Composite Pre-Form with Surface Recesses for Air Voids

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Solution Overview

Problem

Trapped air within composite structures, such as wind turbine blades, weakens the structure and reduces its overall strength, as existing methods struggle to effectively remove air voids during consolidation.

Innovation Solution

A pre-consolidated pre-form with recesses on its surfaces is used, allowing trapped air to escape and excess or infused binding agent to flow through these channels, minimizing air voids and enhancing structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional consolidation methods are used to stack sheets to form composite structures, then the structure can be assembled, but air becomes trapped between layers creating weak zones that reduce overall strength

Engineering Contradiction:

Improveoverall structure strengthVSAvoidtrapped air voids

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The pre-form is pre-consolidated with channels formed within it before being integrated into the composite structure. These channels are prepared in advance to facilitate air removal during the consolidation process, preventing trapped air voids from forming in the final structure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Channels within the pre-form act as intermediary pathways that facilitate the removal of air between the reinforcement layers and the composite structure. These channels provide a controlled route for air to escape during consolidation, preventing harmful air pockets from forming.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If additional binding agent is introduced during consolidation to fill voids, then structure strength is improved, but production cost and complexity increase

Engineering Contradiction:

Improvestructure strengthVSAvoidconsolidation process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Instead of adding more binding agent to fill air voids, the invention extracts or removes the air from the structure through the channels in the pre-form. This approach eliminates the need for additional material and simplifies the consolidation process by focusing on air removal rather than void filling.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If endless sheet material is cut into elements for stacking, then the composite structure can be assembled, but waste sheet material is produced increasing production costs

Engineering Contradiction:

Improvestructure assemblyVSAvoidwaste sheet material

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The pre-form is manufactured in advance with the exact dimensions and shape needed for the final composite structure. This preliminary fabrication eliminates the need to cut endless sheet material into elements, thereby preventing waste material from being generated during assembly.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8986487B2Consolidated composite pre-form

Publication Date: 2015.03.24 VESTAS WIND SYSTEMS AS

AI summary

The present invention relates to a consolidated composite pre-form for reinforcing a composite structure, said pre-form comprising fibers and a binding agent, said pre-form having a sheet-like structure with an upper major surface and a lower major surface, and said pre-form being provided with recesses on at least a portion of at least one of said major surfaces.