Buoyancy Module Syntactic Foam Low Density Pressure Resistance

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Solution Overview

Problem

Existing buoyancy modules for subsea applications face challenges in achieving both low density and high hydrostatic pressure resistance, with epoxy syntactic foams exhibiting poor crush strength and manufacturing issues due to the use of hollow glass microspheres and liquid epoxy resins.

Innovation Solution

The development of buoyancy modules using a combination of thermally fusable powder and glass microspheres, where the mixture is heated under vacuum to create a hardened syntactic foam with low density and high compressive strength, and optionally applying a barrier layer for enhanced protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If composite macrospheres with diameters of 10-100 millimeters are used to make buoyancy modules, then low density is achieved, but hydrostatic pressure resistance deteriorates due to poor crush strength of the macrospheres

Engineering Contradiction:
ImprovedensityVSAvoidhydrostatic pressure resistance
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent uses a composite material system combining thermally fusable powder (epoxy resin) with hollow glass microspheres. This composite approach allows the material to achieve both low density from the microspheres and high hydrostatic pressure resistance from the resin matrix that binds and protects the microspheres, resolving the contradiction between lightness and pressure resistance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the physical state of the resin from liquid to thermally fusable powder form. This parameter change allows the resin to flow and fill voids during heating, creating a dense matrix that thoroughly encapsulates the microspheres, thereby maximizing both density reduction and pressure resistance simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Weight of moving object

If hollow glass microspheres are mixed with liquid epoxy resins to fabricate buoyancy modules, then low density is achieved, but manufacturing quality deteriorates due to increased viscosity limiting filler amount

Engineering Contradiction:
ImprovedensityVSAvoidfiller amount control
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

The patent changes the resin from liquid state to thermally fusable powder state. This parameter change eliminates the viscosity problem entirely, as the powder does not exhibit flow resistance during mixing. The resin only flows when heated during curing, allowing maximum microsphere loading while maintaining easy processability during the mixing stage.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If reactive diluents are blended in to mitigate viscosity issues, then processability is improved, but mechanical properties deteriorate due to brittleness and inferior cured epoxy quality

Engineering Contradiction:
ImproveprocessabilityVSAvoidmechanical properties
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the resin state from liquid to powder, eliminating the need for reactive diluents entirely. The powder form maintains low viscosity during mixing without compromising the epoxy's curing properties, thus preserving both ease of manufacture and mechanical strength without the trade-off required by diluent addition.

Inventive Principle:
Principle #35Parameter changes

4Weight of moving object

If liquid epoxy resins are used to make buoyancy modules, then low density is achieved, but work life deteriorates due to limited working time once mixed with curing agent

Engineering Contradiction:
ImprovedensityVSAvoidwork life
Core Design Contradiction:
Weight of moving objectVSLoss of time

Solution Approach 1:

The patent changes the resin from liquid to thermally fusable powder form. This eliminates the immediate curing reaction that limits work life in liquid systems. The powder resin remains stable during mixing and only begins to cure when heated, providing extended work life and allowing complete microsphere incorporation before the curing process begins.

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 solution provides buoyancy modules with improved hydrostatic pressure resistance and low density, effectively addressing the limitations of previous materials by maintaining structural integrity under deep-sea conditions.

Implementation Method 1

heating the thermally fusable powder under a vacuum to provide a hardened syntactic foam

Methodology Applied
Scientific EffectThermal melting: Melting

Implementation Method 2

heating the thermally fusable powder under a vacuum to provide a hardened syntactic foam, the vacuum being sufficient to remove substantially all embedded voids

Methodology Applied
Scientific EffectVacuum degassing: Vacuum

Data Source

PatentEP3307978B1Buoyancy module and method of making such a module
Publication Date: 2020.04.01 3M INNOVATIVE PROPERTIES CO
  • EP3307978B1 patent drawingFigure 1~2
  • EP3307978B1 patent drawingFigure 3

AI summary

Buoyancy modules (200) are made from a foam composition that includes a combination of a thermally fusable powder and glass microspheres heated in a manner that provides a hardened syntactic foam having both low density and a high degree of compressive strength. An outer barrier (220) may enclose the buoyancy module.