Composite Tank Smooth Helical Layer for Burst and Fatigue Strength
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Solution Overview
Problem
Conventional hydrogen storage tanks face challenges in achieving both burst strength and fatigue strength due to low fiber volume content ratio in the inner layer and structural bends in the hoop layers caused by uneven helical layers.
Innovation Solution
The tank features a smooth innermost helical layer with reduced fiber overlaps and a specific winding pattern to minimize structural bends, enhancing both burst and fatigue strengths by creating a smooth surface for adjacent hoop layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fiber volume content ratio (Vf) of the inner layer is increased to enhance burst strength, then the burst strength is improved, but the fatigue strength lowers
Solution Approach 1:
The tank wall is divided into multiple functional layers with distinct fiber volume content ratios. The inner layer has a lower Vf (30-60%) to maintain fatigue strength, while outer layers have higher Vf (60-80%) to provide burst strength. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
Different regions of the tank wall are assigned different fiber volume content ratios based on their functional requirements. The inner layer near the liner uses lower Vf for fatigue resistance, while outer layers use higher Vf for burst pressure resistance. This local differentiation resolves the contradiction by assigning appropriate material properties to specific locations.
2Ease of manufacture
If the helical layer is wound in a disorder manner to simplify manufacturing, then the ease of manufacture is improved, but structural bends are generated in the hoop layer fibers
Solution Approach 1:
The helical layer is deliberately designed with predetermined overlap regions where fibers are arranged to overlap rather than being wound in a completely disorderly manner. This preliminary arrangement of overlap patterns prevents excessive structural bends in adjacent hoop layers while maintaining manufacturing simplicity.
Solution Approach 2:
The winding parameters of the helical layer are optimized to control the degree and pattern of fiber overlap. By adjusting overlap width, overlap direction, and winding tension parameters, the manufacturing process achieves a balance between ease of winding and minimization of structural bends in adjacent layers.
Data Source
AI summary
There are disclosed a tank having a structure which achieves both a burst strength and a fatigue strength, and a manufacturing method of the tank. In order to realize this, in a tank comprising a liner, and an FRP layer including a hoop layer and a helical layer formed by winding fibers around the outer periphery of the liner, at least an innermost helical layer is formed as a smooth helical layer. When the smooth helical layer, i.e., a helical layer which does not have any unevenness or which has only little unevenness is formed, the unevenness can be prevented from being transferred to the hoop layer adjacent to the helical layer. When structural bends (undulations) of the fibers of the hoop layer are suppressed, a fatigue strength of the fibers themselves can be enhanced.