Fiber placement optimization for steered-fiber plies

Patent metadata

Field	Value
Publication number	US-10169492-B2
Application number	US-201414295441-A
Country	US
Kind code	B2
Filing date	Jun 4, 2014
Priority date	Jun 20, 2011
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

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.

First claim

The invention claimed is:

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, 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.

2. The method as recited in claim 1 , wherein operation (d) comprises generating the following: a list of data for each tow that indicates the potential tow cut locations along a length, a list of parameters representing the tow segments, a list of data specifying respective lengths of the tow segments, and two lists of data specifying a centerline curvature at a minimum cut length distance from each potential tow cut location at either side of the potential tow cut location.

3. The method as recited in claim 1 , further comprising displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows selected for cutting in operation (e) with overlaps that conform to a coverage parameter constraint.

4. The method as recited in claim 1 , wherein said plurality of constraints comprise an overlap constraint, according to which only one segment can be active when there is an overlap, and a non-overlap constraint, according to which a segment is active when there is no overlap.

5. The method as recited in claim 1 , wherein operation (e) takes the following constraint into account: none of the tows between the two outermost tows that are not cut should be cut.

6. The method as recited in claim 1 , wherein operation (e) takes the following constraint into account: if a curvature of a path of a course is larger than a specified threshold, the tows along an outer radius of the course are not cut to avoid fiber straightening, depending on the direction in which the course is being laid down.

7. The method as recited in claim 1 , wherein operation (b) further comprises the following steps performed when one course of a pair of neighboring courses completely exits and then re-enters a specified ply domain:
replacing the re-entering course by multiple courses by splitting up the re-entering course at the domain boundary; and
for each newly created course:
determining the overlap between the new course and the neighboring course;
adjusting the position of the new course to reduce the amount of overlap below a certain threshold if the amount of overlap is larger than this threshold; and
generating course data for the newly created courses and original neighboring course.

8. The method as recited in claim 2 , further comprising displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows selected for cutting in operation (e) with overlaps that conform to a coverage parameter constraint.

9. The method as recited in claim 4 , further comprising displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows selected for cutting in operation (e) with overlaps that conform to a coverage parameter constraint.

10. The method as recited in claim 5 , further comprising displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows selected for cutting in operation (e) with overlaps that conform to a coverage parameter constraint.

11. The method as recited in claim 6 , further comprising displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows selected for cutting in operation (e) with overlaps that conform to a coverage parameter constraint.

12. The method as recited in claim 7 , further comprising displaying a visual representation of a steered-fiber ply comprising a multiplicity of courses, each course comprising a respective multiplicity of tows, including tows selected for cutting in operation (e) with overlaps that conform to a coverage parameter constraint.

13. A method for laying a composite ply comprising steered fibers, 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 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,
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Assignees

• Boeing Co

Inventors

• Blom-Schieber Adriana Willempje
• Kang Laura Sumi
• Vandenbrande Jan Hendrik

Classifications

• G06F2111/06

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• B29C70/386

  Automated tape laying [ATL] · CPC title

• B29C70/38

  Automated lay-up, e.g. using robots, laying filaments according to predetermined patterns {(application heads for tyres B29D30/28)} · CPC title

• B26D7/18

  Means for removing cut-out material or waste · CPC title

• B29C70/545

  Perforating, cutting or machining during or after moulding · CPC title