Hollow Bladder Repair via Vacuum Cured Elastomer Strips
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Solution Overview
Problem
Hollow bladders used for shaping fiber-reinforced polymeric aircraft stringers are prone to damage, making repair challenging and costly, and replacing them is inefficient and expensive.
Innovation Solution
A method involving placing uncured elastomer strips within surface damage, sealing in a vacuum bag, and curing under reduced pressure and heat to repair surface damage and through-holes in hollow bladders, allowing for the reuse of damaged bladders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If damaged hollow bladders are replaced with new ones, then the integrity and functionality of the hollow bladders is restored, but the manufacturing time and cost increase significantly
Solution Approach 1:
Instead of discarding damaged hollow bladders, the invention recovers them by applying repair compositions to restore functionality. The damaged hollow bladder is prepared by cleaning and roughening the surface, then a repair composition is applied and cured to restore structural integrity, allowing the hollow bladder to be reused for forming composite parts.
Solution Approach 2:
The invention extracts only the damaged portion of the hollow bladder and replaces it with a repair composition, rather than replacing the entire hollow bladder. This selective repair approach maintains the overall structure while restoring only the affected areas, significantly reducing repair time and cost.
2Reliability
If damaged hollow bladders are replaced with new ones, then the functionality is restored, but the cost increases significantly
Solution Approach 1:
The invention recovers damaged hollow bladders through a repair process that involves preparing the damaged surface and applying a repair composition. This recovery approach eliminates the need to purchase and manufacture new expensive hollow bladders, significantly reducing material costs while restoring full functionality.
Solution Approach 2:
The repair composition replaces only the extracted damaged portion of the hollow bladder, not the entire component. This minimal material replacement approach reduces the loss of substance and associated costs while maintaining the structural and functional integrity of the hollow bladder.
3Loss of time
If repair methods are applied to hollow bladders, then the manufacturing time and cost are reduced, but the integrity may be compromised
Solution Approach 1:
The repair process begins with preliminary preparation of the damaged surface through cleaning and roughening. This preliminary action ensures proper adhesion of the repair composition to the hollow bladder surface, guaranteeing structural integrity before the actual repair is applied. The surface preparation creates optimal conditions for bonding, preventing future failure.
Solution Approach 2:
The repair composition is applied as a composite material that combines reinforcement fibers embedded in a polymer matrix. This composite structure provides both structural strength and flexibility, matching or exceeding the original hollow bladder properties. The composite repair layer bonds to the existing hollow bladder, creating a unified structure with restored integrity.
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 effectively repairs hollow bladders, reducing labor and costs associated with replacing damaged ones, enabling the reuse of hollow bladders for forming aircraft stringers.
Implementation Method 1
reducing pressure within the vacuum bag relative to outside the vacuum bag
Implementation Method 2
heating the first strips from within the vacuum bag to cure the first strips
Data Source
AI summary
Disclosed herein is a method of repairing surface damage in an exterior surface of a hollow bladder, made of a cured elastomer. The method comprises placing first strips, made of an uncured elastomer, at least partially within the surface damage in the exterior surface of the hollow bladder in a side-by-side arrangement. The method also comprises sealing the surface damage, the first strips, and a portion of the exterior surface surrounding the surface damage in a vacuum bag. The method further comprises reducing pressure within the vacuum bag relative to outside the vacuum bag. The method additionally comprises while the pressure within the vacuum bag is reduced, heating the first strips from within the vacuum bag to cure the first strips.