Inflatable Raft Expanded Weld Joint to Prevent Connection Failure
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Solution Overview
Problem
Inflatable rafts constructed using RF welding face connection failures at weld joints due to small diameter connecting surfaces, leading to potential weaknesses.
Innovation Solution
A design featuring a first tubular member with a larger diameter intersecting perpendicularly with a second tubular member at a weld joint, where the first runner transitions to match the second runner's diameter, and a collar is welded to both runners to enhance the connection, using RF welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If small diameter connecting surfaces are used at weld joints, then the structure remains simple and manufacturing is easier, but connection strength is reduced leading to potential failure
Solution Approach 1:
The tubular member features a localized expanded section at the weld joint area, where the diameter increases from the base diameter to a larger diameter. This local expansion provides a larger connecting surface area specifically at the joint location without increasing the diameter of the entire tubular member, thereby improving connection strength while maintaining overall structural simplicity
Solution Approach 2:
Instead of increasing the diameter of the entire tubular member (one-dimensional solution), the invention expands the diameter only in the radial dimension at the specific joint location, creating a localized bulge or expanded section. This dimensional change at the joint area provides larger connection surface area without proportionally increasing the overall volume or weight of the component
2Reliability
If uniform diameter tubular members are used, then manufacturing is simpler and material usage is optimized, but weld joints experience higher stress concentration
Solution Approach 1:
The tubular member has different diameter characteristics at different locations: a base diameter for most of the length and a larger expanded diameter at the weld joint location. This local variation in geometry reduces stress concentration at the joint while keeping the manufacturing process relatively simple through localized forming or extrusion
Solution Approach 2:
The diameter parameter of the tubular member is changed locally at the weld joint area, transitioning from a constant diameter to a variable diameter profile. This parameter change optimizes the stress distribution at the joint without fundamentally altering the manufacturing process, requiring only localized dimensional modification
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 design strengthens the weld joint, preventing failure during inflation by reducing curvature and ensuring a robust connection.
Implementation Method 1
The RF (radio frequency) welding technology is being used to build rafts eliminates the use of adhesives for joining processes
Data Source
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AI summary
An inflatable raft, having: a base (110), a sidewall (130), front and back ends (150, 140), first and second opposite sides (160, 170); a first tubular member (180) extending between the sides to define a first arch (220); and a second tubular member (230) extending from the back end to the first tubular member at a weld joint (260) to define a second arch, at the weld joint the first tubular member has a first diameter, the second tubular member has, end to end, a second diameter that is smaller than the first diameter, and adjacent to the weld joint, the first tubular member has a third diameter that is the same as the second diameter.