Conductive Composite Laminate Slitting Distortion Control

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Solution Overview

Problem

Composite materials used in aerospace structures have reduced electrical conductivity, making them vulnerable to lightning strikes, and existing methods to enhance conductivity, such as using conductive additives or applying metal, are inefficient or labor-intensive.

Innovation Solution

A laminate structure with a fibrous layer and a conductive layer, where the fibrous layer is melt-bonded to a polymeric sheet, ensuring precise slitting to maintain narrow width tolerance and prevent distortion, allowing for efficient automated lay-up with improved electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If composite materials are used to reduce weight, then weight is reduced, but electrical conductivity deteriorates

Engineering Contradiction:
ImproveweightVSAvoidelectrical conductivity
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The invention uses a hybrid composite structure combining carbon fibers (conductive) and glass fibers (structural) in a single prepreg. The carbon fibers provide electrical conductivity while the glass fibers provide structural strength, and both are impregnated with the same resin matrix to ensure proper bonding and stress distribution throughout the laminate.

Inventive Principle:
Principle #40Composite materials

2Reliability

If metal is applied to surfaces to improve conductivity, then electrical conductivity is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the structural reinforcement function and electrical conductivity function into a single integrated layer. The conductive fiber-reinforced prepreg simultaneously provides mechanical strength from the fiber reinforcement and electrical conductivity from the conductive fiber network, eliminating the need for separate metal coating operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention changes the material parameters by incorporating conductive fibers directly into the prepreg matrix, transforming the conductivity parameter from an external coating property to an intrinsic material property. This allows conductivity to be built-in during the composite manufacturing process rather than added as a separate finishing step.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If slitting is performed to create narrow strips for automated lay-up, then productivity is improved, but width precision deteriorates due to distortion

Engineering Contradiction:
ImproveproductivityVSAvoidwidth precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention uses a flexible release film as a support carrier during slitting and handling. This thin film provides mechanical support to the narrow conductive strips, preventing them from distorting or deforming during the slitting process and subsequent automated lay-up operations, while still allowing for easy removal after placement.

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution achieves tight width tolerance in slit strips, enabling close contact and enhanced electrical conductivity, reducing the risk of lightning strikes and improving manufacturing efficiency.

Implementation Method 1

The fibrous layer may be melt bonded to the conductive layer to adhere the fibrous layer

Methodology Applied
Scientific EffectMelt bonding: Melting

Data Source

PatentEP2758234B1Conductive composite structure or laminate
Publication Date: 2018.01.24 HEXCEL COMPOSITES LTD (GB)
  • EP2758234B1 patent drawingFigure 1

AI summary

A laminate or structure which comprises a conductive layer, a fibrous layer and a support layer adhering to an outer face of the laminate or structure, the support layer preventing distortion of the conductive layer during slitting of the laminate or structure to form a conductive strip.