Thermoplastic Composite Repair Using Thermosetting Patch
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Solution Overview
Problem
Current methods for repairing thermoplastic composite elements, such as aircraft components, face challenges including the need for high temperatures to weld damaged areas, the requirement for specialized tooling for curved surfaces, and the limitations of using equipment on both sides of the repair site.
Innovation Solution
A method involving milling a socket at the damage site, forming a patch of thermosetting material with a reinforcement phase and thermosetting resin, curing the patch, and gluing it into the socket using a thermosetting adhesive, thereby eliminating the need for high heat and specialized tooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperatures are used to weld thermoplastic composite elements, then the welding strength is improved, but the energy consumption and equipment complexity increase
Solution Approach 1:
The patent changes the fundamental parameter from thermoplastic welding (requiring temperatures above 340°C for PEEK) to thermosetting resin curing (effective at lower temperatures with proper catalysts and pressure). This parameter change allows achieving comparable or superior bond strength without the extreme temperatures required for thermoplastic welding, thereby reducing energy consumption.
Solution Approach 2:
The patent replaces the thermal-mechanical welding process with a chemical bonding process using thermosetting resins. Instead of relying on heat-induced plasticization and mechanical interlocking, the solution uses chemical cross-linking and adhesion mechanisms, substituting a thermal system with a chemical system that operates at lower temperatures.
2Manufacturing precision
If specialized tooling is used for curved surfaces, then the manufacturing precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs flexible releasing films and conformable tooling that can adapt to various curvatures without requiring dedicated rigid tooling for each geometry. The flexible nature of these films allows them to conform to complex curved surfaces while maintaining precision, eliminating the need for expensive, geometry-specific hard tooling.
Solution Approach 2:
The patent develops a universal repair methodology that can be applied to various geometries and locations using the same basic process and equipment. The socket preparation and thermosetting resin application process works for flat, curved, and complex geometries alike, making the tooling multi-functional and eliminating the need for dedicated tooling for each repair scenario.
3Strength
If equipment on both sides of the surface is used, then the welding quality is improved, but the ease of operation decreases
Solution Approach 1:
The patent extracts the requirement for bilateral equipment access by using a unidirectional repair process. The socket preparation and resin injection can be performed from one side only, eliminating the need for equipment access to both sides of the structure. This is achieved by injecting the thermosetting resin through channels or holes drilled from the accessible side.
4Strength
If high temperatures are supplied to the repair area, then the bonding strength is improved, but the risk of damaging surrounding areas increases
Solution Approach 1:
The patent changes the temperature parameter from high-temperature thermoplastic welding (>340°C) to lower-temperature thermosetting curing (typically 50-150°C depending on resin system). This parameter change achieves adequate bonding strength through chemical cross-linking rather than thermal plasticization, thereby eliminating the risk of thermal damage to surrounding sensitive areas.
Solution Approach 2:
The patent converts the potential harm of high temperatures by replacing the thermal process with a chemical process. Instead of using heat that could damage surrounding areas, the solution uses chemical reactions (polymerization and cross-linking) that occur at lower temperatures, turning a potentially harmful thermal process into a beneficial chemical bonding process.
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 allows for efficient repair of thermoplastic composite elements with variable geometry without the need for complex equipment or high heat, ensuring a strong and durable repair.
Implementation Method 1
the patch of thermosetting material is cured using a heating blanket provided with an external portable power supply and control device
Implementation Method 2
the cured patch is glued into the socket by means of an adhesive
Data Source
AI summary
The disclosed embodiments relate to a method for repairing a damage to a thermoplastic composite element, in particular an aircraft component, wherein a socket is milled at the site of damage to the thermoplastic composite element. Then, in the socket a patch is formed from a thermosetting material containing a reinforcing phase of fabric layers and a matrix of thermosetting resin, the patch having a shape and size corresponding to the socket geometry. In the next step, the patch is cured, and finally the cured patch is glued into the socket by means of an adhesive.