Honeycomb Core Skin Protrusion Prevention

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Solution Overview

Problem

Traditional core-stiffened structures using honeycomb cores with cell widths greater than 6 mm face challenges in providing sufficient support during curing, leading to skin protrusion into cells and lateral distortion, limiting the manufacture of large-celled composite structures and increasing material thickness for stabilization.

Innovation Solution

The method involves using a honeycomb core with adhesive on its surfaces, stabilization skins, and soluble or thermoplastic plugs in cells to prevent skin protrusion during curing, along with breathable skin edges to allow moisture drainage, enabling the use of large-celled honeycomb cores and reducing lateral movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If large-celled honeycomb core (cell width > 6 mm) is used, then weight of the structure is reduced, but cell walls fail to provide sufficient support during curing causing skin protrusion into cells

Engineering Contradiction:

Improveweight of core-stiffened structureVSAvoidskin position during curing

Core Design Contradiction:

Weight of moving objectVSManufacturing precision

Solution Approach 1:

A support plug is introduced as an intermediary element within the honeycomb core cells. This plug provides internal support to prevent skin protrusion during curing, enabling the use of large-celled cores without compromising manufacturing precision. The plug acts as a temporary mediator that maintains cell wall integrity throughout the curing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The physical state of the support plug is changed during the process - it is inserted in a solid or semi-solid form to provide structural support during curing, then later removed or transformed. This parameter change allows the core structure to transition from needing support during manufacturing to having open cells for final application.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If skin thickness is increased to prevent lateral distortion of core during curing, then core stability is improved, but material thickness exceeds structural requirements

Engineering Contradiction:

Improvecore stability during curingVSAvoidskin thickness

Core Design Contradiction:

Stability of the object's compositionVSLength of moving object

Solution Approach 1:

The support plug serves as an intermediary that stabilizes the core structure during curing, replacing the need for excessive skin thickness. By providing internal support at the cell level, the plug allows skins to maintain their structurally required thickness without causing lateral distortion.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of increasing overall skin thickness uniformly, the support is segmented and distributed at the individual cell level through multiple support plugs. This segmentation provides stability where needed while maintaining thin skins in areas where structural requirements dictate minimal thickness.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If additional material is added to skin or core to resist lateral force during curing, then lateral distortion is prevented, but device complexity and material usage increase

Engineering Contradiction:

Improveresistance to lateral distortionVSAvoidcomplexity of stabilization method

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Rather than adding complex stabilization systems to the skin or core assembly, a simple support plug is inserted into each cell as an intermediary element. This single-component solution prevents lateral distortion through direct internal support, avoiding the complexity of external stabilization mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Object-affected harmful factors

If honeycomb core is sealed to prevent moisture intrusion, then moisture protection is improved, but core material is pushed laterally along tool surface during curing

Engineering Contradiction:

Improvemoisture protectionVSAvoidcore position during curing

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The support plug acts as an internal intermediary that anchors the core structure from within, preventing lateral movement along the tool surface. This internal support mechanism addresses the stability issue without compromising the sealing approach, as the plug works independently of the seal configuration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10369772B2Method of making core-stiffened structure

Publication Date: 2019.08.06 TEXTRON INNOVATIONS INC

AI summary

A method of making a core-stiffened structure includes the steps of providing a honeycomb core having an adhesive disposed on first and second surfaces thereof, providing a first skin and a second skin, and assembling the first skin, the second skin, and the honeycomb core to form the core-stiffened structure. The method further includes the steps of curing the core-stiffened structure and inhibiting at least one of the first skin and the second skin from protruding into at least one cell of the honeycomb core during the step of curing the core-stiffened structure.