Fiber placement optimization for steered-fiber plies
First Claim
1. A method, performed by a computer system, for determining optimum tow cut locations for steered-fiber placement, said method comprising:
- (a) generating stream function data with a multiplicity of corresponding stream lines;
(b) generating course pair data representing successive pairs of neighboring courses having centerlines corresponding to the stream lines representing the stream function data generated in operation (a) such that there is no gap between the neighboring courses; and
for each pair of neighboring courses;
(c) determining potential tow cut locations where any uncut tow from one of the pair of neighboring courses will potentially overlap with any uncut tow from the other of the pair of neighboring courses in dependence on a set of allowable coverage parameter values,(d) generating geometry data for each potential tow cut location, and(e) selecting which tows of the pair of neighboring courses should be cut or added at which tow cut locations selected from the potential tow cut locations determined in operation (c) and in which direction the courses should be laid down, wherein the tows selected for cutting at the selected tow cut locations and the selected direction for course laydown minimize a penalty function taking a plurality of constraints into account;
(f) generating machine code for controlling a fiber placement machine to cut the tows selected for cutting in operation (e) and lay down the courses in the direction selected in operation (e);
(g) storing the machine code generated in operation (f) on a computer-readable medium; and
(h) operating a computer numerical control tow placement machine in accordance with the machine code stored on said computer-readable medium,wherein said plurality of constraints comprise a maximum thickness build-up, a minimum turning radius for a centerline of each neighboring course, a coverage parameter which determines where tows will be terminated and restarted with respect to a boundary, a minimum cut length for each tow, and a maximum number of tow cuts within an overlap area, andwherein operation (e) further comprises generating a list of segment variables for each tow, indicating whether it is active or inactive, and generating a list of cut variables, indicating whether a tow is cut or added at a potential tow cut location or if the status is unchanged.
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Abstract
Methods for optimizing fiber placement programming for use in automated manufacture of steered-fiber composite laminates. The optimization methods are implemented in software capable of optimally translating steered-fiber laminate definitions in fiber placement code for manufacturing steered-fiber laminates without overlaps. The optimization is set up to take into account manufacturing constraints, such as minimum cut length, minimum steering radius, and fiber straightening due to steering. This software includes both geometry and optimization and will take the aforementioned issues into account by optimizing the direction of lay down and the location and sequence of cutting and adding individual tows.
21 Citations
21 Claims
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1. A method, performed by a computer system, for determining optimum tow cut locations for steered-fiber placement, said method comprising:
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(a) generating stream function data with a multiplicity of corresponding stream lines; (b) generating course pair data representing successive pairs of neighboring courses having centerlines corresponding to the stream lines representing the stream function data generated in operation (a) such that there is no gap between the neighboring courses; and for each pair of neighboring courses; (c) determining potential tow cut locations where any uncut tow from one of the pair of neighboring courses will potentially overlap with any uncut tow from the other of the pair of neighboring courses in dependence on a set of allowable coverage parameter values, (d) generating geometry data for each potential tow cut location, and (e) selecting which tows of the pair of neighboring courses should be cut or added at which tow cut locations selected from the potential tow cut locations determined in operation (c) and in which direction the courses should be laid down, wherein the tows selected for cutting at the selected tow cut locations and the selected direction for course laydown minimize a penalty function taking a plurality of constraints into account; (f) generating machine code for controlling a fiber placement machine to cut the tows selected for cutting in operation (e) and lay down the courses in the direction selected in operation (e); (g) storing the machine code generated in operation (f) on a computer-readable medium; and (h) operating a computer numerical control tow placement machine in accordance with the machine code stored on said computer-readable medium, wherein said plurality of constraints comprise a maximum thickness build-up, a minimum turning radius for a centerline of each neighboring course, a coverage parameter which determines where tows will be terminated and restarted with respect to a boundary, a minimum cut length for each tow, and a maximum number of tow cuts within an overlap area, and wherein operation (e) further comprises generating a list of segment variables for each tow, indicating whether it is active or inactive, and generating a list of cut variables, indicating whether a tow is cut or added at a potential tow cut location or if the status is unchanged. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for laying a composite ply comprising steered fibers, said method comprising:
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(a) generating stream function data with a multiplicity of corresponding stream lines; (b) generating course pair data representing successive pairs of neighboring courses having centerlines corresponding to the stream lines representing the stream function data generated in operation (a) such that there is no gap between the neighboring courses; and for each pair of neighboring courses; (c) determining potential tow cut locations and add locations where any uncut tow from one of the pair of neighboring courses will potentially overlap with any uncut tow from the other of the pair of neighboring courses in dependence on a set of allowable coverage parameter values, (d) generating geometry data for each potential tow cut location; (e) selecting tow cut and add locations from the potential tow cut locations determined in operation (c) which result in minimizing a value of a penalty function for simulated placement of tows for one set of courses, taking into account a plurality of constraints; (f) generating machine code for controlling a fiber placement machine to lay down courses and to cut and add tows at the selected tow cut and add locations; and (g) automatically laying down courses and cutting and adding tows in accordance with said machine code, wherein said plurality of constraints comprise a maximum thickness build-up, a minimum turning radius for a centerline of each neighboring course, a coverage parameter which determines where tows will be terminated and restarted with respect to a boundary, a minimum cut length for each tow, and a maximum number of tow cuts within an overlap area, and steps (a) through (f) are performed by processors, and wherein operation (d) comprises generating the following;
a list of data for each tow that indicates the potential tow cut locations along its length, a list of parameters representing the tow segments, a list of data specifying the lengths of the tow segments, and two lists of data specifying the centerline curvature at the minimum cut length distance from the tow cut locations at either side of the potential tow cut location. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A system for designing a steered-fiber ply, comprising one or more processors programmed to execute the following operations:
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(a) generating stream function data with a multiplicity of corresponding stream lines; (b) generating course pair data representing successive pairs of neighboring courses having centerlines corresponding to the stream lines representing the stream function data generated in operation (a) such that there is no gap between the courses; and for each pair of neighboring courses; (c) determining potential tow cut locations and add locations where any uncut tow from one of the pair of neighboring courses will potentially overlap with any uncut tow from the other of the pair of neighboring courses in dependence on a set of allowable coverage parameter values, (d) generating geometry data for each potential tow cut location; and (e) selecting tow cut and add locations from the potential tow cut locations determined in operation (c) which result in minimizing a value of a penalty function for simulated placement of tows for one set of courses, taking into account a plurality of constraints, and (f) generating machine code for controlling a fiber placement machine to cut the tows selected for cutting in operation (e) and lay down the courses in the direction selected in operation (e); (g) storing the machine code generated in operation (f) on a computer-readable medium; (h) controlling a computer numerical control tow placement machine to operate in accordance with the machine code stored on said computer-readable medium; and (i) displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows cut or added at said selected tow cut and add locations, wherein said plurality of constraints comprise a maximum thickness build-up, a minimum turning radius for a centerline of each neighboring course, a coverage parameter which determines where tows will be terminated and restarted with respect to a boundary, a minimum cut length for each tow, and a maximum number of tow cuts within an overlap area, and wherein operation (d) comprises generating the following;
a list of data for each tow that indicates the potential tow cut locations along its length, a list of parameters representing the tow segments, a list of data specifying the lengths of the tow segments, and two lists of data specifying the centerline curvature at the minimum cut length distance from the tow cut locations at either side of the potential tow cut location. - View Dependent Claims (21)
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Specification