Stiffened Composite Wing Panel Warpage Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional composite aircraft wing panels are prone to defects, warpage, and excessive weight due to the incompatibility of open section stringers with prepreg tape, leading to reduced strength and increased manufacturing complexity.

Innovation Solution

A novel panel design featuring an outer and inner face sheet with a foam core structure, including hat-shaped sections and fiber tows, which increases flexural stiffness and reduces warping, while being co-cured with resin to enhance structural integrity and reduce weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If open section stringers are used in composite panels, then manufacturing can be simplified, but the panels are prone to warpage and defects

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidpanel flatness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The panel is divided into multiple segments including face sheets, core structure, and stiffeners that can be manufactured separately and then assembled through co-curing. This segmentation allows each component to be optimized independently while achieving the desired flatness and structural integrity in the final assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite materials throughout the panel construction, including composite face sheets, composite core structure, and composite stiffeners. This uniform composite construction eliminates the incompatibility between aluminum stringers and composite panels, preventing warpage while maintaining manufacturing efficiency.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If conventional composite panels are used, then weight reduction is achieved, but strength is reduced due to warpage and noodle cracking

Engineering Contradiction:

Improvepanel weightVSAvoidpanel strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The panel components are pre-configured with proper geometry and material properties before assembly. The core structure and stiffeners are designed in advance to provide the necessary support and distribute loads evenly, preventing noodle cracking and maintaining strength while keeping the panel lightweight.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention introduces a three-dimensional core structure with hat-shaped sections that provide stiffness and strength in multiple directions. This dimensional approach allows the panel to achieve high strength-to-weight ratio by distributing stresses through the depth of the structure rather than relying solely on face sheet thickness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If shims are installed to align parts, then assembly accuracy is improved, but manufacturing time and cost increase

Engineering Contradiction:

Improveassembly accuracyVSAvoidmanufacturing efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The panel structure is designed to be self-aligning through features such as recesses in the face sheets that receive the core structure, and co-curing processes that bond components together while maintaining precise geometry. This eliminates the need for external shims and manual alignment operations, significantly improving manufacturing efficiency.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Multiple manufacturing operations are merged into the co-curing process, where face sheets, core structure, and stiffeners are bonded together in a single curing cycle. This integration eliminates separate alignment and assembly steps, reducing both time and cost while maintaining high assembly accuracy.

Inventive Principle:

Principle #5Merging (Combining)

4Manufacturing precision

If more stiffeners are added to reduce warpage, then panel stiffness is improved, but device complexity increases

Engineering Contradiction:

Improvewarpage controlVSAvoidpanel structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Stiffeners are strategically placed only where needed to control warpage and provide structural support, rather than uniformly distributing them across the entire panel. The hat-shaped core structure provides localized stiffness in critical areas while maintaining simplicity in other regions, optimizing the balance between warpage control and structural complexity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11878793B2All new multi-purpose internally stiffened composite wing sub-panel

Publication Date: 2024.01.23 THE BOEING CO

AI summary

A panel including an outer face sheet; an inner face sheet; a foam disposed between the outer face sheet and the inner face sheet; and a core structure (e.g., a stringer comprising a hat structure) between the foam and the inner face sheet; and between the foam and the outer face sheet. The core structure is protected from impact damage and increases flexural stiffness of the panel on an aircraft wing.