Polymeric Core Sandwich Structure for Dissimilar Metal Welding
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Solution Overview
Problem
Galvanic corrosion occurs at the interfaces of dissimilar metal components in vehicle structures, reducing the integrity of joints over time, despite existing methods to mitigate this issue.
Innovation Solution
A sandwich structure is employed, comprising one metal skin of each type with a polymeric, electrically non-conducting micro-truss core between them, fabricated using photopolymer waveguides and UV light, to prevent galvanic corrosion during welding of dissimilar metal panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If different electrically conductive metal components are secured together by welds, then structural strength and weight requirements are met, but galvanic corrosion occurs at the interface between different metals
Solution Approach 1:
A sandwich structure comprising two metal skins matching the dissimilar metals being joined, with a polymeric non-conducting core between them, is positioned at the weld interface. This sandwich structure acts as an intermediary that electrically isolates the dissimilar metals while maintaining structural integrity during welding and preventing galvanic corrosion.
Solution Approach 2:
The sandwich structure combines different materials (metal skins and polymeric core) to create a composite structure that provides both electrical isolation and mechanical strength. The metal skins match the adjacent metals while the polymeric core provides electrical non-conductivity, creating a composite solution that addresses both structural and corrosion prevention requirements.
2Reliability
If non-electrical barrier coatings are provided on metal structural elements, then galvanic corrosion is reduced, but additional manufacturing steps and complexity are required
Solution Approach 1:
The sandwich structure merges multiple functions into a single integrated component: the metal skins provide electrical isolation matching the adjacent metals, the polymeric core provides electrical non-conductivity and structural support, and the entire assembly serves as both a structural element and a corrosion prevention device, eliminating the need for separate barrier coatings.
Solution Approach 2:
The sandwich structure serves multiple functions simultaneously: it acts as a structural support member, an electrical barrier to prevent galvanic corrosion, and a welding interface component. This multi-functionality reduces the need for additional specialized components or coating applications.
3Reliability
If sandwich structures are used to prevent galvanic corrosion, then joint integrity is maintained, but the complexity of the structural member increases
Solution Approach 1:
The sandwich structure segments the joint interface into distinct functional layers: outer metal skins that match the adjacent structures, and an inner polymeric core that provides electrical isolation. This segmentation allows each layer to perform its specific function while maintaining overall structural integrity.
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 micro-truss core enhances structural support, reduces repair costs, and eliminates the need for corrosion prevention devices, while allowing for complex geometries and localized reinforcement, effectively preventing galvanic corrosion and maintaining the integrity of the welds.
Implementation Method 1
UV light sources are positioned relative to the mask and exposure to collimated UV light through the mask apertures forms a series of interconnected self-propagating photopolymer waveguides
Data Source
AI summary
A technique for welding two dissimilar metal panels or structures together, such as vehicle structures, by providing a sandwich structure between the dissimilar metal structures that includes one skin being made of the same metal as one of the metal structures and an opposing skin being made of the same metal as the other metal structure, and including an electrically non-conducting core between the skins.