Patent ID: 12240178

DETAILED DESCRIPTION

Aspects disclosed herein present systems and methods for layup strategy analysis and planning. Analysis of layup strategies for manufacturing a particular object using AFP can have significant impact on manufacturing operations, on post-layup inspection and rework, and on laminate quality (e.g., fiber angle distributions, gaps/laps, etc.).

The layup strategy analyses disclosed herein enable production of laminates that have higher quality with less rework and faster manufacturing timelines. The disclosed analyses consider AFP layup parameters such as: a number of tows to be applied per course, a tow width, a course centerline strategy, a tow mask, ply stagger, course layup direction, course sequencing, etc. Selection of these parameters influences in-process cycle times, time spent on inspection and rework, post-processing cycle times, and laminate quality. For example, it is generally faster to manufacture a laminate by applying parallel courses with a large number of wide tows and without steering than it would be to manufacture the same laminate using non-parallel courses, fewer tows per course, narrower tows, or a different steering strategy. Further, while these parameters can be selected more or less independently in some situations, such as to manufacture a large flat object, in some circumstances the selection of one of these parameters influences the selection of one or more other parameters. For example, the selection of a steering strategy may limit the width of tows that can be used. Additionally, in many instances, the geometry of the object to be manufactured is such that parallel courses cannot be applied in a manner that follows a natural path (e.g., without steering). Further, fiber angles of applied courses may diverge from the as-designed fiber angles for various reasons, which may lead to steering of courses, nonparallel courses, or both, or narrower courses to meet fiber angle requirements.

The layup strategy analyses are performed by a software tool executed by one or more processors of a computing device. During execution, the software tool evaluates manufacturability of a composite part based on a 3D model of the part generated during a part design process. The software tool generates a graphical user interface (GUI) to improve part design and AFP process decisions. For example, the GUI may include visualizations of the impact of various part design changes, AFP processing parameters, or both. The software tool uses the 3D model of the object to be manufactured and can be used early in the design process, such as before numerical control (NC) programming of AFP manufacturing tools is performed. NC programming entails generating detailed machine instructions for the AFP process, including, for example, designating course starting locations and course centerlines, which is a time consuming process. In contrast, the layup strategy analyses disclosed herein can generate output indicating best and worst case scenarios for manufacturability of the objects, indicting how changes in course width affect angle deviations and/or compaction, etc., without providing the detailed input needed for NC programming. Results of the analyses can be indicated on or with a visual depiction of the 3D model (e.g., a heat map display) to visually distinguish locations of concern.

The layup strategy analyses result in better part designs and better AFP manufacturing process designs, which can reduce manufacturing time and cost. In this context, manufacturing time and cost includes not just time and expense associated with laying up fibers to form the part, but also time and expense associated with rework, inspection, and post-processing. For example, APF manufacturing sometimes results in placement of one or more tows in a course that are manually adjusted or inspected before the next course or ply is applied. Manual adjustment, inspection, and other so-called “out-of-cycle” processes do not affect “in-cycle” time of the AFP manufacturing process since the equipment is not in operation; however, these manual adjustment and inspection processes are very expensive in terms of labor costs and significantly delay the total, end-to-end manufacturing time of the part. To illustrate, by some estimates, rework and other out-of-cycle processes contribute up to 40% to the total, end-to-end manufacturing time of some parts. The disclosed layup strategy analyses enable detection of such concerns in the design stage so that different AFP manufacturing choices or part design changes can be selected to limit or avoid use of these manual adjustment and inspection processes.

The figures and the following description illustrate specific exemplary embodiments. It will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles described herein and are included within the scope of the claims that follow this description. Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure and are to be construed as being without limitation. As a result, this disclosure is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.

Particular implementations are described herein with reference to the drawings. Common features are designated by common reference numbers throughout the drawings and description. In some drawings, multiple instances of a particular type of feature are used. Although these features are physically and/or logically distinct, the same reference number is used for each, and the different instances are distinguished by addition of a letter to the reference number. When the features as a group or a type are referred to herein (e.g., when no particular one of the features is being referenced), the reference number is used without a distinguishing letter. However, when one particular feature of multiple features of the same type is referred to herein, the reference number is used with the distinguishing letter. For example, referring toFIG.5C, multiple tows are illustrated and associated with reference numbers522A,522B,522C,522D,522E,522F,522G,522H,522I,522J, and522K. When referring to a particular one of these tows, such as the tow522A, the distinguishing letter “A” is used. However, when referring to any arbitrary one of these tows or to these tows as a group, the reference number522is used without a distinguishing letter.

As used herein, various terminology is used for the purpose of describing particular implementations only and is not intended to be limiting. For example, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, some features described herein are singular in some implementations and plural in other implementations. To illustrate,FIG.1depicts a layup strategy analysis tool110that includes one or more processors (“processor(s)”112inFIG.1), which indicates that in some implementations the layup strategy analysis tool110includes a single processor112and in other implementations the layup strategy analysis tool110includes multiple processors112. For ease of reference herein, such features are generally introduced as “one or more” features and are subsequently referred to in the singular unless aspects related to multiple of the features are being described.

The terms “comprise,” “comprises,” and “comprising” are used interchangeably with “include,” “includes,” or “including.” Additionally, the term “wherein” is used interchangeably with the term “where.” As used herein, “exemplary” indicates an example, an implementation, and/or an aspect, and should not be construed as limiting or as indicating a preference or a preferred implementation. As used herein, an ordinal term (e.g., “first,” “second,” “third,” etc.) used to modify an element, such as a structure, a component, an operation, etc., does not by itself indicate any priority or order of the element with respect to another element, but rather merely distinguishes the element from another element having a same name (but for use of the ordinal term). As used herein, the term “set” refers to a grouping of one or more elements, and the term “plurality” refers to multiple elements.

As used herein, “generating,” “calculating,” “using,” “selecting,” “accessing,” and “determining” are interchangeable unless context indicates otherwise. For example, “generating,” “calculating,” or “determining” a parameter (or a signal) can refer to actively generating, calculating, or determining the parameter (or the signal) or can refer to using, selecting, or accessing the parameter (or signal) that is already generated, such as by another component or device. As used herein, “coupled” can include “communicatively coupled,” “electrically coupled,” or “physically coupled,” and can also (or alternatively) include any combinations thereof. Two devices (or components) can be coupled (e.g., communicatively coupled, electrically coupled, or physically coupled) directly or indirectly via one or more other devices, components, wires, buses, networks (e.g., a wired network, a wireless network, or a combination thereof), etc. Two devices (or components) that are electrically coupled can be included in the same device or in different devices and can be connected via electronics, one or more connectors, or inductive coupling, as illustrative, non-limiting examples. In some implementations, two devices (or components) that are communicatively coupled, such as in electrical communication, can send and receive electrical signals (digital signals or analog signals) directly or indirectly, such as via one or more wires, buses, networks, etc. As used herein, “directly coupled” is used to describe two devices that are coupled (e.g., communicatively coupled, electrically coupled, or physically coupled) without intervening components.

FIG.1is a block diagram that illustrates an example of a system100including multiple tools used during design and manufacture of an object190using automated fiber placement. In the example illustrated inFIG.1, the tools include a design tool102, a layup strategy analysis tool110, an NC programming tool160, one or more AFP machines170, and tools to perform post-processing192and assembly194. In other examples, the system100includes more tools, fewer tools, or different tools. For example, in some implementations, the design tool102and the layup strategy analysis tool110are combined in a single tool, such as a computing device that includes both 3D modeling instructions104and layup strategy analysis instructions116. As another example, in some implementations, the system100also includes out-of-cycle manufacturing or inspection tools, such as manual workstations to detect or correct AFP manufacturing defects.

InFIG.1, the design tool102, the layup strategy analysis tool110, and the NC programming tool160include or correspond to computing devices configured to execute software instructions to perform various operations. Each such computing device includes one or more processors and one or more memory devices, such as the processor(s)112and memory114of the layup strategy analysis tool110. In some implementations, one or more of the computing devices also, or alternatively, include other hardware, such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA), to perform the functions described below. The memory device(s) of the computing devices includes volatile memory devices (e.g., random access memory (RAM) devices), nonvolatile memory devices (e.g., read-only memory (ROM) devices, programmable read-only memory, and flash memory), or both. Although specific instructions are described with reference to each computing device, the memory device(s) of each computing device may also store other instructions and data, such as an operating system, other programs, and program data. Each memory device includes or corresponds to a non-transitory, computer-readable storage device (i.e., is not merely a signal). Further, each computing device can include other hardware, such as network interfaces, input/output interfaces, input/output device, etc.

Each of the AFP machine(s)170includes components to enable the respective AFP machine170to build up multiple layers of fiber reinforced polymer material to form a part, such as the object190. In the example illustrated inFIG.1, each AFP machine170includes one or more heads172, and each head172includes one or more rollers174. Additionally, each of the AFP machines170ofFIG.1includes one or more steering mechanisms176and one or more heaters177. Each head172is coupled to a steering mechanism176which moves the head172to direct application of one or more tows to an in-process part or a mandrel to form a course. The heaters177heat the tows before, during, or after application to increase tackiness of the tows so that the tows adhere to or cohere to the working surface. The heaters177include, for example, infrared heaters, hot gas blowers, lasers, etc. Multiple courses can be applied to form a layer or ply, and multiple layers can be formed to generate the part. The steering mechanisms176include, for example, robotic arms, gantries, movable platforms, or other devices to move the head172of the AFP machine170relative to the mandrel or in-process part.

In a particular implementations, a head172of an AFP machine170includes multiple rollers174, each of which is configured to press (e.g., apply compaction force to) a tow onto a working surface of the mandrel or the in-process part to adhere (or cohere) the tow to the working surface. The steering mechanism176moves the head172on a path that defines or is characterized by a course centerline. As the head172moves, the rollers174of the head172can move or deform, within a relatively narrow range, to press the tows onto the working surface. The amount that each roller174can move or deform depends on the configuration of the roller174, the configuration of the head172, or both. For example, a roller174formed of a softer material may be capable of deforming more during use than a roller174formed of a firmer material. Additionally, the mechanism(s) used to couple the rollers174to the head172can influence how the rollers174are able to move relative to one another. As a result of the movement and deformation of the rollers174, the head172is able to apply sufficient compaction force to each of multiple tows of a course despite steering of the head172, curvature of the working surface, or both, within particular limits. As the curvature of the working surface increases, the head172is able to apply fewer tows in a single pass due to differences in compaction force across the head172(as well as other concerns), as described further with reference toFIGS.5A-5C. As the amount of steering needed to follow the course centerline increases, narrower tows may be used due to stresses induced in tows.

Each AFP machine170is associated with manufacturability constraints178, such as steering parameters, compaction parameters, tow add/drop parameters, etc., that limit operations that can be performed by the APF machine170without causing defects in the part. To illustrate, a particular tow material186with a particular tow width188has a minimum steering radius and another material with the same tow width or the same material with another tow width188may have a different minimum steering radius, based on the material properties and process settings. The manufacturability constraints178depend on configurations180of the AFP machines170, available rollers182(e.g., rollers174that can be used by the AFP machine170), tow material186, and tow width188, and possibly other factors. For example, in a first configuration, a particular AFP machine170may have a heater177that enables a first minimum steering radius, and in a second configuration, the AFP machine170may have a different heater177that enables a second (e.g. different) minimum steering radius. As another example, a particular AFP machine170can be used with first available rollers182to provide first compaction parameters or can be used with second available rollers182to provide second (e.g., different) compaction parameters.

In the example illustrated inFIG.1, the manufacturability constraints include tow properties184, such as the material(s)186of the tows and the width(s)188of the tows. The material(s)186of the tows may require, for example, a certain compaction force to ensure cohesion of the tow to the working surface and limit the tension that can be applied to a tow without delamination from the working surface. The width(s)188of the tows limit, for example, a turning radius of a tow. To illustrate, a narrower tow can be properly applied to the working surface through a curve with a smaller turning radius than can a wider tow.

In some implementations, an AFP process designer may have access to multiple AFP machines170that could be used to form a part (e.g., the object190), to multiple distinct types of tows that could be used to form the part, to an AFP machine170that can be reconfigured to multiple different configuration180or used with different available rollers182to form the part, or a combination thereof. The layup strategy analyses performed by the layup strategy analysis tool110can be used to assist the AFP process designer in selecting and configuring (e.g., optimizing) an AFP process to form the part. Additionally, or alternatively, the layup strategy analyses performed by the layup strategy analysis tool110can be used to assist a part designer in designing a part (e.g., the object190) that is well suited (e.g., optimized) for manufacturing using available AFP machines170or machine configurations and available tow widths.

The design tool102is configured to execute the 3D modeling instructions104to generate model data106which can be rendered to display a 3D model152of the object190. The model data106includes data representing as-designed features of the object190. To illustrate, the model data106describes as-designed object geometry154of the object190and may also describe other as-designed features of the object190, such as fiber angles, materials, mechanical properties, material properties, etc. The 3D modeling instructions104enable a user to render the 3D model152for visualization purposes and enable the user to edit or revise aspects of the design of the object190. In some implementations, the 3D modeling instructions104include or are associated with instructions that are executable to analyze properties of the 3D model152, such as to determine mechanical properties of the 3D model152based on the object geometry154and as-designed material properties.

The processor(s)112of the layup strategy analysis tool110execute the layup strategy analysis instructions116to obtain (e.g., retrieve, receive, read from memory, etc.) the model data106representing the 3D model152. The layup strategy analysis tool110may also obtain process data descriptive of the AFP machine(s)170, an AFP process that can be performed using one or more of the AFP machine(s)170, or both. The layup strategy analysis instructions116are executable to perform a variety of analyses based on the obtained data and to generate output140indicating results of the analyses. For example, the layup strategy analysis tool110may determine a count of a number of tows that can be simultaneously applied by the AFP machine170during a single pass based on the object geometry154and the obtained data. In another example, the layup strategy analysis tool110may identify problem locations based on the object geometry154, nominal fiber orientations indicated by the model data106, and other data, such as the manufacturability constraints178.

In some implementations, results of the analyses performed by the layup strategy analysis instructions116are provided as output140to a display150in a manner that visually distinguishes the results, such as by highlighting problem locations of the 3D model152. To illustrate, inFIG.1, the display150includes a graphical user interface depicting the 3D model152to show the object geometry154. Additionally, the 3D model152inFIG.1includes one or more visually distinct locations156to illustrate analysis results from the layup strategy analysis instructions116. The display150can also, or in the alternative, depict other information. For example, inFIG.1, the display includes an indication of a number of tows per pass158that can be applied by the AFP machine170based on the analysis results.

InFIG.1, the memory114includes data118that may be used for various analyses performed by the layup strategy analysis instructions116. The data118inFIG.1includes one or more thresholds128, such as a tow count threshold120, a tow overlap threshold122, a roller deformation threshold124, and a tow nominal-angle deviation threshold. Each threshold represents a value or condition that is considered a minimum or maximum acceptable value under the particular circumstances being analyzed. The threshold(s)128may be set by a user initiating or controlling the analysis, set based on design criteria or manufacturing criteria, or may include default values.

In a particular implementation, the tow count threshold120indicates a desirable (maximum) number of tows to be applied simultaneously in a course. As explained above, successful application of more tows per course tends to decrease the manufacturing time of the object190. However, if a course includes too many tows, one or more of the tows may not be successfully applied, leading to inspection and rework, which tend to increase the manufacturing time of the object190. A value of the tow count threshold120can be assigned to assist the user in identifying portions of the 3D model152that correspond to portions of the object190where a course or courses will need to use fewer tows than is desirable. For example, the analysis performed by the layup strategy analysis instructions116identifies a number of tows that can be applied at each location on the 3D model152, and any portion(s) of the 3D model152where the count of tows that can be simultaneously applied fails to satisfy the tow count threshold120are visually distinguished in the display150(e.g., indicated as visually distinct locations156on the object geometry154).

In a particular implementation, the tow overlap threshold122indicates a constraint on an overlap metric. The overlap metric is indicative of how much two or more fiber paths (e.g., tows or courses) of a single layer overlap as they converge and diverge. The overlap metric is indicative of how much tow cutting or adding should occur while applying a course. When two tows of a layer overlap, the layer is thicker than intended, which leads to rework and/or geometry abnormalities in the as-built part. To avoid or limit such overlap, one or more tows can be cut (or added) as a course is applied; however, cutting or adding tows results in gaps or overlaps (also referred to as “laps”) between tows of the layer and generally slows down the manufacturing process. Additionally, such gaps or laps may also lead to lower strength values, requiring more material to achieve the desired load carrying capability of the structure. A value of the tow overlap threshold122can be assigned to assist the user in identifying portions of the 3D model152that correspond to portions of the object190where fiber paths will overlap excessively (e.g., more than is desirable). For example, the analysis performed by the layup strategy analysis instructions116calculates values of the overlap metric at various locations and generates the GUI such that any portion(s) of the 3D model152where the fiber paths overlap more than the tow overlap threshold122are visually distinguished in the display150(e.g., indicated as visually distinct locations156on the object geometry154). Alternatively, or additionally, the analysis performed by the layup strategy analysis instructions116calculates a number of tows that can be applied simultaneously (e.g., in a single course) while ensuring that the overlap metric at each location satisfies the tow overlap threshold122. The GUI identifies in the display150the number of tows that can be applied at each location (e.g., the number of tows per pass158) on the 3D model152, based on the overlap metric and the tow overlap threshold122.

In a particular implementation, the roller deformation threshold124indicates a constraint on roller deformability as it places a course on the surface. Failure of the compaction roller to conform to the surface may result in insufficient compaction pressure at a particular tow or portion of a tow and can result in delamination of a portion of the tow. A value of the roller deformation threshold124can be assigned to assist the user in identifying portions of the 3D model152that correspond to portions of the object190where insufficient compaction may occur (e.g., due to surface curvature or edges). For example, the analysis performed by the layup strategy analysis instructions116calculates values of the compaction roller deformation that are required for intimate contact between the contact roller and the application surface at various locations and generate the GUI such that any portion(s) of the 3D model152where the roller deformation that can be achieved is less than the roller deformation threshold124are visually distinguished in the display150(e.g., indicated as visually distinct locations156on the object geometry154). Alternatively, or additionally, the analysis performed by the layup strategy analysis instructions116calculates a number of tows that can be applied simultaneously (e.g., in a single course) while ensuring that the roller deformation at each location satisfies the roller deformation threshold124and sufficient compaction pressure is achieved across all tows. The GUI identifies in the display150the number of tows that can be applied at each location (e.g., the number of tows per pass158) on the 3D model152, based on the roller deformation and the roller deformation threshold124.

In a particular implementation, the tow nominal-angle deviation threshold126indicates a constraint on deviation of the fiber angles of a course from the nominal fiber angle of the course. For AFP processes, nominal fiber angles are generally defined for each layer based on rosette directions. The rosette directions are defined by the designer and are usually aligned with the dominant load direction for a particular object190being manufactured. The rosette directions define a zero degree (0°) direction, and one or more other directions are defined based on angular offset (referred to as “fiber angles”) from the zero degree direction within the plane tangent to the surface. Each layer is associated with a fiber angle, and adjacent layers are generally associated with different fiber angles. For example, a first layer is a 0 degree layer, which indicates that the fibers of the first layer are generally oriented parallel to the rosette direction. In this example, a second layer that is adjacent to the first layer is in a 90 degree direction, which indicates that the fibers of the second layer are generally oriented perpendicular to the rosette direction. The fiber angle associated with each layer is also the nominal angle associated with the layer. Significant deviations from the nominal angle can affect mechanical properties of the as-build object190.

Depending on the object geometry154, the manufacturability constraints178, the tow properties184and the number of tows in a course, it may not be possible for each tow to be aligned along its entire length with the nominal angle of the layer in which it resides. The tow nominal-angle deviation threshold126can be assigned to assist the user in identifying portions of the 3D model152that correspond to portions of the object190where the fibers deviate significantly from the nominal angle of the layer. For example, the analysis performed by the layup strategy analysis instructions116calculates values of fiber angles that can be applied at various locations and generate the GUI such that any portion(s) of the 3D model152where the fiber angles of any tow in the course fail to satisfy the tow nominal-angle deviation threshold126are visually distinguished in the display150(e.g., indicated as visually distinct locations156on the object geometry154). Alternatively, or additionally, the analysis performed by the layup strategy analysis instructions116calculates a number of tows that can be applied simultaneously (e.g., in a single course) while ensuring that the fiber angles of each tow satisfy the tow nominal-angle deviation threshold126. The GUI identifies in the display150the number of tows that can be applied at each location (e.g., the number of tows per pass158) on the 3D model152, based on the tow fiber angles and the tow nominal-angle deviation threshold126.

InFIG.1, the data118in the memory114also includes one or more parameters138that are used by the layup strategy analysis instructions116. The parameters138inFIG.1include a steering radius parameter130and one or more roller deformation parameters132, such as a stroke parameter134, a normality angle parameter136, or both. The parameters138include, correspond to, or are used to determine process data descriptive of an AFP process associated with one of the AFP machines170in a particular configuration180. For example, the layup strategy analysis instructions116use the parameters138to determine whether one or more of the thresholds128will be satisfied during manufacture of the object190by a particular AFP machine170in a particular configuration180and using particular tows (e.g., tows of a particular material186and width188).

In a particular implementation, a value or values of the steering radius parameter130are set based on capabilities of the steering mechanism176, the manufacturability constraints178, the tow properties, or a combination thereof. For example, the steering radius parameter130may indicate a minimum turning radius for a particular tow based on the material186of the tow and the width188of the tow. In this context, the minimum turning radius refers to the tightest turn (e.g., highest curvature) that the tow can endure without occurrence (or significant risk of the occurrence) of flaws, such as buckling or delamination of portions of the tow.

In a particular implementation, a value or values of the stroke parameter134and normality angle parameter136are set based on capabilities of the head172, the rollers174, the manufacturability constraints178, or a combination thereof. For example, the number of tows that can be applied during the single pass is limited by the deformability that the set of rollers can achieve across a width of the set of rollers during the single pass. As another example, the number of tows that can be applied during the single pass is limited by the contact area of the particular roller and a corresponding tow and shear force applied to the tow by the particular roller if the roller surface is not tangent to the application surface. Details regarding the stroke parameter134and the normality angle parameter136are described with reference toFIGS.5A-5C.

In some implementations, the data118includes more, fewer, or different parameters138than the steering radius parameter130, the stroke parameter134, and the normality angle parameter136. Additionally, or alternatively, in some implementations, the data118includes more, fewer, or different thresholds128than the tow count threshold120, the tow overlap threshold122, the roller deformation threshold124, and the tow nominal-angle deviation threshold126. To illustrate, additional parameters and thresholds associated with an AFP process are described with reference toFIG.3. Further, in some implementations, one or more of the parameters138or thresholds128is dynamic (e.g., has a value that depends on process conditions). To illustrate, the value of the steering radius parameter130for a particular steering operation may depend on other turns in the same course or tow. To illustrate, turns in the same direction tend to build up tension in outer tows of the course and slacken the inner tows of the course. Some of the tension built up in the outer tows can be alleviated when a turn is made in the other direction. Thus, two adjacent turns in opposite directions (e.g., forming an S-curve) may have a different value of the steering radius parameter130than two adjacent turns in the same direction.

In operation, one or more users, such as stress engineers, use the design tool102to generate the model data106. The model data106defines the object geometry154and may also include information about the object190as-designed, such as the rosette direction and nominal angles of plies and a number of plies for each nominal angle to satisfy mechanical requirements for the object190.

One or more users of the layup strategy analysis tool110access the model data106and execute the layup strategy analysis instructions116to facilitate selection of a layup strategy to form the object190based on the model data106. For example, the layup strategy can specify ply boundaries, course centerlines, tow-add/tow-drop locations, course layup direction, out-of-cycle operations (e.g., inspection or manual operations), etc. The layup strategy analysis instructions116generate the output140based on the model data106, the thresholds128and the parameters138in the memory114, and possibly other data. In a particular implementation, the output140indicates the number of tows per pass158for one or more plies of the object190. In some implementations, the output140includes a heat map or another display technique that visually distinguishes some areas from others to highlight portions of the object geometry154. For example, in some implementations, the output140includes a depiction of the 3D model152of the object190displayed in a manner that visually distinguishes locations at which a roller deformation threshold124is not satisfied for a particular count of tows that can be simultaneously applied during the single pass. As another example, in some implementations, the output140includes a depiction of the 3D model152of the object190displayed in a manner that visually distinguishes locations at which the steering radius parameter130is not satisfied for a particular count of tows that can be simultaneously applied during the single pass. As yet another example, in some implementations, the output140includes a depiction of the 3D model152of the object190displayed in a manner that visually distinguishes locations at which the tow count threshold120is not satisfied. In still another example, in some implementations, the output140includes a depiction of the 3D model152of the object190displayed in a manner that visually distinguishing counts of the number of tows that can be applied during the single pass at various locations.

The layup strategy analysis instructions116enable the user(s) to analyze multiple distinct sets of thresholds128and parameters138in order to select a particular layup strategy. The data descriptive of the selected layup strategy is provided to the NC programming tool160, which uses the NC instructions162to generate machine instruction data164. The machine instruction data164details the specific operations to be performed by one or more of the AFP machines170to manufacture the object190.

The AFP machine(s)170operate according to the machine instruction data164to build up layers of fiber reinforced polymer to manufacture the object190. In some implementations, the AFP machine(s)170may pause or be interrupted while manufacturing the object190so that inspections or manual processes can be performed. After the object190is manufactured, the object190undergoes post processing (e.g., curing, inspection, finishing, painting, etc.) in preparation for assembly194with other parts. As a result of using the layup strategy analysis tool110to develop and model multiple candidate layup strategies and/or to detect potential problem areas in advance, the end-to-end manufacturing time associated with the object190can be significantly reduced relative to conventional workflows in which 3D modelling and structural designs are passed to the NC programming tool160without such layup strategy analysis.

FIG.2is a flow chart of an example of method200of layup strategy analysis according to a particular implementation. For example, the method200can be initiated, controlled, or performed by the processor112of the layup strategy analysis tool110executing the layup strategy analysis instructions116.

The method200includes, at block202, obtaining, at one or more processors of a computing device, model data representing a 3D model of an object to be formed using an automated fiber placement process. For example, the processor112of the layup strategy analysis tool110receive the model data106from the design tool102. The model data106includes data corresponding to a 3D model of the object190.

The method200includes, at block204, obtaining, at the one or more processors, process data descriptive of the automated fiber placement process and one or more automated fiber placement machines. For example, the processor112of the layup strategy analysis tool110receives the thresholds128and the parameters138which are descriptive of the automated fiber placement process and the one or more AFP machines170.

The method200includes, at block206, performing, by the one or more processors, an analysis of the model data and the process data to determine a count of a number of tows that can be simultaneously applied during a single pass based on a geometry of the object and based on manufacturability constraints indicated by the process data. For example, the processor112of the layup strategy analysis tool110executes the layup strategy analysis instructions116to determine, based on the thresholds128, the parameters138, and the object geometry154, the number of tows that can be simultaneously applied during a single pass.

The method200includes, at block208, generating, by the one or more processors, output based on the analysis, where the output includes a depiction of the 3D model of the object displayed in a manner that visually distinguishes problem locations of the 3D model based on differing analysis results associated with each location. For example, the processor112of the layup strategy analysis tool110generates the output140, which includes a depiction of the 3D model152with one or more visually distinct locations156to distinguish problem locations based on analysis results associated with each location.

The method200enables analysis of layup strategies early in a design process to detect potential problem areas in advance. Advance detection of potential problem areas can significantly reduce end-to-end manufacturing time of the object by enabling changes to the design of the object, changes to the AFP machine, changes to the AFP process, or both, that eliminate or reduce issues associated with the potential problem areas.

FIG.3is a diagram that illustrates an example of layup strategy considerations according to a particular implementation. In particular,FIG.3illustrates layup strategy control parameters and AFP process factors that are influenced by, or influence the selection of, the layup strategy control parameters. InFIG.3, the layup strategy control parameters include a number of tows302, a tow width304, a course centerline strategy306, a tow mask308, ply stagger310, layup direction312, and course sequence314. Further, inFIG.3, the AFP process factors include number of courses320, fiber angle distribution322, steering324, course convergence326(e.g., cutting and/or adding tows), gaps and/or laps (“gaps/laps”)328, through-thickness gap/lap density330, fiber straightening332, compaction334, tow puckering and/or wrinkling (“tow puckering/wrinkling”)336, untacked tows in folding zones338, and surface irregularities340. The AFP process factors also include off-cycle work factors, such as off-part motion350and rework352of straightened fibers.

The AFP process factors ofFIG.3include factors related to the quality or properties of a laminate material formed by the AFP process and factors related to the manufacturing time of the laminate material. For example, generally, the number of courses320, steering324, course convergence326, and off-part motion350are factors that affect the total manufacturing time of a laminate. As another example, the fiber angle distribution322, the through-thickness gap/lap density330, and fiber straightening332are factors that tend to influence the quality or properties of the laminate. Further, gaps/laps328, compaction334, tow puckering/wrinkling336, untacked tows in folding zones338, and rework352of straightened fibers are factors that can influence either or both of the manufacturing time and the quality or properties of the laminate. The layup strategy control parameters and AFP process factors illustrated inFIG.3are discussed below and, in some cases, with reference to other figures.

In a particular implementation, the number of tows302and the tow width304together determine the course width, and the course width determines the number of courses320needed per layer of the object190. Using a larger course width reduces time to apply a particular amount of material (e.g., fiber reinforced polymer material) at a given lay down speed of the AFP machine170. Thus, reducing the number of courses320per ply tends to reduce the in-cycle time to manufacture the object190. The tow width304also may also affect out-of-cycle manufacturing time. For example, using larger tows means that fewer tows are needed to cover the working surface to form a single layer (or ply). Assuming that the probability of the AFP machine170stopping due to failed tows is the same for wide tows as for narrow tows, the total number of AFP machine170stops due to failed tows is smaller if a smaller number of wider tows are used rather than a larger number of narrower tows.

In some instances, the course width may be reduced (e.g., by using narrower tows or fewer tows) based on the surface geometry of the object190and roller deformation parameters132of the roller. For example, for a particular course that covers or forms a relatively narrow edge of the object190, the roller(s)174may not be able to deform or displace sufficiently to simultaneously compact tows on the edge and on each side of the edge. Thus, the number of tows applied for the particular course may be limited by the geometry of the working surface of the object190.

As a tow is applied to the working surface, a roller174applies a compaction force to the tow to cause the tow to adhere (or cohere) to the working surface. The compaction force applied should be adequate to keep portions of the tow from delaminating from the working surface, which can lead to puckers, wrinkles, folds, slippage, bridging, etc.

A roller174may not apply sufficient compaction pressure to a tow for several reasons, two of which are characterized by stroke and normality, each of which is illustrated inFIG.5A. For example,FIG.5Aillustrates a segmented roller500that includes a plurality of individual rollers174. The individual rollers174of the segmented roller500share a common axis502. The individual rollers174are able to move individually in a direction along a normal508of the roller174that is required to follow contours of a surface506) by a distance504that defines the stroke of each individual roller174. The normal508of the roller174is determined based on a plane516that is tangent to the segmented roller500at a centerline518of the segmented roller500. The normal508of the roller174may be angularly offset from a normal510of a plane512that is tangent to the surface506at the centerline518of the segmented roller500by an offset angle514(also referred to as the head tilt angle).

Thus, for the segmented roller500ofFIG.5A, the stroke is limited by how much the individual rollers can move or deform with respect to the common axis502and by how much each individual roller segment can deform. If a solid roller, rather than the segmented roller500, is used, the stroke is limited by how much the solid roller can deform (e.g., compress or bend around its axis).

In some instances, such as when the surface506has a concave contour, outer individual rollers174of the segmented roller500may be able to apply sufficient compaction force (e.g., force toward the surface506); however, inner individual rollers174of the segmented roller500may not be able to reach the surface506or may not be able to apply sufficient compaction pressure. For example, referring toFIG.5C, a cross-section of a contoured surface520and plurality of tows522are illustrated without a roller or set of rollers that apply the tows522. A distance526between the upper most tow (e.g., tow522A) being applied and the lower most tow (e.g., tow522F) being applied is illustrated inFIG.5C. In order for the rollers to apply sufficient compaction pressure to tow522F, the stroke allowed by the AFP head must be equal to or greater than the distance526. If the stroke of the roller associated with tow522F is less than the distance526, bridging of tows can occur.FIG.6Dillustrates an example of bridged tows602. Thus, if the stroke of the roller associated with tow522F is less than the distance526, the set of tows522cannot be applied in a single pass. This issue can be resolved by using a narrower head, using a smaller set of rollers, using rollers with a larger stroke distance504, changing the layup strategy, or changing the contour of the surface520.

A similar issue can arise if a surface is convex, except that, when the surface is convex, the course width (rather than the head or roller width) can be changed to resolve the issue. For example, for a convex surface, the upper most tows are interior tows, which can be applied with sufficient compaction force, however the outermost tows are lower that the interior tows and may not be applied with sufficient compaction pressure. Thus, the outermost tows can be dropped or omitted from the course to change the course width and allow for application of sufficient compaction pressure by the roller to the tows.

Normality is a metric related to a contact angle between the individual roller and the working surface.FIG.5Billustrates a portion of a single roller174, such as an individual roller of a segmented roller500. The roller174is in contact with the surface506.FIG.5Balso illustrates a plane516A that is tangent to the roller174at a centerline518A of the roller174, and a plane512A that is tangent to the surface506at the centerline518A of the roller174. The centerline518A is offset along axis502from the centerline518of the segmented roller500ofFIG.5A. A normal508A of the plane516A is angularly offset from a normal510A of the plane512A by an angle514A, which causes a compaction force applied along the normal508A to have a component of force (e.g., a slip component) that is in a direction that is not perpendicular to the plane512A.

For example,FIG.5Cincludes an inset box showing details of a tow522K being applied to the surface520. The roller174applies compaction force along a direction540(which is oriented along the normal508A of the roller174). However, a surface of the roller174(initially approximately coincident with the tow522K inFIG.5C) is angularly offset from the surface520by the angle514A. As a result, the surface of the roller174deforms to a different shape, represented as shape546. In the shape546, a portion of the roller174in a compaction area548may be able to apply sufficient compaction pressure, and the remainder of the roller174is not able to apply sufficient compaction pressure. The shape546and the resulting compaction area548are due to the magnitude of the angle514A, the magnitude of the compaction force along the direction540, and the deformation characteristics of the roller174(e.g., the normality angle parameter136). The resultant compaction force has a compaction component542(e.g., a component of force that tends to press the tow522K into contact with the surface520) and a slip component544(e.g., a component of force that tends to cause the tow522K to slide across the surface520, also referred to herein as a shear force).

In the situation illustrated inFIG.5C, the roller174accommodates some angular offset by deforming to the shape546, but if the shape546does not fully contact the surface520portions of the tow522K (e.g., one edge) may not be compacted sufficiently, which can lead to lifted tows. An example of lifted tows604is illustrated inFIG.6B. The situation illustrated inFIG.5Cmay also, or in the alternative, lead to slippage of tows (e.g., tows that move from their intended layup position) due to the slip component544.

Tow width304and course width influence the amount of steering324that is possible without causing defects. For example,FIG.10illustrates an example of a steered course1000. The steered course1000follows a course centerline1002that has a centerline steering radius1004. An inner tow1006of the steered course1000follows a tow steering radius1008that is smaller than the centerline steering radius1004by an amount corresponding to a distance1010between a centerline of the tow1006and the course centerline1002. An outer tow1020of the steered course1000follows a tow steering radius1022that is larger than the centerline steering radius1004by an amount corresponding to a distance1024between a centerline of the tow1020and the course centerline1002. As shown inFIG.10, the steering radius of individual tows increases with distance from the course centerline1002on one side of the course1000and decreases with distance from the course centerline1002on the other side of the course1000. Thus, wider courses result in tighter steering (shorter turning radii) on the inner tow1006of a steered course1000.

Tow width304has a similar effect on steering as a course width. For example, during a turn, the inner edge of a tow travels less than, and is subjected to higher compression than, the outer edge of the tow. The differences in distance traveled by the outer and inner edges of a tow, or the outer and inner tows of a course can cause defects. For example, as illustrated inFIG.11B, inner edges of a tow can pucker, or as illustrated inFIG.11C, one or more tows of a course can buckle.

In a particular implementation, the course centerline strategy306is selected in part based on fiber angle distribution322requirements, which are based on desired structural properties of the object190. For example, a manufacturing organization may be subject to engineering standards that specify an allowable fiber angle deviation, such as a fiber angle deviation of +3 degrees from the nominal fiber angle. On general curved surfaces, satisfying the fiber angle distribution322requirements leads to steering324fiber paths, as well as course convergence326.

Several course centerline strategies306are illustrated inFIGS.7A and7B. Effects of the course centerline strategies306ofFIGS.7A and7Bare illustrated inFIGS.7C and7D. In particular,FIG.7Cis a diagram720that graphs a normalized longitudinal distance (from x=0 to X=L inFIG.7A) of each fiber path versus fiber angle along each fiber path702.FIG.7Dis a diagram730that graphs the normalized longitudinal distance of each fiber path versus curvature.

InFIG.7A, fiber paths702are shown on a 3D representation of a conical shell704, and inFIG.7B, the conical shell704is shown flattened in a 2D representation. The conical shell704represents a curved working surface to which one or more course are to be applied.

Each of the fiber paths702represents a course and includes a centerline and course edges. A first fiber path702A represents a course following a constant fiber angle of 45 degrees. Thus, as shown inFIG.7C, the first fiber path702A has a constant fiber angle of 45 degrees along the entire distance from x=0 to x=L and is referred to as a constant angle course centerline strategy. The constant angle course centerline strategy of the first fiber path702A perfectly follows the nominal fiber angle for a 45 degree ply. Although the fiber angle distribution of the first fiber path702A is ideal for a nominal 45 degree ply, asFIG.7Dshows, steering (i.e., a non-zero curvature) is required to implement the constant angle course centerline strategy of the first fiber path702B. The amount of steering required varies over the normalized longitudinal distance, with a smaller radius of curvature needed near the small radius of the cone (e.g., near x=0 or x/L=0) than at the large radius of the cone (x=L or x/L=1) to maintain the 45 degree fiber angle orientation.

The third fiber path702C corresponds to a geodesic (or “natural”) course centerline strategy. The fiber path of a geodesic course centerline strategy is fully defined by its starting point and initial direction for a given surface geometry. In the examples illustrated inFIGS.7A and7B, the starting point and initial direction of the third fiber path702C are the same as the starting point and initial direction of the other two fiber paths702A and702B (e.g., at the small radius of the conical shell704, where the fiber angle is 45 degrees). As illustrated inFIG.7C, the fiber angle distribution for the third fiber path702C associated with the geodesic course centerline strategy starts at 45 degrees at x/L=0, but then rapidly decreases, ending at about 20 degrees at the large radius (x/L=1). No steering is applied to achieve the geodesic course centerline strategy; thus, the third fiber path702C is associated with zero curvature inFIG.7D.

The second path702B corresponds to a constant curvature course centerline strategy. As shown inFIG.7D, the constant curvature course centerline strategy of the second fiber path702B entails steering with a constant radius of curvature. The constant curvature course centerline strategy results in some deviation from the nominal fiber angle, as illustrated inFIG.7C, but less deviation than the geodesic course centerline strategy. Thus, the constant curvature course centerline strategy may be appropriate to reduce the deviation from the nominal fiber angle while limiting steering.

Course convergence326is illustrated inFIG.8where six courses750are represented on the conical shell704. Each of the courses is represented by a centerline and course edges. As illustrated inFIG.8, the centerlines converge near the small end of the cone, causing overlaps between edges if the course width is kept constant. Overlaps can be reduced or eliminated by selectively changing the course width near the areas of overlap. For example, if courses are applied from the large end of the conical shell704(e.g., the bottom inFIG.8) toward the small end of the conical shell704(e.g., the top inFIG.8), tows can be cut near the regions of overlap, which reduces the number of tows302in particular portions of a course and thereby changes the course width of the course. Alternatively, if courses are applied from the small end of the conical shell704(e.g., the top inFIG.8) toward the large end of the conical shell704(e.g., the bottom inFIG.8), each course can start with a reduced number of tows302and tows can be added near the regions of decreasing overlap, which increases the number of tows302in particular portions of a course and thereby changes the course width of the course. Thus, depending on the direction in which the courses are applied, avoiding or limiting course convergence326in the example ofFIG.8entails cutting or adding tows on-the-fly.

The number of courses320can also depend on the nominal fiber angle of the ply. As an example, a long thin part can be formed using a first ply with a nominal fiber angle oriented along a length of the part (e.g., a 0 degree ply) and a second ply with a nominal fiber angle oriented along the width of the part (e.g., a 90 degree ply). Since the length of the part is greater than the width of the part, the 0 degree ply will require fewer courses than the 90 degree ply. Additionally, the courses (and tows) of the 0 degree ply will be longer than the courses (and tows) of the 90 degree ply.

Longer courses are more efficient to apply because the average layup speed is larger. For example, AFP machines170generally have a “roll-in” distance, over which no material is deposited and the head172starts accelerating. Subsequently, tows are added and material is deposited, and the AFP machine170can keep accelerating until a maximum speed is reached. As the head172approaches the end of the course, the AFP machine170decelerates and tows are cut. After a “roll-out” distance, the head172is lifted from the working surface. Often, the maximum speed is not reached for short courses, and thus these short courses are less efficient.

As explained above with reference toFIGS.7A-7D, steering324can be used to help satisfy fiber angle distribution322. Steering324can also be used to reduce course convergence326thereby limiting cutting and/or adding of tows in the middle of a ply. However, steering324can introduce defects if the steering radius is too small. Another way this is sometimes described is in terms of curvature. As used herein, curvature refers to in-plane path curvature, which is the inverse of the steering radius. Thus, steering324may introduce defects if the curvature is too large.

The steering radius at which defects occur depends on the tow width304, the material properties of the tows and the AFP process parameters. Steering324involves in-plane bending of a tow, which causes tensile and compressive stresses at the edges of the tow that vary proportional with the distance to the tow centerline. When courses are steered, defects such as tow puckering and/or wrinkling336can occur.

Tow puckers are out-of-plane projections of the tow caused by in-plane bending. As previously noted, examples of tows with puckers are shown inFIG.11B. Puckering can be suppressed by increasing cohesion of the tows to the working surface. However, a disadvantage associated with increasing cohesion is that, if rework is needed, it can be extremely difficult to pry the erroneous tows loose without damaging underlying plies. The size and number of puckers that form can be reduced by applying more tension on the tow. However, other defects can be introduced if there is too much tension on the tow. For example, the tow may bridge on concave surfaces (as illustrated inFIG.6D). Increased tension on the tows also increases the probability of untacked tows or tow folding.

Steering324and cutting tows together influence fiber straightening332. Fiber straightening332refers to a circumstance that can occur when a tow is cut while the course is being steered. The cut tow will tend to follow a geodesic path (e.g., no curvature) after it is cut, while the remaining tows of the course continue to be steered. Tows on the inside of the turn tend to be constrained by adjacent tows and are more likely to follow the steered path. However, tows on the outside of the course tend to straighten. As a result, the cut tow may not align with the course as expected (e.g., a portion of the cut tow is straightened). Layup strategy analysis may flag areas on the part surface that exhibit both high steering and convergence.

Cutting tows on the inside of a turn rather than on the outside of a turn can reduce fiber straightening332. Avoiding cutting tows while steering with large curvatures can also reduce fiber straightening332. One way to avoid cutting tows on a turn is to reverse the layup direction312so that tows are added instead of cut during steering324.

Generally, straightened tows need to be reworked352. For example, the straightened tow may be lifted off of the working surface and realigned with other tows of the course. This is often a manual process that tends to be very labor intensive and adds time to the end-to-end manufacturing process. Rework352of straightened fibers is also impacted by course sequence314. For example, courses with a smaller radius should be laid down after courses with a larger radius if fiber straightening332cannot be avoided. If courses with a smaller radius are laid down before courses with a larger radius and fiber straightening332occurs, the inner tows of the later applied course (e.g., the larger radius course) will be laid on top of the straightened outer tow of the earlier applied course (e.g., the smaller radius course), making it difficult or impossible to lift and adjust the straightened tows. Other defects can also arise when tows are added or cut while steering.

Constraints regarding acceptable amounts of steering324for particular tow material and tow widths are determined based on steering trials. Based on such trials, a minimum value may be set for the steering radius parameter130. As long as a layup strategy uses steering324with steering radii greater than the steering radius parameter130, layup defects due to steering should be limited. In some implementations, the layup strategy may also specify adapting AFP process parameters, such as speed and heat, to increase the tack.

In some implementations, a layup strategy may seek to avoid steering324altogether when possible since, when no steering324is used, wider tows and/or wider courses can be used, which increases the layup speed. However, as described with reference toFIGS.7A-7D, for certain surface geometries, fiber angles can deviate considerably from nominal fiber angles if no steering is used. Additionally, geodesic paths on some surfaces converge/diverge, requiring tow cuts and adds.

Course convergence326cause overlaps (e.g., laps328) to occur if the course width is kept constant. AFP machines170generally allows individual tows to be added or cut independently of one another, which enables varying the course width to avoid large overlaps. When a tow is cut, the cut is perpendicular to the fiber direction, as shown inFIG.12A.FIG.12Aillustrates a region1200of a layup surface in which two courses are converging. The courses include a first course1202, the tows of which are illustrated in dotted lines, and a second course1204, the tows of which are illustrated in dashed lines. As the courses1202,1204converge in the region1200, an upper tow1208of the second course1204is cut (at cut end1210), which limits the amount of overlap between the upper tow1208of the second course1204and a lower tow1206of the first course1202. However, cutting the upper tow1208leaves an area1212in which no tow of either course1202,1204is present. This area1212is referred to as a gap.FIG.12Aalso shows that the lower tow1206of the first course1202is cut (at cut end1214) later in the AFP process, but not before the lower tow1206of the first course1202partially overlaps the upper tow of the second course1204, resulting in an area1216referred to as a lap or overlap. Another gap area1212is also form after the cut end1214of the lower tow1206of the first course1202.

Non-smooth course boundaries formed by gaps (e.g., by the area1212) and laps (e.g., the area1216) between adjacent courses caused by adding or cutting tows reduces the stiffness and strength of the resulting laminate. Stress engineers apply safety factors (often referred to as “knockdowns”) to account for the stiffness and strength reductions due to gaps and laps, and extra plies may be added to the laminate to offset the knockdowns. These extra plies increase manufacturing time and the final weight of the object190. Additionally, some AFP machines170slow down to add or cut tows, which increases manufacturing time. Further, large gaps may require inspection or rework. Thus, a layup strategy that avoids course convergence to the extent possible (e.g., by using parallel courses) may enable faster manufacturing times, stronger parts, lighter parts, or a combination thereof. However, laying parallel courses on surfaces can increase fiber angle deviations and require more steering.

The tow mask308identifies which tows are being laid down within each course and will change along a course as tows are cut and added. The tow mask308is affected by the course centerline strategy306since the course centerline strategy306affects course convergence326. However, multiple different tow masks308may be compatible with a particular course centerline strategy306. For example, as described with reference toFIG.12A, tows can be cut or added on both of two adjacent courses, or tows can be cut or added on only one of the adjacent courses. Also, the selection of a particular tow mask308can affect the occurrence of defects, such as fiber straightening332.

Ply stagger310refers to offsetting plies that have identical nominal fiber angles. For example, two 0 degree plies should be offset so that tow edges of the plies do not align with one another. Ply stagger310is usually accomplished by offsetting the starting point for course generation from one ply to the next. However, surface geometry and thickness buildup of consecutive plies can cause a natural shift in the course pattern, such that course boundaries of plies with the same nominal fiber angle do not meet the stagger requirements at some locations.

The layup direction312refers to the direction in which a course is laid down. As describe above, reversing the layup direction312can change whether tows are added or cut to limit course convergence326. Reversing the layup direction312can also help prevent fiber straightening332by changing tow cuts into tow adds. In some circumstances, layup speed can be different for one layup direction312than for the reverse layup direction312. For example, some AFP machines170operate at a different speed to add tows than to cut tows. Thus, changing from adding to cutting tows (or vice versa) can reduce manufacturing time. Additionally, the amount of off-part motion350needed can be different for one layup direction312than for another layup direction312. It is possible that the AFP machine170may operate faster in first layup direction312than in a second layup direction, but the first layup direction312may require more off-part motion350than the second layup direction312. In such instances, the layup strategy analysis may include simulations of layup speed and off-part motion to determine which layup direction312is more efficient overall.

The course sequence314refers to the order in which courses of a ply are laid down. The course sequence314, together with the layup direction312for each course, determines the off-part motion350, thus influencing the in-cycle time. Additionally, the course sequence314can affect rework352. For example, if courses are steered and fiber straightening332cannot be avoided by changing tow masks308and/or layup directions312, the course sequence314may be adjusted to avoid applying a new course on top of a straightened tow, so that the straightened tow can be reworked when the full ply is done rather than between courses.

FIG.4is a diagram that illustrates an example of inputs402and outputs404of a layup strategy analysis400according to a particular implementation. The layup strategy analysis400is performed by the processor(s)112ofFIG.1while executing the layup strategy analysis instructions116. In a particular implementation, the outputs404include, correspond to, or are included within the output140ofFIG.1. In some implementations, the inputs402include, correspond to, or are included within the data118, the model data106, the manufacturability constraints178, the tow properties184, or a combination thereof.

InFIG.4, the inputs402include 3D model inputs410, design inputs412, and process data414. In other implementations, the inputs402include more, less, or different data. For example, any one or more of the controllable factors discussed with reference toFIG.3can be provided as input to the layup strategy analysis400. The 3D model inputs410include, for example, a surface description, such as a surface triangulation in which surfaces of the 3D model152are tessellated to define a set of triangles or other surface approximation elements (also referred to herein as “elements”). The 3D model inputs410inFIG.4may also include, for example, layup definitions, such as data indicating ply boundaries and ply nominal angles (also referred to herein as rosette directions) and a designation of a 0 degree direction.

The design inputs412include, for example a designation of one or more course centerline strategies306to be analyzed. InFIG.4, the course centerline strategies306include a rosette centerline strategy (which generates the constant angle fiber path702A described with reference toFIGS.7A-7D) and a natural centerline strategy (which generates the geodesic fiber path702C described with reference toFIGS.7A-7D). The parallel-rosette centerline strategy starts off with a first fiber path that exactly goes through a specified initial element in the specified direction (e.g., with no fiber angle deviation) and then follows the constant angle fiber path. Other fiber paths of the ply are arranged parallel to the first fiber path. Fibers of the other plies can deviate from the nominal fiber orientation. The parallel-rosette centerline strategy may use significant steering but eliminates overlaps between adjacent courses. The parallel-natural centerline strategy starts off with a first fiber path that exactly goes through a specified initial element in the specified direction (e.g., with no fiber angle deviation) and then follows a natural (geodesic) path. Other fiber paths of the ply are arranged parallel to the first fiber path. The parallel-natural centerline strategy eliminates overlaps between adjacent courses and reduces steering as compared to the parallel-rosette centerline strategy. However, the parallel-natural centerline strategy generally results in larger fiber angle deviations than does the parallel-rosette centerline strategy. In other examples, additional or different centerline strategies may be considered, such as a constant curvature centerline strategy (which generates the constant curvature fiber path702B described with reference toFIGS.7A-7D).

InFIG.4, the process data414includes tow width304, number of tows302, compaction limits (e.g., roller deformation parameters132), and steering limits (e.g., steering radius parameters130). In other implementations, the process data414includes more, fewer, or different parameters, such as parameters descriptive of tow materials186.

The layup strategy analysis tool110, at block420, uses the inputs402to build a course centerline model for each element. As an example, the layup strategy analysis tool110uses the design inputs412to determine a starting location (if required for a course centerline strategy) and one or more course centerline strategies306to be modeled. In a particular implementation, the layup strategy analysis tool110determines a course centerline through each element in the triangulated surface model to facilitate selection of actual centerlines and/or starting locations used during NC programming. To illustrate, the set of course centerlines determined by the layup strategy analysis tool110reveals best case centerlines, worst case centerlines, or intermediate case centerlines to assist with centerline planning. During NC programming, a subset of the analyzed centerlines are used. Manufacturability checks performed without the layup strategy analysis tool110require full NC programming and running an end-to-end manufacturing simulation to account for multiple layers and ply stagger (which will cause the starting location to shift from ply to ply). Such end-to-end manufacturing simulation is time consuming and resource intensive and comes relatively late in the design process (e.g., after NC programming). The layup strategy results generated by the layup strategy analysis tool110disclosed herein facilitate selection of start points before NC programming is performed and uses a simpler, and less resource intensive model than an end-to-end manufacturing simulation based on the NC programming. As a result, changes can be made earlier in the process, resulting in significant time and resource savings. Other factors described with reference toFIG.3may also be considered and modeled. To illustrate, the layup strategy analysis tool110models the course centerline of each course of each ply; in which case, ply stagger310can be accounted for while modeling the course centerlines.

At block430, the layup strategy analysis tool110determines vector fields on the surface(s) of the 3D model using a particular centerline strategy (e.g., one of the centerline strategies described above). For example, when a rosette centerline strategy is used, the vector field is determined by projecting the rosette direction onto tangent planes (e.g., triangles of the triangulated surface) defined by the surface(s). Each surface modeled represents a ply including one or more courses. The vector fields indicate the fiber angle direction in each triangle of the surface modeled.

At block440, the layup strategy analysis tool110performs one or more analyses based on the vector fields. The particular analysis or analyses performed may be based on user input or settings. InFIG.4, the analyses include one or more compaction analyses442, one or more steering analyses448, an angle deviation analysis454, a gap/lap analysis456, and a number of tows limit analysis458. In other implementations, the analyses include more, fewer, or different analyses.

InFIG.4, the compaction analyses442include a stroke analysis444and a normality angle analysis446. The stroke analysis444determines stroke data for each vector field analyzed. For example, in a particular implementation, the stroke data indicates a stroke value required for the roller (or each individual roller of a segmented roller) to apply sufficient compaction force to a respective tow. Additionally, or alternatively, the stroke data indicates extremes of the stroke values (e.g., largest stroke values for the roller) or stroke values that are greater than a stroke threshold of the roller deformation thresholds124ofFIG.1. In some implementations, the stroke data may identify locations associated with the stroke values that exceed the stroke threshold.

The normality angle analysis446determines normality angle data for each vector field analyzed. For example, in a particular implementation, the normality angle data indicates a normality angle at each location for the roller (or each individual roller of a segmented roller). Additionally, or alternatively, the normality angle data indicates extremes of the normality angle value (e.g., a largest normality angle) or normality angle values that are greater than a normality angle threshold of the roller deformation thresholds124ofFIG.1. In some implementations, the normality angle data may identify locations associated with the normality angle values that exceed the normality angle threshold.

InFIG.4, the steering analyses448include a radius of curvature analysis450and an edge length differential analysis452. The radius of curvature analysis450determines radius of curvature data for each vector field analyzed. For example, in a particular implementation, the radius of curvature data indicates a radius of curvature at each location for each tow. Additionally, or alternatively, the radius of curvature data indicates extremes of the radius of curvature value (e.g., a smallest radius of curvature) or radius of curvature values that are less than a curvature threshold. In some implementations, the radius of curvature data may identify locations associated with the radius of curvature values that fail to satisfy the curvature threshold.

The edge length differential analysis452determines edges lengths of each tow and generates edge length differential data. The edge length differential data indicates how much longer (or shorter) one edge of a tow is as compared to the other edge. In some implementations, the edge length differential data is for a specified length of the tow, such as 1 meter along a centerline of the tow. The edge length differential data indicates how much steering the tow has endured and is indicative of differential stresses between the edges. To illustrate, a first edge of a tow may be significantly longer than a second edge of the tow if the first edge has been the outer edge during steering for a greater distance that the second edge has been the outer edge. Such edge length differentials can indicate that one edge is subjected to too much tension and is therefore likely to delaminate, or that the other edge is subjected to too little tension and is therefore likely to pucker or fold. In some implementations, the edge length differential data indicates extremes of the edge length differential values (e.g., a largest edge length differential value) or edge length differential values that exceed an edge length differential threshold. In some implementations, the edge length differential data identify locations associated with the edge length differential values that fail to satisfy the edge length differential threshold.

The angle deviation analysis454determines fiber angle deviation data for each vector field analyzed. For example, in a particular implementation, the fiber angle deviation data indicates deviation from the nominal fiber angle at each triangle of the surface triangulation (e.g., for each ply). Additionally, or alternatively, the fiber angle deviation data indicates extremes of fiber angle deviation within a course. For example, the fiber angle deviation data may identify locations that are associated with the largest fiber angle deviation or locations associated with particular ranges of fiber angle deviation. As another example, the fiber angle deviation data may identify locations associated with the fiber angle deviations that exceed a threshold, such as the tow nominal-angle deviation threshold126ofFIG.1.

The gap/lap analysis456determines gap data, lap data, or both, (referred to herein as “gap/lap data”) for each vector field analyzed. For example, in a particular implementation, the gap/lap data indicates locations and/or sizes of gaps, laps, or both, for one or more plies. Additionally, or alternatively, the gap/lap data summarizes gap and/or lap information for a ply or for the entire 3D model. For example, the gap/lap data indicates an average or range of overlap or gap values for a particular ply or for the entire 3D model. To illustrate, a percentage of surface area of a ply that is associated with gaps or laps can be used to indicate an average gap or lap for the ply. As another example, the gap/lap data identifies one or more locations associated with gap/lap data that exceed a threshold, such as the tow overlap threshold122ofFIG.1.

The number of tows limit analysis458determines tow count data indicating a number of tows that can be applied per course (e.g., in a single pass) at various locations for each vector field analyzed. For example, in a particular implementation, the tow count data indicates the number of tows that can be applied at each location based on results of one more of the other analyses of block440. As explained with reference toFIG.3, the number of tows that can be applied at a particular location depends on compaction334, steering324, course convergence326, other factors, or a combination thereof. In some implementations, the tow count data indicates an average or range of tow counts for a particular course of a particular ply. In some implementations, the tow count data identifies locations associated with the tow counts that are below a threshold, such as the tow count threshold120ofFIG.1.

Results of the analysis or analyses performed at block440are used to generate the outputs404. InFIG.4, the outputs404include recommendations460, statistics462, visualizations464, or a combination thereof. In other implementations, the outputs404include more, fewer, or different outputs. For example, in some implementations, the statistics462are merged with the visualizations464.

The recommendations460include suggestions for decreasing manufacturing time of a part based on the 3D model within defined constraints, such as the fiber angle deviation constraints. As an example, generally, factors that decrease manufacturing time include: applying more tows in each pass, decreasing off-part motion, and decreasing rework and inspection. The recommendations460may be directed, based on the analysis of block440, to one or more of these manufacturing-time reducing factors. To illustrate, if the number of tows limit analysis458indicates that fewer than a target number of tows can be applied at a particular location in a single pass, the compaction analyses442and the stroke analyses444for the particular location may be evaluated to determine which is limiting the number of tows in the particular location. In this example, the recommendations460may suggest changes to address the limitation on the number of tows that can be applied at the particular location. For example, if the compaction analyses442are indicated as limiting the number of tows, the recommendations460may suggest modifying a shape or contour of the 3D model (e.g., to a less extreme contour) to reduce effects of stroke or normality angle on the number of tows that can be applied in a single pass. As another example, if the steering analyses448are indicated as limiting the number of tows, the recommendations460may suggest evaluating an alternative course centerline strategy. As another example, if the AFP machine170can use multiple different rollers with different roller compaction parameters, the recommendations460may include data indicating multiple values of the number of tows that can be applied during a single pass, where each value is associated with a particular roller.

The statistics462summarize results of one or more of the analyses442,448,454,456,458. For example, the statistics462may indicate a count of the number of tows that can be applied in a single pass for a particular ply or for the entire 3D model. To illustrate, the statistics462may indicate the smallest number of tows that can be applied at any location of the 3D model in a single pass, the largest number of tows that can be applied at any location of the 3D model in a single pass, the average number of tows that can be applied in a single pass for the 3D model, or other data summarizing results of the number of tows limit analysis458. As another example, the statistics462may indicate a largest or average angle deviation for a ply or for the 3D model.

The visualizations464display results of one or more of the analyses442,448,454,456,458as a visually distinct location on a representation of the 3D model. Several examples of such visualizations464are shown in the figures.

For example,FIGS.6A and6Cillustrate examples of visualizations based, at least partly, on the compaction analyses442. Each of the visualizations ofFIGS.6A and6Cincludes a representation of the 3D model152and a key. The representation of the 3D model152includes a plurality of visually distinct regions (indicated by various fill patterns), and the key indicates the meanings (e.g., relevant data values) associated with the various fill patterns

FIG.6Aillustrates a visualization610based on the stroke analysis444. A key614associated with the visualization610indicates that the fill patterns are associated with tow stroke in inches. For example, a largest stroke value inFIG.6Ais 0.24 inches), and a smallest stroke value inFIG.6Ais 0.04 inches. MatchingFIG.6AtoFIG.6D, the bridged tows602inFIG.6Dmay be associated with the largest stroke value in the visualization620.

FIG.6Cillustrates a visualization620based on the normality angle analysis446. A key624inFIG.6Cindicates that the fill patterns represent the normality angle (e.g., in degrees) in each of the visually distinct regions. MatchingFIG.6CtoFIG.6B, the lifted tows604inFIG.6Bmay be associated with the highest normality angle in the visualization610.

FIGS.9A and9Billustrate examples of visualizations based, at least partly, on the angle deviation analysis454. Each visualization ofFIGS.9A and9Bincludes a representation of the 3D model152and a key. The representation of the 3D model152includes a plurality of visually distinct regions (indicated by various fill patterns), and the key indicates the meanings (e.g., relevant data values) associated with the various fill patterns.

FIG.9Aillustrates a visualization902for a 45 degree ply of another example of the 3D model152. InFIG.9A, a key912indicates a count of a number of tows that can be applied in each region without exceeding a specified fiber angle deviation threshold (e.g., 1 degree in the example illustrated). To illustrate, in some regions a course can include 16 tows; whereas, in other regions a course can only include 8 tows.

FIG.9Billustrates a visualization952for a 45 degree ply of another example of the 3D model152. InFIG.9B, a key954indicates values of the differential angle (e.g., the absolute value of the difference between the nominal fiber angle and the actual fiber angle) associated with each visually distinct region of the 3D model152. The key954also indicates a fiber angle deviation threshold956(e.g., the tow nominal-angle deviation threshold126) enabling a user to quickly identify portions of the 3D model that are associated with fiber angles that do not satisfy (e.g., are greater than) the fiber angle deviation threshold956, such as portions of a region1058. In some implementations, the visualization952ofFIG.9Bmay visually distinguish locations at which the tow nominal-angle deviation threshold126is not satisfied for a particular count of tows that can be simultaneously applied during the single pass.

FIG.11Aillustrates an example of a visualization based, at least partly, on the steering analyses448. The visualization ofFIG.11Aincludes a representation1100of an example of the 3D model152and a key1102. The representation of the 3D model152includes a plurality of visually distinct regions (indicated by various fill patterns), and the key1102indicates the meanings (e.g., relevant data values) associated with the various fill patterns. InFIG.11A, each fill pattern indicates a radius of curvature (e.g., in inches). Thus, a smaller value in the key1102corresponds to a smaller radius of curvature or a tighter turn. Regions of high curvature (e.g., smaller radius of curvature) may be associated with puckering (as illustrated inFIG.11B) or buckling (as illustrated inFIG.11C).

FIG.12Billustrates an example of a visualization based, at least partly, on the gap/lap analysis456. The visualization ofFIG.12Bincludes a representation1230of an example of the 3D model152and a key1232. The representation1230of the 3D model152includes a plurality of visually distinct regions (indicated by various fill patterns), and the key1232indicates that the various fill patterns are associated with respective percentages of overlap along an X axis. In a particular implementation, if a tow overlap threshold122is specified, the visualization ofFIG.12Bmay indicate a number of tows that can be simultaneously applied during a single pass while satisfying the tow overlap threshold122.

FIG.13Aillustrates an example of a visualization based, at least partly, on the number of tows limit analysis458for a layer in the composite part that has a 0 degree nominal fiber angle.FIG.13Billustrates a visualization of the same number of tow limit analysis as the visualization ofFIG.13Afor a layer that has a nominal fiber angle of 45 degrees. InFIG.13A, the visualization includes a representation1300of an example of the 3D model152and a key1302. The representation1300of the 3D model152includes a plurality of visually distinct regions (indicated by various fill patterns), and the key1302indicates that the various fill patterns are associated with counts of a number of tows that can be applied in each region in a single pass. InFIG.13B, the representation1320of the 3D model152includes a plurality of visually distinct regions that are approximately scaled to represent course widths, and each course width is associated with a value indicating the number of tows in the course. For example, in a first region1310, each course can include up to 10 tows; whereas in a second region1312, each course can include up to 16 tows.

The visualizations described above enable production of laminates that have higher quality with less rework and faster manufacturing timelines. For example, the visualizations illustrate the impact of various part or manufacturing design choices, enabling a user to quickly and easily modify the 3D model152or parameters138associated with the manufacturing process to improve manufacturability of the object190.

The illustrations of the examples described herein are intended to provide a general understanding of the structure of the various implementations. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other implementations may be apparent to those of skill in the art upon reviewing the disclosure. Other implementations may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. For example, method operations may be performed in a different order than shown in the figures or one or more method operations may be omitted. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

Moreover, although specific examples have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar results may be substituted for the specific implementations shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various implementations. Combinations of the above implementations, and other implementations not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.

The Abstract of the Disclosure is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single implementation for the purpose of streamlining the disclosure. Examples described above illustrate but do not limit the disclosure. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the present disclosure. As the following claims reflect, the claimed subject matter may be directed to less than all of the features of any of the disclosed examples. Accordingly, the scope of the disclosure is defined by the following claims and their equivalents.