Fiber Placement Optimization for Steered-Fiber Plies

• US 20140288893A1
• Filed: 06/04/2014
• Published: 09/25/2014
• Est. Priority Date: 06/20/2011
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Blom, Adriana Willempje, Kang, Laura Sumi, Vandenbrande, Jan Hendrik
• Granted Patent: US 10,169,492 B2
• Time in Patent Office: Days
• US Class Current: 703/1
• CPC Class Codes: B26D 7/18 Means for removing cut-out material or waste
• CPC Class Codes: B29C 33/58 Applying the releasing agents
• CPC Class Codes: B29C 70/16 using fibres of substantial or continuous length non-woven fabrics per se D04H3/00
• CPC Class Codes: B29C 70/38 Automated lay-up, e.g. using robots, laying filaments according to predetermined patterns application heads for tyres B29D30/28
• CPC Class Codes: B29C 70/382 Automated fiber placement [AFP]
• CPC Class Codes: B29C 70/384 Fiber placement heads, e.g. component parts, details or accessories
• CPC Class Codes: B29C 70/386 Automated tape laying [ATL]
• CPC Class Codes: B29C 70/388 Tape placement heads, e.g. component parts, details or accessories
• CPC Class Codes: B29C 70/545 Perforating, cutting or machining during or after moulding
• CPC Class Codes: B65H 35/0013 and applying the article or the web by adhesive to a surface B65H35/002 takes precedence
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G05B 19/4097 characterised by using design data to control NC machines, e.g. CAD/CAM G05B19/4093 takes precedence
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G06F 2111/06 Multi-objective optimisation, e.g. Pareto optimisation using simulated annealing [SA], ant colony algorithms or genetic algorithms [GA]
• CPC Class Codes: G06F 2113/26 Composites
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]
• CPC Class Codes: G06F 30/15 Vehicle, aircraft or watercraft design
• CPC Class Codes: G06F 30/23 using finite element methods [FEM] or finite difference methods [FDM]
• CPC Class Codes: G06T 7/0004 Industrial image inspection

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.

Claims

1. A method, performed by a computer system, for determining 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 courses and the overlap is minimized; and

for each pair of neighboring courses;

(c) determining potential tow cut locations in areas of overlap between courses and splitting up individual tows at these locations to create tow segments,

(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 potential tow cut locations and in which direction the course should be laid down, taking a plurality of constraints into account; and

(f) generating machine code for controlling a fiber placement machine to cut tows and lay down courses in accordance with selections made in operation (e).

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 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 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 operation (e) comprises finding a set of tow cuts which minimize a penalty function for one set of courses.

5. The method as recited in claim 4, 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.

6. The method as recited in claim 5, 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.

7. The method as recited in claim 1, wherein said plurality of constraints comprise a maximum thickness build-up, a minimum turning radius, a coverage parameter, a minimum cut length, and a maximum number of cuts within an overlap area.

8. 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.

9. 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.

10. 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.

11. The method as recited in claim 1, further comprising storing the machine code generated in operation (f) on a computer-readable medium.

12. The method as recited in claim 11, further comprising operating a computer numerical control tow placement machine in accordance with the machine code stored on said computer-readable medium.

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 courses and the overlap is minimized; and

for each pair of neighboring courses;

(c) determining potential tow cut locations in areas of overlap between courses and splitting up individual tows at these locations to create tow segments,

(d) generating geometry data for each potential tow cut location, and

(e) 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 cut tows and lay down courses in accordance with the results of operation (e); and

(g) automatically laying down courses and cutting and adding tows in accordance with said machine code,

wherein steps (a) through (f) are performed by processors.

14. The method as recited in claim 13, 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 tow cuts for neighboring courses with overlaps that conform to a coverage parameter constraint.

15. The method as recited in claim 13, 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.

16. The method as recited in claim 15, wherein said plurality of constraints comprise an overlap constraint, according to which only one tow segment can be active when there is an overlap, and a non-overlap constraint, according to which a tow segment is active when there is no overlap.

17. The method as recited in claim 13, 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.

18. The method as recited in claim 13, 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.

19. A system for designing a steered-fiber ply, comprising one or more processors programmed to execute the following operations:

(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 the overlap is minimized; and

for each pair of neighboring courses;

(c) determining potential tow cut locations in areas of overlap between courses and splitting up individual tows at these locations to create tow segments,

(d) generating geometry data for each potential tow cut location, and

(e) 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 and add tows and lay down courses in accordance with the results of operation (e).

20. The system as recited in claim 19, further comprising a display device, wherein one of said processors is programmed to control said display device to display 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.

21. The system as recited in claim 19, 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.