Stitched Composite Barrier Layers for Cryogenic Tank Permeation

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Solution Overview

Problem

Cryogenic propellant tanks in space launch vehicles face issues with transverse micro-cracking and gas permeation due to thermal and mechanical stresses, leading to hazardous leakage, which existing solutions like metal liners and unstitched composites fail to adequately address without compromising structural strength.

Innovation Solution

A stitched polymer matrix composite with thin plies and nanographene-reinforced resin is used, where thin plies deflect transverse cracks and nanographene enhances fracture toughness, reducing micro-crack networks and gas permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal liners are used to reduce gas permeation, then gas permeation is reduced, but the coefficient of thermal expansion mismatch causes debonding and excessive permeation

Engineering Contradiction:

Improvegas permeation resistanceVSAvoidbond strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent employs a composite liner system combining thermoplastic polymer liner with nanocomponents (nano-clay, nano-silica, or carbon nanotubes) embedded within the polymer matrix. This composite structure provides both gas permeation resistance and thermal expansion compatibility, eliminating the debonding issue while maintaining low permeability

Inventive Principle:

Principle #40Composite materials

2Reliability

If nanocomponents are added to reduce gas permeability, then gas permeability is reduced, but agglomeration and filtration issues prevent use in VARTM process

Engineering Contradiction:

Improvegas permeabilityVSAvoidmanufacturability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the nanocomponent parameters by selecting specific particle sizes, shapes, and surface treatments that prevent agglomeration. The nanocomponents are carefully dispersed in the thermoplastic matrix before VARTM processing, with controlled concentration levels (typically 0.1-5% by weight) that maintain both permeability reduction and processability

Inventive Principle:

Principle #35Parameter changes

3Reliability

If thin plies are embedded to stop micro-crack progression, then micro-crack propagation is mitigated, but the very low cured thickness does not provide sufficient energy to prevent crack propagation

Engineering Contradiction:

Improvecrack resistanceVSAvoidcrack propagation resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent creates a multi-layer composite structure where thin plies (prepregs) are embedded within unstitched laminates. These thin plies act as crack arrestors by forcing cracks to change direction and consume additional energy. The combination of thin plies with nanocomponent-reinforced thermoplastic matrix provides synergistic crack resistance that neither component achieves alone

Inventive Principle:

Principle #40Composite materials

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 hybrid composite material effectively reduces gas permeability and maintains structural integrity by deflecting cracks and enhancing resin-rich area toughness, enabling the formation of lightweight, unitized cryogenic tanks without bonded joints.

Implementation Method 1

nanographene-strengthened resin

Methodology Applied

Scientific EffectNanocomposite reinforcement: Nanocomposite

Implementation Method 2

enhances fracture toughness

Methodology Applied

Scientific EffectFracture mechanics: Fracture Mechanics

Implementation Method 3

thin plies deflect transverse cracks

Methodology Applied

Scientific EffectCrack deflection: Fracture Mechanics

Implementation Method 4

reduce gas permeability

Methodology Applied

Scientific EffectPermeation barrier: Permeation

Data Source

PatentUS12529450B2Stitched polymer matrix composites using barrier layers for cryogenic applications and methods of making the same

Publication Date: 2026.01.20 MISSISSIPPI STATE UNIVERSITY

AI summary

Provided herein are polymer matrix composites, articles including the polymer matrix composites, and methods of forming the polymer matrix composites. The polymer matrix composite includes a stitched composite and a hybrid barrier layer incorporated within the stitched composite, the hybrid barrier layer including a thin ply and a nanographene dispersed resin. The article includes a high-pressure composite cryogenic tank including the polymer matrix composite. The method includes positioning a dry thin ply between composite plies, stitching the composite plies to form a stitched preform, dispersing nanographene into the resin, and infusing the stitched preform with the modified resin.