Burred Sheet Joint Structure for Higher Shear and Cross-Tension Strength
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Solution Overview
Problem
High-strength steel sheet spot-welded joints experience a decrease in cross tension strength and tensile shear strength due to embrittlement, limiting the load capacity of automotive components, and existing joint structures face challenges in maintaining joint strength across varying sheet thicknesses.
Innovation Solution
A joint structure featuring a cylindrical rising portion on one metal sheet and a through hole in the target material, with a joint member having a shaft portion and protruding portions that allow for differential positioning of the tip end and first surface in the axial direction, enhancing the contact area and distributing shear stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a joint member is inserted into a through-hole to join metal sheets, then the joining process is simplified, but the contact area is limited and shear stress is concentrated
Solution Approach 1:
The patent extends the joint member beyond the simple through-hole insertion by adding protruding portions that extend into the base material, utilizing the additional dimensional space to increase the contact surface area and distribute shear stress more effectively
2Adaptability or versatility
If the sheet thickness varies, then different applications can be accommodated, but the joint structure must be redesigned to maintain strength
Solution Approach 1:
The patent designs a joint member with a universal structure that can accommodate varying sheet thicknesses through its protruding portions, which can be configured to extend to different depths, allowing the same basic joint structure to function across multiple thickness specifications without requiring complete redesign
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 configuration ensures preferable joint strength according to the sheet thickness, preventing embrittlement and improving both cross tension and tensile shear strengths, while allowing for flexible formation of the burring portion without cracking, even with varying sheet thicknesses.
Implementation Method 1
the outer circumferential surface in contact with an inner circumferential surface of the burring portion is formed... distributing shear stress effectively
Data Source
AI summary
A joint structure according to an aspect of the present invention includes: a first metal sheet on which a cylindrical first rising portion is formed; at least one target material in which a through hole into which the first rising portion is inserted is formed and which is joined to the first metal sheet; and a joint member which is inserted into the first rising portion and joins the first metal sheet and the target material which are superimposed on each other to each other, wherein the joint member has a shaft portion which is inserted inside the first rising portion, and a first surface which is a surface opposite to a surface facing the first metal sheet of both surfaces of the target material and a tip end portion of the first rising portion are at different positions in an axial direction of the first rising portion.