Patent Application
20210397761
The present disclosure is generally related to fiber path planning for automated fiber placement manufacturing processes.
Advanced (or automated) fiber placement (AFP) refers to automation of some steps of a process of manufacturing fiber reinforced polymer laminates. Generally, AFP manufacturing uses one or more automated fiber placement machines to build a composite layup, layer-by-layer. Each layer (or ply) typically includes multiple courses, and each course typically includes multiple tows of resin impregnated or dry fiber material. Material properties of composite layups formed in this way vary based on the orientation angle of the fibers. To illustrate, a part may have a greater tensile strength along a direction parallel to the fibers than the tensile strength along a direction perpendicular to the fibers. Thus, for some applications, it may be important for a part manufactured using AFP to have fibers that are oriented in a particular manner specified during design.
Constraints associated with AFP manufacturing place certain limitations on manufacturing composite layups with complex shapes while maintaining specified fiber angle orientations. For example, for some composite layups, a tow may need to change directions (e.g., turn) one or more times to keep the fibers aligned with the as-designed fiber orientation; however, such turns can inhibit cohesion of the tow to the underlying surface, resulting in folds, puckers, or other flaws. Some fiber placement and orientation concerns can be addressed by using fewer and smaller tows; however, using fewer or smaller tows increases manufacturing time since the number of courses to cover the same area increases, taking longer to build up each layer.
In a particular implementation, a system for planning fiber paths for a composite ply of a composite layup includes one or more processors and one or more memory devices. The one or more memory devices store instructions that are executable by the one or more processors to cause the one or more processors to perform operations including determining a first unit vector field representing a first approximation of target directions to be followed by tow centerlines of the composite ply. The first unit vector field is determined based on a specified rosette direction, a surface approximation of a nonplanar contoured surface of an object to be formed via the composite layup, and a fiber angle distribution. The operations also include determining, based on specified angle deviation bounds and the first unit vector field, a second unit vector field representing a second approximation of the target directions. The second approximation has reduced in-plane curvature relative to the first approximation. The operations further include planning a fiber placement head path for forming the composite ply of the composite layup based on the second unit vector field.
In another particular implementation, a method of planning fiber paths for a composite ply of a composite layup includes determining, by one or more processors, a first unit vector field representing a first approximation of target directions to be followed by tow centerlines of the composite ply. The first unit vector field is determined based on a specified rosette direction, a surface approximation of a nonplanar contoured surface of an object to be formed via the composite layup, and a fiber angle distribution. The method also includes determining, by the one or more processors based on specified angle deviation bounds and the first unit vector field, a second unit vector field representing a second approximation of the target directions. The second approximation has reduced in-plane curvature relative to the first approximation. The method further includes planning, by the one or more processors, a fiber placement head path for forming the composite ply of the composite layup based on the second unit vector field.
In another particular implementation, a computer-readable storage device stores instructions that, when executed by one or more processors, cause the one or more processors to initiate, perform, or control operations including determining a first unit vector field representing a first approximation of target directions to be followed by tow centerlines of a composite ply. The first unit vector field is determined based on a specified rosette direction, a surface approximation of a nonplanar contoured surface of an object to be formed via a composite layup, and a fiber angle distribution. The operations also include determining, based on specified angle deviation bounds and the first unit vector field, a second unit vector field representing a second approximation of the target directions. The second approximation has reduced in-plane curvature relative to the first approximation. The operations further include planning a fiber placement head path for forming the composite ply of the composite layup based on the second unit vector field.
The features, functions, and advantages described herein can be achieved independently in various implementations or may be combined in yet other implementations, further details of which can be found with reference to the following description and drawings.
Aspects disclosed herein present systems and methods for planning fiber paths for manufacturing a composite ply of a composite layup using AFP. The fiber path planning operations disclosed reduce in-plane curvature of tows, which reduces the occurrence of AFP defects, such as poor compaction, wrinkles, and excessive gaps or overlaps. The fiber path planning operations disclosed may also reduce demand for manual rework and increase fiber lay down speed, which reduces overall manufacturing time and corresponding cost for parts made using AFP.
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 to
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. 1 depicts a computing device 102 that includes one or more processors (“processor(s)” 104 in
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.
The computing device 102 includes one or more processors 104, one or more memory devices 108, and one or more interfaces 106. In some implementations, the computing device 102 also, or alternatively, includes 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 108 includes one or more volatile memory devices (e.g., random access memory (RAM) devices), one or more nonvolatile memory devices (e.g., read-only memory (ROM) devices, programmable read-only memory, and flash memory), or both. Each memory device 108 includes or corresponds to a non-transitory, computer-readable storage device (i.e., is not merely a signal). The processor 104 is configured to execute software instructions 110 to perform various operations. Although specific instructions 110 are described below, the memory device 108 may also store data 112 (e.g., program data) and other instructions, such as an operating system and other programs. Further, the computing device 102 can include other hardware, such as input/output interfaces, input/output device, etc.
Although the details of the modeling device 140 are not shown in
As used herein, the rosette direction 146 indicates a reference direction of the 3D model 142 or the object 180. A fiber angle distribution 148 indicates a nominal fiber orientation, relative to the rosette direction 146, for a ply. For example, a composite layup 182 includes multiple composite plies 184 (also referred to as “plies”), and the plies typically have different nominal fiber orientations indicated by an angle relative to the rosette direction 146. To illustrate, the composite layup 182 may include one or more 0 degree plies 184 in which the nominal fiber angle of tows is parallel to the rosette direction 146, may include one or more 45 degree plies 184 in which the nominal fiber angle of tows is angularly offset by 45 degrees relative to the rosette direction 146, and may include one or more 90 degree plies 184 in which the nominal fiber angle of tows is angularly offset by 90 degrees relative to the rosette direction 146. Although the example above illustrates three nominal fiber angles that can be indicated by the fiber angle distribution 148, in other implementations, the fiber angle distribution indicates more than three nominal fiber angles (one per ply 184). Also, although the example above refers to a single rosette direction 146, in some implementations, such as very complex objects 180, multiple rosette directions 146 are specified.
The AFP machine 170 includes one or more fiber placement heads 172 and other components to enable the AFP machine 170 to build up multiple layers of fiber reinforced polymer material to form the object 180. Each head 172 is coupled to a steering mechanism that is configured to move the head 172 to direct application of one or more tows to form a course (e.g., a set of tows applied in a single pass). The steering mechanisms include, for example, robotic arms, gantries, movable platforms, or other devices to move the head 172 of the AFP machine 170.
When complete, the object 180 includes or corresponds to the composite layup 182 formed of or including the plurality of composite plies 184. Each composite ply 184 includes multiple tows arranged along respective tow centerlines 186. The tow centerlines 186 define fiber paths 188. An angle between a fiber path 188 and a target fiber path is referred to as a fiber angle deviation. To illustrate, in a 90 degree ply, one or more tows may include portions in which the fibers are oriented at 92 degrees relative to the rosette direction 146, which corresponds to a 2 degree fiber angle deviation from the nominal 90 degree orientation of the fibers of the ply. The composite plies 184 have anisotropic material properties that vary relative to the fiber directions. To illustrate, mechanical properties measured along the fiber directions of a particular composite ply 184 are generally greater than the same mechanical properties measured across the fiber directions of the particular composite ply 184.
The head 172 of the AFP machine 170 can dispense each tow independently, thereby enabling a certain amount of in-plane steering of the course by allowing the tows on the outside of a turn to be paid out faster than the tows on the inside of a turn. The lack of differential material pay out within a tow introduces stresses within the material during steering, which can result in the tow folding over if the tension is too high, or puckers or wrinkles forming if the compression is too high. For a given in-plane steering radius, the stresses in wider tows are higher than those in narrower tows, making them more susceptible to puckering or wrinkling.
The modeling device 140 generates model data 152 based on the 3D model 142, the rosette direction 146, the fiber angle distributions 148, the angle deviation bounds 150, other data descriptive of the as-designed object 180, or a combination thereof. The model data 152 is provided to the computing device 102 for fiber path planning or optimization.
In the example illustrated in
The processor 104 of the computing device 102 also executes fiber path instructions 116 to generate a unit vector field 120 representing the fiber paths 188 and to modify or update the unit vector field 120 to reduce in-plane curvature of the planned fiber paths 188. Each unit vector field 120 includes a set of unit vectors 122 including one unit vector 130 per planar surface element 128, as illustrated in further detail in
To illustrate, in a particular implementation, a first unit vector field 120 is generated based on the specified rosette direction and rotations of the unit vectors 130 around respective normals 132 based on the fiber angle distribution 148. In this implementation, the first unit vector field 120 is updated or modified, based on curvature metric values 124 to generate a second unit vector field 120′ representing reduced in-plane curvature of the planned fiber paths 188. Subsequently, in this implementation, the second unit vector field 120′ is modified or further refined by the local smoothing operations 118 to generate a third unit vector field 120. In this implementation, the third unit vector field 120″ is used to generate the fiber placement head paths 136. Modifying the planned fiber paths 188 to reduce in-plane curvature reduces the occurrence of AFP defects, such as poor compaction and wrinkles, which results in reduced demand for manual rework and increased fiber lay down speed. Accordingly, modifying the fiber paths to reduce in-plane curvature leads to reduced overall manufacturing time and reduced cost for manufacturing parts using AFP.
The fiber placement head paths 136 are used to generate path data 160, which is provided to the AFP machine 170. In a particular implementation, the path data 160 include machine instructions that are executable by a controller of the AFP machine 170 to generate commands and/or control signals that cause actuators or other mechanism of the AFP machine 170 to manufacture the object 180. As an example, the path data 160 include G-code instructions or other numerical control instructions for the AFP machine 170.
A detailed view 212 in
A unit vector field 120 representing the rosette direction 146 is generated by projecting a unit vector 206 onto each planar surface element 128. The set of such projected unit vectors 206 forms an initial unit vector field 120. For example, in
A unit vector 214 is determined for each planar surface element 128 by rotating the corresponding unit vector 206 around the respective normal 132 of the planar surface element 128 by an angle indicated by the fiber angle distribution 148 to generate a first unit vector field representing the target fiber direction 208. For example, in
A second detail view 216 illustrates an example of modifying the first unit vector field representing the target fiber direction 208 to generate a second unit vector field 120′ with reduced in-plane curvature. The second unit vector field 120′ includes a set of unit vectors 130, such as unit vector 130A of the first planar surface element 128A and unit vector 130B of the second planar surface element 128B as illustrated in
In the example illustrated in view 222A, the unit vector 130A (also denoted as vector xj) is rotated clockwise (in the orientation illustrated) from the direction of the unit vector 214A by an angle 218A (also denoted as angle θj). The amount that the unit vector 130A is allowed to rotate with respect to the unit vector 214A is limited by angle deviation bounds 150, which in
In the example illustrated in view 222B, the unit vector 130B (also denoted as vector xk) is rotated counterclockwise (in the orientation illustrated) from the direction of the unit vector 214B by an angle 218B (also denoted as angle θk). The amount that the unit vector 130B is allowed to rotate with respect to the unit vector 214B is limited by angle deviation bounds 150.
As illustrated in
In a particular aspect, the fiber path instructions 116 determine values of the angles illustrated in
As a particular example, the unit vectors 130 of the second unit vector field 120′ can be determined using Function 1:
where δj and θk are constrained by the angle deviation bounds 150 (e.g., θ−limit≤θj≤θ+limit and θ−limit≤θk≤θ+limit). In Function 1, ejk refers to the edge between two adjacent planar surface elements, the set int(E) refers to the set of interior (non-boundary) edges in the discrete representation of the surface, θj refers to the angle 218A, θk refers to the angle 218B, and γjk refers to the difference angle 238. Also in Function 1, wjk represents a weighting value determined based on the angles αj and αk of
w
jk=½(sin2(αj)+sin2(αk)) Equation 1
In an alternative implementation, the weighting value wjk for a pair of adjacent planar surface elements 128 can be determined using Equation 2:
w
jk=λ+(1−λ)½(sin2(αj)+sin2(αk)) Equation 2
where λ is a tuning value having a value specified by a user or as a default. For example, λ may have a value of about 0.05 in some implementations. In still other implementations, the weighting value wjk for a pair of adjacent planar surface elements 128 can be determined based on a length of the shared edge 250, or an average area of the pair of adjacent planar surface elements 128, or on a combination of the aforementioned factors.
In Function 1, θj−θk+γjk is discrete approximation of the in-plane curvature across the edge ejk which is used as a curvature metric and (θj−θk+γjk)2 is a quadratic loss function. In other implementations, other forms of loss function are used, such as an absolute loss function of the form |θj−θk+γjk| or a trigonometric loss function of the form −cos(θj−θk+γjk). Reducing the value of θj−θk+γjk (e.g., by selection of the unit vectors 130) reduces in-plane curvature of fiber paths generated based on the unit vectors.
Values of θj and θk that are associated with the minimum value of Function 1 are used as the second unit vector field 120′. In some implementations, the fiber placement head paths 136 are generated from the second unit vector field 120′. The system and/or method is configured for planning, defining or generating fiber placement head paths that provide path data to an automated fiber placement machine, where the generated fiber placement head paths are followed by a fiber placement head to form a plurality of composite plies/courses of a composite ply layup. In one example, the system is configured for planning (or generating) a first fiber placement head path 136, by integrating over the second unit vector field 120′ from a first starting point on the nonplanar contoured surface 144, and at least a second fiber placement head path by integrating over the second unit vector field 120′ from a second point that is selected on the nonplanar contoured surface 144 such that a distance between the first fiber placement head path and second fiber placement head path results in no gap between two adjacent composite plies/courses placed on the first fiber placement head path and second fiber placement head path. However, in some situations, the second unit vector field 120′ can include areas with localized high curvature. To reduce the effects of areas with localized high curvature, the computing device 102 uses the local smoothing operations 118 to smooth out such areas.
In a particular implementation, the local smoothing operations 118 identify each pair of adjacent planar surface elements 128 with values of the curvature metric (e.g., values of θj−θk+γjk) that are greater than a threshold curvature. In an example, the threshold curvature is based on a largest value of the curvature metric (e.g., a largest value of θj−θk+γjk) among all of the adjacent planar surface elements 128 of the surface approximation 126. To illustrate, in a particular implementation, the threshold curvature is a percentage or fraction of the largest value of the curvature metric. In a particular example, the threshold curvature is 70% of the largest value of the curvature metric.
After identifying a pair of adjacent planar surface elements 128 with a curvature metric value greater than the threshold curvature, the local smoothing operations 118 average the angle deviations of the pair of adjacent planar surface elements and neighboring planar surface elements to smooth the local curvature. The local smoothing operations 118 generate a third unit vector field 120, and the fiber placement head paths 136 are generated using the third unit vector field 120. For example, the fiber placement head paths 136 can be generated by integrating over the second unit vector field 120′ from a starting point on the nonplanar contoured surface 144. In this example, subsequent fiber placement head paths 136 are generated by picking a second point on the nonplanar contoured surface 144 such that a distance between the first and the second fiber placement head paths 136 is such that there is no gap between adjacent courses and minimal overlap.
Planning the fiber paths to have reduced in-plane curvature reduces the occurrence of AFP defects, which improves the reliability of parts manufactured using AFP, increases manufacturing rates of AFP machines, and decreases time and cost associated with rework and inspection.
The method 300 includes, at block 302, determining a first unit vector field representing a first approximation of target directions to be followed by tow centerlines of the composite ply, where the first unit vector field is determined based on a specified rosette direction, a surface approximation of a nonplanar contoured surface of an object to be formed via the composite layup, and a fiber angle distribution.
In the example illustrated in
The example of
The example of
The example of
Returning to
In the example illustrated in
The method 600 includes, at block 602, determining a 2D projection of unit vectors of a pair of adjacent planar surface elements. For example,
The method 600 includes, at block 604, determining a set of intersection angles including a pair of intersection angles for each pair of adjacent planar surface elements. Each intersection angle indicates an angle between a unit vector of one of the adjacent planar surface elements and an edge shared by the adjacent planar surface elements. For example, as illustrated in
The method 600 includes, at block 606, determining the weighting values for calculating the curvature metric based on the set of intersection angles. For example, the weighting values, wjk, can be determined using Equation 1 or Equation 2, above.
Returning to
Returning to
The example illustrated in
The example illustrated in
The example illustrated in
Thus, the method 300 enables planning fiber paths for AFP manufacturing in a manner that reduces in-plane curvature of tows. Reducing the in-plane curvature of the tows reduces the occurrence of defects, which results in reduced demand for manual rework and increased fiber lay down speed. Path data representing planned fiber paths is provided to the AFP machine. The AFP machine implements the planned fiber paths using tows to produce the object.
In some implementations, the fiber placement head paths 136 correspond to or enable formation of a single ply 184 composite layup 182. The composite layup 182 include a plurality of composite plies 184. Accordingly, the operations described with reference to
In some implementations, the angle deviation bounds 150 are specified as angular offset limits, as in the example illustrated in
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.
