Joint Molding Apparatus with Inflatable Bladders for Composite Panel Curing
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Solution Overview
Problem
Existing methods for joining aircraft structural panels using adhesive Pi joints lack efficient control over the curing process, particularly in maintaining the desired configuration and preventing resin escape during curing.
Innovation Solution
A joint molding apparatus employing inflatable bladders with a support structure that applies radial pressure and embedded heaters to maintain the joint configuration and cure the composite resin, along with semi-rigid reinforcements for precise shaping and sealing, allows for the molding of joints between composite panels without a curing oven.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adhesive Pi joints are used to join aircraft structural panels, then the panels can be connected at intersections, but the curing process lacks control over maintaining desired configuration and preventing resin escape
Solution Approach 1:
The curing process is segmented into multiple independent functions: inflatable bladders provide confinement pressure and shape control, embedded heaters provide thermal curing, and sealing regions prevent resin escape. Each segment addresses a specific aspect of the curing process, allowing precise control without requiring a complex curing oven system.
Solution Approach 2:
The inflatable bladders act as intermediaries between the uncured composite resin and the external environment. They provide the necessary confinement pressure and geometric control during curing, mediating the transformation from liquid resin to solid joint structure while maintaining desired configuration.
2Reliability
If a curing oven is used to cure composite resin joints, then the curing can be performed, but manual adjustment and monitoring become difficult
Solution Approach 1:
The joint molding apparatus is designed to be self-contained, with all curing functions (pressure application, heating, sealing) integrated directly at the joint location. The system serves itself by providing localized curing without requiring external oven equipment, enabling easy manual adjustment and monitoring while ensuring complete curing.
3Manufacturing precision
If pressure is applied to the joint during curing, then the joint configuration is maintained, but resin may escape through gaps
Solution Approach 1:
The inflatable bladders function as flexible shells that conform to the joint geometry while providing uniform confinement pressure. The flexible nature allows them to adapt to the joint shape and maintain dimensional control, while the sealed construction prevents resin escape through gaps.
Solution Approach 2:
The potential harmful effect of resin escape is converted into a benefit by using the resin itself as part of the sealing mechanism. The expandable sealing regions are designed to fill gaps and prevent resin leakage, turning the resin flow that could be harmful into a controlled process that ensures complete joint formation without material loss.
4Manufacturing precision
If four inflatable bladders are used in respective panel joint quadrants, then radial pressure is applied to hold the joint configuration, but the device complexity increases
Solution Approach 1:
The use of four bladders positioned in respective quadrants creates a symmetric pressure distribution that is actually asymmetric in its approach to a common problem. Each bladder independently controls pressure in its quadrant, allowing precise configuration control through distributed rather than centralized pressure application, which simplifies the overall control mechanism despite the multi-component structure.
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 solution enables precise control over the curing process, maintaining joint dimensions and preventing resin escape, allowing for manual adjustment and monitoring, and results in a robust and accurately formed joint without the need for an oven.
Implementation Method 1
when inflated, the bladders apply radially inwardly-directed pressure to the joint from each joint quadrant while the uncured portion of the joint is curing
Implementation Method 2
each bladder includes an embedded silicone rubber flexible heater configured to provide heat sufficient to cure the composite resin
Implementation Method 3
while the uncured portion of the joint is curing
Data Source
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AI summary
A joint molding apparatus(10) for molding joints between composite panels (18) comprising inflatable molding bladders (12) connectable to a source of pressurized fluid. A bladder support structure (16) supports the bladders (12) in respective positions adjacent an intersection of panels (17) where, when inflated, the bladders (12) support a joint (20) formed at the intersection of panels (17) while an uncured portion of the joint (20) is curing to hold the joint in a desired configuration at the panel intersection (17).