Highly Contoured Composite Stringers With Vacuum-Assisted Forming

Solution Overview

Problem

Existing methods for creating highly contoured composite structures, such as composite stringers or stiffening elements, often result in wrinkling due to the formation of voids or discontinuities, which are undesirable and require expensive or time-consuming solutions.

Innovation Solution

A system and method involving a flexible stringer assembly and a contoured mandrel are used to re-form an uncured composite stringer into a highly contoured shape, utilizing a heating source and vacuum to minimize wrinkling by conforming the composite material to the desired design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If traditional methods are used to create highly contoured composite structures, then the structures can be formed, but wrinkles and voids form in the composite laminate

Engineering Contradiction:

Improvecontoured shapeVSAvoidwrinkle-free surface

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The composite plies are pre-cut and pre-spliced to the final configuration before forming, ensuring proper alignment and reducing the risk of wrinkles during the forming process. This preliminary preparation allows the material to be more compliant when contoured to the mandrel.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A flexible mandrel is used as an intermediary tool to form the composite laminate. The mandrel provides a contoured surface that guides the material into the desired shape while the flexible caulking tool acts as a mediator to apply pressure and eliminate wrinkles during the curing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If cutting and splicing plies are used to reduce wrinkling, then wrinkle formation is reduced, but the process becomes expensive and time-consuming

Engineering Contradiction:

Improvewrinkle-free surfaceVSAvoidproduction efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The plies are pre-cut and pre-spliced to the final configuration before forming, ensuring proper alignment and reducing the risk of wrinkles during the forming process. This preliminary preparation allows the material to be more compliant when contoured to the mandrel.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical state of the composite material by controlling temperature and pressure parameters during the curing process. By maintaining the material in a compliant state longer and using controlled pressure application, wrinkles are eliminated without requiring extensive cutting and splicing.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If cutting and splicing plies are used to reduce wrinkling, then wrinkle formation is reduced, but the process becomes expensive and time-consuming

Engineering Contradiction:

Improvewrinkle-free surfaceVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The plies are pre-cut and pre-spliced to the final configuration before forming, ensuring proper alignment and reducing the risk of wrinkles during the forming process. This preliminary preparation allows the material to be more compliant when contoured to the mandrel.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A flexible mandrel is used as an intermediary tool to form the composite laminate. The mandrel provides a contoured surface that guides the material into the desired shape while the flexible caulking tool acts as a mediator to apply pressure and eliminate wrinkles during the curing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Significantly reduces wrinkling in the final cured composite structure, ensuring a uniform texture and improved structural integrity by minimizing defects to less than 0.010 inches, enhancing the production efficiency and reducing material waste.

Implementation Method 1

A system and method involving a flexible stringer assembly and a contoured mandrel are used to re-form an uncured composite stringer into a highly contoured shape, utilizing a heating source

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

A system and method involving a flexible stringer assembly and a contoured mandrel are used to re-form an uncured composite stringer into a highly contoured shape, utilizing a heating source and vacuum to minimize wrinkling

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentEP3782803B1Highly contoured composite structures and system and method for making the same

Publication Date: 2025.09.10 THE BOEING CO

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AI summary

A system for making highly contoured composite stringers, including a flexible stringer assembly to support an uncured composite stringer; and a contoured mandrel to contour the uncured composite stringer into a highly contoured shape, wherein the contoured mandrel comprises one or more curvatures with a radius of 2540 mm (100 inches) or less along at least one of an x, y, or z axis.