parameters sent by wave generator <NUM> into surface <NUM> of workpiece <NUM> generate Rayleigh wave propagation <NUM>. In view <NUM>, Rayleigh wave propagation <NUM> is illustrated. Rayleigh wave propagation <NUM> emanates from a source location where a source signal sent by wave generator <NUM> enters surface <NUM>. In view <NUM>, a surface wave does not propagate to wave sensor <NUM> from Rayleigh wave propagation <NUM> due to surface roughness <NUM>. Surface roughness <NUM> has at least one of an undesirable roughness width or undesirable roughness height.

As a surface wave does not propagate to wave sensor <NUM> from Rayleigh wave propagation <NUM>, a signal having a sufficient strength is not received by wave sensor <NUM>. In view <NUM>, wave sensor <NUM> does not receive a signal.

Data output from wave sensor <NUM> is directed to an associated roughness evaluator (not depicted). In some illustrative examples, a receiver (not depicted) outputs electrical signals representing the acquired ultrasonic inspection data from wave sensor <NUM> to a roughness evaluator (not depicted). When wave sensor <NUM> does not receive a signal, an associated roughness evaluator determines surface <NUM> has surface roughness <NUM> outside of a roughness threshold.

Turning now to <FIG>, a cross-sectional side view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is depicted in accordance with an illustrative embodiment. Surface roughness analysis system <NUM> is a physical implementation of surface roughness analysis system <NUM> of <FIG>. Workpiece <NUM> can be a physical implementation of workpiece <NUM> of <FIG>. In some illustrative examples, view <NUM> is a cross-sectional view of workpiece <NUM>.

Components of surface roughness analysis system <NUM> include number of wave generators <NUM> and number of wave sensors <NUM>. Number of wave generators <NUM> has only one wave generator, wave generator <NUM>. Wave generator <NUM> is acoustically coupled to surface <NUM> of workpiece <NUM>.

Number of wave sensors <NUM> comprises series of wave sensors <NUM>, each wave sensor of series of wave sensors <NUM> having a different distance from wave generator <NUM> of number of wave generators <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. Number of wave sensors <NUM> includes wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>.

Number of wave sensors <NUM> is acoustically coupled to surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>. Surface <NUM> has surface roughness <NUM>. As depicted, surface roughness <NUM> disrupts propagation of surface waves along surface <NUM> of workpiece <NUM>. Surface roughness <NUM> can cause immediate or partial attenuation of a wave.

In some illustrative examples, number of wave generators <NUM> is acoustically coupled to surface <NUM> through contact with surface <NUM>. In some illustrative examples, number of wave generators <NUM> is acoustically coupled to surface <NUM> through a coupling fluid. In some illustrative examples, number of wave generators <NUM> is a number of non-contact ultrasonic wave generators.

Number of wave generators <NUM> sends source signals having signal parameters into surface <NUM> of workpiece <NUM>. The signal parameters are determined by an ultrasonic analysis system and take into account material mechanical parameters of workpiece <NUM>.

In some illustrative examples, at least one of number of wave sensors <NUM> is acoustically coupled to surface <NUM> through contact with surface <NUM>. In some illustrative examples, at least one of number of wave sensors <NUM> is acoustically coupled to surface <NUM> through a coupling fluid. In some illustrative examples, at least one of number of wave sensors <NUM> is a non-contact ultrasonic wave sensor.

Wave generator <NUM> is positioned relative to workpiece <NUM> to send a source signal into workpiece <NUM> at source location <NUM>. Number of wave sensors <NUM> is oriented relative to workpiece <NUM> such that number of wave sensors <NUM> is oriented to sense waves at at least two different distances from source location <NUM>. In this illustrative example, number of wave sensors <NUM> is oriented to sense waves at three different distances from source location <NUM>.

Each of number of wave sensors <NUM> is positioned a different distance from wave generator <NUM>. Wave sensor <NUM> is distance <NUM> from wave generator <NUM>. Wave sensor <NUM> is distance <NUM> from wave generator <NUM>. Wave sensor <NUM> is distance <NUM> from wave generator <NUM>.

In this illustrative example, determining if surface roughness <NUM> of workpiece <NUM> is within a roughness threshold comprises determining if surface roughness <NUM> in a plurality of locations of workpiece <NUM> is within a roughness threshold for at least one of roughness width or roughness height based on output of number of wave sensors <NUM>.

By positioning number of wave sensors <NUM> different distances from wave generator <NUM>, different locations of surface <NUM> in second direction <NUM> are analyzed. For example, surface roughness <NUM> in location <NUM> between wave generator <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in location <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. The signal threshold is set to differentiate signals from noise. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> is within a roughness threshold.

As another example, surface roughness <NUM> in location <NUM> between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in location <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, surface wave has propagated through location <NUM> and location <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> in location <NUM> and location <NUM> is within a roughness threshold.

As yet another example, surface roughness <NUM> in location <NUM> between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in location <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, the surface wave has propagated through location <NUM>, location <NUM>, and location <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> in location <NUM>, location <NUM>, and location <NUM> is within a roughness threshold. When a surface wave does not reach wave sensor <NUM>, surface roughness <NUM> prior to wave sensor <NUM> can be outside a roughness threshold.

Using number of wave sensors <NUM> in combination can analyze surface roughness <NUM> in each of location <NUM>, location <NUM>, and location <NUM> individually. Using number of wave sensors <NUM> in combination can detect localized surface roughness <NUM> outside of a roughness threshold. For example, if a surface wave is detected at wave sensor <NUM> but a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in location <NUM> is within a roughness threshold but surface roughness <NUM> in location <NUM> is not within the roughness threshold. As another example, if a surface wave is detected at wave sensor <NUM> but a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in location <NUM> is within a roughness threshold but surface roughness <NUM> in location <NUM> is not within the roughness threshold. If a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in location <NUM> is outside a roughness threshold. If a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in location <NUM> and location <NUM> is not analyzed.

Number of wave sensors <NUM> is positioned at least a designated distance from the number of wave generators to detect surface waves from a workpiece, wherein the designated distance is selected based on a cut-off wavelength calculated by the ultrasonic analysis system. The designated distance is selected such that receiving a surface wave of a threshold value indicates an acceptable surface roughness.

Source signals having signal parameters sent by wave generator <NUM> into surface <NUM> of workpiece <NUM> generate Rayleigh wave propagation <NUM>. In view <NUM>, Rayleigh wave propagation <NUM> is illustrated. Rayleigh wave propagation <NUM> emanates from a source location where a source signal sent by wave generator <NUM> enters surface <NUM>. In view <NUM>, a surface wave does not propagate to any of wave sensor <NUM>, wave sensor <NUM>, or wave sensor <NUM> from Rayleigh wave propagation <NUM> due to surface roughness <NUM>. Surface roughness <NUM> has at least one of an undesirable roughness width or undesirable roughness height.

Data output from number of wave sensors <NUM> is directed to an associated roughness evaluator (not depicted). In some illustrative examples, a number of receivers (not depicted) outputs electrical signals representing the acquired ultrasonic inspection data from number of wave sensors <NUM> to a roughness evaluator (not depicted). When a wave sensor of number of wave sensors <NUM> does not receive a signal, an associated roughness evaluator determines surface <NUM> has surface roughness <NUM> outside of a roughness threshold.

Turning now to <FIG>, a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is depicted in accordance with an illustrative embodiment. Surface roughness analysis system <NUM> is a physical implementation of surface roughness analysis system <NUM> of <FIG>. In some illustrative examples, workpiece <NUM> is a physical implementation of workpiece <NUM> of <FIG>. In some illustrative examples, view <NUM> is a perspective view of workpiece <NUM>. In some illustrative examples, view <NUM> is a perspective view of surface roughness analysis system <NUM> and workpiece <NUM> of <FIG>.

Components of surface roughness analysis system <NUM> include number of wave generators <NUM> and number of wave sensors <NUM>. Number of wave generators <NUM> includes wave generator <NUM>, wave generator <NUM>, and wave generator <NUM>. Wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> are acoustically coupled to surface <NUM> of workpiece <NUM>.

Each wave sensor of number of wave sensors <NUM> is positioned at least a designated distance from one of number of wave generators <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. Number of wave sensors <NUM> includes wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>.

Number of wave sensors <NUM> is acoustically coupled to surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>. Surface <NUM> has surface roughness <NUM>. Surface roughness <NUM> can disrupt propagation of surface waves along surface <NUM> of workpiece <NUM>. Surface roughness <NUM> can cause immediate or partial attenuation of a wave.

Determining if surface roughness <NUM> of workpiece <NUM> is within a roughness threshold comprises determining if surface roughness <NUM> in each of a plurality of locations of workpiece <NUM> is within a roughness threshold. The determination is based on output of the number of wave sensors, wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>.

Having wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM> allows for analysis of surface roughness <NUM> at the plurality of locations. Wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM> are separated from each other in first direction <NUM>. In <FIG>, the plurality of locations is spread across first direction <NUM>.

Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>. The designated distance is selected based on cut-off wavelength calculated by the ultrasonic analysis system. The designated distance is selected such that receiving a surface wave of a threshold value indicates an acceptable surface roughness.

Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>. Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>.

Number of wave generators <NUM> is separated in first direction <NUM> of workpiece <NUM>. In view <NUM>, wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> are equally spaced across first direction <NUM>. In other illustrative examples, number of wave generators <NUM> has different spacing.

In this illustrative example, surface roughness analysis system <NUM> analyzes surface roughness <NUM> of surface <NUM> between number of wave generators <NUM> and number of wave sensors <NUM>. As depicted, number of wave generators <NUM> and number of wave sensors <NUM> are separated by substantially all of surface <NUM> in second direction <NUM>.

Turning now to <FIG>, a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is depicted in accordance with an illustrative embodiment. Surface roughness analysis system <NUM> is a physical implementation of surface roughness analysis system <NUM> of <FIG>. Workpiece <NUM> can be a physical implementation of workpiece <NUM> of <FIG>. In some illustrative examples, view <NUM> is a perspective view of workpiece <NUM>.

Each wave sensor of number of wave sensors <NUM> is positioned at least a designated distance from one of number of wave generators <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. Number of wave sensors <NUM> includes series of wave sensors <NUM>, series of wave sensors <NUM>, and series of wave sensors <NUM>.

Series of wave sensors <NUM>, series of wave sensors <NUM>, and series of wave sensors <NUM> form network of wave sensors <NUM>. Network of wave sensors <NUM> is spread across surface <NUM> to analyze surface roughness <NUM> of surface <NUM>. Having network of wave sensors <NUM> allows for analysis of surface roughness <NUM> at a plurality of locations. Having network of wave sensors <NUM> allows for identifying localized surface roughness <NUM> outside of a roughness threshold. Having network of wave sensors <NUM> allows for analysis of surface roughness <NUM> at the plurality of locations. In <FIG>, network of wave sensors <NUM> is spread in first direction <NUM> and second direction <NUM>. In <FIG>, the plurality of locations is spread across first direction <NUM> and second direction <NUM>.

Series of wave sensors <NUM> is positioned a plurality of distances from wave generator <NUM> in second direction <NUM> to detect surface waves from workpiece <NUM>. Series of wave sensors <NUM> includes wave sensor <NUM>, wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>.

By positioning series of wave sensors <NUM> different distances from wave generator <NUM>, different locations of surface <NUM> in second direction <NUM> are analyzed. For example, surface roughness <NUM> in a location between wave generator <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. The signal threshold is set to differentiate signal from noise. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> is within a roughness threshold.

As another example, surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location between wave sensor <NUM> and wave sensor <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, surface wave has propagated through surface <NUM> between wave generator <NUM> and wave sensor <NUM> and then surface <NUM> between wave sensor <NUM> and wave sensor <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold.

As yet another example, surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, a surface wave has propagated through surface <NUM> from wave generator <NUM> through a location between wave sensor <NUM> and wave generator <NUM>, through the location between wave sensor <NUM> and wave sensor <NUM>, and through the location between wave sensor <NUM> and wave sensor <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. When a surface wave does not reach wave sensor <NUM>, surface roughness <NUM> prior to wave sensor <NUM> can be outside a roughness threshold.

As yet another example, surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, a surface wave has propagated through surface <NUM> from wave generator <NUM> through a location between wave sensor <NUM> and wave generator <NUM>, through the location between wave sensor <NUM> and wave sensor <NUM>, through the location between wave sensor <NUM> and wave sensor <NUM>, and through the location between wave sensor <NUM> and wave sensor <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. When a surface wave does not reach wave sensor <NUM>, surface roughness <NUM> prior to wave sensor <NUM> can be outside a roughness threshold.

Using series of wave sensors <NUM> in combination can analyze surface roughness <NUM> in locations between wave sensors. Using series of wave sensors <NUM> in combination can detect localized surface roughness <NUM> outside of a roughness threshold.

Series of wave sensors <NUM>, series of wave sensors <NUM>, and series of wave sensors <NUM> are spaced apart in first direction <NUM>. Series of wave sensors <NUM> is separated from series of wave sensors <NUM> in first direction <NUM>. Series of wave sensors <NUM> is separated from series of wave sensors <NUM> in first direction <NUM>.

Number of wave generators <NUM> is separated in first direction <NUM> of workpiece <NUM>. In view <NUM>, wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> are equally spaced across first direction <NUM>. In other illustrative examples, number of wave generators <NUM> has different spacing. Wave generator <NUM> is separated from wave generator <NUM> in first direction <NUM>. Series of wave sensors <NUM> is positioned to sense surface waves generated from wave generator <NUM>. Series of wave sensors <NUM> is positioned to sense surface waves at a plurality of locations between wave generator <NUM> and each of series of wave sensors <NUM>.

A surface wave propagating across surface <NUM> from wave generator <NUM> will encounter wave sensor <NUM>, wave sensor <NUM>, wave sensor <NUM>, and then wave sensor <NUM>. In some illustrative examples, wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM>. The designated distance is selected based on cut-off wavelength calculated by the ultrasonic analysis system. The designated distance is selected such that receiving a surface wave of a threshold value indicates an acceptable surface roughness.

If a surface wave is received at wave sensor <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. If a surface wave is received at subsequent wave sensors of series of wave sensors <NUM>, each subsequent location is within a roughness threshold. For example, when wave sensor <NUM> receives a surface wave, the location between wave sensor <NUM> and wave sensor <NUM> has surface roughness <NUM> within a roughness threshold. As another example, when wave sensor <NUM> receives a surface wave, the location between wave sensor <NUM> and wave sensor <NUM> has surface roughness <NUM> within a roughness threshold. As yet another example, when wave sensor <NUM> receives a surface wave, the location between wave sensor <NUM> and wave sensor <NUM> has surface roughness <NUM> within a roughness threshold.

Series of wave sensors <NUM> is separated from series of wave sensors <NUM> in first direction <NUM>. Series of wave sensors <NUM> is positioned to sense surface waves generated in surface <NUM> by wave generator <NUM>. Wave sensors of series of wave sensors <NUM> is spread in second direction <NUM>. Series of wave sensors <NUM> includes wave sensor <NUM>, wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>.

Turning now to <FIG>, a perspective view of a workpiece with components of a surface roughness analysis system associated with a surface of the workpiece is depicted in accordance with an illustrative embodiment. Surface roughness analysis system <NUM> is a physical implementation of surface roughness analysis system <NUM> of <FIG>. Workpiece <NUM> can be a physical implementation of workpiece <NUM> of <FIG>. In some illustrative examples, view <NUM> is a perspective view of workpiece <NUM>. In some illustrative examples, view <NUM> is a perspective view of surface roughness analysis system <NUM> and workpiece <NUM> of <FIG>.

Components of surface roughness analysis system <NUM> include number of wave generators <NUM> and number of wave sensors <NUM>. Number of wave generators <NUM> includes only one wave generator, wave generator <NUM>. Wave generator <NUM> is acoustically coupled to surface <NUM> of workpiece <NUM>.

Number of wave sensors <NUM> comprises series of wave sensors <NUM>, each wave sensor of series of wave sensors <NUM> having a different distance from wave generator <NUM> of number of wave generators <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. Number of wave sensors <NUM> includes wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>. Each wave sensor of number of wave sensors <NUM> is positioned at least a designated distance from one of number of wave generators <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. Number of wave sensors <NUM> includes wave sensor <NUM>, wave sensor <NUM>, and wave sensor <NUM>.

Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>. Wave sensor <NUM> is farther away from wave generator <NUM> than wave sensor <NUM>.

Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM> to detect surface waves from workpiece <NUM>. Wave sensor <NUM> is farther away from wave generator <NUM> than both wave sensor <NUM> and wave sensor <NUM>.

By positioning number of wave sensors <NUM> different distances from wave generator <NUM>, different locations of surface <NUM> in second direction <NUM> are analyzed. For example, surface roughness <NUM> in a location between wave generator <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. The signal threshold is set to differentiate signals from noise. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> is within a roughness threshold.

As another example, surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location between wave sensor <NUM> and wave sensor <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, the surface wave has propagated through surface <NUM> from wave generator <NUM> to wave sensor <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. When a surface wave does not reach wave sensor <NUM>, surface roughness <NUM> prior to wave sensor <NUM> can be outside a roughness threshold.

As yet another example, surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is analyzed using data from wave sensor <NUM>. If wave sensor <NUM> generates output indicative of a surface wave, surface roughness <NUM> in the location between wave sensor <NUM> and wave sensor <NUM> is within a roughness threshold. For example, output of wave sensor <NUM> above a signal threshold indicates detection of a surface wave. When a surface wave propagates to wave sensor <NUM>, the surface wave has propagated through surface <NUM> from wave generator <NUM> to wave sensor <NUM>. When a surface wave propagates to wave sensor <NUM>, surface roughness <NUM> in locations between wave generator <NUM> and wave sensor <NUM> is within a roughness threshold. When a surface wave does not reach wave sensor <NUM>, surface roughness <NUM> prior to wave sensor <NUM> can be outside a roughness threshold.

Using number of wave sensors <NUM> in combination can analyze surface roughness <NUM> in each respective location between each of the sensors individually. Using number of wave sensors <NUM> in combination can detect localized surface roughness <NUM> outside of a roughness threshold. For example, if a surface wave is detected at wave sensor <NUM> but a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in a location prior to wave sensor <NUM> is within a roughness threshold but surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is not within the roughness threshold. As another example, if a surface wave is detected at wave sensor <NUM> but a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in a location prior to wave sensor <NUM> is within a roughness threshold but surface roughness <NUM> in a location between wave sensor <NUM> and wave sensor <NUM> is not within the roughness threshold. If a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in a location between wave generator <NUM> and wave sensor <NUM> is outside a roughness threshold. If a surface wave is not detected at wave sensor <NUM>, surface roughness <NUM> in the locations after wave sensor <NUM> is not analyzed.

Number of wave sensors <NUM> comprises only one wave sensor, wave sensor <NUM>. Wave sensor <NUM> is positioned at least a designated distance from wave generator <NUM> in second direction <NUM> of surface <NUM> of workpiece <NUM>. The designated distance is selected based on a cut-off wavelength calculated by the ultrasonic analysis system. The designated distance is selected such that receiving a surface wave of a threshold value indicates an acceptable surface roughness.

In view <NUM>, wave generator <NUM> and wave sensor <NUM> are used to analyze surface roughness <NUM> of the whole of surface <NUM>. In view <NUM>, wave sensor <NUM> is separated from wave generator <NUM> by more than half of surface <NUM> in second direction <NUM>.

The illustrations of surface roughness analysis system <NUM> in <FIG>, surface roughness analysis system <NUM> in <FIG>, surface roughness analysis system <NUM> in <FIG>, and surface roughness analysis system <NUM> in <FIG>, surface roughness analysis system <NUM> in <FIG>, and surface roughness analysis system <NUM> in <FIG> are not meant to imply physical or architectural limitations to the manner in which an illustrative embodiment may be implemented. Other components in addition to or in place of the ones illustrated may be used. Some components may be unnecessary. For example, a number of wave generators in any of the surface roughness analysis systems is only illustrative. A number of wave generators includes any desirable quantity of wave generators positioned relative to a workpiece at any desirable locations and in any desirable pattern to send at least one source signal into the workpiece. As another example, a number of wave sensors in any of the surface roughness analysis systems is only illustrative. A number of wave sensors includes any desirable quantity of wave sensors positioned relative to a workpiece at any desirable locations and in any desirable pattern to sense surface waves in the workpiece.

Turning now to <FIG>, a block diagram of surface roughness analysis system associated with a surface of a workpiece is depicted in accordance with an illustrative embodiment. Surface roughness analysis system <NUM> is a representation of surface roughness analysis system <NUM> of <FIG>. Surface roughness analysis system <NUM> can be used to analyze workpiece <NUM> of <FIG>. Workpiece <NUM> could be the same as workpiece <NUM> of <FIG>. Surface roughness analysis system <NUM> includes wave generator <NUM> and wave sensor <NUM>. In some illustrative examples, wave generator <NUM> is a representation of wave generator <NUM> and wave sensor <NUM> is a representation of wave sensor <NUM> of <FIG>. In some illustrative examples, wave generator <NUM> is a representation of wave generator <NUM> of <FIG> and wave sensor <NUM> is representative of one of wave sensor <NUM>, wave sensor <NUM>, or wave sensor <NUM> of <FIG>. In some illustrative examples, wave generator <NUM> is a representation of one of number of wave generators <NUM> of <FIG> and wave sensor <NUM> is representative of one of number of wave sensors <NUM> of <FIG>. In some illustrative examples, wave generator <NUM> is a representation of one of number of wave generators <NUM> of <FIG> and wave sensor <NUM> is representative of one of number of wave sensors <NUM> of <FIG>. In some illustrative examples, wave generator <NUM> is a representation of one of number of wave generators <NUM> of <FIG> and wave sensor <NUM> is representative of one of number of wave sensors <NUM> of <FIG>. In some illustrative examples, wave generator <NUM> is a representation of one of number of wave generators <NUM> of <FIG> and wave sensor <NUM> is representative of one of number of wave sensors <NUM> of <FIG>.

Wave generator <NUM> is acoustically coupled to workpiece <NUM>. In some illustrative examples, wave generator <NUM> is acoustically coupled to workpiece <NUM> through contact with workpiece <NUM>. In some illustrative examples, wave generator <NUM> is acoustically coupled to workpiece <NUM> through a coupling fluid. In some illustrative examples, wave generator <NUM> is a non-contact ultrasonic wave generator.

Wave generator <NUM> sends source signals having signal parameters into surface <NUM> of workpiece <NUM> of <FIG>. The signal parameters are determined by an ultrasonic analysis system and take into account material mechanical parameters of workpiece <NUM>.

Wave sensor <NUM> is acoustically coupled to workpiece <NUM>. In some illustrative examples, wave sensor <NUM> is acoustically coupled to workpiece <NUM> through contact with workpiece <NUM>. In some illustrative examples, wave sensor <NUM> is acoustically coupled to workpiece <NUM> through a coupling fluid. In some illustrative examples, wave sensor <NUM> is a non-contact ultrasonic wave sensor.

In <FIG>, ultrasonic analysis system <NUM> receives material mechanical parameters <NUM> for workpiece <NUM>. Ultrasonic analysis system <NUM> determines signal parameters <NUM> for simulating Rayleigh wave propagation within workpiece <NUM>. Ultrasonic analysis system <NUM> sends signal parameters <NUM> to controller <NUM>.

Controller <NUM> is configured to send electrical control signals to pulser <NUM>. In response to those control signals, pulser <NUM> outputs electrical signals representing the ultrasonic waves to be generated to wave generator <NUM>. Wave generator <NUM> may comprise one or more ultrasonic transducer elements. Wave generator <NUM> transduces the electrical signals from pulser <NUM> into ultrasonic waves. More specifically, the electrical signals sent to pulser <NUM> are configured to cause pulser <NUM> to generate a burst of ultrasonic waves having wave characteristics which are the same or similar to the wave characteristics of the simulated ultrasonic waves used in the simulation. In some illustrative examples, wave generator <NUM> may be excited using a sinusoidal signal.

Wave generator <NUM> is acoustically coupled to workpiece <NUM>. Wave generator <NUM> is activated to generate ultrasonic waves that propagate through the material of workpiece <NUM>.

Wave sensor <NUM> is also acoustically coupled to workpiece <NUM>, but at a different location. Wave sensor <NUM> may comprise one or more ultrasonic transducer elements. The distance traveled by the Rayleigh wave as it propagates from wave generator <NUM> to wave sensor <NUM> is selected such that the distance is equal to or greater than a designated distance. The designated distance is selected based on cut-off wavelength calculated by the ultrasonic analysis system. The cut-off wavelength is a ratio of surface wavelength over incident wavelength.

Wave sensor <NUM> converts impinging ultrasonic waves into electrical signals which are sent to receiver <NUM>. Receiver <NUM> receives electrical signals from controller <NUM> representing the source signal transmitted by wave generator <NUM>. Receiver <NUM> in turn outputs electrical signals representing the acquired ultrasonic inspection data to the roughness evaluator <NUM>.

Roughness evaluator <NUM> is a computer system configured to analyze the acquired ultrasonic inspection data from wave sensor <NUM> and determine if a surface roughness of workpiece <NUM> is within a roughness threshold. Roughness evaluator <NUM> is configured to compare the data from wave sensor <NUM> to a signal threshold. The signal threshold is set to differentiate signals from noise. In some illustrative examples, roughness evaluator <NUM> is configured to generate a flag in response to the surface roughness being outside the roughness threshold. The flag may be any one of the following: an analog signal, a digital code, a report, a notice, an alert, or a warning. The flag may be displayed on a display device. In the alternative, the flag may take the form of an aural alert.

Turning now to <FIG> and <FIG>, an illustration of a flowchart of a method of analyzing surface roughness of a workpiece is depicted in accordance with an illustrative embodiment. Method <NUM> can be implemented using surface roughness analysis system <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of surface <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of surface <NUM> of workpiece <NUM> in <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be implemented used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be implemented using surface roughness analysis system <NUM> to analyze a surface roughness of workpiece <NUM> of <FIG>.

Method <NUM> receives material mechanical parameters of the workpiece (operation <NUM>). Material mechanical parameters include any desirable material mechanical parameters, such as shear modulus, density, elastic modulus, or any other desirable material mechanical parameters. Method <NUM> determines signal parameters for a source signal to be sent into a workpiece using the material mechanical parameters (operation <NUM>). To determine the signal parameters, effective wave propagation is determined using the material mechanical parameters. The incident wave frequency is determined for the workpiece. The incident wavelength is a function of the incident wave frequency.

Method <NUM> determines a designated distance for a number of wave sensors from the number of wave generators such that the number of wave sensors receiving a surface wave of a threshold value indicates a surface roughness within a roughness threshold (operation <NUM>). Afterwards, method <NUM> terminates.

In some illustrative examples, method <NUM> determines a cut-off wavelength using the material mechanical parameters, wherein the cut-off wavelength is a ratio of surface wavelength over incident wavelength, and wherein the designated distance is determined based on the cut-off wavelength (operation <NUM>). In some illustrative examples, method <NUM> sends the source signal having the signal parameters into the workpiece using a pulser and wave generator (operation <NUM>). Method <NUM> determines if the surface roughness of the workpiece is within a roughness threshold for at least one of roughness width or roughness height based on output of a number of wave sensors (operation <NUM>).

In some illustrative examples, method <NUM> orients the wave generator relative to the workpiece to send the source signal into the workpiece at a source location (operation <NUM>). The source location is on any desirable location of the surface of the workpiece. In some illustrative examples, orienting the wave generator includes acoustically coupling the wave generator to the surface. In some illustrative examples, the wave generator is in contact with the surface of the workpiece. In some illustrative examples, the wave generator is a non-contact wave generator.

In some illustrative examples, method <NUM> orients at least one wave sensor of the number of wave sensors relative to the workpiece to sense waves a designated distance from the source location (operation <NUM>). The designated distance is selected based on a cut-off wavelength calculated by the ultrasonic analysis system. the cut-off wavelength is a ratio of surface wavelength over incident wavelength. The cut-off wavelength can be customized for different roughness profiles. In some illustrative examples, the cut-off threshold is when λsurface / λwave = <NUM>.

In some illustrative examples, method <NUM> orients the number of wave sensors relative to the workpiece such that the number of wave sensors is oriented to sense waves at at least two different distances from the source location (operation <NUM>). In some illustrative examples, a series of wave sensors is at different distances from a wave generator. When the number of wave sensors is oriented to sense waves at at least two different distances, surface roughness can be located on the surface. In one illustrative example, operation <NUM> is performed in <FIG> with series of wave sensors <NUM>. In another illustrative example, operation <NUM> is performed in <FIG> using at least one of series of wave sensors <NUM>, series of wave sensors <NUM>, or series of wave sensors <NUM>. In yet another illustrative example, operation <NUM> is performed in <FIG> using series of wave sensors <NUM>.

In some illustrative examples, determining if the surface roughness of the workpiece is within a roughness threshold comprises determining if the surface roughness in a plurality of locations of the workpiece is within a roughness threshold for at least one of roughness width or roughness height based on output of the number of wave sensors (operation <NUM>). In some illustrative examples, determining if the surface roughness in a plurality of locations of the workpiece is within a roughness threshold comprises determining if surface roughness in a plurality of locations spread in a second direction of the workpiece is within a roughness threshold, and wherein the second direction extends through the at least two different distances (operation <NUM>). In these illustrative examples, each of the plurality of locations is associated with a respective wave sensor of a series of wave sensors separated in the second direction.

In some illustrative examples, method <NUM> sends a plurality of source signals having the 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, wherein sending the source signal into the workpiece is one of the plurality of source signals sent into the workpiece (operation <NUM>). In some illustrative examples, operation <NUM> is performed in <FIG> by wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> sending source signals sent into workpiece <NUM>. In these illustrative examples, wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> send a plurality of source signals at a plurality of source locations spaced in first direction <NUM>. In some illustrative examples, operation <NUM> is performed in <FIG> by wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> sending source signals sent into workpiece <NUM>. In these illustrative examples, wave generator <NUM>, wave generator <NUM>, and wave generator <NUM> send a plurality of source signals at a plurality of source locations spaced in first direction <NUM>. In some illustrative examples, determining if the surface roughness of the workpiece is within a roughness threshold comprises determining if the surface roughness in a plurality of locations of the workpiece is within a roughness threshold for at least one of roughness width or roughness height based on output of the number of wave sensors (operation <NUM>).

In some illustrative examples, the plurality of locations is spread in a first direction of the workpiece, and wherein the plurality of source signals is spread across the workpiece in the first direction (operation <NUM>). In some illustrative examples, the plurality of locations is spread across the surface in the first direction of the surface. In some of these illustrative examples, a number of wave generators and an associated number of wave sensors is separated in the first direction.

In some illustrative examples, the plurality of locations is spread across the surface in the first direction and the second direction of the surface. In some of these illustrative examples, a number of wave generators is spread in the first direction and a number of wave sensors is spread in both the first direction and the second direction to form a network of wave sensors. In these illustrative examples, the network of wave sensors may also be referred to as a grid of wave sensors.

Turning now to <FIG> and <FIG>, an illustration of a flowchart of a method of analyzing surface roughness of a workpiece is depicted in accordance with an illustrative embodiment. Method <NUM> can be implemented using surface roughness analysis system <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of surface <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of surface <NUM> of workpiece <NUM> in <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be used to analyze surface roughness <NUM> of workpiece <NUM> of <FIG>. Method <NUM> can be implemented using surface roughness analysis system <NUM> to analyze a surface roughness of workpiece <NUM> of <FIG>.

Method <NUM> determines signal parameters for a source signal to be sent into a workpiece by a number of wave generators for analyzing the surface roughness of the workpiece (operation <NUM>). Method <NUM> determines a cut-off wavelength using material mechanical parameters of the workpiece, wherein the cut-off wavelength is a ratio of surface wavelength over incident wavelength (operation <NUM>). Method <NUM> determines, using the cut-off wavelength, a designated distance for a number of wave sensors from the number of wave generators such that the number of wave sensors receiving a surface wave of a threshold value indicates a surface roughness within a roughness threshold (operation <NUM>). Afterwards, method <NUM> terminates.

In some illustrative examples, method <NUM> positions a number of wave sensors relative to the workpiece to sense waves at least a designated distance from a respective wave generator of a number of wave generators based on the cut-off wavelength (operation <NUM>). In some illustrative examples, method <NUM> sends a number of source signals having the signal parameters into the workpiece at a number of source locations using a number of wave generators (operation <NUM>). In some illustrative examples, method <NUM> senses surface waves by the number of wave sensors to generate sensor output (operation <NUM>). In some illustrative examples, method <NUM> determines if the surface roughness of the workpiece is within a roughness threshold based on the sensor output (operation <NUM>).

The surface roughness is within a roughness threshold if the surface waves sensed by the number of wave sensors meet a minimum strength value (operation <NUM>). When the surface waves meet a minimum strength value, a signal created by the number of wave sensors in response will meet a signal threshold. The signal threshold is set to differentiate signal from noise.

In some illustrative examples, determining if the surface roughness is within a roughness threshold comprises determining if the surface roughness in a plurality of locations of the workpiece is within a roughness threshold for at least one of roughness width or roughness height based on output of the number of wave sensors (operation <NUM>).

In some illustrative examples, positioning the number of wave sensors comprises positioning the number of wave sensors relative to the workpiece such that the number of wave sensors is oriented to sense waves at at least two different distances from a wave generator of the number of wave generators (operation <NUM>). In these illustrative examples, the number of wave sensors includes a series of wave sensors positioned at a plurality of distances from the wave generator. When a series of wave sensors is present, a plurality of locations can be analyzed for surface roughness. In some illustrative examples, determining if the surface roughness in a plurality of locations of the workpiece is within a roughness threshold comprises determining if surface roughness in a plurality of locations spread in a second direction of the workpiece is within a roughness threshold, and wherein the second direction extends through the at least two different distances (operation <NUM>).

In some illustrative examples, method <NUM> sends a plurality of source signals having the 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, wherein sending the source signal into the workpiece is one of the plurality of source signals sent into the workpiece (operation <NUM>). In some of these illustrative examples, determining if the surface roughness of the workpiece is within a roughness threshold comprises determining if the surface roughness in a plurality of locations of the workpiece is within a roughness threshold for at least one of roughness width or roughness height based on output of the number of wave sensors (operation <NUM>). In some illustrative examples, the plurality of locations is spread in a first direction of the workpiece, and wherein the plurality of source signals is spread across the workpiece in the first direction (operation <NUM>).

The terms "approximately", "about", and "substantially" as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms "approximately", "about", and "substantially" may refer to an amount that is within less than <NUM>% of, within less than <NUM>% of, within less than <NUM>% of, within less than <NUM>% of, and within less than <NUM>% of the stated amount.

As used herein, the phrase "at least one of," when used with a list of items, means different combinations of one or more of the listed items may be used and only one of each item in the list may be needed. For example, "at least one of item A, item B, or item C" may include, without limitation, item A, item A and item B, or item B. Of course, any combinations of these items may be present. In other examples, "at least one of" may be, for example, without limitation, two of item A; one of item B; and ten of item C; four of item B and seven of item C; or other suitable combinations. The item may be a particular object, thing, or a category. In other words, at least one of means any combination items and number of items may be used from the list but not all of the items in the list are required.

The flowcharts and block diagrams in the different depicted embodiments illustrate the architecture, functionality, and operation of some possible implementations of apparatuses and methods in an illustrative embodiment. In this regard, each block in the flowcharts or block diagrams may represent at least one of a module, a segment, a function, or a portion of an operation or step.

In some alternative implementations of an illustrative embodiment, the function or functions noted in the blocks may occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may be executed substantially concurrently, or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved. Also, other blocks may be added in addition to the illustrated blocks in a flowchart or block diagram. Some blocks may be optional. For example, operations <NUM> through <NUM> may be optional. As another example, operations <NUM> through <NUM> may be optional.

Illustrative embodiments of the present disclosure may be described in the context of aircraft manufacturing and service method <NUM> as shown in <FIG> and aircraft <NUM> as shown in <FIG>. Turning first to <FIG>, an illustration of an aircraft manufacturing and service method is depicted in accordance with an illustrative embodiment. During pre-production, aircraft manufacturing and service method <NUM> may include specification and design <NUM> of aircraft <NUM> in <FIG> and material procurement <NUM>.

During production, component and subassembly manufacturing <NUM> and system integration <NUM> of aircraft <NUM> takes place. Thereafter, aircraft <NUM> may go through certification and delivery <NUM> in order to be placed in service <NUM>. While in service <NUM> by a customer, aircraft <NUM> is scheduled for routine maintenance and service <NUM>, which may include modification, reconfiguration, refurbishment, or other maintenance and service.

With reference now to <FIG>, an illustration of an aircraft is depicted in which an illustrative embodiment may be implemented. In this example, aircraft <NUM> is produced by aircraft manufacturing and service method <NUM> of <FIG> and may include airframe <NUM> with plurality of systems <NUM> and interior <NUM>. Examples of systems <NUM> include one or more of propulsion system <NUM>, electrical system <NUM>, hydraulic system <NUM>, and environmental system <NUM>. Any number of other systems may be included.

Apparatuses and methods embodied herein may be employed during at least one of the stages of aircraft manufacturing and service method <NUM>. One or more illustrative embodiments may be used to analyze surface roughness of components manufactured or used during at least one of component and subassembly manufacturing <NUM>, system integration <NUM>, in service <NUM>, or maintenance and service <NUM> of <FIG>. Aircraft <NUM> can include structures analyzed using surface roughness analysis system <NUM> of <FIG>. Surface roughness analysis system <NUM> of <FIG> can be used during component and subassembly manufacturing <NUM> to analysis surface roughness of workpieces manufactured during component and subassembly manufacturing <NUM>. As an example, method <NUM> or method <NUM> can be used during component and subassembly manufacturing <NUM> to analyze surface roughness of a structure. In some illustrative examples, surface roughness analysis system <NUM> of <FIG> can be used during in service <NUM>, or maintenance and service <NUM> of <FIG> to analyze any surface roughness caused during in service <NUM>. In some illustrative examples, the structure inspected using surface roughness analysis system <NUM> of <FIG> is a component of aircraft <NUM>.

The illustrative examples provide methods to inspect surfaces for roughness after manufacturing applications. Surface acoustic waves are produced by series of transducers and propagate along a surface. The surface roughness analysis system determines a predefined cut-off threshold for Rayleigh wave propagation, which is indicative of the surface roughness description. This cut-off occurs for a particular ratio of the spatial surface waviness and the acoustic wavelength, and the detection of the resulting wave attenuation and decay characterizes the surface roughness.

The illustrative examples can be used in-line with a production process. By using the illustrative examples in-line, the results from the surface roughness analysis system could then be used to adjust manufacturing equipment or processes. For example, using the illustrative examples in-line could identify a time for maintenance or cleaning of manufacturing equipment. The illustrative examples are a particularly an effective approach to measure the quality of 3D printed components formed with additive manufacturing technologies. As another example, using the illustrative examples could signal adjustment of the material deposition rate of an additive manufacturing process to achieve the required product quality. As yet another example, using the illustrative examples could identify workpieces for rework or cleaning prior to further manufacturing processes.

The illustrative examples demonstrate a novel in-line ultrasonic inspection technique using high frequency ultrasonic Rayleigh waves to characterize the surface roughness parameters during manufacturing process. The frequency of incident wave excitation to be used for roughness measurement is adjusted based on the mechanical property structure. The method uses surface wave energy loss and attenuation to characterize surfaces roughness. In some illustrative examples, other wave parameters such as the rate of wave speed changes can also be used to measure surface roughness profile.

Claim 1:
A surface roughness analysis system (<NUM>) comprising:
an ultrasonic analysis system (<NUM>) configured to:
receive material mechanical parameters (<NUM>) for a workpiece (<NUM>);
determine incident surface wave signal parameters (<NUM>) for a source signal (<NUM>) to be sent by a number of wave generators (<NUM>) using the material mechanical parameters (<NUM>);
determine a cut-off wavelength (<NUM>) using the material mechanical parameters (<NUM>), wherein the cut-off wavelength (<NUM>) is a ratio of surface wavelength (<NUM>) over incident wavelength (<NUM>); and
determine a designated distance (<NUM>) for a number of wave sensors (<NUM>) from the number of wave generators (<NUM>) based on the cut-off wavelength (<NUM>) such that the number of wave sensors (<NUM>) receiving a surface wave (<NUM>) of a threshold value indicates a surface roughness (<NUM>) within a roughness threshold (<NUM>);
wherein the number of wave generators (<NUM>) are configured to send the source signal (<NUM>) having the signal parameters (<NUM>) into the workpiece (<NUM>); and
the number of wave sensors (<NUM>) are positioned at least the designated distance (<NUM>) from the number of wave generators (<NUM>);
the system further comprising a roughness evaluator (<NUM>) configured to determine if the surface roughness (<NUM>) of the workpiece (<NUM>) is below the roughness threshold (<NUM>) based on the surface wave (<NUM>) sensed by the number of wave sensors (<NUM>).