Variable Thickness Metal Strakes for Sealed Tank Fatigue Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current waterproof and thermally insulating tanks face challenges in achieving good fatigue resistance while minimizing material usage, particularly in the welds of the watertight barriers, which affects the structural integrity and efficiency of the tank's design.
Innovation Solution
The tank design incorporates metal strakes with variable thickness, extending between two opposite edges of the tank wall, with thicker end portions for assembly with stopping structures, and a secondary sealing barrier made of nickel steel alloy with low expansion coefficient, such as Invar®, to enhance fatigue resistance and reduce material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal strakes with uniform thickness are used throughout, then manufacturing is simpler, but material usage increases and fatigue resistance decreases
Solution Approach 1:
The metal strake is designed with variable thickness along its length, featuring thicker end portions for assembly zones and thinner intermediate portions. This local quality variation optimizes material distribution: thicker sections provide enhanced fatigue resistance at critical connection points, while thinner sections reduce overall material usage in less critical areas.
Solution Approach 2:
The thickness parameter of the metal strake is changed along its length rather than remaining uniform. The strake transitions from thicker end portions to thinner intermediate portions, creating a gradient structure that adapts the material properties to the functional requirements of different zones.
2Strength
If thicker metal strakes are used throughout, then fatigue resistance improves, but material usage and weight increase
Solution Approach 1:
The metal strake incorporates local quality variations with thicker end portions positioned at assembly zones where high strength is needed for fatigue resistance, while intermediate portions are thinner to reduce overall weight. This selective thickening provides strength where required without uniformly increasing tank weight.
3Reliability
If variable thickness metal strakes are used, then material usage is optimized and fatigue resistance improves, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process incorporates parameter changes by varying the thickness of the metal strip during fabrication. The strip is formed with thicker end portions and thinner intermediate portions in a continuous process, which while more complex than uniform thickness manufacturing, enables optimized material usage and enhanced fatigue resistance.
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 design achieves high fatigue resistance in the watertight barriers, reducing the quantity of material needed and allowing for a more efficient construction of the tank, while maintaining structural integrity and meeting dynamic and static hull criteria.
Implementation Method 1
a secondary sealing barrier made of nickel steel alloy with low expansion coefficient, such as Invar®, to enhance fatigue resistance
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A continuous metal strip with turned-up lateral edges suited to creating a sealed membrane is obtained from a blank which along its length has a first, reinforced, end zone (114) having a first thickness and a second, central, zone (113) having a second thickness smaller than the first thickness. The metal strip across its width has a flat central zone and two lateral edges (13) which are bent substantially at right angles to the flat central zone, the two lateral edges being of small width in comparison with the flat central zone. Application to the creation of a sealed and thermally insulated tank built into a bearing structure comprising a plurality of bearing walls.