Panel Joint Structure With Load-Transfer Bead for Peeling Stress
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Solution Overview
Problem
Conventional panel joint structures experience stress concentration at the flange corner section due to peeling loads, leading to adhesive cracking and reduced joint strength, especially in automotive applications where repeated loads cause significant stress on the adhesive.
Innovation Solution
A panel joint structure design that incorporates a load transmission section, formed by a bead with an inclined surface, which diffuses the peeling load from the corner section to the joint section, reducing stress concentration and enhancing joint strength by ensuring the adhesive fills both the corner and internal spaces of the bead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a joint section is provided to ensure sufficient adhesive thickness, then joint strength is improved, but stress concentration occurs at the flange corner section leading to adhesive cracking
Solution Approach 1:
The invention divides the flange section into two functional parts: a load transmission section with a smaller cross-sectional area and a flange section with a larger cross-sectional area. This segmentation allows the load transmission section to carry tensile loads away from the adhesive joint, preventing stress concentration at the flange corner while the flange section provides sufficient adhesive thickness for joint strength.
Solution Approach 2:
The load transmission section acts as an intermediary element between the tensile load source and the adhesive joint. It transfers the peeling load away from the corner section of the flange, reducing the stress concentration that would otherwise cause adhesive cracking while maintaining the joint's load-bearing capacity.
2Strength
If adhesive thickness is increased to ensure sufficient bonding, then joint strength is improved, but peeling load causes stress concentration and crack initiation
Solution Approach 1:
The flange is segmented into a load transmission section and a flange section, allowing the adhesive to be applied primarily on the flange section where it is needed for bonding strength, while the load transmission section carries the peeling load away from the adhesive interface, reducing stress concentration despite adequate adhesive thickness.
3Stress or pressure
If the flange cross-sectional area is increased to reduce stress, then stress concentration is reduced, but device complexity and material usage increase
Solution Approach 1:
Rather than uniformly increasing the entire flange cross-sectional area, the invention segments the flange into a load transmission section with smaller area and a flange section with larger area. This localized geometric variation reduces stress concentration at the critical interface while minimizing additional material usage and structural complexity.
Solution Approach 2:
The flange cross-sectional area is varied locally: smaller at the load transmission section where tensile loads are concentrated, and larger at the flange section where adhesive bonding is required. This local quality optimization addresses stress distribution needs without unnecessarily increasing overall complexity or material usage.
Data Source
Figure 1
Figure 2
Figure 3~3(b)
AI summary
A first panel member (10) including a panel body section (14), a corner section (15,16), and a first flange section (14); a second panel member (30) arranged to oppose the first flange section (15, 16); a joint section (40) joining the first flange section (15, 16) and the second panel member in a contact state thereof; and an adhesive (20) continuously provided in a longitudinal direction of the corner section (17) to adhere the elements are provided. The first panel member (10) includes a load transmission section (50) near the joint section, and the load transmission section (50) is provided between the elements, and an angle (θ2) thereof that is defined with the panel body section (14) is larger than an angle (θ1) defined by the panel body section (14) and a portion in a short direction of the first flange section (15, 16). A flange distal end side end portion of the load transmission section (50) in the short direction of the first flange section (15, 16) is provided to be located in a region between a corner section side end portion (40a) and a distal end side end portion (40b) of the joint section (40) in the short direction of the first flange section (15, 16).