Thermoplastic Composite Repair Patch With Integrated Resistance Heating
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Solution Overview
Problem
Current methods for repairing thermoplastic composite laminate structures, particularly in aircraft, are inefficient and require specialized equipment and materials that are costly and difficult to manage in diverse environmental conditions, limiting their applicability in various repair locations.
Innovation Solution
A standardized method using prefabricated repair patches with integrated heating elements and predetermined welding parameters, enabling efficient and uniform heat distribution for resistance welding, allowing repairs to be performed with standardized equipment and materials at different locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current repair methods using sanding and repair plies with warm air box are used, then repairs can be performed on composite parts, but the equipment is specialized and costly, and the process is difficult to manage in diverse environmental conditions
Solution Approach 1:
The repair patch integrates multiple functions into a single component: the heating element provides controlled thermal energy, the thermoplastic material serves as both structural repair material and bonding medium, and the patch itself acts as the repair structure. This eliminates the need for separate warm air boxes, heating apparatus, and complex environmental control systems, making the repair process universally applicable across diverse locations and conditions.
Solution Approach 2:
The heating element within the repair patch generates heat directly at the repair site through electrical resistance heating, eliminating the need for external heating equipment. The thermoplastic material self-bonds to the composite structure when heated and pressed, requiring no additional adhesives or complex curing equipment. This self-contained approach simplifies the repair process and enables deployment in remote or diverse environmental conditions.
2Reliability
If warm air box with vacuum pressure is used for epoxy repair, then the repair patch can be cured, but the equipment is complex and not easily deployable in diverse environments
Solution Approach 1:
The invention extracts the heating function from the complex warm air box system and embeds it directly within the repair patch as an electrical heating element. This eliminates the need for large, complex heating apparatus and vacuum systems, reducing equipment complexity while maintaining reliable curing through direct electrical resistance heating combined with simple pressing.
Solution Approach 2:
The invention replaces the mechanical warm air heating system with an electrical resistance heating element embedded in the patch. This substitution eliminates the need for complex air circulation, temperature control, and vacuum equipment, while achieving reliable thermoplastic material curing through direct electrical heating and mechanical pressing.
3Adaptability or versatility
If standardized prefabricated repair patches with integrated heating elements are used, then repairs can be performed with standardized equipment at different locations, but the welding parameters must be precisely controlled
Solution Approach 1:
The heating element is pre-integrated into the repair patch during manufacturing, and welding parameters are predetermined for each patch type. This preliminary preparation eliminates the need for on-site equipment calibration and parameter optimization, enabling standardized repairs at diverse locations while maintaining precise control through pre-configured patches with specified electrical and dimensional characteristics.
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 standardized and efficient repairs of thermoplastic composite structures by ensuring uniform heat distribution and stable welding, reducing the need for specialized equipment and materials, making repairs feasible in diverse environments.
Implementation Method 1
a stainless steel mesh is used in between two join partners to generate heat by applying an electric current
Implementation Method 2
The heat and pressure cure the repair patch and the parts structural integrity is restored
Data Source
Figure 1
Figure 2
AI summary
In order to improve repair and maintenance of composite parts of aircraft, such as the fuselage or wing, the invention proposes a repair method and associated repair patch (18). After detecting the presence of a damage portion (12), the laminate structure (10) is scarfed. Subsequently, the prefabricated repair patch (18) is chosen according to the size of the damage portion (12). Based on the choice of repair patch (18), welding parameters are chosen which were predetermined by experiment and stored for future use. The repair patch (18) is then welded while being pressed to the laminate structure (10) for repair by means of an integrated heating element (20) that is energized based on the predetermined welding parameters.