Composite Tank Fiber Winding Angles for Strength Efficiency

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Solution Overview

Problem

Conventional hydrogen gas tanks face issues with reduced strength development efficiency due to high-angle helical layers, uneven fiber lamination, and increased mass, particularly under high pressure and large diameter conditions, where stress gradients and fiber rigidity are significant concerns.

Innovation Solution

A tank design with an FRP layer comprising axial fiber layers wound at angles between 0° and 30° and peripheral fiber layers wound at angles between 30° and 90°, where the folded fiber ends are positioned to narrow towards the center, optimizing the lamination configuration to enhance strength development and reduce fiber usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If high-angle helical layers are used extensively, then the tank can store high-pressure hydrogen gas, but the rigidity of fibers in the peripheral direction decreases and strength development efficiency deteriorates

Engineering Contradiction:
Improveinternal pressureVSAvoidstrength development efficiency
Core Design Contradiction:
Stress or pressureVSStrength

Solution Approach 1:

The patent applies local quality by differentiating fiber winding angles in different regions of the tank. The peripheral fiber layer uses winding angles of 30° or more (preferably 60° or more) to maximize circumferential strength where hoop stress is highest, while the axial fiber layer uses winding angles of less than 30° (preferably 0° to 10°) to provide axial support. This localized optimization ensures each fiber layer contributes most effectively to the stress state in its specific region, resolving the contradiction between pressure containment and strength development efficiency.

Inventive Principle:
Principle #3Local quality

2Device complexity

If peripheral fiber layers and axial fiber layers are uniformly formed by successive winding, then the FRP layer structure is simplified, but strength development efficiency deteriorates

Engineering Contradiction:
ImproveFRP layer structureVSAvoidstrength development efficiency
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The patent segments the FRP layer into distinct peripheral fiber layers and axial fiber layers with clearly defined winding angle ranges. The peripheral fiber layer comprises one or more layers with winding angles of 30° or more, while the axial fiber layer comprises one or more layers with winding angles of less than 30°. This segmentation allows each layer type to be optimized independently for its specific functional requirement, preventing the uniform structure from compromising overall strength development efficiency.

Inventive Principle:
Principle #1Segmentation

3Area of stationary object

If axial fiber layers are laminated on and under high-angle helical layers, then the FRP layer provides comprehensive coverage, but fiber bends and meanderings occur due to transfer of unevenness

Engineering Contradiction:
ImproveFRP layer coverageVSAvoidstrength development efficiency
Core Design Contradiction:
Area of stationary objectVSStrength

Solution Approach 1:

The patent applies preliminary action by carefully controlling the winding parameters and tension of each fiber layer during the fabrication process. By optimizing the winding tension and path of the peripheral and axial fiber layers before subsequent layers are applied, the structure is pre-conditioned to minimize the transfer of surface unevenness. This preliminary control prevents fiber bends and meanderings in subsequently laminated layers, maintaining both comprehensive coverage and high strength development efficiency.

Inventive Principle:
Principle #10Preliminary action

4Area of stationary object

If folded positions during winding extend up to the dome part, then complete coverage is achieved, but the amount of fibers increases causing mass increase

Engineering Contradiction:
Improvetank coverageVSAvoidtank mass
Core Design Contradiction:
Area of stationary objectVSWeight of moving object

Solution Approach 1:

The patent optimizes the winding parameters, specifically the winding angles and layer thickness distribution, to minimize fiber usage while maintaining complete coverage. By adjusting the winding angle parameters and controlling the number of layers in different regions, the design achieves efficient coverage of the dome part without excessive fiber overlap. This parameter optimization reduces the total amount of fibers required, thereby decreasing tank mass while preserving complete structural coverage.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2418412B1Tank and fabrication method thereof
Publication Date: 2015.05.27 TOYOTA JIDOSHA KK
  • EP2418412B1 patent drawingFigure 1
  • EP2418412B1 patent drawingFigure 2
  • EP2418412B1 patent drawingFigure 3

AI summary

There are disclosed a tank which optimizes a laminating configuration of hoop layers and helical layers to enhance an efficiency of strength development by wound fibers, and a manufacturing method of the tank. In order to realize this, the tank includes a liner (20), and an FRP layer (21) constituted of an axial fiber layer (72) formed by winding fibers (70) around the outer periphery of the liner (20) at a winding angle in a range exceeding 0° and less than 30° with respect to a tank axis (12) in the center of the tank (1) and a peripheral fiber layer (71) formed by winding the fibers (70) around the outer periphery of the liner (20) at a winding angle in a range of 30° or more and less than 90° with respect to the tank axis (12), and folded fiber ends (70e) of the peripheral fiber layer (71) in a tank axial direction draw a track which narrows from the inside toward the outside in a laminating direction of the fiber layers. The folded fiber ends (70e) formed outwardly in the laminating direction of the fiber layers are in principle positioned closer to the center of the tank (1) than the folded fiber ends (70e) of the peripheral fiber layer (71) in the tank axial direction formed inwardly in the laminating direction.