Aluminum Riveted Assemblies for Dissimilar Metal Joining
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Solution Overview
Problem
Conventional methods for joining multi-material assemblies, such as resistance spot welding and self-piercing riveting, face challenges like galvanic corrosion, recycling issues, and increased costs due to the use of steel rivets, especially when combining aluminum, magnesium, and advanced high-strength steel, which are difficult to weld due to melting point and solubility differences.
Innovation Solution
The use of aluminum or aluminum alloy rivets with high strain rate riveting techniques, employing impulsive loads and specialized tools like powder-actuated fastening and gas-gun striker bars to form mechanical interlocks between components, reducing processing time and avoiding galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steel rivets are used for self-piercing riveting to join multi-material assemblies, then the joining strength and reliability are improved, but galvanic corrosion and recycling issues occur
Solution Approach 1:
The patent introduces an intermediary coating layer (such as zinc, aluminum, or organic coatings) on the steel rivet surface to act as a barrier between the steel rivet and the aluminum or magnesium components. This coating mediates the galvanic interaction, preventing direct contact and reducing galvanic corrosion while maintaining the structural integrity and joining reliability of the multi-material assembly
Solution Approach 2:
The patent changes the material parameters of the rivet by using coated steel rivets instead of bare steel rivets. The coating modifies the electrochemical properties of the rivet surface, altering the galvanic potential difference between dissimilar materials and thereby reducing corrosion risk while preserving mechanical joining performance
2Productivity
If conventional resistance spot welding is used to join multi-material assemblies, then the joining efficiency is improved, but the process becomes infeasible due to melting point differential and solubility issues
Solution Approach 1:
The patent replaces the thermal-based resistance spot welding process with a mechanical self-piercing riveting process. Instead of using heat and pressure to fuse materials (which fails due to melting point differences), the system uses a mechanically driven rivet that pierces through the materials and forms a mechanical interlock, achieving joining without thermal effects that cause manufacturing infeasibility
3Strength
If steel SPR rivets are used to join aluminum and magnesium components, then the joining strength is improved, but cost and recycling issues increase
Solution Approach 1:
The patent changes the material composition parameters of the rivet by incorporating aluminum or magnesium content into the steel rivet matrix, creating composite or alloyed rivet materials. This modification reduces the galvanic potential difference between the rivet and the joined components, thereby reducing corrosion risk and associated costs while maintaining joining strength
Solution Approach 2:
The patent employs composite rivet structures combining steel with aluminum or magnesium phases. The composite material structure leverages the high strength of steel while incorporating lighter, more compatible materials to reduce galvanic corrosion and improve recyclability, thereby reducing overall manufacturing cost despite the complexity of the multi-material system
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 approach enables efficient, cost-effective joining of dissimilar materials like aluminum and magnesium with reduced galvanic corrosion risks, facilitating lightweight vehicle construction while maintaining performance and recyclability, and is compatible with existing body shop operations.
Implementation Method 1
employing impulsive loads and specialized tools like powder-actuated fastening and gas-gun striker bars
Data Source
AI summary
Riveted assemblies are provided that can include: a first component having opposing first and second sidewalls; a second component having opposing third and fourth sidewalls; and a rivet extending between a head along a shank to an end, the rivet piercing the first sidewall with the end of the rivet being between the first and fourth sidewalls, wherein the end of the rivet is deformed and interlocks the first and second components. Methods for affixing at least two components using a rivet are provided that can include: providing a first component having opposing first and second sidewalls; providing a second component having opposing third and fourth sidewalls; providing a rivet extending between a head along a shank to an end; and projecting the rivet through at least the third sidewall of the second component to deform and form an affixing interface to interlock the first and second components.