Patent Description:
Vehicles, including air-borne vehicles, increasingly are being made with components formed from composite materials. For examples, large portions of aircraft, such as wings, empennages, stabilizers, and fuselages, may be constructed of fiber-reinforced polymer laminates. Many other smaller components of aircraft are also being formed of composite laminates. To ensure safety, these components must pass rigorous testing procedures. Non-destructive testing techniques, such as ultrasonic quantitative analysis techniques, provide information on manufacturing quality, material strength, and useful lifetime of the components. However, such non-destructive techniques may require a reference or calibration structure, which is often hand-made and requires a significant amount of time to fabricate, to ensure proper testing of manufactured parts.

Document <CIT>, according to its abstract, states a method in a computer system having a display for producing a representation of an article having embedded features including calibration target(s) or simulated defect(s) on the display. The method can include generating a representation of a test component on the display, generating a representation of embedded features on the display and combining the representations of the test component and the embedded features on the display to generate a combined representation. The method can further include converting the combined representation to a layer-by-layer format including manufacturing parameters for additive manufacturing, and producing the test article with an additive manufacturing process.

Document <CIT>, according to its abstract, states an ultrasonic inspection reference standard for a composite material including a block comprising the composite material. The block further comprises a first plurality of parallel rectangular-shaped channels within the block and a second plurality of parallel rectangular-shaped channels within the block, wherein the second plurality of channels extend at about a ninety degree angle to the first plurality of channels and wherein the second plurality of channels is located on a separate plane as the first plurality of channels.

The subject matter of the present application provides example calibration panels that overcome the above-discussed shortcomings of prior art techniques. The subject matter of the present application has been developed in response to the present state of the art, and in particular, in response to shortcomings of current methods of component design, testing, and fabrication. The presently claimed invention is defined by a method according to claim <NUM>. Optional embodiments are defined by the dependent claims.

Disclosed herein is a calibration panel that includes a body, formed by additive manufacturing from a first digital material having an acoustic property selected to approximate an acoustic property of a composite material. The calibration panel also includes an insert embedded within the body, the insert formed of at least a second digital material having an acoustic property selected to approximate an acoustic property of a defect within the composite material. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure.

The calibration panel, in certain examples, includes a front surface and an opposing back surface. The insert, in certain examples, is embedded within the body at a distance from the front surface selected to approximate a depth of the defect within the composite material. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The defect is selected from the group consisting of a void, porosity, a non-uniform material distribution, a delamination, a contaminant, an inclusion, and damage. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to any one of examples <NUM> or <NUM>, above.

The second digital material, in certain embodiments, is selected based on a determined acoustic impedance value Z'd according to the equation: <MAT> where Zd is an impedance of an actual defect, Zb is an impedance of the composite material, Z'd is an impedance of the simulated defect, and Z'b is an impedance of the body. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to any one of examples <NUM>-<NUM>, above.

The insert, in certain examples, is formed of the second digital material and at least a third digital material. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter of any one of examples <NUM>-<NUM>, above.

The insert is formed with a thickness based on a difference between a velocity of sound through the defect and a velocity of sound through the composition. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter of example <NUM> above.

In certain examples, volume fraction f of the second digital material is based on a desired velocity of sound Cd, an elastic moduli E<NUM> of the second digital material, an elastic moduli E<NUM> of the third digital material, a density ρ<NUM> of the second digital material, a density ρ<NUM> of the third digital material, a Poisson ratio ν<NUM> of the second digital material, and a Poisson ration ν<NUM> of the third digital material, and where the volume fraction f is determined according to an equation: <MAT>.

The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter of example <NUM>, above.

The desired velocity of sound Cd, is a velocity of sound through the defect, and where a velocity of sound through the second digital material is less than the desired velocity of sound Cd. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

Additionally, disclosed herein is a method of manufacturing a calibration panel. The method includes, in certain examples, forming a body by additive manufacturing from a first digital material having an acoustic property selected to approximate an acoustic property of a composite material, and mixing a second digital material and a third digital material to form an insert where the second digital material has an acoustic property value less than an acoustic property value of a defect within the composite material, and where the third digital material has an acoustic property value greater than the acoustic property value of the defect. The method also includes embedding the insert within the body. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure.

The method also includes forming a front surface and an opposing back surface. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The method also includes embedding the insert within the body at a distance from the front surface selected to approximate a depth of the defect within the composite material. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The method also includes embedding the insert within the body at a distance from the front surface selected based on a difference between a speed of sound of the composite material and a speed of sound of the first digital material. The preceeding subject mater of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The method also includes selecting the defect from the group consisting of a void, porosity, a non-uniform material distribution, a delamination, a contaminant, an inclusion, and damage. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to any one of examples <NUM>-<NUM>, above.

The method also includes determining a volume fraction f of the second digital material based on a desired velocity of sound Cd, an elastic moduli E<NUM> of the second digital material, an elastic moduli E<NUM> of the third digital material, a density ρ<NUM> of the second digital material, a density ρ<NUM> of the third digital material, a Poisson ratio ν<NUM> of the second digital material, and a Poisson ration ν<NUM> of the third digital material. The method, in certain examples, also includes determining the volume fraction f according to an equation:
<CHM>.

The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to any one of examples <NUM>-<NUM>, above.

The desired velocity of sound Cd, is equivalent to a velocity of sound through the defect, and the method also includes selecting a digital material from a plurality of digital materials as the second digital material, where the second digital material has a velocity of sound through the second digital material less than the desired velocity of sound Cd. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The method also includes, selecting a digital material from a plurality of digital materials as the third digital material, where the third digital material has a velocity of sound through the third digital material greater than the desired velocity of sound Cd. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

Additionally disclosed herein, is a method of manufacturing a non-destructive evaluation (NDE)-compliant component. The method, in certain examples, includes receiving design data indicative of a proposed design of a component, and manufacturing a reference standard model of the component. The reference standard model includes a body formed by additive manufacturing from a first digital material having an acoustic property selected to approximate an acoustic property of a composite material specified within the design data, and an insert embedded within the body, the insert formed of at least a second digital material having an acoustic property selected to approximate an acoustic property of a defect within the composite material. The method also includes testing the reference standard model to determine if the insert is detectable using acoustic emission testing, and rejecting, in response to a not-detectable status of the insert, the proposed design of the component. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure.

The method also includes forming the insert from a composition of the second digital material and at least a third digital material. The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The preceding subject matter of this paragraph characterizes example <NUM> of the subject disclosure, wherein example <NUM> also includes the subject matter according to example <NUM>, above.

The described features, structures, advantages, and/or characteristics of the subject matter of the subject disclosure can be combined in any suitable manner in one or more examples, including embodiments and/or implementations. In the following description, numerous specific details are provided to impart a thorough understanding of examples of the subject matter of the subject disclosure. One skilled in the relevant art will recognize that the subject matter of the subject disclosure can be practiced without one or more of the specific features, details, components, materials, and/or methods of a particular example, embodiment, or implementation. In other instances, additional features and advantages can be recognized in certain examples, embodiments, and/or implementations that can not be present in all examples, embodiments, or implementations. Further, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the subject matter of the subject disclosure. The features and advantages of the subject matter of the subject disclosure will become more fully apparent from the following description and appended claims, or can be learned by the practice of the subject matter as set forth hereinafter.

In order that the advantages of the subject matter can be more readily understood, a more particular description of the subject matter briefly described above will be rendered by reference to specific examples that are illustrated in the appended drawings. Understanding that these drawings depict only typical examples of the subject matter, they are not therefore to be considered to be limiting of its scope. The subject matter will be described and explained with additional specificity and detail through the use of the drawings, in which:.

Reference throughout this specification to "one example," "an example," or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the subject disclosure. Appearances of the phrases "in one example," "in an example," and similar language throughout this specification can, but do not necessarily, all refer to the same example. Similarly, the use of the term "implementation" means an implementation having a particular feature, structure, or characteristic described in connection with one or more examples of the subject disclosure, however, absent an express correlation to indicate otherwise, an implementation can be associated with one or more examples.

The subject disclosure describes an apparatus and a method for fabricating, by additive manufacturing in some examples, a reference panel (e.g., calibration panel) that mimics the acoustic properties of a vehicle component or part. In some examples, an insert, having acoustic properties selected to model a defect, is embedded within the calibration panel. Many vehicle components have a requirement to be "non-destructive evaluation" (NDE) capable. Determining if a newly proposed design is NDE capable requires creating a calibration panel with intentional defects and then performing NDE testing to determine if the defects are detected. The systems and methods disclosed herein provide the ability to achieve quantifiable and/or repeatable acoustic properties, which is valuable in NDE reference standard fabrication. Additive manufacturing (e.g., 3D printing) of the calibration panel greatly speeds up iterations of the design cycle of the proposed component design. As will be described below in greater detail, the materials used to create the calibration panel are selected to mimic the acoustic properties of the proposed component design. In particular, mimicking (or modeling) the acoustic properties of a defect in a composite structure is achieved by mixing two or more materials in some examples.

<FIG> is a schematic block diagram illustrating a system <NUM> that includes an additive manufacturing or three-dimensional (3D) printer <NUM>, according to examples of the subject disclosure. The 3D printer <NUM> is configured for building three dimensional objects by selectively depositing chemical compositions (e.g., polymer compositions) onto a platform <NUM>. The chemical compositions are made of one or more different materials, each supplied by a corresponding one of one or more supply tanks <NUM> of the 3D printer <NUM>. The one or more materials that form the chemical compositions are combined and presented to one or more print heads <NUM> of the 3D printer <NUM>. A controller <NUM> receives a design plan and directs the 3D printer <NUM> to fabricate a calibration panel <NUM> by depositing chemical compositions on the platform <NUM> layer-by-layer using the print head(s) <NUM>. Each chemical composition is deposited as dispensed droplets from the print head <NUM>. The layers are cured or solidified using a suitable mechanism (not shown), including a heater or a ultraviolet (UV) radiator, for instance. In another example, the curing or solidification of each deposited droplet of chemical composition is activated by contact with an adjacent droplet.

In some examples, each voxel of the calibration panel <NUM> is printed with a different chemical composition. A "voxel" refers to a value in the design plan that represents an element of volume in three-dimensional space. Similar to pixels in a two-dimensional space, a voxel is an individually addressable volume element that has definable physical properties. A multitude of voxels define the configuration of the calibration panel <NUM>. The controller <NUM> directs the 3D printer <NUM> to form a different chemical composition for each voxel of one or more "digital materials" in some examples. The volume fraction f of the digital materials in the chemical composition of each voxel is selected according to a desired acoustic property, as will be discussed below in greater detail with reference to <FIG>. As used herein, the phrase "digital material" refers to a modeling material on a voxel-level scale that is useful in 3D printing to form the calibration panel <NUM>. In certain examples, a digital material is also a material composed of one or more base materials with variable (but controlled) mixture ratios. The base materials are made from chemically compatible and stable resins that can be mixed and matched together. In various examples, photomolymers with rubber-like properties are mixed with photopolymers resembling ABS properties.

Many of the components of the 3D printer <NUM> are omitted for clarity, such as heaters, radiation sources, leveling devices, gas supply devices, etc. The one or more print heads <NUM> receive one or more digital materials from the supply tanks <NUM>. Each supply tank <NUM> is a reservoir or hopper for feeding the print heads <NUM>. The 3D printer also includes a curing system suitable for the type of material being deposited. In some examples, the curing system uses ultraviolet, visible, or infrared light to cure the material. Other examples of curing systems include microwave radiation sources, ultrasound radiation sources, etc..

The print head <NUM>, in certain examples, is moveable with reference to the platform <NUM>. Alternatively, the print head <NUM> and the platform <NUM> are moveable with reference to a frame (not show) that houses the 3D printer <NUM>. Typically, the platform <NUM> is configured to move upward and downward towards and away from the print head <NUM> (a Z axis) while the print head <NUM> is configured to move in an XY plane (Y axis defined as into and out of the page, and X axis defined as to the left and the right). In some examples, a heater is provided within the 3D printer <NUM> enclosure to maintain an elevated temperature that ensures that the compositions are in a liquid form allowing them to be dispensed by the print head <NUM>.

In certain examples, the digital materials used to form the calibration panel <NUM> are selected to mimic an acoustic property of a proposed vehicle component. For example, if the proposed vehicle component is formed of a carbon-fiber composite, the calibration panel <NUM> is formed of a "base" digital material that mimics the acoustic properties of the carbon fiber. According to some examples, inserts (see <FIG>) formed of a second digital material are embedded within the calibration panel to mimic defects that potentially exist or are prone to exist within the proposed vehicle component. Testing of the calibration panel <NUM> for compatibility with NDE ultrasonic testing equipment allows the component designer to determine if the proposed component design is going to satisfy NDE-capable requirements.

The controller <NUM>, as will be described in greater detail below, controls the print head <NUM> and the mixing of the digital materials from the supply tanks <NUM>. The controller, in certain examples, translates the design plan into instructions that are executable by the 3D printer <NUM>. For example, the design plan can be a Standard Tessellation Language (STL) format. Further, the controller <NUM> is configured to modify the STL format of the design plan to include voxel-level material composition information, as is described below with reference to <FIG>.

<FIG> is a schematic block diagram illustrating a controller <NUM>, according to examples of the subject disclosure. The controller <NUM> is an example of a computing device, which, in some examples, is used to implement one or more components of examples of the disclosure, and in which computer usable program code or instructions implementing the processes can be located for the illustrative examples. In this illustrative example, the controller includes a communications fabric <NUM>, which provides communications between a processor unit <NUM>, a mixture generator <NUM>, memory <NUM>, persistent storage <NUM>, a communications unit <NUM>, and a display <NUM>.

The processor unit <NUM> serves to execute instructions for software that are loaded into memory <NUM> in some examples. In one example, the processor unit <NUM> is a set of one or more processors or can be a multi-processor core, depending on the particular implementation. Further, the processor unit <NUM> is implemented using one or more heterogeneous processor systems, in which a main processor is present with secondary processors on a single chip, according to some examples. As another illustrative example, the processor unit <NUM> is a symmetric multi-processor system containing multiple processors of the same type.

The mixture generator <NUM> is configured to determine a composition of different digital materials that will match or approximate an acoustic property of a base composite material, and the acoustic properties of different defects within the base composite material. In certain examples, the acoustic property is the speed of sound through the material. Other acoustic properties include, but are not limited to, reflection, frequency, noise, attenuation, and/or impedance. Mixing various materials together in different volume fractions results in different speeds of sound. Accordingly, the mixture generator <NUM> can beneficially create a composition that mimics the acoustic properties of both the base (or bulk) composite material and a different composition that mimics the acoustic properties of a defect within the composite material. This allows for the rapid fabrication of a calibration panel that serves as a stand-in for a proposed component design to determine if the proposed component design will be NDE compliant or not. The ability to achieve quantifiable and repeatable acoustic properties is valuable in NDE reference standard fabrication. The defects, such as air gaps, overlays, and foreign objects, can be modeled by embedding an insert (see <FIG>) within a body of the calibration panel <NUM>.

The mixture generator <NUM>, in certain examples, maintains a database of acoustic properties (e.g., speeds of sounds through specific materials, reflectivity, etc.), and in particular, those digital materials in the supply tanks <NUM>. The mixture generator <NUM> receives from the design plan desired position, quantity, and type of defects to model in the calibration panel <NUM> and modifies the design plan with composition information that mimics or models the defects. In certain examples, the mixture generator <NUM> receives the design plan via the communications unit <NUM>. The design plan is stored in storage devices <NUM>. For example, the mixture generator <NUM> is configured to determine a volume fraction of a first digital material and a volume fraction of a second digital material that will result in a desired acoustic property. The desired acoustic property (e.g., speed of sound) corresponds to a desired defect type. In certain examples, the design plan is received via the communications unit <NUM> and/or is stored in the storage devices <NUM>.

In one example, the composition of a mixture selected to mimic a desired acoustic property is determined, by the mixture generator <NUM>, according to the formula: <MAT> where a volume fraction f of a first digital material is based on a desired velocity of sound Cd, an elastic moduli E<NUM> of the first digital material, an elastic moduli E<NUM> of a second digital material, a density ρ<NUM> of the first digital material, a density p<NUM> of the second digital material, a Poisson ratio v<NUM> of the first digital material, and a Poisson ration v<NUM> of the second digital material. Sound waves propagate due to the vibrations or oscillatory motions of particles within a material, and therefore are a function of the elastic module E.

In selecting the first and second digital materials, the mixture generator <NUM>, in certain examples, selects a digital material with an acoustic velocity less than the desired velocity of sound Cd (i.e., the acoustic velocity of a desired defect), and another digital material with an acoustic velocity greater than Cd. The mixture generator <NUM> then determines the appropriate volume fractions of the two digital materials to achieve Cd. As discussed above, this determination is be made according to the formula, or alternatively, according to a lookup table maintained by the mixture generator <NUM> (e.g., stored in storage devices <NUM>).

In certain examples, the mixture generator <NUM> also considers frequency of an acoustical signal, as changing the frequency when the sound velocity is fixed will result in a change in the wavelength of sound. Therefore, the wavelength of an ultrasonic NDE tester has a significant effect on the probability of detecting a discontinuity. According to some examples, the mixture generator <NUM> also considers noise, which is the result of competing reflections in microstructure grains. A good measure of defect detectability is the signal-to-noise ratio, which is a measure of how the signal from the defect compares to other background reflections (categorized as "noise"). One example of a suitable signal-to-noise ratio according to examples of the subject disclosure is <NUM> to <NUM>.

In certain embodiments, the mixture generator <NUM> considers reflectivity. When an ultrasonic signal reflects, and the rest of the signal transmits through the body <NUM>, this reflectivity is used to identify defects within the body <NUM> in some examples. Correspondingly, inserts embedded in to a calibration panel mimic the acoustic property of reflectivity in some examples. Reflectivity R is generally determined by the equation: <MAT> where Zd is the ultrasonic impedance of a defect, and Zb is the ultrasonic impedance of the body. The impedance of the defect or the body is related to the density of either the defect or the body and the acoustic velocity of either the defect or the body. The mixture generator <NUM> is configured to mimic reflection of a defect in proposed component design with an insert in the body by adjusting the acoustic impedance of the insert (see <FIG>). Where Zd is the impedance of an actual defect, Zb is the impedance of a composite material to be used in the proposed component design, Z'd is the impedance of the simulated defect, and Z'b is the impedance of the body of a calibration panel, in some examples, the mixture generator <NUM> selects a digital material based on a calculated Z'd value using the equation: <MAT> and impedance values of known materials. Stated differently, a digital material, with a known impedance that matches the impedance determined by the equation, is selected by the mixture generator <NUM> to mimic the impedance of a desired defect in some examples.

R<NUM> represents the reflectivity of the actual defect in the composite material, while R<NUM> represents the reflectivity of the simulated defect (e.g. the insert) in the simulated material (the body) produced using additive manufacturing.

In certain embodiments, the mixture generator <NUM> also considers attenuation, which is how the intensity of sound diminishes with distance. Additionally, in some examples, the mixture generator <NUM> considers impedance, which is defined as the product of the materials density and acoustic velocity. Impedance is useful in the determination of acoustic transmission and reflection at the boundary of two materials having different acoustic impedances to assess absorption of sound in a medium.

Memory <NUM> and persistent storage <NUM> are examples of storage devices <NUM>. A storage device is any piece of hardware that is capable of storing information, such as, for example, without limitation, data, program code in functional form, and/or other suitable information either on a temporary basis and/or a permanent basis. Memory <NUM>, in these examples, is a random-access memory, or any other suitable volatile or non-volatile storage device. Persistent storage <NUM> takes various forms, depending on the particular implementation. In one example, persistent storage <NUM> contains one or more components or devices. In an example, persistent storage <NUM> is a hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, or some combination of the above. The media used by persistent storage <NUM> is removable in some examples. For example, a removable hard drive is used for persistent storage <NUM> in various implementations.

The communications unit <NUM>, in these examples, provides for communication with other data processing systems or devices. In these examples, the communications unit <NUM> is a network interface card. The communications unit <NUM> provides communications through the use of either, or both, physical and wireless communications links. In some examples, the communication unit <NUM> also provides a connection for user input through a keyboard, a mouse, and/or some other suitable input device. Further, the input/output unit sends output to a printer or receive input from any other peripheral device in various examples. The display <NUM> provides a mechanism to display information to a user.

In some examples, instructions for the operating system, applications, and/or programs are located in the storage devices <NUM>, which are in communication with the processor unit <NUM> through the communications fabric <NUM>. In these illustrative examples, the instructions are in a functional form on persistent storage <NUM>. These instructions are loaded into memory <NUM> for execution by the processor unit <NUM> in some examples. In certain examples, the processes of the different examples are performed by the processor unit <NUM> using computer implemented instructions, which is located in a memory, such as the memory <NUM>.

These instructions are referred to as program code, computer usable program code, or computer readable program code that can be read and executed by a processor in the processor unit <NUM>. The program code, in the different examples, is embodied on different physical or computer readable storage media, such as the memory <NUM> or the persistent storage <NUM>.

Program code <NUM> is located in a functional form on computer readable media <NUM> that is selectively removable and can be loaded onto or transferred to the controller <NUM> for execution by the processor unit <NUM>. In some examples, the program code also contains the repair plan discussed above with reference to <FIG>. The program code <NUM> and computer readable media <NUM> form computer program product <NUM>. In one example, the computer readable media <NUM> is a computer readable storage media <NUM> or a computer readable signal media <NUM>. The computer readable storage media <NUM> includes, in one example, an optical or magnetic disc that is inserted or placed into a drive or other device that is part of the persistent storage <NUM> for transfer onto a storage device, such as a hard drive, that is part of the persistent storage <NUM>. In other examples, the computer readable storage media <NUM> also takes the form of a persistent storage, such as a hard drive, a thumb drive, or a flash memory that is connected to the controller <NUM>. In some instances, the computer readable storage media <NUM> is not be removable from the controller <NUM>.

Alternatively, the program code <NUM> is transferred to the controller <NUM> using computer readable signal media <NUM>. Computer readable signal media <NUM> is, as one example, a propagated data signal containing program code <NUM>. For example, the computer readable signal media <NUM> is an electromagnetic signal, an optical signal, and/or any other suitable type of signal in one example. These signals are transmitted over communications links, such as wireless communication links, an optical fiber cable, a coaxial cable, a wire, and/or any other suitable type of communications link. In other words, the communications link and/or the connection is physical or wireless in the illustrative examples. The computer readable media also takes the form of non-tangible media, such as communications links or wireless transmissions containing the program code, in some examples.

In some illustrative examples, the program code <NUM> is downloaded over a network to the persistent storage <NUM> from another device or data processing system through the computer readable signal media <NUM> for use within the controller <NUM>. In one instance, program code stored in a computer readable storage media in a server data processing system is downloaded over a network from a server to the controller <NUM>. According to various examples, the system providing the program code <NUM> is a server computer, a client computer, or some other device capable of storing and transmitting program code <NUM>.

The different components illustrated for the controller <NUM> are not meant to provide physical or architectural limitations to the manner in which different examples can be implemented. The different illustrative examples can be implemented in a controller including components in addition to and/or in place of those illustrated for the controller <NUM>. Other components shown in <FIG> can be varied from the illustrative examples shown. The different examples can be implemented using any hardware device or system capable of executing program code. For example, a storage device in the controller <NUM> is any hardware apparatus that can store data. The memory <NUM>, persistent storage <NUM>, and the computer readable media <NUM> are examples of storage devices in a tangible form.

In another example, a bus system is used to implement communications fabric <NUM> and can be comprised of one or more buses, such as a system bus or an input/output bus. Of course, in some examples, the bus system is implemented using any suitable type of architecture that provides for a transfer of data between different components or devices attached to the bus system. In addition examples, a communications unit includes one or more devices used to transmit and receive data, such as a modem or a network adapter. Further, a memory is, for example, the memory <NUM> or a cache such as found in an interface and memory controller hub that can be present in the communications fabric <NUM>.

Computer program code for carrying out operations for aspects of the subject disclosure can be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server.

These computer program instructions can also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks. The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

<FIG> is a schematic block diagram illustrating a top of the calibration panel <NUM>, according to examples of the subject disclosure. The calibration panel <NUM>, in certain examples, is formed as a block that is rectangular in shape. The calibration panel <NUM> is formed of a bulk material selected to mimic the acoustic properties of a proposed component design. The proposed component is be formed of a composite material, such as carbon fiber and resin, in some examples. The bulk material selected to mimic the acoustic properties, therefore, has acoustic properties that mimic composite carbon fiber. Embedded within the calibration panel are inserts <NUM>. Each of the inserts <NUM> is selected to mimic a different type of defect within the proposed component. For example, one of the inserts <NUM> is formed of a composition that mimics an air gap. In alternative examples, the controller <NUM> is configured to control the 3D printer <NUM> to form an air gap within the calibration panel <NUM>. In certain examples, the inserts <NUM> are formed of compositions that mimic other types of defects including, but not limited to, foreign materials within a composite, overlapping facesheets, and/or other acoustic anomalies.

Each insert <NUM> is formed of a different composition of digital materials. The composition is determined, as described above with reference to <FIG>, by the mixture generator <NUM>. Although the inserts <NUM> are depicted as uniformly distributed, it is to be understood that the inserts <NUM> can be positioned in a random manner, and/or stacked on top of each other.

<FIG> is a schematic block diagram of a side of the calibration panel <NUM>, according to examples of the subject disclosure. In the depicted embodiment, the calibration panel <NUM> has a thickness between a front surface <NUM> and a back surface <NUM>. This thickness is selected to approximate a thickness of a proposed component design in some examples. The controller <NUM> is configured to embed inserts <NUM> at different distances (i.e., depth) <NUM> between the front surface <NUM> and the insert <NUM>. This beneficially allows the component designer to test defects at different depths of the proposed component. For example, if the proposed component is formed of multiple layers of carbon fiber, the controller <NUM> is configured to adjust the distance <NUM> at which the insert <NUM> is embedded to mimic a defect between, for example, the third and fourth layers of the composite material. In addition examples, the inserts <NUM> are formed and embedded with different thicknesses <NUM>. By varying the thickness of an insert <NUM>, the insert <NUM> is adjusted to approximate the speed of sound in an actual defect. For example, if a digital material is not available to approximate a certain defect, a digital material with a similar but faster acoustic speed can be selected and embedded with an increased thickness. The increased thickness causes a longer amount of time for sound to pass through the defect, thereby approximating a defect with a slower speed of sound.

In certain embodiments, the calibration panel <NUM> is substantially rectangular, as depicted. Alternatively, the calibration panel <NUM> is formed in a shape that resembles the proposed component design. In some examples, the proposed component is a panel or other structural piece for use in the manufacture of a vehicle, especially airplanes. In certain examples, the proposed component is any component of a vehicle that benefits from NDE testing, or otherwise has a requirement to be NDE capable. If a calibration panels <NUM> fails NDE testing (i.e., the equipment fails to detect one of the inserts <NUM>) this is indicative of a high probability that the proposed design will not be NDE capable.

<FIG> is a schematic flowchart diagram illustrating a method <NUM> of iterative component design, according to examples of the subject disclosure. In certain examples, the method <NUM> includes receiving, at step <NUM>, design data indicative of a proposed component design and selecting a first digital material that approximates an acoustic property of a composite material specified within the design data. In some examples, the design data is a digital representation of a proposed 3D component having information for each voxel that defines the 3D component. The method also includes, at step <NUM>, selecting defects and mapping the defects into the proposed component design. In certain examples, mapping the defects into the proposed component design includes determining a position and a depth of an insert that models a selected defect.

At step <NUM>, the method <NUM> determines the volume fraction of the acoustic modeling materials (e.g., digital materials) that correspond to the acoustic properties of the selected defects. The acoustic properties include, in certain examples, an acoustic velocity, or stated differently, the speed of sound through the defect. As described above with reference to <FIG>, a second digital material is selected with an acoustic property value less than the acoustic property value of the defect, and a third digital material is selected with an acoustic property value greater than the acoustic property value of the defect. The volume fraction of the digital materials is determined by a formula in some examples.

At step <NUM>, the method <NUM> determines a position of the modeled defects within the calibration panel <NUM>. At step <NUM>, the method <NUM> includes fabricating a calibration panel based on the determined volume fractions and positions, and embeds inserts <NUM> into the calibration panel <NUM>.

At decision step <NUM>, the method <NUM> determines if the fabricated calibration panel <NUM> is NDE capable. In other words, the method <NUM> determines if NDE testing equipment is able to detect the inserts <NUM> that mimic defects in the proposed component design. The method <NUM>, in certain examples, indicates that the calibration panel has one of a "detectable status" or a "not-detectable status. " If the determination is negative, the method <NUM> rejects the proposed component design at step <NUM> and the method <NUM> returns to step <NUM>.

In the above description, certain terms can be used such as "up," "down," "upper," "lower," "horizontal," "vertical," "left," "right," "over," "under" and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an "upper" surface can become a "lower" surface simply by turning the object over. Nevertheless, it is still the same object. Further, the terms "including," "comprising," "having," and variations thereof mean "including but not limited to" unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. Further, the term "plurality" can be defined as "at least two.

Additionally, instances in this specification where one element is "coupled" to another element can include direct and indirect coupling. Direct coupling can be defined as one element coupled to and in some contact with another element. Indirect coupling can be defined as coupling between two elements not in direct contact with each other, but having one or more additional elements between the coupled elements. Further, as used herein, securing one element to another element can include direct securing and indirect securing. Additionally, as used herein, "adjacent" does not necessarily denote contact. For example, one element can be adjacent another element without being in contact with that element.

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 can be used and only one of the items in the list can be needed. The item can be a particular object, thing, or category. In other words, "at least one of" means any combination of items or number of items can be used from the list, but not all of the items in the list can be required. For example, "at least one of item A, item B, and item C" can mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of item A, item B, and item C" can mean, 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 some other suitable combination.

To the extent that terms "includes," "including," "has," "contains," and variants thereof are used herein, such terms are intended to be inclusive in a manner similar to the term "comprises" as an open transition word without precluding any additional or other elements.

For purposes of this disclosure, a system, apparatus, structure, article, element, component, or hardware described as being "configured to" perform a particular function can additionally or alternatively be described as being "adapted to" and/or as being "operative to" perform that function.

Claim 1:
A method of manufacturing a calibration panel, the method comprising:
forming a body (<NUM>) by additive manufacturing from a first digital material having an acoustic property selected to approximate an acoustic property of a composite material;
mixing a second digital material and a third digital material to form an insert (<NUM>), where the second digital material has an acoustic property value less than an acoustic property value of a defect within the composite material, and where the third digital material has an acoustic property value greater than the acoustic property value of the defect, said first, second and third digital materials being modeling materials on a voxel-level scale, wherein a voxel is an individual addressable volume element in three-dimensional space, the acoustic property of the composite material and of the defect being the speed of a sound wave through the composite material and the defect or the frequency, the attenuation, the impedance of a sound wave; and
embedding the insert (<NUM>) within the body (<NUM>).