Composite Blade Skin Overlap for Delamination Resistance

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Solution Overview

Problem

Aerodynamic and hydrodynamic blades made of composite materials face issues with detachment and delamination due to high load fluctuations, particularly at the adhesion points between skin and spar layers, leading to fatigue and potential failure.

Innovation Solution

The blade design integrates body portions seamlessly into the skin layers, with overlapping skin portions that extend towards the trailing edge, forming a U-shaped structure, reducing the risk of delamination and enhancing structural integrity by creating a torsion box and using fillers like foam material for added strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the spars are attached to the interior surface of the skins using adhesive layers, then the blade structure can be assembled, but the adhesion between skins and spars becomes vulnerable to detachment under high load fluctuations

Engineering Contradiction:

Improveassembly of blade structureVSAvoidadhesion between skins and spars

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The spar and skin are merged into a single integral composite structure through continuous fiber layers that form both the body portion and skin portions. This eliminates the adhesive interface between separate components, preventing detachment while maintaining structural assembly capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The blade uses composite material layers where fibers run continuously from the body portion into the skin portions, creating an integrated composite structure. This composite construction eliminates weak adhesive bonds and provides unified structural integrity under load fluctuations.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the fiber material layers extend continuously between the leading edge and trailing edge, then the skin structure is formed, but delamination can progress across the entire flow profile without being hindered

Engineering Contradiction:

Improveformation of skin structureVSAvoidresistance to delamination progression

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The continuous skin structure is segmented into overlapping skin portions within the composite layers. Each skin portion is bounded by edges that do not extend across the entire chord, creating segments that overlap with adjacent portions. This segmentation limits delamination progression to individual segments rather than allowing continuous spread across the entire skin.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The skin portions are arranged in overlapping layers within the thickness dimension of the composite structure. This layered overlap creates a three-dimensional configuration where delamination in one layer is contained and does not automatically propagate through all layers, adding dimensional containment to the anti-delamination strategy.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Force

If the spars have flanges at both outer ends for adhesion to skins, then force transmission is ensured, but the adhesion points become vulnerable to fatigue under fluctuating loads

Engineering Contradiction:

Improvetransmission of forcesVSAvoidresistance to fatigue at adhesion points

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The force transmission function previously performed by spar flanges adhering to skins is merged into the integral composite structure. Fibers run continuously from the body portion through the skin portions, providing force transmission without requiring separate adhesion interfaces, thereby eliminating fatigue vulnerabilities at connection points.

Inventive Principle:

Principle #5Merging (Combining)

4Ease of manufacture

If the body and skin portions are separate components glued together, then manufacturing is simplified, but the risk of delamination increases

Engineering Contradiction:

Improvemanufacturing of separate componentsVSAvoidrisk of delamination

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The body portion and skin portions are merged into a single integral component formed from continuous composite material layers. The fibers run continuously from the body into the skin portions, eliminating the need for separate components and adhesive bonding, thereby preventing delamination while maintaining manufacturing feasibility through composite forming processes.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11753946B2Aerodynamic or hydrodynamic blade made of layered material

Publication Date: 2023.09.12 FIBERCORE IP

AI summary

A blade made of layered material, such as composite material, configured for exposure to a fluid flow, comprises skins (1, 2) defined between a leading edge (3) and a trailing edge (4) which skins in cross-section form a flow profile. The layered material may consist of several layers of fiber material (5, 5′, . . . ) impregnated with a matrix material, wherein layers of fiber material each comprise a respective body portion (6, 6′, . . . , 13) between and transverse to the skins and each at least a respective skin portion (7, 7′, . . . ; 8, 8′, . . . ) that forms part of the skins. The said skin portions all extend from the related body portion in the direction of the trailing edge. Of said skin portions at least two consecutive skin portions of the one skin overlap and/or two consecutive skin portions of the other skin overlap each other.