Membrane Assembly with Bistable Tape Spring for Vacuum Bagging
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Solution Overview
Problem
The vacuum bagging process for long structural parts, such as aircraft fuselage stringers, is labor-intensive and time-consuming due to the manual unrolling of non-gas permeable bagging film over very long, thin tools.
Innovation Solution
A membrane assembly featuring an elongate sheet with a bistable tape spring and inflatable tubes that can transition between rolled-up and flattened configurations, allowing for easy unrolling and rolling up with assistive forces, facilitating efficient positioning and vacuum creation over the tool surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual unrolling of bagging film is used for long tools, then the process is simple and requires basic equipment, but the operation becomes labor-intensive and time-consuming
Solution Approach 1:
The membrane assembly is designed to dynamically transition between rolled-up and flattened configurations. The bistable tape spring provides mechanical memory to maintain these states, while inflatable tubes enable controlled transitions. This dynamic design eliminates the need for manual unrolling operations along the full length of the tool.
Solution Approach 2:
Inflatable tubes are integrated into the membrane assembly to provide pneumatic assistance for unrolling. By inflating these tubes, the membrane assembly can be easily unrolled onto the tool surface without manual effort. This pneumatic mechanism directly addresses the labor-intensive nature of manual unrolling.
2Ease of operation
If manual positioning of bagging film is used, then equipment requirements are minimal, but operator effort and difficulty increase for long tools
Solution Approach 1:
The membrane assembly is segmented into functional components: the elongate sheet for vacuum sealing, the bistable tape spring for mechanical memory and state maintenance, and inflatable tubes for assisted positioning. This segmentation allows each component to perform its specific function while working together as an integrated system.
Solution Approach 2:
The bistable tape spring provides self-service by automatically maintaining the membrane assembly in either rolled-up or flattened states without external intervention. This mechanical memory system eliminates the need for continuous manual positioning adjustments during the vacuum bagging process.
3Volume of moving object
If rolled-up configuration is used for transport, then space efficiency is improved, but transition to flattened state requires manual intervention
Solution Approach 1:
The inflatable tubes enable pneumatic deployment of the membrane assembly. By inflating these tubes, the rolled-up membrane assembly can be easily unrolled and positioned onto the tool surface, eliminating the need for manual unrolling operations while maintaining compact storage capabilities.
4Productivity
If traditional vacuum bagging method is used, then equipment simplicity is maintained, but productivity decreases for long structural parts
Solution Approach 1:
The dynamic transition capability between rolled-up and flattened states enables rapid deployment and removal of the vacuum bagging membrane. This dramatically reduces the time required for setup and teardown operations, significantly improving productivity for long structural parts while maintaining the essential vacuum bagging function.
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 streamlines the vacuum bagging process by enabling quick and efficient unrolling and rolling up of the membrane assembly, reducing operator effort and time, while maintaining a vacuum seal for resin infusion or prepreg use.
Implementation Method 1
a bistable tape spring attached to or captured by the elongate sheet and disposed along the longitudinal direction, wherein the bistable tape spring has a first stable state which is a straightened-out state, a second stable state which is a rolled-up state, and a transition state between the first and second stable states
Implementation Method 2
a first inflatable tube attached to or captured by the elongate sheet and disposed along the longitudinal direction. The first inflatable tube has a first tube end disposed proximate the first distal end and a second tube end disposed proximate the second distal end, wherein the first inflatable tube is sealed at the second tube end and has an orifice proximate the first tube end for admission of a fluid therethrough for inflation of the first inflatable tube
Data Source
AI summary
A membrane assembly for vacuum bagging includes an elongate sheet of flexible material capable of being rolled up into a cylindrical configuration and unrolled from the cylindrical configuration into a flattened-out configuration, a bistable tape spring attached to or captured by the elongate sheet, and an inflatable tube attached to or captured by the elongate sheet. The bistable tape spring has a first stable state which is a straightened-out state, a second stable state which is a rolled-up state, and a transition state between the first and second stable states. The inflatable tube is sealed at one end and has an orifice at the other end for admission of a fluid therethrough for inflation of the inflatable tube.