Composite Core Structure Using Thermal Compression Layers

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Solution Overview

Problem

Residual thermal stresses during the curing process of composite structures with foam or honeycomb cores lead to cracks and delamination, reducing the service life and increasing rejection rates.

Innovation Solution

A composite structure design with asymmetrically oriented compression layers on the skin, featuring different thermal expansion coefficients, which induces compressive forces on the core material upon cooling, mitigating tensile stresses and enhancing structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional symmetric composite structure is used, then manufacturing process is simple, but thermal stress causes cracks and delamination

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoidstructural integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by positioning compression layers at different locations on the skin surface (e.g., leading edge vs trailing edge, or different circumferential positions) rather than symmetrically. This asymmetric arrangement creates differential thermal contraction that generates compressive forces on the core material during cooling, counteracting tensile thermal stresses and preventing cracks and delamination while maintaining manufacturing simplicity

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent changes the spatial parameter of compression layer positioning from symmetric to asymmetric arrangements. By modifying the position parameters (angular position, radial position, or circumferential distribution) of compression layers, the structure generates beneficial compressive thermal stresses that improve reliability without significantly complicating the manufacturing process

Inventive Principle:
Principle #35Parameter changes

2Reliability

If compression layers are added to mitigate thermal stress, then structural integrity improves, but device complexity increases

Engineering Contradiction:
Improvestructural integrityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by placing compression layers only at specific critical locations on the skin (such as leading edge, trailing edge, or specific circumferential positions) rather than uniformly across the entire structure. This localized approach generates the necessary compressive thermal stresses to improve structural integrity while minimizing the additional complexity compared to a uniform symmetric design

Inventive Principle:
Principle #3Local quality

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 design effectively reduces thermal stress-induced failures by applying compressive forces to the core, thereby improving structural durability and reducing defects.

Implementation Method 1

A composite structure design with asymmetrically oriented compression layers on the skin, featuring different thermal expansion coefficients, which induces compressive forces on the core material upon cooling

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3318394B1Composite structure
Publication Date: 2026.03.18 RATIER FIGEAC SAS
  • EP3318394B1 patent drawingFigure 1~2
  • EP3318394B1 patent drawingFigure 3~6

AI summary

Method of manufacturing a composite component (10) comprises forming a core (22), surrounding the circumference of the core with a first layer of fabric (24), applying a second layer of fabric (26) having a different coefficient of thermal expansion from the first layer such that the second layer extends around at least a portion of the circumference of the core and curing the component such that the second layer imparts a compressive or tensile force on the core.