Pressure Vessel Outer Layer with Unidirectional Braiding
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Solution Overview
Problem
Existing methods for manufacturing pressure vessels, such as CNG and LPG tanks, do not fully utilize the intrinsic fibre tensile properties due to crimp effects in braided layers, leading to inefficiencies in fibre usage and increased material requirements for achieving predetermined strength.
Innovation Solution
A method combining hoop layers with substantially unidirectional layers, where the unidirectional layers are formed using a braiding machine with minimal crimp, allowing for improved fibre alignment and reduced fibre usage, and the layers are arranged to resist radial and axial pressures effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional braided layer is used to form the outer layer, then the manufacturing time is shortened and manufacturing cost is reduced, but the intrinsic fibre tensile properties are not fully used due to crimp effects
Solution Approach 1:
The outer layer is segmented into two distinct functional layers: a hoop layer for radial pressure resistance and a unidirectional layer for axial pressure resistance. This segmentation allows each layer to be optimized for its specific function, with the unidirectional layer minimizing crimp effects to fully utilize fibre tensile properties while the hoop layer provides lateral support.
Solution Approach 2:
Different regions of the pressure vessel are assigned different fibre orientations and layer compositions. The hoop layer uses fibres oriented circumferentially (80-100 degrees) to resist radial pressure, while the unidirectional layer uses fibres oriented axially (+5 to -5 degrees) to resist axial pressure, with each region optimized for its local stress conditions.
2Strength
If more fibres are used to compensate for crimp effects, then the predetermined strength is achieved, but the weight of the pressure vessel increases
Solution Approach 1:
The invention changes the critical parameter of fibre orientation from random or crimped braiding to highly aligned unidirectional arrangement with +5 to -5 degrees relative to the axial direction. This parameter change maximizes the effective tensile strength of the fibres, allowing achievement of predetermined strength with minimal fibre quantity and thus reduced weight.
3Productivity
If a unidirectional layer is formed using a braiding machine, then production efficiency is enhanced, but the device complexity increases
Solution Approach 1:
The braiding machine is configured to perform multiple functions: it can produce both the hoop layer with circumferential fibre orientation and the unidirectional layer with axial fibre orientation by adjusting its operational parameters. This multi-functionality enhances production efficiency while managing device complexity through versatile equipment utilization.
Data Source
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AI summary
A method for forming an outer layer around a cylindrical portion of a liner (1), in order to obtain a pressure vessel (10), said method comprising: forming at least a first hoop layer (2) of one or more first fibre bundles (F1) arranged with a first fibre angle between 80 and 100 degrees with respect to the axial direction of the cylindrical portion; forming at least a first substantially unidirectional layer (3) of one or more second fibre bundles (F2) arranged with a second fibre angle between +5 and -5 degrees with respect to the axial direction of the cylindrical portion; wherein the one or more second fibre bundles (F2) are laid adjacent to each other so as to form a continuous first substantially unidirectional layer; wherein the forming of the first substantially unidirectional layer (3) is done using a braiding machine (50).