Pre-tensioning Composite Tank Wrinkles
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Solution Overview
Problem
Conventional methods for manufacturing multi-section composite tanks for aircraft potable water systems often result in wrinkles during the curing process, leading to uneven mechanical stresses due to the bunched plies of composite materials and complex geometries, which compromise the strength and integrity of the vessels under internal pressure.
Innovation Solution
The method involves pre-tensioning of composite materials around soluble tools with an elastomeric layer to prevent wrinkling, using a soluble tool made of a washout mandrel material, and applying additional reinforcing portions to prone areas, followed by curing in an autoclave with controlled temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If multiple plies of composite materials are placed together to create multi-section tank sections, then the tank can be made of lightweight composite materials, but wrinkles arise in the placement or layup process causing bunched plies
Solution Approach 1:
The patent applies preliminary action by pre-tensioning the composite material plies before placement and curing. The plies are tensioned in the radial direction during the layup process to prevent wrinkling, and this pre-applied tension is maintained throughout curing to ensure wrinkle-free composite sections while maintaining the lightweight advantage
Solution Approach 2:
The patent changes physical parameters by applying and maintaining specific tension forces during the layup and curing processes. The composite plies are subjected to controlled tensile parameters that prevent wrinkle formation, transforming the manufacturing condition from relaxed placement to tensioned placement, thereby eliminating the wrinkle problem while preserving the lightweight composite structure
2Reliability
If the multi-section tank is cured in high pressure conditions in an autoclave, then the composite material cures properly, but wrinkles are amplified and additional wrinkles can form
Solution Approach 1:
The patent applies preliminary action by pre-tensioning the composite plies before autoclave curing and maintaining this tension throughout the curing process. This pre-applied tension counteracts the wrinkle-amplifying effect of high-pressure curing, allowing proper curing to occur while preventing wrinkle formation and amplification
Solution Approach 2:
The patent applies preliminary anti-action by applying tension forces that oppose the wrinkle-forming tendencies during curing. The pre-applied tension acts as a counter-force to the compressive and buckling stresses that occur during high-pressure autoclave curing, thereby preventing wrinkle amplification while maintaining curing quality
3Ease of manufacture
If the composite material plies are bunched together into one area, then wrinkles form, but this causes uneven mechanical stresses throughout the vessel sections when pressurized
Solution Approach 1:
The patent applies preliminary action by pre-tensioning the composite plies during placement to prevent bunching and wrinkle formation. This pre-applied tension ensures uniform distribution of plies before curing, eliminating the root cause of uneven mechanical stresses while maintaining ease of manufacture through controlled tensioning during the layup process
Solution Approach 2:
The patent changes the physical state of the composite plies by applying controlled tension parameters during placement. This parameter change transforms the material from a relaxed, easily pliable state to a tensioned, wrinkle-resistant state, ensuring uniform stress distribution while maintaining manufacturing efficiency
4Device complexity
If conventional methods are used to make multi-section composite tanks, then the manufacturing process is simpler, but operator expertise is heavily depended upon and wrinkle formation is more likely
Solution Approach 1:
The patent applies preliminary action by implementing pre-tensioning mechanisms and controlled tensioning procedures during the layup process. This systematic pre-applied tension reduces dependence on operator expertise by providing a controlled, repeatable method to prevent wrinkles, thereby improving manufacturing precision while maintaining reasonable process complexity
Solution Approach 2:
The patent changes the manufacturing parameters by introducing controlled tension forces and maintaining specific tension levels throughout the layup and curing processes. These parameter changes create a more controlled and predictable manufacturing process that reduces wrinkle formation and decreases reliance on operator skill, achieving better precision with manageable complexity
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 effectively reduces wrinkle formation, enhances the consistency and strength of the tank sections, and minimizes the dependence on operator expertise, resulting in a higher-quality, wrinkle-resistant multi-section composite tank.
Implementation Method 1
filling a first chamber defined by a first liner, which can be made of an elastomeric material, with a soluble granulated material
Implementation Method 2
a soluble granulated material... which can be made of an elastomeric material
Implementation Method 3
applying vacuum to the first chamber and enveloping the liner with a first layer of fibre reinforced material
Implementation Method 4
cured in high pressure conditions, such as in an autoclave
Implementation Method 5
cured in high pressure conditions, such as in an autoclave
Data Source
Figure 1
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AI summary
A method of making a multi-section tank with composite material includes pretensioning the composite material (22), wrapping a soluble tool (20) in the composite material, and curing the composite material around the soluble tool. The composite material is pre-tensioned with force to align fibers in the composite material.