Honeycomb Sandwich Panel Joint Geometry to Prevent Curling

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Solution Overview

Problem

Conventional methods for joining honeycomb sandwich panels, such as in aerospace applications, often result in inconsistent production, rippling, and curling issues, leading to defective parts and increased production costs.

Innovation Solution

A joint is formed by creating a rabbet along a longitudinal edge of a first panel and a notch along a second longitudinal edge of a second panel, with the rabbet positioned within the notch, and an adhesive applied to secure the joint, allowing for alignment at a non-parallel angle and eliminating the need for scraping the honeycomb core.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional staggered joint method with fingers and recesses is used, then panels can be joined together, but production time increases and visual quality deteriorates due to scraping requirements

Engineering Contradiction:
Improveease of assemblyVSAvoidproduction time
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The joint is divided into discrete modular components: male joints with protruding fingers and female joints with corresponding recesses. This segmentation allows each component to be manufactured independently and assembled systematically, eliminating the need for time-consuming scraping operations while maintaining ease of assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fingers and recesses are pre-formed during the panel manufacturing process using automated machining. This preliminary action eliminates the need for subsequent manual scraping to remove core material, thereby reducing production time while maintaining the interlocking joint functionality.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If conventional staggered joint method is used, then panels can be joined, but manufacturing precision deteriorates due to curling and rippling

Engineering Contradiction:
Improvejoint consistencyVSAvoidjoint flatness
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The joint design incorporates localized structural features (fingers and recesses) that distribute stresses and constrain panel deformation at specific locations. This local quality enhancement prevents curling and rippling along the joint line, maintaining joint flatness and manufacturing precision.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The male and female joints have asymmetric complementary geometries with fingers on one panel matching recesses on the other. This asymmetric design creates a mechanical interlock that constrains relative movement and prevents deformation, ensuring consistent and precise joint formation.

Inventive Principle:
Principle #4Asymmetry

3Manufacturing precision

If manual scraping is performed to remove core remnants, then clean joints are achieved, but device complexity increases and production time increases

Engineering Contradiction:
Improvejoint cleanlinessVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The design extracts and removes core material during the automated machining process that forms the fingers and recesses. By taking out the core material in the initial machining step rather than requiring separate scraping operations, the joint achieves cleanliness without increasing process complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

4Reliability

If conventional joint method with core removal is used, then panels can be joined, but loss of substance increases due to core material waste

Engineering Contradiction:
Improvejoint strengthVSAvoidcore material waste
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The finger and recess geometry is designed to nest together efficiently, with the protruding fingers of one panel fitting into the recesses of the other. This nesting arrangement maximizes the utilization of core material in the joint region, maintaining joint strength while minimizing material waste compared to conventional removal methods.

Inventive Principle:
Principle #7Nested doll (Nesting)

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

This method reduces production time, simplifies assembly and cleaning, improves visual appearance, and minimizes the need for scrapping defective parts by ensuring a strong and consistent joint.

Implementation Method 1

an adhesive, applied to at least one of the first longitudinal edge and the second longitudinal edge

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3854571B1Sandwich panel joints and methods for joining sandwich panels
Publication Date: 2023.08.23 THE BOEING CO

AI summary

Joints for joining panels together, such as for joining honeycomb sandwich panels used in aerospace applications, and methods of joining said panels are disclosed. In some examples of disclosed joints, a first panel and a second panel can be joined together to form a joint. The first panel can be a flat panel that includes a rabbet formed along a first longitudinal edge, and the second panel can be a curved panel that includes a notch formed along a second longitudinal edge. In forming the joint, a portion of the rabbet can be positioned within the notch, and the flat panel and curved panel can be oriented at a non-parallel and non-perpendicular angle to one another. Adhesive can be applied along the rabbet and/or the notch in order to secure the joint.