Composite Tank End Fitting Assembly for Dome Leak Tightness
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Solution Overview
Problem
Existing fibre composite tanks experience leaks around the dome area due to thermal deformation of plastic annular end fittings, leading to compromised fluid tightness and reliability.
Innovation Solution
A method using a metal boss assembled in a tight fit inside a metal end fitting, with a shrinking and expanding process to ensure a secure seal, combined with thermoplastic resin layers for improved bonding and fluid tightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plastic annular end fitting is used to assemble the metal boss, then the ease of manufacture is improved, but the reliability deteriorates due to thermal deformation during resin heating causing leaks
Solution Approach 1:
The material of the annular end fitting is changed from plastic to metal, fundamentally altering the thermal and mechanical parameters of the component. This substitution eliminates thermal deformation during resin curing and ensures dimensional stability under high-temperature processing conditions, thereby preventing leaks while maintaining manufacturability through standard metal forming and assembly techniques.
Solution Approach 2:
The solution employs a composite structure where a metal annular end fitting is used instead of plastic, creating a hybrid assembly of metal boss, metal end fitting, and fiber composite shell layers. This composite approach leverages the thermal stability and strength of metal components to prevent the deformation and leakage issues associated with plastic materials during high-temperature resin curing.
2Reliability
If the metal boss is tightly fitted inside the annular end fitting, then the fluid tightness is improved, but the device complexity increases due to the shrinking and expanding process
Solution Approach 1:
The assembly process utilizes thermal phase transitions of the metal boss through heating and cooling cycles. The metal boss is heated to expand its dimensions for insertion into the annular end fitting, then cooled to contract and create a tight interference fit. This thermal expansion and contraction mechanism enables a secure, leak-proof connection without requiring complex fastening devices or multi-step assembly procedures.
Solution Approach 2:
The solution exploits the thermal expansion property of metal to facilitate the assembly of the boss inside the annular end fitting. By heating the metal boss, its dimensions increase allowing easy insertion; upon cooling, it contracts to create a tight interference fit. This thermal expansion principle simplifies the assembly process while ensuring a reliable, leak-proof connection, avoiding the need for complex mechanical fastening systems.
3Ease of operation
If the annular end fitting is made larger to accommodate mandrel removal, then the ease of operation is improved, but the manufacturing precision may deteriorate
Solution Approach 1:
The annular end fitting features localized quality differentiation: the opening is enlarged specifically for mandrel removal, while the sealing surface maintains precise dimensional tolerances. This local quality approach ensures that the larger opening does not compromise the precision of the sealing contact area, as each region is optimized for its specific function - ease of operation for mandrel extraction and manufacturing precision for fluid-tight sealing.
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
The method enhances the tank's seal at the dome, ensuring improved fluid tightness and ability to withstand overpressure, with a fibre composite tank design that can endure at least 2 bars of overpressure.
Implementation Method 1
a step of shrinking a metal boss by cooling it to a negative temperature
Implementation Method 2
a step of expanding the metal boss by warming it to a positive temperature
Data Source
AI summary
A method for producing a fibre composite tank, includes assembling a removable moulding mandrel; applying an end fitting to the moulding mandrel, the end fitting being a metal ring having an opening; forming a first fibre composite shell layer on the moulding mandrel and on the end fitting; disassembling and removing the moulding mandrel through the opening; shrinking a metal boss by cooling; inserting the metal boss in the opening of the end fitting; expanding the metal boss by warming.