Vehicle Body Structural Node Joining Dissimilar Materials
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Solution Overview
Problem
The challenge lies in assembling vehicle structural nodes that combine hard materials like hot-stamped steel with softer materials like aluminum, while ensuring impact resistance and meeting industrial production constraints within the vehicle body structure, particularly at junction zones that are highly stressed during impacts.
Innovation Solution
A body structure with structural nodes comprising an extruded aluminum spar, a cast aluminum spar elbow, and a hot-stamped steel deck cross member, connected using cold-stamped steel brackets with self-drilling or self-piercing connections, ensuring integral assembly and enhanced impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot-stamped steel elements are used for high impact resistance, then strength is improved, but assembly difficulty with aluminum elements increases
Solution Approach 1:
A steel bracket serves as an intermediary element between the hot-stamped steel deck cross member and the aluminum spar/spar elbow assembly. The bracket is welded to the steel cross member and mechanically connected to the aluminum elements via self-piercing rivets, enabling reliable joining of dissimilar materials while maintaining impact resistance
Solution Approach 2:
The connection method uses self-piercing rivets that create cold-formed connections between the steel bracket and aluminum elements. This parameter change in connection technology allows joining of hard steel with softer aluminum without the complexity of traditional welding or drilling operations
2Weight of moving object
If aluminum elements are used for weight reduction, then weight is reduced, but impact resistance decreases
Solution Approach 1:
The structural node employs a composite construction combining aluminum extrusions for the spar and spar elbow with a hot-stamped steel deck cross member and steel bracket. This composite approach leverages the weight advantage of aluminum while incorporating steel elements to maintain impact resistance at critical junctions
Solution Approach 2:
The design applies different material qualities at different locations: aluminum is used for the longitudinal spar elements where weight reduction is prioritized, while hot-stamped steel is used for the transverse deck cross member and bracket at the junction zone where impact resistance is most critical
3Device complexity
If traditional welding or drilling connections are used between steel and aluminum, then assembly is simplified, but manufacturing complexity increases due to material incompatibility
Solution Approach 1:
The connection system is segmented into distinct functional zones: the steel bracket is welded to the steel deck cross member, while separate self-piercing rivet connections join the bracket to the aluminum spar and spar elbow. This segmentation allows each connection type to be optimized for its specific material interface
Solution Approach 2:
Self-piercing rivets are used to create connections between the steel bracket and aluminum elements without requiring pre-drilled holes or complex alignment fixtures. The rivets self-pierce the materials during installation, simplifying the manufacturing process and reducing assembly complexity
Data Source
Figure 1~3
AI summary
The invention relates to a motor vehicle body structure having at least one structural node, providing resistance to impacts, between at least one first, extruded longitudinal element (2, 4), a second, cast element (3, 5) that is secured to the first element, and a third, hot-stamped element (1), a set of cold-stamped joining and reinforcing brackets (7, 8) interfacing with said first and second elements by connections comprising holes (814, 815, 825, 835, 825'), and by welded connections with said third element, and where relevant interfacing with one another by connections (8183, 8283), in particular by welds, such that said elements are secured to one another, and such that the joint between said first and second elements has inertia with respect to impacts, in particular transverse inertia, and comes to bear against said hot-stamped element in the event of impacts.