One-Sided Resin Infusion for Composite Reworking
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Solution Overview
Problem
Existing methods for reworking composite structures, such as mechanical fastening and wet layup techniques, face challenges like increased weight, drag, porosity issues, and labor-intensive processes, particularly when access to both sides of the structure is limited.
Innovation Solution
A method and apparatus for resin infusion of a dry fiber preform patch from one side of the structure, using a vacuum source to create a pressure differential and eliminate air entrapment, allowing for efficient reworking of load-carrying composite structural members without human contact with wet resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fasteners are used to rework localized areas, then structural reinforcement is achieved, but aircraft weight increases and drag increases
Solution Approach 1:
The patent replaces mechanical fastening systems with a chemical bonding system using resin infusion. The resin-saturated fiber patch is bonded to the structure through chemical adhesion and curing, eliminating the need for mechanical fasteners and their associated weight and drag penalties while maintaining structural reinforcement.
Solution Approach 2:
The patent changes the bonding mechanism from mechanical (fasteners) to chemical (resin bonding). By using resin saturation and curing processes, the reinforcement method transitions from a mechanically-dominated system to a chemically-dominated system, achieving weight reduction while maintaining strength.
2Reliability
If mechanical fasteners are used to provide secondary load paths, then arrestment mechanism is formed, but device complexity increases
Solution Approach 1:
The patent eliminates the complex mechanical fastener system required to create secondary load paths and arrestment mechanisms. Instead, the resin-impregnated fiber patch provides continuous load distribution through chemical bonding, simplifying the overall structure while maintaining reliability through the arrestment function inherent in the bonded composite material.
3Ease of manufacture
If wet layup technique is used to apply fiber reinforcement, then patch application is achieved, but air entrapment occurs causing porosities
Solution Approach 1:
Instead of applying wet resin and hoping air bubbles escape upward, the patent inverts the approach by using vacuum pressure to actively draw air and excess resin out through the patch. The vacuum bagging system creates negative pressure that forces trapped air and resin toward designated evacuation points, ensuring complete saturation without porosity.
Solution Approach 2:
The patent employs vacuum pressure (pneumatic principle) to control resin infusion and eliminate air entrapment. By applying vacuum through the vacuum bagging system, the process actively removes air bubbles and ensures complete resin penetration, achieving high manufacturing precision while maintaining ease of application.
4Ease of manufacture
If wet layup technique is used to hand-layup wet plies, then fiber reinforcement application is achieved, but labor intensity increases and cleanup activity increases
Solution Approach 1:
The patent prepares the fiber reinforcement in advance as a dry preform or mat that is cut to shape and positioned on the structure before resin application. This preliminary preparation eliminates the need for manual layer-by-layer application of wet plies, significantly reducing labor intensity and cleanup requirements while maintaining the ability to apply fiber reinforcement effectively.
Solution Approach 2:
The patent extracts the labor-intensive steps of manual wet ply application and cleanup from the manufacturing process. By using pre-cut dry fiber mats or preforms that are simply positioned and then vacuum-infused with resin, the process removes the need for technicians to manually handle wet resin and perform extensive cleanup, improving productivity.
5Manufacturing precision
If resin infusion from both sides is used to infuse dry fiber preform, then complete resin saturation is achieved, but access to both sides of structure is required
Solution Approach 1:
The patent transitions from a two-sided resin infusion approach to a one-sided approach by adding the dimension of vacuum pressure applied through the single accessible side. The vacuum bagging system creates a pressure differential that drives resin through the fiber preform from the accessible side, eliminating the need for access to both sides while maintaining complete saturation.
Solution Approach 2:
The patent uses vacuum pressure applied from a single accessible side to achieve complete resin saturation of the fiber preform. The vacuum creates a pressure differential that draws resin through the entire thickness of the patch, eliminating the need for physical access to both sides of the structure while ensuring thorough saturation.
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 approach reduces porosities, minimizes labor, and enables reworking of composite structures from one side, optimizing structural properties and avoiding air entrapment, while being suitable for applications with limited access.
Implementation Method 1
using the vacuum source to creating a very low pressure area causing the incoming higher pressure resin to flow through the patch to an inner side of the patch
Implementation Method 2
inserting a vacuum source into the patch from an outer side of the patch; and using the vacuum source to force resin through the patch
Implementation Method 3
evacuating the bag thereby compacting the dry fiber patch
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An area of a structure is reworked from one side of the structure using resin infusion of a dry fiber patch. Entrapped air and excess resin is removed from the patch during the infusion process by inserting a vacuum device into the patch, and forcing the area resin through the vacuum device.