Composite Structure Moisture Analysis via Decoupled Thermal Modeling

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Solution Overview

Problem

Conventional methods for determining the allowable moisture content in composite structures, particularly in thick aircraft components, require significant computing power and time, leading to over-engineered designs that increase weight and costs, as they rely on constant saturation levels designed for thinner structures.

Innovation Solution

A computer-implemented method and system that perform iterative thermal and moisture content analyses independently, using environmental parameter profiles to determine a temporal surface temperature profile and moisture content, allowing for the calculation of allowable moisture content based on thickness, reducing computational requirements and optimizing design for thicker structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a constant saturation level is used in the design of composite structures, then the design is conservative and ensures service lifetime, but the composite structure becomes over-engineered and increases weight

Engineering Contradiction:

Improveservice lifetimeVSAvoidaircraft weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent changes the saturation level parameter from a constant value to a variable that depends on composite structure thickness. Thinner structures use lower saturation levels (e.g., 2-4%) while thicker structures use higher saturation levels (e.g., 6-8%), optimizing the balance between reliability and weight for each specific application.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The design approach transitions from a static, one-size-fits-all saturation level to a dynamic, thickness-dependent saturation level. This allows the design parameters to adapt to the specific geometry and moisture absorption characteristics of each composite structure.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If conventional thermal and moisture diffusion analyses are performed as a coupling, then accurate moisture content is determined, but significant computing power and time are required

Engineering Contradiction:

Improvemoisture content determination accuracyVSAvoidcalculation time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the coupled thermal-moisture analysis into two independent sequential analyses: first a thermal analysis to determine temperature profiles, then a moisture diffusion analysis using those temperature profiles as input. This decoupling maintains accuracy while dramatically reducing computational complexity and time requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The thermal analysis is performed first as a preliminary step to establish the temperature field before conducting the moisture diffusion analysis. This preliminary determination of temperature profiles eliminates the need for iterative coupled calculations, reducing overall computation time.

Inventive Principle:

Principle #10Preliminary action

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 approach enables the production of thinner gauge composite structures that maintain strength while reducing aircraft weight and manufacturing costs, by accurately determining moisture content based on thickness and environmental exposure, thus providing a more efficient design process.

Implementation Method 1

Certain groups of materials, such as certain plastics and epoxy resin composite structures, readily absorb moisture by diffusion

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

performing a thermal analysis calculation on the composite structure to determine a temporal surface temperature profile of the composite structure based on temporal environmental parameter profiles

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10983078B2Methods and systems for designing a composite structure

Publication Date: 2021.04.20 THE BOEING CO

AI summary

A computer-implemented method of determining moisture content of a composite structure is provided. The method includes performing a thermal analysis calculation on the composite structure to determine a temporal surface temperature profile of the composite structure based on temporal environmental parameter profiles, wherein the surface temperature profile is determined independently of a moisture content of the composite structure. The method also includes performing a moisture content analysis calculation on the composite structure to determine a moisture content of the composite structure, wherein the moisture content analysis calculation is based on the determined temporal surface temperature profile and a thickness of the composite structure. The thermal analysis calculation is performed iteratively with a first time period and the moisture content analysis calculation is performed iteratively with a second time period that is longer than the first time period.