Flanged Hole Forming in Thermoplastic Composite Panels
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Solution Overview
Problem
Existing methods for producing flanged holes in composite panels with continuous fiber reinforcement, particularly those with thermoplastic matrices like PEEK, are inefficient and mass-inefficient, as they require additional reinforcement or are not applicable due to thermal expansion issues and consolidation challenges.
Innovation Solution
A method involving a shouldered cylindrical punch with a projecting support face and a rigid smoothing plate, combined with a heating-cooling cycle under pressure, to create flanged holes in composite panels with thermoplastic polymer matrices, allowing for effective compaction and differential expansion compensation without the need for hot punch-die devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional lamination plies or reinforcement pieces are assembled around the hole, then the panel rigidity is improved, but the mass increases
Solution Approach 1:
The reinforcement is segmented into discrete strips of fibrous material that are positioned in specific orientations around the hole perimeter, allowing targeted reinforcement without adding unnecessary mass throughout the entire panel
Solution Approach 2:
The reinforcement strips are arranged in multiple dimensional orientations (radial, circumferential, and angled patterns) around the hole, creating a three-dimensional reinforcement structure that maximizes rigidity while minimizing material usage
2Ease of manufacture
If forming processes like Guérin process or hydraulic bladder are used, then flanged holes are created in metal panels, but these processes are not applicable to composite material panels
Solution Approach 1:
The invention changes the fundamental parameter of the forming process from mechanical deformation (pressing) to thermal-mechanical processing (heating above melting point followed by compaction), making it applicable to thermoplastic composite materials while achieving the desired flanged hole geometry
Solution Approach 2:
The process utilizes the phase transition of the thermoplastic matrix from solid to molten state during heating, allowing the fibrous reinforcement to be repositioned and consolidated into the flanged hole configuration, then solidifies upon cooling to maintain the formed shape
3Productivity
If a shouldered cylindrical punch with projecting support face is used, then the flanged edge is formed during consolidation, but the smoothing plate is required to ensure uniform compaction
Solution Approach 1:
The punch and smoothing plate are merged into a single integrated tooling component, where the smoothing plate is positioned on the punch's support face, combining the hole-forming and surface-smoothing functions into one operation that maintains uniform compaction pressure
Solution Approach 2:
The smoothing plate acts as an intermediary element between the punch and the fibrous reinforcement, distributing the compaction pressure uniformly across the reinforcement strips while allowing the punch's shouldered geometry to define the flanged hole shape
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
This method enables the production of composite panels with flanged holes and local reinforcements in a single operation, enhancing panel rigidity without adding mass, and ensuring clean edges and uniform compaction pressure, suitable for aeronautical applications.
Implementation Method 1
consolidating the panel by subjecting it to a heating-cooling cycle under pressure, which cycle comprises heating to a temperature greater than or equal to the melting temperature of the thermoplastic polymer
Implementation Method 2
This clearance makes it possible to compensate for the differential expansion between the tooling and the lamination
Data Source
Figure 1~2
Figure 3A~4
Figure 5~6
AI summary
The method involves draping a punch (220) on a marble (200), where sides of the punch are stepped to produce a contour of a flange edge having a support surface. Pre-impregnated fibers of thermoplastic polymer are deposited on marble strips to a desired stratification, and a smoothing plate (350) having a rigid surface is rested on the support surface. A stack surmounted by a panel (450) conforming to a surface of the stratification is bagged, and the panel is consolidated by heating the panel to a temperature higher or equal to the melting point of thermoplastic polymer. An independent claim is also included for a tool for producing a composite laminate panel having a fibrous reinforcement in a thermoplastic polymer matrix.