Reinforced Bladder for Composite Stringer Manufacturing
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Solution Overview
Problem
In the manufacturing of aircraft composite stringers, inflatable bladders without reinforcement can tear during removal from the composite stringer, leading to manufacturing inconsistencies and increased costs due to resin richness and the need for reworking, as they fail to conform to complex composite structures and apply even pressure.
Innovation Solution
A reinforced bladder with a polymeric material and strategically placed reinforcements, such as fiberglass, that cover only a portion of the cross-sectional shape, providing axial and circumferential reinforcement to prevent tearing and ensure even pressure distribution, allowing the bladder to conform to features like joggles and curvatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bladder without reinforcement is used, then the bladder is simple and easy to manufacture, but it tears during removal from composite stringers
Solution Approach 1:
The patent applies reinforcement materials (such as fiberglass mesh or fabric) to specific high-stress areas of the bladder, including the ends and regions that contact composite stringers during removal. This localized reinforcement strengthens the bladder where tearing is most likely to occur while maintaining simplicity in other areas.
Solution Approach 2:
The patent combines polymeric bladder material with reinforcement materials (fiberglass, carbon fiber, or other composite materials) to create a composite structure. This composite construction provides both the flexibility needed for conforming to complex shapes and the strength required to prevent tearing during removal.
2Reliability
If a reinforced bladder is used, then the bladder prevents tearing and maintains reliability, but the device complexity increases
Solution Approach 1:
The reinforcement is applied only where needed - at the ends and high-stress contact areas - rather than uniformly across the entire bladder surface. This selective approach maintains reliability while minimizing added complexity and weight.
3Ease of manufacture
If a bladder is used without strategic reinforcement placement, then the manufacturing process is simple, but pressure distribution is uneven causing manufacturing inconsistencies
Solution Approach 1:
Reinforcement materials are strategically positioned at the bladder ends and in regions that contact composite stringers during curing. This strategic placement ensures even pressure distribution across the composite structure while maintaining manufacturing simplicity through a straightforward reinforcement application process.
Data Source
AI summary
A method and apparatus for a reinforced bladder are provided. The reinforced bladder comprises a bladder with a cross-sectional shape formed of a polymeric material and a number of reinforcements. Each of the number of reinforcements covers only a portion of the cross-sectional shape such that part of the cross-sectional shape remains uncovered by the number of reinforcements.