Bead-Stiffened Composite Panels Slit Layup Method

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Solution Overview

Problem

Existing methods for forming bead-stiffened composite panels face challenges such as ply wrinkling and distortion due to differences in fiber length, requiring specialized equipment and materials, and often result in hidden forming processes that can lead to undetected issues like deformation or breakage.

Innovation Solution

The method involves cutting slits in the plies to allow them to conform to bead features on the tool, with patches covering the gaps formed, ensuring structural strength and reducing wrinkling and distortion during the layup process using conventional materials and simplified tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If standard prepreg plies are used without modification, then material availability is improved, but ply wrinkling and distortion occur during bead forming

Engineering Contradiction:

Improvematerial availabilityVSAvoidply surface quality

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The ply is segmented by cutting slits through it before forming. These slits allow the ply to be divided into sections that can independently conform to the bead geometry without wrinkling or distorting, while still maintaining structural integrity when patched together.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The slits are cut in the ply before the forming process begins. This preliminary modification prepares the ply to accommodate the bead features during forming, preventing wrinkling and distortion from occurring in the first place.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If slits are cut in plies to allow conforming to bead features, then wrinkling and distortion are reduced, but gaps are created that compromise structural strength

Engineering Contradiction:

Improveply surface qualityVSAvoidpanel structural strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

Patches serve as intermediary elements that fill the gaps created by the slits. These patches are applied over the slit areas after forming to restore the continuous fiber structure and maintain the panel's structural strength and stiffness.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If specialized equipment and carrier materials are used to force plies over beads, then forming accuracy is improved, but device complexity and material costs increase

Engineering Contradiction:

Improvebead forming accuracyVSAvoidequipment complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts the problematic areas of the ply (where the slits will be cut) before forming. This eliminates the need for complex specialized equipment by using a simple cutting operation that prepares the ply to conform to standard bead features without requiring additional tools or carrier materials.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9724891B2Bead-stiffened composite parts

Publication Date: 2017.08.08 THE BOEING CO

AI summary

A beaded composite panel is fabricated using composite plies. An opening is formed in each of plies, and each ply is laid up on a bead feature and drawn down over the bead feature in the area of the opening so as to widen the opening into a gap allowing the ply to conform to the contour of the bead feature. Patches are fabricated and placed on the plies overlying over the openings. The laid-up plies are compacted and cured.