Friction Stir Welded Rib-and-Receptacle Joint for Complete Penetration
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Solution Overview
Problem
Friction stir welding (FSW) faces issues with tunnel defects, discontinuities in the bond, and incomplete penetration due to insufficient forging, which affect the sufficiency of the weld formed.
Innovation Solution
A method involving a first member with a base and spaced walls forming a receptacle, and a second member with an elongate rib having a uniform root portion thickness and a tip portion sized for insertion into the receptacle, where the tip portion engages a closed end, allowing for a friction stir weld joint with a radiused cross-sectional profile to form a stronger weld by relocating discontinuities out of the plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction stir welding is used to join structural components, then the advantages of welding over bolting are achieved, but tunnel defects and discontinuities occur due to insufficient forging
Solution Approach 1:
The patent applies local quality by creating a non-uniform wall thickness distribution in the receptacle, with the first wall being thicker than the second wall. This localized variation in geometry creates different forging conditions at different locations during friction stir welding, ensuring adequate material flow and consolidation throughout the weld zone to eliminate tunnel defects and discontinuities while maintaining overall weld strength
2Strength
If friction stir welding is used to join structural components, then solid-state joining advantages are achieved, but incomplete penetration occurs due to insufficient tool penetration
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the receptacle, specifically the wall thickness distribution and the configuration of the closed end. These parameter changes create optimal conditions for tool penetration and material flow during friction stir welding, ensuring complete penetration and thorough mixing of materials to eliminate voids and achieve sound welds
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 method enhances the strength of the weld joint by ensuring complete penetration and minimizing discontinuities, resulting in a more reliable bond between structural components.
Implementation Method 1
friction stir welding (FSW). FSW is a solid-state joining process (i.e., the metal is not melted) that uses heat generated between a tool the components to be joined to soften and mechanically intermix portions of the component
Implementation Method 2
The softened material is then joined using mechanical pressure, which may be applied by the tool
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A friction stir welded structure (10) includes first and second members (12, 14). The first member (12) has a base (16) defining opposed first and second surfaces (18, 20), and spaced first and second walls (24, 26) extending outwardly from the second surface (20) of the base (16) to define a receptacle therebetween. The second member (14) includes an elongate rib (46) extending from a root portion to a first tip portion, the root portion having a uniform root portion thickness and the first tip portion having a first tip portion thickness not greater than the root portion thickness. The first tip portion is sized for insertion into the receptacle and shaped conformally with the receptacle so that the first tip portion engages a closed end of the receptacle. A friction stir weld joint extends through the base (16) and at least portions of the first and second walls (24, 26) of the first member (12) and into the first tip portion of the second member (14), thereby to join the first and second members (12, 14).