Composite Ply Fiber Path Determination via Potential Function

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Solution Overview

Problem

Existing methods for determining fiber paths in composite laminates with non-planar contours and non-constant fiber angles result in overlaps and gaps during manufacturing, affecting structural properties, surface quality, and manufacturability, and fail to consider convergence and divergence effects in design.

Innovation Solution

A method and system that generate a triangulated surface approximation, define unit vector fields, and determine a potential function to optimize fiber path direction and spacing, using a processor-based system to minimize curl and normalize the potential function for uniform contour line distribution, enabling accurate fiber path determination for automated layup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fiber paths are determined to follow specified fiber angle distribution on curved surfaces, then fiber direction accuracy is improved, but course spacing uniformity deteriorates causing overlaps and gaps

Engineering Contradiction:
Improvefiber direction accuracyVSAvoidcourse spacing uniformity
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent transforms the fiber path determination problem from direct angle specification to potential function-based contour line generation. By changing the parameter representation from angular coordinates to potential function values, the system achieves both accurate fiber directions (through gradient alignment) and uniform course spacing (through equipotential line properties), resolving the contradiction between directional accuracy and spacing uniformity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a potential function as an intermediary between the specified fiber angle distribution and the actual fiber path geometry. This intermediary allows the system to indirectly control fiber paths through its gradient field, ensuring that contour lines naturally maintain uniform spacing while their tangents align with the desired fiber directions, thus eliminating overlaps and gaps.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If conventional fiber path methods are used, then design simplicity is maintained, but manufacturing rework increases due to unanticipated overlaps and gaps

Engineering Contradiction:
Improvedesign simplicityVSAvoidmanufacturing rework time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The patent performs preliminary optimization of fiber path spacing during the design phase by computing the potential function and its contour lines before manufacturing. This preliminary action identifies and corrects potential convergence and divergence issues in advance, preventing overlaps and gaps that would otherwise require costly rework during manufacturing, thus reducing time loss while maintaining design feasibility.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If fiber paths are optimized for uniform spacing, then course alignment is improved, but fiber angle distribution accuracy may deteriorate

Engineering Contradiction:
Improvecourse alignmentVSAvoidfiber angle distribution accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent resolves this contradiction by changing the optimization parameter from direct spacing control to potential function gradient alignment. The contour lines of the potential function naturally provide uniform spacing, while their tangential directions are constrained to match the specified fiber angle distribution through the gradient relationship, achieving both course alignment and fiber angle accuracy simultaneously.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3422219B1System and method for determining the direction and spacing of fiber paths for a composite ply
Publication Date: 2020.07.08 THE BOEING CO
  • EP3422219B1 patent drawingFigure 1
  • EP3422219B1 patent drawingFigure 2~3
  • EP3422219B1 patent drawingFigure 4

AI summary

A method (100) of determining fibers paths (314) for a composite ply (202) includes generating a triangulated surface (218) of the composite ply (202), and defining a first unit vector field establishing a 0-degree direction (302) for the triangulated surface. A second unit vector field (306) is defined by rotating, through specified fiber angles measured relative to the 0-degree direction, the first unit vector field about surface normals of the triangulated surface. A third unit vector field representing a gradient (308) direction of a potential function is defined by rotating the second unit vector field over 90° about the respective surface normal (304). The third unit vector field is scaled to create a non-unit vector field, and a first potential function is determined by performing a least-squares fit such that the direction and magnitude of the gradient best approximate the direction and the magnitude of the non-unit vector field. A normalization of the potential function uniformly distributes contour lines (310) of the potential function across the triangulated surface. The contour lines are used as fiber paths (314) for laying up courses (206) of composite material to fabricate the composite ply (202).