Tapered Disk Plug for Composite Repair Bonding
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Solution Overview
Problem
Current methods for repairing mis-machined holes or small local surface damage in composite materials, such as split fan ducts, are labor-intensive and require expensive equipment, with risks of leaks or bag failures, especially for high-temperature polyimide materials.
Innovation Solution
A tapered disk with a central hole is used, assembled with a bolt and spring assembly to apply compressive load during adhesive bonding, allowing for heat application via an oven or local heating source, and subsequently replaced with a metal bushing for a flat surface or hardware attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum bag assembly and autoclave are used for adhesive bonding, then heat and pressure can be applied for consolidation and cure, but the method requires expensive capital equipment and is subject to leaking or bag failures
Solution Approach 1:
The patent extracts the essential function of heat and pressure application from the complex autoclave-vacuum bag system. A simple press applies compressive load directly to the bond line through the plug and into the substrate, eliminating the need for vacuum bags and autoclaves while maintaining effective pressure for adhesive consolidation and cure
Solution Approach 2:
The patent introduces a spring-loaded plunger as an intermediary mechanism between the press and the bond line. The spring maintains continuous compressive force on the adhesive joint during curing, ensuring reliable bonding without requiring complex vacuum sealing or high-temperature autoclave equipment
2Adaptability or versatility
If a custom clamping mechanism with local heating device is developed, then heat and pressure can be applied locally, but the approach requires specially designed equipment and is cumbersome to apply on large structures
Solution Approach 1:
The patent creates a universal repair system where a simple press with spring-loaded plunger can be used on various composite structures regardless of size or shape. The apparatus is not structure-specific like custom clamping mechanisms, making it adaptable to different applications from small repairs to large structures like split fan ducts
Solution Approach 2:
Instead of developing complex custom clamping mechanisms that conform to the structure, the patent inverts the approach by using a simple overhead press that applies force downward through the plug. This eliminates the need for structure-specific tooling while achieving effective local heating and pressure application
3Manufacturing precision
If conventional adhesive bonding methods are used, then proper consolidation and cure can be achieved, but the process is labor intensive and requires expensive fixtures or equipment
Solution Approach 1:
The patent replaces expensive, reusable capital equipment (autoclaves, vacuum bag assemblies, custom fixtures) with a simple, inexpensive press that can be easily set up and dismantled. The focus shifts from expensive durable equipment to a simple apparatus that achieves the same bonding quality without the complexity or cost
Solution Approach 2:
The spring-loaded plunger automatically maintains compressive force on the bond line throughout the curing process. The spring rate and pre-compression are designed to provide consistent pressure without requiring complex control systems or continuous operator intervention, simplifying the manufacturing process while ensuring bonding quality
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 simplifies and cost-reduces the repair process by applying necessary load and heat effectively for adhesive bonding, providing a durable and efficient solution for composite material repairs.
Implementation Method 1
a bolt and spring assembly that applies load to the disk during the adhesive bonding process
Implementation Method 2
Heat to cure the adhesive can be applied by placing the part in an oven or by using a local heating source such as a heat blanket or heat lamp
Data Source
AI summary
An apparatus and method for repairing defects in composite materials using a tapered disk sized to fit the part being repaired. Also included is a bolt sized to fit through a central hole in the disk. A spring is positioned on the bolt with a washer. A nut is attached to the end of the bolt and tightened to place pressure on the washer to compress the biasing device. An adhesive is applied to the tapered disk prior to engaging the composite material. A threaded bushing is used to fixedly attach a second bolt completely in the hole.