Syntactic Foam Coating Structure for Reduced Stress Risers

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Solution Overview

Problem

Conventional methods for making syntactic foams face challenges in creating stress-resistant and durable buoyancy foams with efficient and cost-effective manufacturing processes, as single contact points between low-density spheres can create stress risers and increase foam density.

Innovation Solution

A method involving coating low-density spheres in situ with a variable thickness resin coating where they contact each other, followed by infusing them in a resin to form a lattice arrangement, minimizing stress risers and enhancing strength-to-weight ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If low-density spheres are arranged in a lattice with single contact points, then the manufacturing process is simplified, but stress risers increase and durability decreases

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoiddurability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating variable thickness resin coatings that are thicker at contact points between spheres and thinner at non-contact areas. This localized variation in coating thickness provides enhanced stress distribution at critical contact regions while maintaining the overall lattice structure simplicity, thereby improving durability without complicating the manufacturing process

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If resin coating is applied uniformly around low-density spheres, then manufacturing is easier, but stress distribution is poor and strength-to-weight ratio decreases

Engineering Contradiction:
Improvecoating application simplicityVSAvoidstrength-to-weight ratio
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The invention implements local quality through variable thickness resin coatings where the coating thickness is intentionally varied - thicker at contact points between spheres and thinner at non-contact areas. This localized differentiation optimizes stress distribution at critical regions, improving the strength-to-weight ratio while maintaining relatively simple manufacturing processes

Inventive Principle:
Principle #3Local quality

3Productivity

If excess resin is not drained from the mold, then production time is reduced, but foam density increases and buoyancy performance decreases

Engineering Contradiction:
Improveproduction speedVSAvoidfoam density
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by controlling the resin quantity and drainage parameters during the molding process. By optimizing the drainage process to remove excess resin while maintaining efficient production timing, the method achieves the desired foam density for optimal buoyancy performance without significantly compromising production speed

Inventive Principle:
Principle #35Parameter changes

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

The method produces syntactic-foam parts with reduced stress risers and improved durability by distributing stress through thickened resin regions, resulting in stronger and more reliable buoyancy foams.

Implementation Method 1

coating the low-density spheres in the lattice arrangement with the first resin to form a coating, made of the first resin, around an entirety of each one of the low-density spheres

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP4686552A1Syntactic-foam parts and associated methods of making the same
Publication Date: 2026.02.04 THE BOEING CO
  • EP4686552A1 patent drawingFigure 1
  • EP4686552A1 patent drawingFigure 2
  • EP4686552A1 patent drawingFigure 3A

AI summary

A method (200) of making a syntactic-foam part (142) includes loading low-density spheres (120) into a mold (102). The method also includes introducing a first resin (138) into the mold. The method further includes coating the low-density spheres with the first resin to form a coating (136), made of the first resin, around an entirety of each one of the low-density spheres. The method additionally includes solidifying the first resin after the first resin is coated on the low-density spheres. The method also includes solidifying the second resin (140) after the second resin fills the mold.