Automated Lay-Up Backing Sheet Burst Strength and Pattern Transfer

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Solution Overview

Problem

Automated tape laying machines face issues with backing sheet failure and contamination due to tensional spikes and pattern transfer of fibre reinforcement into the resin, leading to increased waste and reduced efficiency.

Innovation Solution

Incorporating a fibre-reinforced cellulose paper as the first backing layer and a pattern-free, incompressible second backing paper, such as glassine paper, to enhance burst strength and reduce tear resistance, while a third backing paper can be added to prevent curling and wrinkling, and using a structural layer with unidirectional fibres and a curable thermosetting resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If fibre reinforcement is added to the backing paper to improve burst strength, then burst strength is improved, but fibre pattern transfer occurs into the resin

Engineering Contradiction:

Improveburst strengthVSAvoidfibre pattern transfer

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

A release film is introduced as an intermediary layer between the fibre-reinforced backing paper and the resin-impregnated structural layer. This release film prevents direct contact between the fibres and resin, thereby eliminating fibre pattern transfer while allowing the fibre-reinforced backing paper to maintain high burst strength. The release film acts as a barrier that mediates the interaction between the two layers.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The backing system is segmented into distinct functional layers: a fibre-reinforced backing paper for mechanical strength, a release film for preventing fibre transfer, and a structural layer with resin. This segmentation allows each layer to perform its specific function without interfering with others, solving the contradiction between strength and fibre transfer.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the backing sheet is made more resistant to tear and burst, then reliability is improved, but the complexity of the backing sheet structure increases

Engineering Contradiction:

Improvebacking sheet integrityVSAvoidbacking sheet structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The backing sheet is constructed as a composite material system combining cellulose paper with fibre reinforcement (such as glass fibre, carbon fibre, or aramid fibre). This composite structure provides enhanced tear and burst resistance while maintaining a relatively simple overall architecture. The composite nature allows the backing sheet to achieve high reliability without excessive complexity.

Inventive Principle:

Principle #40Composite materials

3Strength

If the ATL apparatus applies high tension to the composite material during lay-up, then adhesion is improved, but tensional spikes cause backing layer breakage

Engineering Contradiction:

ImproveadhesionVSAvoidbacking layer continuity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The fibre reinforcement in the backing paper acts as a cushioning element that absorbs and distributes tensional spikes before they can propagate through the entire backing layer. The high-strength fibres prevent the formation of run-length defects and maintain backing layer continuity even under high tension conditions during automated lay-up.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP2822758B1Composite material for automated lay-up

Publication Date: 2018.10.17 HEXCEL COMPOSITES LTD (GB)

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AI summary

A sheet-like composite material comprising a structural layer and curable thermosetting resin, and comprising a fibre-reinforced backing paper on one of its external faces.