Polysiloxane Rocket Motor Seals for Cavitation-Resistant Flexibility

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Solution Overview

Problem

Conventional flexible seals for rocket motor assemblies face limitations in production efficiency and performance due to material compositions and properties, such as high production costs, low strength, susceptibility to cavitation and loading damage, poor low-temperature capabilities, and poor aging characteristics.

Innovation Solution

A method of forming flexible structures using a polysiloxane composition comprising at least two different silicone materials, which are crosslinked to form a flexible annular seal with improved material properties, such as tailored Shore A hardness and shear modulus, suitable for a wide range of rocket motor assembly applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional flexible seals are formed from natural rubber or polyisoprene formulations, then the seals can provide basic flexibility and sealing function, but the production costs increase significantly due to the large number of ingredients required

Engineering Contradiction:
Improvesealing functionVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses composite silicone rubber formulations combining multiple silicone base polymers with different molecular weights and structures to achieve the desired balance of flexibility, strength, and sealing properties while reducing dependence on numerous additives required by conventional rubber formulations

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent systematically varies key material parameters including silicone polymer molecular weight, crosslinking density, and Shore A hardness to optimize the seal performance and production efficiency, demonstrating how parameter optimization can reduce material complexity

Inventive Principle:
Principle #35Parameter changes

2Strength

If conventional flexible seals use natural rubber or polyisoprene formulations, then the seals can provide basic elastic properties, but the strength and resistance to cavitation and loading damage are significantly reduced

Engineering Contradiction:
Improveresistance to cavitation and loading damageVSAvoiddurability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent employs composite silicone rubber formulations that combine high-molecular-weight silicone polymers for strength with lower-molecular-weight polymers for flexibility, creating a material system that simultaneously achieves high resistance to cavitation and loading damage while maintaining durability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent implements different material properties in different regions of the seal cross-section, with harder, more strength-oriented formulations in load-bearing regions and softer, more flexible formulations in sealing-contact regions, optimizing both strength and durability

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If conventional flexible seals use silicone rubber formulations with a single preselected grade, then the material properties are consistent, but the adaptability to different rocket motor assembly types is very limited

Engineering Contradiction:
Improvematerial property consistencyVSAvoidapplicability to different rocket motor assembly types
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent establishes a systematic approach to varying silicone rubber formulation parameters including molecular weight distribution, crosslinking density, and Shore A hardness to create a family of adaptable seal formulations that can be optimized for different rocket motor assembly types while maintaining material consistency within each formulation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent develops a universal silicone rubber seal platform with adjustable parameters that can serve multiple rocket motor assembly applications, replacing the need for completely different material formulations for different applications

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Reliability

If conventional flexible seals are formed with complex multi-ingredient formulations, then the desired material properties can be achieved, but the production efficiency is significantly reduced

Engineering Contradiction:
Improvematerial propertiesVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent uses composite silicone rubber formulations that achieve desired material properties through the synergistic combination of a limited number of well-selected silicone base polymers and minimal additives, simplifying the manufacturing process while maintaining reliable material properties

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent extracts and eliminates unnecessary ingredients from conventional rubber formulations, retaining only the essential components needed to achieve the required seal performance, thereby streamlining the production process

Inventive Principle:
Principle #2Taking out (Extraction)

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 flexible structures exhibit enhanced capabilities, performance, durability, and reliability compared to conventional structures, enabling their use in a broader array of aerospace applications while simplifying component standardization and customization.

Implementation Method 1

The preliminary structure is cured and the cured polysiloxane composition comprises crosslinked polysiloxane chains of the first silicone material and the second silicone material

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentEP3059082B1Methods of forming flexible structures for a rocket motor assembly, related flexible structures, and related assemblies including the flexible structures
Publication Date: 2025.04.30 NORTHROP GRUMMAN SYSTEMS CORP
  • EP3059082B1 patent drawingFigure 1
  • EP3059082B1 patent drawingFigure 2
  • EP3059082B1 patent drawingFigure 3

AI summary

A method of forming a flexible structure for a rocket motor assembly comprises forming a polysiloxane composition comprising at least two different silicone materials. A preliminary structure is formed from the polysiloxane composition. The preliminary structure is cured to crosslink at least a portion of different polysiloxane chains of the preliminary structure. A flexible structure for a rocket motor assembly, a flexible assembly for a rocket motor assembly, a moveable thrust nozzle assembly for a rocket motor assembly, and a rocket motor assembly are also described.