Vehicle Body Joint Structure for Stronger Bumper Beam Welding
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Solution Overview
Problem
Conventional vehicle body structures with T-shaped joints for bumper beams have lower welding strength compared to coupling joints and fillet lap joints, leading to potential breakage under tensile loads, and require increased weight and manufacturing costs to achieve sufficient strength.
Innovation Solution
A vehicle body structure design that includes a fixing plate, a crushing body, and a coupling strip extending between the bumper beam and side frame, providing a reinforced joint configuration that absorbs collision loads and disperses tensile loads without increasing weight or costs, using spot welding and a specific geometric arrangement to enhance joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a T-shaped joint is used to join the bumper beam to the side frame, then the structure is simple and easy to manufacture, but the welding strength is insufficient under tensile loads
Solution Approach 1:
The extension is divided into multiple functional parts: a fixing plate for attachment to the side frame, a crushing body for energy absorption, and a coupling strip for load-bearing connection to the bumper beam. This segmentation allows each part to perform its specific function optimally while maintaining overall structural strength without requiring complex manufacturing processes.
Solution Approach 2:
The extension combines different material forms and functions: a plate member (fixing plate) for rigid attachment, a crushable body for energy absorption, and a strip member for tensile load bearing. This composite structure achieves both strength and energy absorption capabilities while remaining manufacturable with standard automotive processes.
2Strength
If the length of the welded portion is extended or plate thickness is increased to improve welding strength, then the joint strength increases, but the weight and manufacturing costs increase
Solution Approach 1:
Instead of increasing the size of a single welded component, the solution segments the load-bearing function across multiple components: the coupling strip handles tensile loads, the crushing body absorbs collision energy, and the fixing plate provides attachment. This allows achieving required strength without increasing overall weight through dimensional increases.
Solution Approach 2:
The extension acts as an intermediary component between the bumper beam and side frame, distributing loads through its multiple parts. The coupling strip specifically mediates the tensile loads, while the crushing body mediates collision energies, allowing the joint to achieve sufficient strength without excessive material usage.
3Strength
If the plate thickness is increased to prevent breakage of the T-shaped joint under tensile loads, then the joint strength increases, but the manufacturing costs increase
Solution Approach 1:
The extension segments the strength requirements across different components with appropriate thicknesses and geometries. The coupling strip is optimized for tensile strength, the crushing body for energy absorption, and the fixing plate for attachment strength. This allows achieving required joint strength without uniformly increasing plate thickness across all components, reducing manufacturing costs.
Solution Approach 2:
Each part of the extension has locally optimized properties: the coupling strip has geometry optimized for tensile loading, the crushing body has structure optimized for controlled deformation, and the fixing plate has configuration optimized for attachment. This local optimization achieves required joint strength without excessive material usage and manufacturing costs.
Data Source
AI summary
A vehicle body structure includes an extension to be held between a bumper beam extending in a vehicle width direction and a side frame extending in a vehicle front-rear direction. The extension includes: a fixing plate made of a plate member and fixed to a projecting end of the side frame so as to face in the vehicle front-rear direction; a crushing body arranged on the fixing plate; and a coupling strip made of a plate member, extending along the vehicle front-rear direction, and coupling an outer end in the vehicle width direction of the fixing plate with an outer end in the vehicle width direction of the bumper beam so as to integrally continue to the fixing plate and the bumper beam.