Curved Thermoplastic Composite Fabrication with Varying Thickness

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Solution Overview

Problem

Current methods for fabricating thermoplastic composite laminates are unable to produce parts with varying thicknesses and curvature in a continuous process, which is essential for lightweight aerospace structures and other applications where weight is a critical factor.

Innovation Solution

A novel method involving the formation of a multi-ply stack with non-uniform thickness, cutting a curved blank, and using automated equipment or hand lay-up to create a preformed part that is then compacted using a press with customized tooling to achieve tailored and varying thicknesses, allowing for the production of curved thermoplastic composite laminates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional continuous processes (extrusion, pultrusion, roll forming) are used to fabricate thermoplastic composite laminates, then production efficiency and continuity are improved, but the ability to produce parts with varying thicknesses and curvature is lost

Engineering Contradiction:

Improvecontinuous production capabilityVSAvoidability to produce varying thicknesses and curvature

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The continuous production process is segmented into distinct functional zones: a pre-forming zone that imparts curvature and initial shape, and a consolidation zone that applies compression to achieve final thickness and density. This segmentation allows each zone to perform its specific function optimally while maintaining continuous production.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pre-forming zone performs preliminary shaping of the laminate stack before consolidation. Curved tooling and pre-forming rollers are used to bend and shape the laminate to the desired curvature and thickness profile before the material enters the consolidation zone, enabling complex geometries to be achieved in continuous production.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If automated equipment is used to collate plies and maintain orientation, then manufacturing precision and consistency are improved, but equipment complexity increases

Engineering Contradiction:

Improveply orientation and location accuracyVSAvoidautomation equipment complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The automated ply collation system uses universal fixtures and positioning mechanisms that can accommodate multiple ply configurations and orientations. The same equipment infrastructure supports different laminate designs by reconfiguring the ply stacking sequence, reducing the need for dedicated complex equipment for each part design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If curved tooling is used to impart surface features and achieve varying thickness, then part geometry flexibility is improved, but tooling complexity and cost increase

Engineering Contradiction:

Improvepart geometry flexibilityVSAvoidcurved tooling complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The tooling system incorporates curvature in the third dimension to impart complex surface features and varying thickness profiles. Curved tooling surfaces and three-dimensional pre-forming fixtures enable the laminate to achieve sophisticated geometries that cannot be obtained with flat, two-dimensional tooling, while the continuous production approach amortizes the tooling complexity across high-volume manufacturing.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

Enables the production of curved thermoplastic composite laminates with tailored thicknesses in a continuous process, suitable for aerospace and automotive applications, such as structural stiffened members in aircraft, while being cost-effective and utilizing automated equipment.

Implementation Method 1

The plies in the stack are tacked together by local melting of the thermoplastic resin so that the plies are held in fixed relationship to each other

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

pressing the curved tool against the preformed part within the press imparts the surface features of the tool into the part as the plies are compacted

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS8333858B2Method for fabricating curved thermoplastic composite parts

Publication Date: 2012.12.18 THE BOEING CO

AI summary

A fabrication method of forming curved thermoplastic composite laminate parts with tailored and varying thickness in a continuous process. Automated equipment or hand lay-up are used to collate parts or components into a multi-layer stack. Each stack contains all plies, including ply build-up areas, tacked in the proper location to maintain orientation and location. Ply consolidation tooling contains all necessary part features and is coordinated to the customized multiple ply stacks to form a single integrated thermoplastic composite laminate potentially having areas of differing thickness from the multiple ply stacks.