Hygrothermal-Mechanical Interface Noodle Modeling for Progressive Cracking

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Solution Overview

Problem

Conventional methods for analyzing stresses and loads on composite filler materials in connection interfaces are inadequate, particularly for modern aircraft designs, failing to accurately predict progressive cracking due to residual and thermal stresses, and are limited to single failure events, lacking the ability to model the density and spacing of multiple cracks.

Innovation Solution

A method that models initial and residual stresses on composite filler materials using a computer to predict progressive cracking, refining the mesh of the FEM function, comparing crack density to a baseline, and modifying the ILS strength to generate a refined computer model that accurately predicts crack density and spacing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods are used to analyze stresses on composite filler materials, then the analysis process is simple, but the accuracy of predicting progressive cracking is insufficient

Engineering Contradiction:
Improvecrack prediction accuracyVSAvoidmodeling complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the filler material into multiple discrete crack elements, each capable of independent crack initiation and propagation. This segmentation allows the model to track individual crack development through the material thickness, significantly improving crack prediction accuracy while maintaining manageable computational complexity through systematic element formulation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from conventional 2D surface analysis to 3D volumetric modeling by introducing crack elements that extend through the filler material thickness. This dimensional enhancement enables accurate prediction of progressive cracking patterns in three dimensions, capturing the true complexity of crack propagation while providing comprehensive structural assessment.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If conventional analysis methods are used, then the computational process is fast, but the ability to model multiple crack density and spacing is limited

Engineering Contradiction:
Improveprogressive cracking predictionVSAvoidcomputational efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements parameter changes by introducing crack density and spacing as explicit model parameters that can be systematically varied. This allows reliable prediction of progressive cracking under different loading scenarios and material properties, while the parameterized formulation enables efficient computational exploration of design spaces through sensitivity studies and optimization.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary action by pre-defining crack element positions, orientations, and properties before structural analysis. This preliminary configuration enables the model to efficiently track crack initiation and propagation sequences, improving predictive reliability while reducing computational overhead during the actual structural simulation by avoiding dynamic crack path calculation.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If detailed FEM mesh refinement is performed to improve crack prediction, then the modeling precision increases, but the computational cost increases

Engineering Contradiction:
Improvecrack density modeling precisionVSAvoidcomputational energy
Core Design Contradiction:
Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The patent extracts the crack modeling function from the general FEM mesh by introducing separate, dedicated crack elements that are independently formulated and analyzed. This extraction allows high-precision crack density modeling in critical regions while using coarser mesh elsewhere, significantly reducing overall computational energy requirements while maintaining manufacturing precision for crack prediction.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by refining the FEM mesh only in regions where crack initiation and propagation are expected, rather than uniformly refining the entire model. This selective refinement achieves the necessary crack density modeling precision in critical areas while minimizing computational energy consumption in regions where detailed meshing is not required for crack prediction accuracy.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3663960B1Method for determining noodle and interface residual stresses and properties under hygrothermal-mechanical loadings
Publication Date: 2025.07.09 THE BOEING CO
  • EP3663960B1 patent drawingFigure 1A
  • EP3663960B1 patent drawingFigure 1B
  • EP3663960B1 patent drawingFigure 2

AI summary

A computer is configured to generate a computer model predicting the progressive creation, density, and spacing of a plurality of cracks in a filler material, such as a "noodle," for example, disposed at a connection interface between a load-bearing composite structural component, such as a stringer or a spar, for example, and the structural framework of a vehicle on which those structural components are utilized.