Composite Pre-form with Non-Continuous Resin for Gas Escape

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Solution Overview

Problem

Existing pre-forms for fibre-reinforced composites face challenges with reproducibility, porosity, and handling due to sliding layers and time-consuming resin infusion, which can lead to trapped gas and undesirable shape restrictions during curing.

Innovation Solution

A pre-form comprising multiple layers of oriented fibre tows with a non-continuous resin distribution and selective adhesive application, facilitating automated processing and gas escape, while allowing for higher freedom in design and reduced waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resin infusion is used to cure the pre-form, then the pre-form achieves structural integrity, but the process becomes time-consuming and may trap gas

Engineering Contradiction:

Improvestructural integrityVSAvoidcuring time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The resin is distributed in non-continuous layers rather than as a continuous medium, creating segmented resin zones that allow gas to escape through the spaces between resin layers while still providing structural integrity where needed

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces gas escape paths in the thickness direction (z-direction) perpendicular to the fibre layer planes, adding a new dimension for gas removal that doesn't interfere with the in-plane structural integrity provided by continuous fibre layers

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If cross-ply stitching is used to prevent layer sliding, then handling stability improves, but the process becomes tedious and introduces shape restrictions

Engineering Contradiction:

Improvelayer stabilityVSAvoidprocess complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent removes the stitching element entirely and replaces it with adhesive application at specific locations, extracting the unnecessary complexity of cross-ply stitching while maintaining layer stability through targeted adhesive bonding

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Adhesive is introduced as an intermediary substance applied selectively between fibre layers to prevent sliding, replacing the mechanical stitching approach with a chemical bonding approach that is simpler to apply and doesn't restrict shape

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If continuous resin layers are used, then structural strength is achieved, but gas removal becomes difficult and porosity increases

Engineering Contradiction:

Improvestructural strengthVSAvoidgas entrapment

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The resin distribution is made non-uniform with different properties in different locations: continuous resin layers provide strength where needed, while non-continuous resin distribution with gaps allows gas escape in other areas, creating local variations in resin continuity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The non-continuous resin distribution creates a porous or gap-containing structure that facilitates gas permeation and escape during curing, reducing porosity and gas entrapment while maintaining structural integrity through strategic resin placement

Inventive Principle:

Principle #31Porous materials

4Adaptability or versatility

If individual fibres are used instead of prepregs, then design freedom and cost improve, but fibre rearrangement during processing becomes more difficult

Engineering Contradiction:

Improvedesign freedomVSAvoidfibre rearrangement

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Adhesive is applied preliminarily to fibre layers before final assembly, temporarily fixing fibres in their desired orientations and preventing unwanted rearrangement during subsequent processing steps, enabling use of individual fibres with full design freedom

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8778479B2Pre-form and method of preparing a pre-form

Publication Date: 2014.07.15 VESTAS WIND SYSTEMS AS

AI summary

A pre-form and a method of preparing pre-forms are provided. The pre-forms comprise a resin and at least two layers of oriented fiber tows. The pre-forms comprise fiber tows instead of the traditional prepregs to enhance rearranging of resin and/or fibers during subsequent processing as well as provide greater freedom, a price reduction and/or a reduction of waste. The pre-forms may be formed three-dimensionally to enhance coupling to further pre-forms or other structures and/or to enhance shaping of the pre-form to a final three-dimensional shape. The method of preparation of pre-forms involves providing an adhesive between layers of fibers and providing a resin in contact with at least one of the layers of fibers. The resin is preferably provided in a non-continuous layer to allow for removal of gas at least partially in a direction orthogonal to the layers of resin. The pre-forms are suitable for preparation of composite structures like for example spars for wind turbine blades.